IB SYLLABUS

Question 1

where did life begin, how did it begin?
ur mom

Answer 1

• in water
• small volume of water + other substances enclosed in membrane and chemical reactions occurred

Question 2

how are hydrogen bonds formed in water

Answer 2

• covalent bond in water molecule has unequal sharing of electrons as oxygen is more EN
• partial charges creates attraction b/w molecules

Question 3

what is cohesion of water caused by

Answer 3

hydrogen bonds

Question 4

how is cohesion used in the transport of water under tension in the xylem

Answer 4

• continuous columns of water in xylem experience tension from root and leaves, but move up as tension is stronger in leaves
• water can withstand tension bcus of hydrogen bonds
• breaking of water column typically takes more energy than available

Question 5

how are water surfaces used as habitats

Answer 5

• water molecules are much more attracted to each other than air causing surface tension
• able to float much denser objects as cohesion b/w water molecules > water and floating object
• to break surface: many hydrogen bonds must be broken at once

Question 6

what does water adhere to

Answer 6

materials that are polar are charged

Question 7

capillary action in soil

Answer 7

• water is attracted to many chemical substances in soil
• porous soil: water drawn up by capillary action through dry soil, wetting it
• how water can rise from underground source

Question 8

capillary action in plant cell walls

Answer 8

• water adheres to cellulose in cell walls
• if water evaporates from cell walls in leaves, adhesive forces cause water to be drawn from nearest xylem vessel
• keeps walls moist to absorb CO2 for photosynthesis

Question 9

why is water used as medium of metabolism and transport in plants and animals

Answer 9

• solvent properties
• wide variety of hydrophilic molecules dissolve in water + most enzymes catalyse rxns in aq solutions

Question 10

how does buoyancy allow for organisms to use water as a habitat

Answer 10

• if density of object < density of fluid, buoyancy force will be greater than gravity force, causing it to float
• living organisms have overall density close to water, not much energy needed to float
• ex. bony fish have air-filled swim bladder to control their density

Question 11

viscosity as a property of water

Answer 11

• due to internal friction when one part of fluid moves relative to another
• pure water has higher viscosity than organic solvents bcus hydrogen bonds
• solutes increase viscosity

Question 12

specific heat capacity as a property of water

Answer 12

• heat needed to raise 1g of material by 1C
• water has high SHC because hydrogen bonds must be broken to raise temp, needs a lot of energy
• as result, aquatic habitats are quite thermally stable

Question 13

thermal conductivity of water

Answer 13

• rate in which heat passes material
• water has high thermal conductivity, useful to absorb and transfer heat
• ex. high water content of blood allow it to carry heat from parts of body where it is generated to ones that need it

Question 14

physical properties of air vs. water on individuals

Answer 14

• air less dense, less buoyant force on individual
• water more viscous, ind. needs more energy to move through it
• water more thermal conductivity, conducts heat away from ind’s body
• water higher SHC, more stable environment for ind

Question 15

_____ is the genetic material for all living organisms, how abt viruses?

Answer 15

DNA (deoxyribonucleic acid)
- viruses have RNA (ribonucleic acid), but cannot reproduce, therefore not living

Question 16

3 main parts of a nucleotide

Answer 16

• pentose sugar
• phosphate group
• base

Question 17

how does sugar-phosphate bonding work to link nucleotides tgt

Answer 17

• covalent bonds formed b/w phosphate of one nucleotide to pentose sugar of another to make continuous chain
• creates sugar-phosphate backbone

Question 18

what are the bases in DNA vs RNA

Answer 18

adenine, cytosine, guanine, thymine (uracil replaces thymine in RNA)

Question 19

what is RNA, how is it created

Answer 19

a polymer formed by condensation of nucleotide monomers
- OH on carbon 3 of sugar and OH on phosphate group have H2O removed, leaving a single O (sugar phosphate backbone)
- covalent bonds to this O links nucleotides (condensation reaction)

Question 20

structure of DNA

Answer 20

• double helix made of 2 antiparallel strands of nucleotides
• strands linked with hydrogen bonding
• bonds b/w complementary base pairs

Question 21

differences of DNA vs RNA

Answer 21

1. DNA is double stranded (2 polymers of nucleotides), RNA is single stranded(1 polymer of nucleotides)
2. bases are different (thymine vs. uracil)
3. pentose sugar in DNA is deoxyribose (one less oxygen than ribose), sugar in RNA is ribose

Question 22

role of complimentary base pairing

Answer 22

• allows genetic information to be replicated and expressed
• based on hydrogen bonding

Question 23

semi-conservative replication

Answer 23

the process where DNA replication results in two new DNA molecules
- each contains one original strand and one newly synthesized strand

Question 24

possible DNA base sequences

Answer 24

• any length of DNA in any sequence is possible
• diameter of DNA is 2 nanometers, immense lengths of DNA can be stored in a small volume (small space, lots of info)

Question 25

genetic code in living organisms and viruses

Answer 25

- all living organisms and viruses use same genetic code (64 codons) - minor exceptions where stop codon codes for AA instead - evidence of common ancestry

Question 26

cell theory

Answer 26

- all living organisms are composed of cells - cells are the basic unit of life - all cells come from pre-existing cells

Question 27

how to calculate real magnification of microscope lens

Answer 27

eyepiece lens x objective lens

Question 28

advantages of electron microscopes

Answer 28

- good resolution, very high magnification - allows scientists to investigate detailed structure of cells

Question 29

advantages of freeze-fracture electron microscopy

Answer 29

- produces images of surface of cells - allowed fundamental change in theories about membrane structure - gives impression of 3D image through shadowing

Question 30

advantages of cryogenic electron microscopy

Answer 30

- mostly used to research structure of proteins - previous methods only produced images of protein in most stable form, but cryo-EM analyses proteins when water around them froze - allows scientists to research proteins changing from one form to another as they carry out function

Question 31

advantages of fluorescent stains and immunofluorescence

Answer 31

- locates chemicals that are difficult to find without stains - generates bright images

Question 32

how do fluorescent stains and immunofluorescence work

Answer 32

- stains (coloured substances) bind into some chemicals but not others allowing substances to be distinguished under microscope

Question 33

how does freeze-fracture electron microscopy work

Answer 33

- sample plunged into liquified propane at -190C for rapid freeze - frozen sample fractured at weakest points - some ice at surface removed to enhance texture(etching) - vapour of platinum or carbon fired on surface to create replica <- can be examined

Question 34

how does cryogenic electron microscopy work

Answer 34

- thin layer of pure protein solution applied on grid <- flash frozen in liquid ethane - place in electron microscope and patterns of electrons transmitted by individual protein molecules recorded

Question 35

structures that are common to cells in all living organisms

Answer 35

1. plasma membrane (outer boundary of lipids that controls entry, exit of substances) 2. cytoplasm (mostly water w/ substances dissolved/suspended, allows metabolism in cell) 3. DNA (genetic materials w/ info needed for cell to carry out all functions)

Question 36

plasma membrane + cell wall of prokaryotic cells

Answer 36

- all cells have plasma membrane - vast majority of prokaryotic cells have cell walls - cell wall thicker + stronger than membrane - protects cell, maintains shape - in prokaryotes, contains peptidoglycan

Question 37

cytoplasm in prokaryotic cells

Answer 37

- no nucleus, entirely filled w cytoplasm - not divided into compartments by membranes, one chamber

Question 38

naked DNA in prokaryotic cells

Answer 38

- aka plasmid DNA - part of cytoplasm looks lighter, contains DNA - typically a single molecule of DNA that forms loop/circle - unlike eukaryotic DNA, not associated with proteins ("naked")

Question 39

ribosomes in prokaryotic cells

Answer 39

- only cytoplasmic organelle in prokaryotic cells - smaller than eukaryote ribosomes (70S vs. 80S)

Question 40

basic eukaryotic organelle structure

Answer 40

- plasma membrane enclosing compartmentalized cytoplasm with 80S ribosomes - membrane bound cytoplasmic organelles

Question 41

mitochondria in eukaryotic cells

Answer 41

- surrounded by double membrane - inner membrane folded inwards to increase SA for energy production - carry out aerobic respiration, in all cells that perform aerobic respiration

Question 42

structure nucleus in eukaryotic cells

Answer 42

- containing chromosomes made of DNA bound to histones contained in a double membrane - pores to transport nutrients

Question 43

rough endoplasmic reticulum in eukaryotic cells

Answer 43

series of connected, flat, continuous single membranous sacs playing central role in synthesis and transport of polypeptides

Question 44

smooth endoplasmic reticulum in eukaryotic cells

Answer 44

series of connected, flat, continuous membranous sacs NOT involved in protein synthesis - synthesizes phospholipids and cholesterol for repair+formation of membrane

Question 45

golgi apparatus in eukaryotic cells

Answer 45

modifies polypeptides and lipids + pack into vesicles - packs dispatched for transport or to lysosomes/plasma membrane and secreted vis exocytosis

Question 46

vesicles in eukaryotic cells

Answer 46

- transport: transports molecules by budding off one organ and fusing onto another - secretory: secretes molecules via exocytosis + adds new phospholipids into cell membrane

Question 47

lysosomes in eukaryotic cells

Answer 47

- single membrane - contains enzymes that digest large molecules to recycle cells own organelles if old/damaged - immune defense: digests pathogens engulfed by phagocytes

Question 48

vacuoles in eukaryotic cells

Answer 48

- storage of water/nutrition/waste - maintains tugor pressure against cell wall, allows plants to stay upright

Question 49

cytoskeleton in eukaryotic cells

Answer 49

formed w microtubule, and microfilaments - maintains cell shape, organizes parts, allows movements/division of cell - NOT AN ORGANELLE

Question 50

processes of life in unicellular organisms

Answer 50

homeostasis, metabolism, nutrition, excretion, growth, response to stimuli, reproduction

Question 51

homeostasis as a process of life in unicellular organisms

Answer 51

maintenance of a "stable"/constant internal environment in an organism

Question 52

metabolism as a process of life in unicellular organisms

Answer 52

sum of all biochemical reaction in a living organism

Question 53

nutrition as a process of life in unicellular organisms

Answer 53

supplying nutrients required for energy/growth/repair in an organism

Question 54

excretion as a process of life in unicellular organisms

Answer 54

removal of waste products of metabolism of organism

Question 55

growth as a process of life in unicellular organisms

Answer 55

an increase in size/number of cells

Question 56

response to stimuli as a process of life in unicellular organisms

Answer 56

perception of stimuli and carrying out action in response

Question 57

reproduction as a process of life in unicellular organisms

Answer 57

production of offspring sexually or asexually

Question 58

plastids definition then how it's present in animals vs. fungi vs. plants

Answer 58

- a family of organelles w two outer membranes and internal membrane sacs a: none f: none p: varied types such as chloroplasts for photosynthesis and amyloplasts to store starch

Question 59

cell wall definition then how it's present in animals vs. fungi vs. plants

Answer 59

- rigid layer outside plasma membrane to strengthen+protect a: none f: cell wall composed of chitin p: cell wall composed of cellulose

Question 60

vacuoles definition then how it's present in animals vs. fungi vs. plants

Answer 60

- flexible fluid-filled compartment w single membrane a: small temporary vacuoles expel excess water/digest food or pathogens taken in by endocytosis f+p: large permanent vacuole for storage + pressure in cell

Question 61

centrioles definition then how it's present in animals vs. fungi vs. plants

Answer 61

- cylindrical organelles that organize assembly of structures composed of microtubules a: used to construct spindle fibre used in mitosis and the 9+2 microtubules in cilia + flagella f+c: none unless swimming male gametes that have centriole at base of flagellum

Question 62

undulipodia definition then how it's present in animals vs. fungi vs. plants

Answer 62

- cilia + flagella used to generate movement of cell or fluid around it a: present in many, including tail of male gametes f+c: non except male gametes that swim using flagella

Question 63

atypical number of nuclei in red blood cells

Answer 63

- do not have nucleus, removed during late stages of development - smaller/more flexible but cannot repair itself therefore short lifespan of 100-120 days

Question 64

atypical number of nuclei in skeletal muscle

Answer 64

- groups of cells fuse together, bcus each cells has own nucleus, creates large multinucleate structure forming long muscle fibres

Question 65

how is variation between organisms a defining feature of life

Answer 65

- no two individuals are identical in all their traits as they will always adapt to slightly diff environments - patterns of variations are complex, basis of naming and classifying organisms

Question 66

how were species originally classified, by who?

Answer 66

- as groups of organisms with shared traits by Carl Linnaeus - morphological species concept "morphology"

Question 67

how does the binomial system for naming organisms work

Answer 67

- first part identifies genus (capitalized), species in same genus have similar traits - second part identifies species - always written in italics - after used once, can be abbrev. to first letter of genus w full species name

Question 68

what does the biological species concept state

Answer 68

species is a group of organisms that can successfully interbreed and create fertile offspring

Question 69

what are some challenges with the biological species concept

Answer 69

- asexual organisms - geographical separation and gradual divergence make it difficult to apply - when migrations brings closely related but distinct species together - ex. female ligers can sometimes be fertile, however saying lions and tigers are the same species is not acceptable

Question 70

how do we currently classify species

Answer 70

- using the biological species concept - however there are many competing definitions/classifications of species

Question 71

define speciation

Answer 71

splitting/divergence of one species into two or more - species separated and cannot interbreed, natural selection acts differently on each population and they evolve differently

Question 72

how does speciation occur, how to differentiate b/w populations and species

Answer 72

- speciation happens gradually when interbreeding doesn't occur with populations getting more and more different w/ their traits as generations pass - arbitrary decision whether two populations are the same species

Question 73

number of chromosomes in humans vs chimpanzees, why is this the case?

Answer 73

46 in humans vs. 48 in chimps - both are even numbers as all diploid cells have an even number of chromosomes

Question 74

does chromosome number matter? does more make an organism more complex?

Answer 74

- not really as long as all members of the species have the same number of chromosomes - no, lengths of chromosomes can still vary (some may have few large ones while others have many small ones)

Question 75

where did human chromosome 2 arise from

Answer 75

fusion of chromosomes 12 and 13 of a shared primate ancestor

Question 76

what can be looked for to classify chromosomes?

Answer 76

- banding patterns - length - centromere position

Question 77

define genome

Answer 77

all the genetic information of an organism (entire base sequence of each DNA molecule)

Question 78

what are single nucleotide polymorphisms (SNPs)

Answer 78

positions in a gene where more than one base may be present in diff individuals of population (when at least 1% if individuals have a diff base in a spot)

Question 79

variation of genome in same species

Answer 79

- share most of genome, but mutations/variations like SNPs can give diversity - alleles can be present in an individual, but very small number of bases are different or else gene can lose function

Question 80

variation in genome size of eukaryotic organisms

Answer 80

- determined by total amount of DNA - large genomes can contain a lot of non-functional DNA (junk DNA)

Question 81

variation of genome size within species vs. b/w species

Answer 81

variation b/w species is much larger than within a species

Question 82

how do base sequence change in diff populations of eukaryotic organisms

Answer 82

- two populations of species will have varied base sequence as variations accumulate - infrequent changes in base sequence in genes with vital functions

Question 83

current uses of whole genome sequencing

Answer 83

- research in evolutionary relationships to better conserve/protect biodiversity - research into genomes of pathogenic bacteria and viruses to help prevent infectious disease

Question 84

future uses of whole genome sequences

Answer 84

- personalized medicine <- sequences genomes of individuals to understand human origins and migration, genetic diseases

Question 85

how has whole genome sequencing become more accessible

Answer 85

- speed is increasing and price is decreasing because of technological developments

Question 86

define Darwinism evolution vs. Lamarckism

Answer 86

D: the change in heritable characteristics(genes) of a population (natural selection) <-- current definition L: evolution as the inheritance of acquired characteristics <-- not true

Question 87

base sequences as evidence of common ancestry/evolution

Answer 87

- bcus evolution is the change in heritable characteristics, genes should change whenever evolution occurs - change occurs in DNA/RNA/AA - the more closely related two species are morphologically/other traits, fewer differences in base sequence <- shows that species develop overtime thru divergence

Question 88

selective breeding as evidence of evolution

Answer 88

- selectively bred animals/plants are drastically different from og ones - artificial selection causes rapid evolution, suggests natural selection also caused major evolutions but in a longer period of time (billions of years)

Question 89

homologous structures as evidence of evolution + define

Answer 89

- same structure but different function (divergence evolution) - inherited from common ancestor, but have evolved in diff ways in diff organisms to adapt <- now look very different, but same bone structure - difficult to explain w/o evolution

Question 90

pentadactyl limb as an example of homologous structures

Answer 90

- shared by humans, moles, horse, bats - very different functions, but same bones - a common ancestor of all tetrapods (4 legged vertebrates) had pentadactyl limbs, all descendants retain same basic arrangement

Question 91

define analogous structures

Answer 91

structures of an organism that have the same function but different structure/evolutionary origin

Question 92

human eye vs. octopus eye as an analogous structure

Answer 92

- strikingly similar, both are used to see - human eye has nerve fibres in front of retina, creating blind spot - octopus has nerve fibres behind retina, no blind spot - difference in structure suggests convergence evolution

Question 93

how does number of species on earth change

Answer 93

- speciation is the only way in which new species occur, increasing # of speices - extinction causes the number of species to decrease

Question 94

the role of reproductive isolation and differential selection in speciation

Answer 94

- must have RI as it stops the mixing of gene pools and blending of traits - natural selection will cause traits to change - if natural selection remains same b/w 2 populations, will not become different, but if it changes, differential selection occurs - leads to divergence evolution/divergence selection

Question 95

how does geographical isolation lead to reproductive isolation

Answer 95

geographical isolation leads to reproductive isolation and allows for different selection pressures on population

Question 96

chimpanzees and bonobos as example of divergence

Answer 96

- long ago, the congo river was dry and chimps could cross it however now it's deep, separating the 2 populations on either side as none can swim - geographical isolation caused reproductive isolation and different traits developed due to diff selection pressures

Question 97

define ecosystem diversity

Answer 97

variety in the combinations of species living together in communities due to varied adaptations to varied environments on earth

Question 98

define species diversity

Answer 98

the many species in an area that have varied body plans, internal structure, life cycles etc. - encompasses both species richness and eveness

Question 99

define genetic diversity

Answer 99

variety of gene pool of each species b/w both geographically separated populations and within populations

Question 100

current number of species on earth vs. biodiversity in the past

Answer 100

- currently 2M species discovered + named, however many more exist - fossils suggest # of species now is higher than ever before - cus 66M years since last mass extinction, biodiversity can develop

Question 101

over harvesting as an anthropogenic cause of species extinction

Answer 101

- humans take plants/animals from natural ecosystem faster than they can reproduce, causing extinction - ex. fishing rates

Question 102

habitat destruction as an anthropogenic cause of species extinction

Answer 102

- 13B hectares of land are used for livestock and agriculture - land used to build towns/cities - leads to loss of species

Question 103

invasive species as an anthropogenic cause of species extinction

Answer 103

- introduced to area by humans - alien species can drive native species to extinction by predation.comp for resources - endemic species can be lost in they hybridize w alien species

Question 104

pollution as an anthropogenic cause of species extinction

Answer 104

- chemical industries produce many substances that enter environment - no part of the world can be unaffected by pollution

Question 105

global climate change as an anthropogenic cause of species extinction

Answer 105

- human changes causing very rapid changes in environment, animals cannot adapt as quickly - can face extinction

Question 106

what are examples of anthropogenic causes of ecosystem loss

Answer 106

land use/agricultural expansion, urbanization, overexploitation, mining, building dams, drainage, leaching of fertilizers, climate change

Question 107

what can be used as evidence for a biodiversity crisis

Answer 107

population size, range of species, diversity of species, richness/evenness of biodiversity, area occupied, genetic diversity

Question 108

what counts as good evidence for a biodiversity crisis

Answer 108

- reliable surveys from all around the world that's peer reviewed - "citizen science" where individuals monitor population/ecosystem regularly - surveys need to be repeated many times to ensure it's accurate

Question 109

what is the main cause of the current biodiversity crisis

Answer 109

human population growth - anthropogenic causes of species extinction and ecosystem loss

Question 110

advantage of in situ conservation

Answer 110

- species lives in environments it’s adapted to - retains natural habitat and prevents loss of other endangered species - costs are low if wildlife reserve in good state, limited human intervention

Question 111

examples of in situ conservation

Answer 111

- rewilding - management of nature reserves - reclamation of degraded ecosystems

Question 112

advantages of ex situ conservation

Answer 112

- species may not be able to safely remain in natural habitats - allows for control of conditions - improve chances of successful breeding - store living materials long term for future use

Question 113

examples of ex situ conservation

Answer 113

- zoos -

Question 114

disadvantages of ex situ conservation

Answer 114

- doesn’t prevent destruction of natural habitats - species raised in captivity are less likely to be successfully reintroduced into environment - increases inbreeding

Question 115

what two criteria determine species most need of conservation

Answer 115

1. does the species have few or no close relatives? 2. is the species in danger of extinction because all remain populations are theatened?

Question 116

what does EDGE stand for

Answer 116

evolutionarily distinct and globally endangered

Question 117

why is carbon so important for life

Answer 117

- can form 4 covalent bonds w other carbons or other non-metallic elements to create complex and stable structures - can be linked by covalent bonds to form chain of any length (branched or unbranched) - can form single or multiple rings

Question 118

what are macromolecules, what are the main classes?

Answer 118

- molecules composed of a very large # of atoms - main classes: polysaccharides, polypeptides, nucleic acids

Question 119

what is a condensation reaction

Answer 119

- when two molecules are linked together and at the same time a smaller molecule is released

Question 120

how are polysaccharides/polypeptides/nucleic acids constructed

Answer 120

- by removing a hydroxyl group from one of the molecules being linked and a hydrogen from the other - creates water which is released, allows bond to be made - requires ATP

Question 121

what occurs during the synthesis of polysaccharides

Answer 121

- glucose is monosaccharide used to make glycogen (polysaccharide) - glucose linked w glycosidic bonds (C-O-C linkages thru condensation) - unbranched: C1 of glucose linked to C4 of another (1-->4 bond) - branhces: C1 of glucose linked to C6 of another (1-->6 bond)

Question 122

examples of polysaccharides, polypeptides and nucleic acids

Answer 122

polysaccharides: starch, glycogen, cellulose polypeptides: insulin, glucagon, hemoglobin nucleic acids: DNA, RNA

Question 123

how are polymers broken/digested into monomers

Answer 123

- thru hydrolysis reactions - polymers deconstructed so monomers can be reused for new polymers or source of energy

Question 124

how does hydrolysis work

Answer 124

water molecules are split to provide hydrogen and hydroxyl groups - used to make bonds on monomers that replace broken bond

Question 125

forms of monosaccharides

Answer 125

- pentose (ribose) or hexose (fructose, glucose) - one oxygen atom in ring and 4-5 carbon atoms in ring

Question 126

how doe the properties of glucose affect how it's used

Answer 126

- soluble, small molecule so easy to transport (dissolved in blood) - chemically stable, however would cause osmotic problems in stored in cells so typically converted into glycogen or starch - yields energy when oxidized, can be used as substrate for respiration

Question 127

why are polysaccharides good energy storage compounds

Answer 127

- large size, low solubility so doesn't really affect osmotic balance - branched structure makes them relatively compact - glucose can be removed from starch + glycogen when needed by hydrolysis (break 1-->4 glycosidic bond to separate 1 glucose) allowing it to be transported elsewhere

Question 128

how is the structure of cellulose formed

Answer 128

- composed of beta-glucose - condensation rxn link C1 of free b-glucose to C4 of b-glucose at end of chain (all 1-->4 bonds therefore unbranched chain) - naturally OH group of C1 is diagonal to OH group of C4, so must be inverted so OH groups are horizontal for condensation rxn

Question 129

how is cellulose's structure related to function as structural polysaccharide in plants

Answer 129

- straight chain of beta-glucose allows for bundles of molecules arranged in parallel, hydrogen bonds can form - bundles are microfibril and are basis of plant cell walls - high tensile strength because of the cross-linked hydrogen bonds, prevents plant cells from bursting

Question 130

define oligosaccharide

Answer 130

a short chain of monosaccharides linked by glycosidic bonds

Question 131

what are glycoproteins, what do they do

Answer 131

- polypeptides with carbohydrate attached (oligosaccharide) - facing outwards of cell, allows other cells to recognize them

Question 132

how are glycoproteins present in ABO blood

Answer 132

- no known function but affect blood transfusion - oligosaccharides present are O, A, B - affects how blood can be transfused from person to person

Question 133

properties of lipids, what are some examples

Answer 133

- substances in living organisms that dissolved in non-polar solvents <- hydrophobic - sparingly soluble in aqueous (water based) solvents - not repelled by water, more attracted to non-polar substances - ex. fats, oils, waxes, steroids

Question 134

how are triglycerides (mainly oils/fats) created

Answer 134

- combine 3 fatty acids and one glycerol with 3 condensation rxns, producing 3 H2O molecules - link b/w each fatty acid and glycerol is ester bond

Question 135

how are ester bonds formed

Answer 135

when an acid reacts with the hydroxyl group (OH) in an alcohol

Question 136

structure of phospholipds

Answer 136

- 2 fatty acids + phosphate group linked to glycerol - because phosphate is hydrophilic, phospholipids are both hydrophilic and hydrophobic

Question 137

differences in carbon bonds and H in saturated, monounsaturated, and polyunsaturated fatty acids

Answer 137

saturated: no double bonds in C (as many H as possible) monounsaturated: 1 double bond in C (less that max # of H) polyunsaturated: 1+ double bond in C (less that max # of H)

Question 138

how does # of double bonds in fatty acids affect melting point

Answer 138

- presence of double bonds lower the melting points of fatty acids as they prevent tight packing leading to weaker intermolecular interactions

Question 139

what properties of triglycerides make them good for long term energy storage

Answer 139

- very chemically stable, energy not lost - don't affect osmotic balance - release 2x energy compared to carbohydrates, more energy can be stored - poor conductor of heat, insulator to conserve body heat - liquid at room temp, shock absorber

Question 140

define amphipathic

Answer 140

substances that consist of both hydrophilic and hydrophobic parts

Question 141

how do phospholipids form phospholipid bilayer

Answer 141

- hydrophobic tails, hydrophilic head - when mixed with water, phosphate heads attracted to water, hydrocarbon tails attracted to each other - forms double layer w heads outside, tails inside - basis of all cell membranes

Question 142

how can steroids be identified, examples

Answer 142

- 4 fused rings of C atoms - 3 cyclohexane rings, 1 cyclopentane ring - 17 carbon atoms total - ex. testosterone and oestradiol

Question 143

how are non-polar steroids able to pass phospholipid bilayer

Answer 143

- mostly hydrocarbon-->hydrophobic - allows to pass thru phospholipid bilayer to enter/leave cells

Question 144

structure of an amino acid

Answer 144

- central carbon atom (alpha carbon) with single covalent bonds to N of amine group, C of carboxyl group - covalent bond to H and R group

Question 145

how are dipeptides formed

Answer 145

- two AA with condensation rxn to form peptide bond - peptide bond: C-N bond formed b/w amine group and carboxyl group, catalyzed in cells by ribosomes - H2O is removed - peptide bond is same no matter R group

Question 146

oligopeptides vs polypeptides vs dipeptides

Answer 146

dipeptides: 2 AA oligo: 2-20 AA poly: 20+ AA

Question 147

essential AA vs. non-essential AA

Answer 147

essential: AA that cannot be synthesized by animal, must be obtained non-essential: AA can be synthesized by animal using metabolic pathways

Question 148

essential AA and non-essential AAs in plants and animals

Answer 148

- plants can synthesize all 20 AA (non-essential) - animals have 9 essential and 11 non-essential AA, must obtain from diet

Question 149

number of amino acids possible in a chain

Answer 149

- practically infinity as there are 20 which can be combined in any order to any length - however, not all occur as ribosomes don't make random sequences, receives info from genetic code

Question 150

examples of polypeptides

Answer 150

- beta-endorphin (natural painkiller) - insulin - alpha amylase (enzyme in saliva aiding in digestion of starch) - titin (largest polypeptide)

Question 151

define denaturation

Answer 151

when protein loses folded structure when bonds are broken resulting in change of conformation of protein, loses function - often occurs in extreme environments and is not reversible

Question 152

how can temp cause denaturation

Answer 152

- causes vibration within molecule that can break intermolecular bonds - proteins vary in heat tolerance (ex. thermus aquaticus in hot springs->80C)

Question 153

how can pH cause denaturation

Answer 153

- extreme pH cause pos/neg charges on R-groups to change, breaking ionic bonds or forming new ionic bonds - proteins vary in pH tolerance (ex. pepsin in stomach ->1.5pH)

Question 154

structure of cell membranes

Answer 154

- basic structure of all biological membranes is same -> bilayer of phospholipids/amphipathic molecules

Question 155

how do lipid bilayers act as a barrier b/w aqueous solutions

Answer 155

- hydrocarbon tails interact w each other to form membrane that has low permeability to hydrophilic particles, ions, polar molecules - solutes close to membrane surface may pass thru heads of phospholipds but are drawn back if they enter hydrophobic core

Question 156

how does diffusion work

Answer 156

- more particles move from area of higher concentration to lower conc. than the other way - passive process

Question 157

how does oxygen diffuse through membranes

Answer 157

- non-polar particle so can diffuse easily - if conc. inside cell is lower than outside cus aerobic respiration, oxygen will enter thru passive diffusion

Question 158

integral proteins

Answer 158

- hydrophobic on some of surface so embedded into hydrocarbon chains in centre of membrane - transmembrane proteins

Question 159

peripheral proteins

Answer 159

- hydrophilic on surface, not embedded into membrane - attached to inside and outside surface of plasma membrane and integral proteins, often reversible - some have single hydrocarbon chain to insert into membrane as anchor to surface

Question 160

define osmosis

Answer 160

when water (solvent) moves thru a semi-permeable membrane from a less concentrated solution to a higher concentrated solution to equalize their concentrations

Question 161

how does osmosis work

Answer 161

- substances that dissolve in water do so by forming intermolecular bonds - these bonds restrict movement of water - regions of higher solute conc have less freely moving water molecules vv. - bcus of this, net movement from low solute conc. to high solute conc.

Question 162

what are aquaporins

Answer 162

- channel proteins that transport water across membrane in a single file - positive charges in middle of aquaporins prevents protons (H+) from passing thru

Question 163

what is a channel protein, what does it allow for

Answer 163

- an integral transmembrane protein with a pore that connects cytoplasm to outside - allows for facilitated diffusion of ions and polar molecules

Question 164

how do channel proteins support facilitated diffusion

Answer 164

- diameter of pore and chem properties ensure one type of particle passes thru - allows particles to pass thru both ways but more go from high conc->low conc - can close to prevent diffusion

Question 165

differences in pump proteins vs. channel proteins

Answer 165

- pump proteins used energy (ATP) to carry out active transport, channel proteins is passive diffusion - pump proteins move particles in one direction, channel moves both - pump proteins usually move particles against conc. gradient while channel almost moves down conc. gradient

Question 166

how do pump proteins work

Answer 166

- 2 different conformations - transported particle enters from one side to reach the centre of pump protein - pump protein changes to other conformation allowing particle to pass to other side of membrane before returning to og conformation - energy is used change conformations

Question 167

define selectively permeable vs semi-permeable membrane, what are cell membranes?

Answer 167

- selectively: allows for passage of particular particles but not others - semi: allows for passage of certain small solutes and freely permeable to solvent - have both (partially permeable)

Question 168

what is selective permability membranes, what is not

Answer 168

- facilitated diffusion and active transport allow for selective permeability as they're specific to particular particles - simple diffusion is not selective as it depends on size/polarity of particles

Question 169

define glycoproteins, place in cell

Answer 169

- molecule comprised of protein and carb chain - protein part embedded in membrane and carb part in exterior environment of cell

Question 170

define glycolipids, place in cell

Answer 170

- molecule comprised of lipids and carb chain (1-4 sugar units) - lipid part have 1-2 hydrocarbons which fit into hydrophobic core of phospholipid bilayer, carb chain on exterior

Question 171

functions of glycoproteins and glycolipids

Answer 171

- cell recognition, helps immune system distinguish foreign cells - creates carbon rich layer outside of cell (glycocalyx), allows for cell adhesion when fusion of glycocalyx

Question 172

what are organelles

Answer 172

discrete structure in cells that are adapted to perform one or more vital functions

Question 173

examples of organelles, examples of what are not organelles

Answer 173

organelles: nuclei, vesicles, ribosomes, plama membrane not organelles: cell wall, cytoskeleton, cytoplasm

Question 174

what are the advantages of separation of nucleus in cytoplasm

Answer 174

- safeguards DNA - separation of transcription and translation as translation cannot occur until mRNA has left nuclear membrane, modification of mRNA can occur (eukaryotic cells) - translation can happen right after transcription, mRNA cannot be modified (prokaryotic cells)

Question 175

what are the advantages of compartmentalization in cells

Answer 175

- enzyme/substrates for particular process are more concentrated - substances that could cause damage kept inside a membrane - conditions can be mantained to ideal level for particular process - organelles+content can be moved within cell

Question 176

lysosomes ad advantage of compartmentalization in cells

Answer 176

- digestive enzymes of lysosome could digest+kill cell if not safely stored in lysosome membrane

Question 177

how do gradients affect gene expression of early-stage embryo

Answer 177

- position of cell in embryo determines how it differentiates - gradients cell's position in embryo and determines pathway of differentiation, regulating gene expression

Question 178

define fertilization

Answer 178

fusion of male and female gamete to produce a single cell

Question 179

how are embryos of multicellular organisms created

Answer 179

- cel produced by fertilization undergoes mitosis so all cells are genetically identical - cells are unspecialized, develop along diff pathways as embryo grows

Question 180

properties of stem cells

Answer 180

- can divide repeatedly and endlessly - can differentiate along diff pathways (no longer stem cells)

Question 181

what is a stem cell niche, what does it do

Answer 181

- precise location of stem cells within a tissue (stem cell niche) - provides conditions needed for stem cells to remain inactive over long periods of time and differentiate when required

Question 182

examples of stem cell niches

Answer 182

- bone marrow (produces replacement blood cells) - hair follicles (generates new hair growth)

Question 183

totipotent stem cells

Answer 183

can differentiate into any cell type (ex. early stage embryos)

Question 184

pluripotent stem cells

Answer 184

capable of differentiating into all cells in adult human body but create a new organism - (ex. late stage embryos)

Question 185

multipotent stem cells

Answer 185

can differentiate into several types of cell in the same group (ex. haematopoietic stem cells in bone marrow can become many blood cells)

Question 186

cell size of sperm as aspect of specialization

Answer 186

- 50micrometers, long but narrow - smallest volumes of any human cell - reduces resistance allowing it to reach egg easier

Question 187

cell size of egg as aspect of specialization

Answer 187

- 110micrometers, spherical - largest volume of any human cell - allows for large quantities of food reserves to be stored in cytoplasm

Question 188

cell size of RBC as aspect of specialization

Answer 188

- 6-8micrometers, disk shaped - small size and shape allows to pass thru narrow capillaries and good SA:V ratio

Question 189

cell size of WBC as aspect of specialization

Answer 189

- 10micrometers when inactive 30micrometers when active - extra volume: cytoplasm, rER, golgi apparatuses for protein synthesis to secrete antibodies

Question 190

cell size of motor neurons as aspect of specialization

Answer 190

- 20 micrometers in diameter, long - large size allows enough proteins to be made to maintain very long axon

Question 191

cell size of striated muscle fibre as aspect of specialization

Answer 191

- 20-100micrometres diameter w/ lengths >100mm (10cm) - allow fibre to exert greater force and contract by greater length

Question 192

how do SA:V ratios put constraints on cell size

Answer 192

- rate in which substances used and waste products enter/leave cell depends on SA - ratio too small: waste products will accumulate, substance will not enter as quick and required, may overheat as metabolism produces heat faster than it can be lost

Question 193

how can gas exchange be maximized

Answer 193

- large SA:V ratio means distance b/w centre and exterior environment is smaller vv. - often specialized gas-exchange surfaces are required to sufficient gas exchange (ex. alveoli)

Question 194

define gas exchange

Answer 194

- all organisms absorb one gas and release another one into environment - (ex. O2 and CO2 thru plasma membrane)

Question 195

what are the properties of gas-exchange surfaces

Answer 195

- permeable - for easy diffusion - large - for big SA:V ratio - moist - so gases can dissolve - thin - short distance for gas to diffuse

Question 196

why are concentration gradients at exchange surfaces important in animals

Answer 196

- allows for diffusion which works to even out concentration gradients - when even, gas exchange stops, so gradient must be maintained

Question 197

how is a concentration gradient maintained in lungs/blood vessels

Answer 197

- continuous blood flow in capillaries of new low O2, high CO2 blood - constant respiration in lungs allows for lung air to maintain high O2, low CO2 - diffusion of O2 and CO2 at fast rate bcus dense networks of blood vessels

Question 198

adaptations of human lungs for gas exchange

Answer 198

- cells in walls secrete pulmonary surfactant (like phospholipid structure) to reduce surface tension and prevents collapse of lung - many capillaries and alveoli making for a lot of SA - many branched bronchioles for SA

Question 199

how does breathing work

Answer 199

- gas will always move from areas of high pressure to lower pressure - inhalation: pressure in thorax drops below atmospheric pressure, gas drawn in - exhalation: pressure in thorax rises above atmospheric pressure, gas expelled

Question 200

what does the diaphragm do during inspiration vs expiration?

Answer 200

i: contracts, moves downwards to push abdomen wall out e: relaxes, pushed upwards into more domed shape

Question 201

what does the abdomen wall muscles do during inspiration vs expiration?

Answer 201

i: relax allowing pressure from diaphragm to push it outwards e: contract to push abdominal organs and diaphragm up (forced expiration)

Question 202

what do external intercostal muscles do during inspiration vs expiration?

Answer 202

i: contract, pulls ribcage up and out e: relax, pulled into elongated state

Question 203

what do internal intercostal muscles do during inspiration vs expiration?

Answer 203

i: relax, pulled into elongated state e: contract, pulls ribcage up and out

Question 204

what is used to measure lung volumes

Answer 204

spirometers

Question 205

waxy cuticle as adaptation for gas exchange and water conservation in leaves

Answer 205

- secreted by epidermis cells - waterproof layer, particularly think in upper leaves of plants in dry habitats (prevents water loss)

Question 206

epidermis as adaptation for gas exchange in leaves

Answer 206

- acts as barrier between external environment and internal environment

Question 207

spongy mesophyll as adaptation for gas exchange and water conservation in leaves

Answer 207

- connected to outside air via stomata - large SA for gas exchange, spaces b/w - walls permanently moist (from xylem) to allow CO2 to dissolve and enter cells

Question 208

guard cells (stoma) as adaptation for gas exchange and water conservation in leaves

Answer 208

- two guard cells cover pore called stoma - close stoma at night when no photosynthesis and gas exchange and when plant is dehydrated

Question 209

factors affecting transpiration rates

Answer 209

- temperature: at higher temps, more energy available for evaporation and can hold more water vapour - humidity: higher humidity of air, smaller concentration gradient in and out of plant, lower rate of diffusion

Question 210

how is transpiration a result of gas exchange

Answer 210

- walls in spongy mesophyll are moist, when stomata opens for gas exchange, water vapour will diffuse out

Question 211

how to calculate stomatal density

Answer 211

mean # of stomata/area of field of view

Question 212

what are the adaptations of capillaries for exchange of materials

Answer 212

- branching of capillary network, narrow diameters (10micromemters), thin walls (one layer of endothelium cells) to maximize SA - some have fenestrations (large pores) that allow larger volumes of materials to be exchanged, speeding up exchange b/w blood and tissues

Question 213

differences in structure of veins and arteries

Answer 213

a: thicker wall, narrower lumen, circular, corrugated inner surface, visible fibres in wall v: thinner wall, wider lumen, circular or flattened, not corrugated inner surface, few visible fibres in wall

Question 214

adaptation of arteries to successfully transport blood away from heart

Answer 214

- narrow lumens: help maintain high BP and high velocities of blood flow - walls are thick/contain elastic fibres: helps arteries withstand BP w/o bulging and allows size of lumen to return to normal after pulse of blood - smooth muscles to control rate of blood flow to tissues (vasoconstriction and vasodilation)

Question 215

how to pulse oximeters measure pulse

Answer 215

- red LED and infrared light goes thru tissues of finger - detection of variation in amount of blood in tissues each heartbeat

Question 216

adaptation of veins to successfully transport blood towards heart

Answer 216

- contain pocket valves - if blood flows backwards, gets caught in flaps + closes it - assisted by gravity and pressures exerted by adjacent tissues (skeletal muscles) -> contraction makes muscles shorter and wider, squeezing on veins like pump

Question 217

what causes occlusion of coronary arteries

Answer 217

- fatty deposits (plaque) which build up on wall of artery and contain variety of lipids - can be (impregnated?) w calcium salts which harden artery and makes inner surface rough, maybe triggering formation of blood clot

Question 218

what are the consequences of occlusions in coronary arteries

Answer 218

- blood clots can form and block flow of blood to heart muscles (heart attack) - tissue death in heart (myocardial infarction) - all these conditions associated w coronary heart disease (CHD)

Question 219

transport of water from roots to leaves during transpiration as explained by cohesion-tension theory

Answer 219

1. transpiration (evaporation), occurs in stomata and created tension (negative pressure) 2. tension from transpiration “pulls” water up xylem upwards 3. cohesion, water moves like a “chain” as water is pulled out of stomata 4. adhesion, water creates hydrogen bonds to xylem walls, allowing it to “crawl” up

Question 220

adaptation of xylem vessel for water transport

Answer 220

- formed by column of cells end to end where material b/w adjacent cells is removed and contents break down to make one continuous tube - lignified wall thickening which help xylem withstand tension - pits to allow entry and exit of water

Question 221

define habitat, what can it mean

Answer 221

- a place where the organism lives - can be geographical location or the physical conditions or the type of ecosystem

Question 222

adaptations of lyme grass to sand dunes

Answer 222

- adaptation to abiotic environment - thick waxy cuticle on leaves to reduce transpiration - stomata in furrows where humid air can remain even in windy conditions - leaves roll up during droughts, humid chamber, reduces SA - rhizomes (underground stems) that extend deep into dune for water - accumulation of carbs in root and leaf cells, increasing osmotic potential (more H2O)

Question 223

adaptations of mangrove trees to mangrove swamps

Answer 223

- secretion of excess salt from salt glands - root epidermis coated in suberin (cork) reducing permeability to salt - large buoyant seeds that can be carried by ocean - cable roots grow close to soil surface (more O2) - some roots grow vertical into air to absorb O2

Question 224

abiotic variables that affect species distribution for plants and animals

Answer 224

plants: temp, water, light, soil pH+salinity animals: water, temp

Question 225

what is the range of tolerance of a species

Answer 225

the range of environmental conditions within which an organism has adapted to survive, grow, and reproduce

Question 226

how is range of tolerance a limiting factor

Answer 226

- plants/animals can only grow/survive in environments that they are adapted to

Question 227

what conditions are required for hard coral formation

Answer 227

- depth <50m so light penetrates (for coral and zooxanthellae) - pH above 7.8 for deposition of calcium carbonate in skeleton - salinity b/w 32-42 ppt of dissolved ions to maintain osmotic factors - clear water for light - temp 23-29C

Question 228

what two abiotic factors determine biome of ecosystem

Answer 228

- temp - rainfall - for any given temp and rainfall pattern, one natural ecosystem is likely to develop

Question 229

define biome

Answer 229

a group of ecosystems with similar communities due to similar abiotic conditions and convergent evolution

Question 230

climate conditions of a tropical rainforest biome

Answer 230

- high temp - high precipitation - high light intensity - minimal seasonal variation

Question 231

climate conditions of a temperate forest biome

Answer 231

- medium temp - high/medium precipitation - medium light intensity - warm summers, colder winters

Question 232

climate conditions of a taiga (boreal forest) biome

Answer 232

- low temp - high/medium precipitation - medium/low light intensity - short summers, long cold winters

Question 233

climate conditions of a hot desert biome

Answer 233

- high/medium temp - medium precipitation - high/medium light intensity - has dry season or cold season

Question 234

climate conditions of a tundra biome

Answer 234

- very low temp - medium/low precipitation - low light intensity - very short summer, very cold winter

Question 235

how are saguaro (cactus) adapted to hot desert climates

Answer 235

- wide-spreading root system for water - deep roots ~1m down - fat stems w storage tissue to conserve water after rare rainfall - pleated stems allow shrinkage in droughts, swelling after rains - thick waxy cuticle on stem to reduce transpiration - stomata opens at night, closes during day

Question 236

how are fennec foxes adapted to hot desert climates

Answer 236

- nocturnal, avoid high temps of day - underground den to stay cool - long thick hair for insulation on cool nights and hot days - pale fur to not absorb sunlight - can ventilate at 600breaths/min for heat loss

Question 237

how are the meranti trees adapted to the tropical rainforest climates

Answer 237

- can grow very high, higher than other trees to avoid comp for light - hard dense wood trunk w extra support at base to provide support against wind - smooth trunk+oval leaves to shed rainwater rapidly - enzymes of photosynthesis adapted to temps as high as 35C

Question 238

how are spider monkeys adapted to the tropical rainforest climates

Answer 238

- long arms+legs+flexible shoulders for climbing and swinging - large hooklike hands and feet to grasp branches - long tail acts like 5th hand - developed larynx for wide range of sounds to communicate in dense rainforest - breeds at any time of year bcus resources always abundant

Question 239

define ecological niche

Answer 239

- central hypothesis in biology that states that every species in an ecosystem fulfils a unique role

Question 240

what biotic and abiotic factors affect ecological niches

Answer 240

- zones of tolerance (where it lives in ecosystem) - adaptations to obtain food efficiently (better than competitors)

Question 241

obligate aerobes vs. obligate anaerobes vs facultative anaerobes

Answer 241

obligate aerobes: require continuous O2 supply, only live in oxic environments (ex. all animals and plants) obligate anaerobes: inhibited or killed by oxygen, only live in anoxic environments (ex. clostridium tetani) facultative anaerobes: use O2 if available (ex. e coli, yeast)

Question 242

what organisms use photosynthesis as a mode of nutrition

Answer 242

- plants, eukaryotic algae, several groups of bacteria - occurs in two of three domains of life, in eukaryotes and bacteria but not archaea

Question 243

how do animals obtain nutrition | method of consumption

Answer 243

- use holozoic nutrition meaning that pieces of food swallowed before being fully digested inside body

Question 244

stages of holozoic nutrition

Answer 244

1. ingestion - taking food in 2. digestion - breaking large food molecules into smaller ones 3. absorption - transport of digested food into blood and tissues of body 4. assimilation - using digested foods to synthesize proteins, making them part of body 5. egestion - getting rid of undigested material from end of gut

Question 245

define mixotrophic nutrition, what organisms use this?

Answer 245

- organism that uses methods of autotrophs and heterotrophs to obtain nutrition - some unicellular eukaryotes (protists) use (ex. euglena)

Question 246

obligate vs. facultative mixotrophs

Answer 246

obligate: must use both autotrophic and heterotrophic modes of nutrition facultative: can be entirely autotrophic or heterotrophic or use both

Question 247

define saprotrophic nutrition, what organisms use this?

Answer 247

- obtain nutrition by secreting digestive enzymes into dead organic matter and digesting it externally - used by many bacteria and fungi (aka decomposers)

Question 248

what are the 3 domain of life

Answer 248

archaea, bacteria, eukaryotes

Question 249

3 types of nutrition in archaea

Answer 249

phototrophic: absorption of light by pigments other than chlorophyll chemotrophic: oxidation of inorganic chemicals heterotrophic: oxidation of carbon compounds obtained from other organisms

Question 250

how can dentition be used to determine diet in the family of Hominidae

Answer 250

- hominidae: includes humans, orangutans, gorillas, chimps - teeth of herbivores are large and flat to grind plant tissue - omnivores have mix of sharp teeth for meats and flat molars for plants

Question 251

adaptations of insect herbivores for feeding on plants

Answer 251

- beetles/others insects have jaw-like mouth parts for biting/chewing leaf - aphids/other insects have tubular mouth parts for piercing leaves/stem to reach phloem and feed on sap

Question 252

adaptations of plants to resist the feeding of herbivores

Answer 252

- tough, sharp spines - stingers to cause pain - synthesize substances that are toxic to herbivores

Question 253

some physical adaptations of vampire bats as predators

Answer 253

- unique dentition to catch and kill prey - razor sharp teeth to pierce prey and feed on blood

Question 254

some physical adaptations of buff-tip moths as preys

Answer 254

- camouflage as they resemble birch twigs, so predators cannot spot them

Question 255

some chemical adaptations of black mambas as predators

Answer 255

- produce venom containing neurotoxins - paralyzes prey when injected via fangs so it can be eaten without resistance

Question 256

some chemical adaptations of caterpillars of cinnabar moth as prey

Answer 256

- plant it feeds on contains toxic alkaloids, accumulates - black and yellow stripes are warnings to predators that they have toxins

Question 257

some behavioural adaptations of grizzly bears as predators

Answer 257

- ambush strategies to catch migrating salmon by trial and error/copying others

Question 258

some behavioural adaptations of blue striped snappers as prey

Answer 258

- swim in tight group with sudden changes of direction "schooling" - threats more likely to be detected and difficult for predator to catch

Question 259

rank behavioural/chemical/physical adaptations from fastest changing to slowest

Answer 259

- behavioural - physical: requires genetic change - chemical: requires change in enzymes

Question 260

adaptations of trees for harvesting light

Answer 260

- dominant leading shoot that grows rapidly to reach great height where they are unshaded by others

Question 261

adaptations of lianas for harvesting light

Answer 261

- climb through other trees, using as support to reach light

Question 262

adaptations of epiphytes for harvesting light

Answer 262

- grow on trunks and branches of trees, receive higher light than if growing on forest floor

Question 263

adaptations of strangler epiphytes for harvesting light

Answer 263

- climb up trees, encircle them and outgrows their branches shading leaves of tree, killing tree

Question 264

adaptations of shade-tolerant shrubs for harvesting light

Answer 264

- live off the light that reaches forest floor

Question 265

fundamental niche vs. realized niche

Answer 265

fundamental: the potential of a species based on adaptations and tolerance limits realized: actual extent of a species niche when in competition with other species.

Question 266

define competitive exclusion

Answer 266

- when two fundamental niches of different species overlap, one species will exclude the other from that part of it's range thru competitions

Question 267

why do ecological niches need to be unique

Answer 267

- if 2 species have overlapping fundamental niches and one outcompetes the other in all areas, they will be excluded from ecosystem - w/o realized niche, cannot exist in ecosystem - every species must have different realized niche to survive

Question 268

what are enzymes, why are they important

Answer 268

- biological catalysts that increases the rate of a chemical reaction - processes would be too slow to sustain life w/o enzymes

Question 269

define metabolism

Answer 269

the complex network of interdependent and interacting chemical reactions occurring in living organisms

Question 270

specificity of enzymes in metabolism

Answer 270

- specificity means each enzyme catalyzes one specific reaction or group - organisms must make large numbers of enzymes

Question 271

benefits of enzymes role in metabolism

Answer 271

- enzymes can be made at different speeds to change rate of rxn - enzyme production an be temp stopped in rxn not required - gives organisms some control over metabolism

Question 272

what are anabolic reactions

Answer 272

- build up smaller molecules into larger ones, formation of macromolecules from monomers by a condensation rxn - rxn requires energy

Question 273

examples of anabolic reaction

Answer 273

- photosynthesis - protein synthesis - DNA synthesis - synthesis of complex carbs (starch, cellulose, glycogen)

Question 274

what are catabolic reactions

Answer 274

- breaking down or larger molecules into smaller ones, hydrolysis of macromolecules into monomers - releases energy

Question 275

examples of catabolic reactions

Answer 275

- digestion of food - oxidation of glucose/lipids in cell respiration - digestion of complex carbon compounds

Question 276

structure of enzymes

Answer 276

- globular proteins with precise 3D structure and chemical properties

Question 277

how do active site of enzymes work for catalysis

Answer 277

- where substrate binds to enzyme - shape and chemical properties of active site of substrate must match - ensures specific substrate binds

Question 278

structure of the active site

Answer 278

- vary in size depending on substrate - just a few amino acids at active site needed to change substrates into products - AAs brought together by folding of polypeptides so 3D structure of enzyme is crucial

Question 279

what occurs during interaction bw substrate and active site

Answer 279

- substrate movement random until chemical properties of enzyme attract it - both enzyme and substrate change shape to allow for binding - substrate can bind - changes in substrate molecules allow easier break/formation of bonds, converting into products - product detach, enzyme reused

Question 280

define induced fit binding

Answer 280

change of bond angles and bond lengths in substrate and active site in order to bind

Question 281

how does molecular motion affect substrate-active site collision

Answer 281

- substrate must get very close to enzyme to bind, can be achieve thru molecular motion - more movement means higher rate of substrate-active site collision - sometimes large substrates or enzymes in membranes cannot move, other enzyme/substrate must move

Question 282

define enzyme-substrate specificity

Answer 282

- shape/chemical properties of an enzyme's active site allows substrate to bind but not other substances

Question 283

how does temp affect rate of enzyme activity

Answer 283

- at higher temps, enzymes and substrates move quickly higher chance to bind - bonds in enzyme vibrate more, can break, changes structure, cannot bind to substrate (denatured) - if temp gets too high, all enzymes will denature, no activity

Question 284

how does pH affect rate of enzyme activity

Answer 284

- if pH changes from optimum, ionic bonds bw amino acids are altered - changes structure of enzyme, active site cannot bind to substrates - beyond certain pH, denaturation will be irreversible

Question 285

how does substrate concentration affect rate of enzyme activity

Answer 285

- if higher substrate conc, substrate-active site collision will occur more, inc rate of rxn - plateaus at optimum point as all enzymes are taken by substrates, rxn cannot occur any quicker

Question 286

what is activation energy

Answer 286

- the energy required for substrates to pass thru transition state before conversion to products (breaks bonds in substrates)

Question 287

what are the effect of enzymes on activation energy, why?

Answer 287

- bonds in substrate are weaker when binded to active site, less activation energy needed to break them - release of energy is unchanged as new bonds are made, but activation energy smaller - rate of reaction increases

Question 288

what does ATP stand for, what kind of molecule is it

Answer 288

adenosine triphosphate - a nucleotide

Question 289

structure of ATP

Answer 289

- 3 phosphate groups - ribose (5 carbon sugar) - adenine (nitrogen-containing base)

Question 290

what properties of ATP make it suitable as energy currency in cells

Answer 290

- third phosphate group can be easily removed and added by hydrolysis and condensation rxns - hydrolysis releases small amount of energy enough for processes in cell

Question 291

hydrolysis/condensation of ATP equation

Answer 291

ATP+H2O -->ADP + phosphate + energy - or other way around for condensation

Question 292

what life processes in cells need ATP

Answer 292

- synthesizing of macromolecules - active transport - movements

Question 293

how is ATP used to synthesize macromolecules

Answer 293

- endothermic process, needs ATP - one or more ATP molecules used to link a monomer to polymer - ex. synthesis of DNA during replication, RNA in transcription

Question 294

how is ATP used for active transport

Answer 294

- used to cause reversible changes in conformation of pump protein (more stable--> less stable shape)

Question 295

how is ATP used for movements in cell during mitosis

Answer 295

- ATP is needed to move chromosomes to poles and pinch cytoplasm during mitosis

Question 296

what does conversion from ADP to ATP require

Answer 296

- requires energy that can come from cell respiration, photosynthesis, chemosynthesis

Question 297

how does cell respiration produce ATP

Answer 297

- uses energy released from oxidization of carbon compounds - wide range of carbon compounds can be used, glucose and fatty acids are main ones

Question 298

relationship between gas exchange and cell respiration

Answer 298

- cell respiration cannot continue w/o gas exchange cus of excess of CO2, lack of O2 - gas exchange cannot continue w/o cell respiration cus there will be no concentration gradient - interdependent

Question 299

formula of aerobic respiration in humans/animals/plants

Answer 299

glucose + oxygen --> CO2 + H2O

Question 300

formula of anaerobic respiration in humans/animals/plants

Answer 300

glucose --> lactate

Question 301

formula of anaerobic respiration in yeast (fermentation)

Answer 301

glucose --> ethanol + CO2

Question 302

oxygen in aerobic vs. anaerobic cell respiration

Answer 302

aer: oxygen used anaer: oxygen not used

Question 303

yield in aerobic vs. anaerobic cell respiration

Answer 303

aer: higher yield (30 ATP per glucose) anaer: lower yield (2 ATP per glucose)

Question 304

waste products in aerobic vs. anaerobic cell respiration

Answer 304

aer: CO2 and water anaer: CO2 + lactate or ethanol, NO water

Question 305

possible substrates in aerobic vs. anaerobic cell respiration

Answer 305

aer: carbs like glucose, lipids (fats, oils) anaer: only carbs

Question 306

location of occurrence of aerobic vs. anaerobic cell respiration

Answer 306

aer: initial rxns in cytoplasm, more in mitochondria anaer: all rxns in cytoplasm, none in mitochondria

Question 307

what is photosynthesis

Answer 307

- transformation of light energy into carbon compounds (chemical energy)

Question 308

equation for photosynthesis

Answer 308

CO2 + water+(sunlight) --> glucose + oxygen

Question 309

how is carbon converted into glucose in photosynthesis

Answer 309

- hydrogen needed, obtained from photolysis (splitting molecules of water) - rxn only occurs when light is available - splitting leaves oxygen as the waste product

Question 310

why do plants appear green

Answer 310

- chlorophyll (main pigment in photosynthesis) as red and blue wavelengths can excite it but green cannot <- reflected

Question 311

absorption spectrum vs action spectrum

Answer 311

absorption: graph showing % of light absorbed at each wavelength by pigment/group of pigments action: graph showing rate of photosynthesis at each wavelength of light

Question 312

correlation b/w absorption spectrum and action spectrum

Answer 312

photosynthesis occurs at a higher rate when a greater percent of light is being absorbed

Question 313

what does FACE stand for, what is it

Answer 313

- “free air carbon dioxide enrichment experiments” - tests if pollution could increase plant growth bcus when temp + light intensity are at optimal levels, increase in CO2 leads to a higher rate of photosynthesis - circle towers that release CO2 and air are built into semi natural vegetation to increase CO2 conc.

Question 314

structure of neurons

Answer 314

- cytoplasm+nucleus make up cell body - dendrites are many short branched nerve fibres - axons are one very long nerve fibre

Question 315

why is the resting potential in neurons negative

Answer 315

- sodium-potassium pumps use ATP to pump 3 Na molecules out and 2 K molecules in - generates charge imbalance and concentration gradients - pumped ions leak back thru membrane by diffusion, membrane is 50x more permeable to K+, so leakage is faster, increasing overall charge imbalance - neg charged proteins in nerve fibre

Question 316

define depolarization and repolarization

Answer 316

depolarization: change in membrane potential from negative to positive repolarization: change back from positive to negative membrane potential

Question 317

what are depolarization and repolarization caused by

Answer 317

- movement of positively charged ions across the membrane

Question 318

what occurs during depolarization

Answer 318

- Na channels open, Na diffuses into neuron - when threshold potential reached, depolarization reaches critical level where Na channels open, Na rushes in, full depolarization occurs - reverses charge imbalance across membrane from -70mV to +30mV

Question 319

what occurs during repolarization

Answer 319

- K channels open, K diffuses into neuron so that the inside of neuron is neg again - k channels remain open until membrane potential is -70mV

Question 320

how does the diameter of the axon affect the speed of an impulse

Answer 320

- humans: diameter of one nerve is ~1um and impulses travel ~1m/s - some animals have larger diameters allowing for faster impulses bcus less resistance - larger axons used to coordinate rapid rxns for survival - ex. giant axons in squids have: d=500um, impulses are up to 25m/s

Question 321

what is myelination and how does it affect the speed of a nerve impulse

Answer 321

- coating of fatty substance (myelin) forming myelin sheath, acts as insulator - coating consists of Schwann cells with gaps called nodes of ranvier - allows nerve impulses to jump from node of raniver to node of ranvier <- faster, up to 100m/s

Question 322

what are synapses, 3 main types

Answer 322

- a junction b/w two cells in the nervous system - b/w sensory receptors and neurons, b/w neurons in brain and spinal cord, neurons and muscle fibres/glands

Question 323

movement of signals in a synapse

Answer 323

- can only pass in one direction - presynaptic neurons brings signal to synapse in AP - postsynaptic neurons carries signa; away from synapse in AP

Question 324

what occurs in the presynaptic neuron during synaptic transmission

Answer 324

- AP propagated along presynaptic nerve - depolarization of presynaptic membrane causes Ca to diffuse in thru membrane channels - influx in Ca-> vesicles containing NTs fuse w/ presynaptic membrane - NT release into synaptic cleft via exocytosis

Question 325

what occurs in the postsynaptic neuron during synaptic transmission

Answer 325

- NTs diffuse across synapse - NTs bind to receptors in postsynaptic membrane, ion channels open - Ions diffuse into postsynaptic neuron -> membrane potential less neg - if excitatory postsynaptic potential strong enough, triggers AP - NTs rapidly broken down and removed from synapse

Question 326

how is acetylocholine used when signalling b/w neurons

Answer 326

- binds to receptor in postsynaptic membrane (open Na channel) - Na diffuses in -> excitatory postsynaptic potential - ACh binds to receptor for short time, generates one AP - acetylcholinesterase in synapse breaks down ACh back into choline and acetyl group - choline reabsorbed and turned back into ACh

Question 327

what is system integration, what is its importance

Answer 327

- coordination b/w different systems to perform various functions of life - necessary for organism to function

Question 328

what is the hierarchy of subsystems integrated in a multicellular organism

Answer 328

cells, tissues, organs, organ systems, and organisms

Question 329

what are tissues, what are the structures

Answer 329

- group of cells adapted to specific function, larger organisms have more cells in tissue rather than larger cells - cells in tissue stick to each other - cells within a tissue can communicate with each other

Question 330

what are organs, what are the structures

Answer 330

- a group of tissues that work together to carry out a specific function of life - tissues in organ are interdependent

Question 331

what are emergent properties

Answer 331

properties that are not evident in the individual components of a system, but show up when combining those components

Question 332

type of signal in hormone vs. nervous signalling

Answer 332

chemical vs. electrical (passing of cations)

Question 333

transmission of signal in hormone vs. nervous signalling

Answer 333

in bloodstream. vs in neurons

Question 334

destination of signal in hormone vs. nervous signalling

Answer 334

widespread throughout body but only certain cells respond vs. highly focused to one specific effector cells

Question 335

effectors in hormone vs. nervous signalling

Answer 335

target cells in any type of tissue vs. muscles or glands

Question 336

speed of response in hormone vs. nervous signalling

Answer 336

slower vs. very rapid

Question 337

duration of response in hormone vs. nervous signalling

Answer 337

long (until hormone broken down) vs. short (unless nerve impulses sent repeatedly)

Question 338

types of response in hormonal signalling

Answer 338

growth, development (puberty), reproduction, metabolic rate, solute conc. in blood, mood

Question 339

types of response in nervous signalling

Answer 339

striated muscle, smooth muscle, cardiac muscle, exocrine glands, endocrine glands

Question 340

how are materials transported b/w organs

Answer 340

- thru circulatory system as blood circulates thru all tissues

Question 341

how does the brain help integrate organs

Answer 341

- receives info from many inputs, processes it, stores some, and sends to parts of body - stored info can be short or long term, crucial for learning

Question 342

unconscious vs. conscious processes

Answer 342

unconscious: performed when awake or asleep, involuntary and coordinated by brain+ spinal cord (ex. secretion of glands) conscious: performed when awake, voluntary and only coordinated by cerebral hemispheres of brain (ex. movement of striated muscle)

Question 343

how does the spinal cord help integrate organs

Answer 343

- only coordinates unconscious processes - in some cases quicker than if signals were conveyed to and from the brain

Question 344

white matter vs. grey matter in spinal cord

Answer 344

white: contains myelinated axons + other nerve fibres which convey signals from sensory receptors->brain->organs grey: contains cell body of motor neurons and interneurons w/ many synapses which processes info and decision making in spinal cord

Question 345

how do sensory neurons convey messages to CNS

Answer 345

- external and internal stimuli perceived by receptor cells - signals from receptor cells conveyed to CNS using sensory neurons - brain receives signals from organs in head, spine receives from body

Question 346

how are messages conveyed from CNS to target cells (using muscle contraction as example)

Answer 346

- primary motor cortex sends signal via motor neuron to striated muscle - signals in motor neurons are nerve impulses - when nerve impulse reaches end of axon, stimulates muscle fibres to contract

Question 347

what is a nerve, structure?

Answer 347

- a bundle of nerve fibres enclosed in a protective sheath that can vary in size - most contain nerve fibres of sensory and motor neurons - all organ served by >1 nerve

Question 348

outline the process of a pain reflex arc

Answer 348

- receptor cells sense a stimulus - sensory neurons receive signals from receptor cells or own nerve endings, long axons carry nerve impulse to interneurons in CNS - interneurons receive signal, make decisions and decide response - motor neurons receive signal from interneurons, if threshold potential reached, impulse passed along axon to effector - effector carries out response to stimulus

Question 349

what is the role of the cerebellum

Answer 349

- control skeletal muscle and balance - does NOT make decisions about what muscles to contract but will fine-tune timing of contraction

Question 350

what are circadian rhythms, what are they dependent on

Answer 350

- the 24 hour sleep wake pattern (rhythms in behaviour) - depend on superchiasmatic nuclei or SCN cells in hypothalamus

Question 351

how does melatonin secretion support the circadian rhythms

Answer 351

- secretion increases in evening for drowsiness and drops to low level at dawn for waking to control sleep-wake cycle - contributes to nighttime drop in temp, and less urine production

Question 352

what is melatonin, where is it secreted

Answer 352

- hormone that plays role in sleep - secreted from pineal gland

Question 353

what is epinephrine, where is it secreted

Answer 353

- aka adrenaline, hormone that prepares body for vigorous physical activity - secreted by adrenal glands

Question 354

how does epinephrine (adrenaline) prepare body for physical activity

Answer 354

- muscle cells break glycogen to glucose to be used in aerobic or anaerobic respiration - liver cells break glycogen to glucose releasing it into bloodstream - bronchi and bronchioles dilate, easier ventilation - ventilation rate increases, sinoatrial node speeds up HR - arterioles to liver and muscles widen while ones to gut, kidney etc. are narrower

Question 355

why is epinephrine useful for preparing for physical activity

Answer 355

- increases supply of O2 and glucose to muscles maximizing production of ATP

Question 356

role of the hypothalamus

Answer 356

to link the nervous system to the endocrine system via pituitary gland - directs secretion in pituitary gland

Question 357

parts of the pituitary gland

Answer 357

- anterior and posterior lobe - operate in different ways however both secrete hormones into capillaries under direction of nuclei in hypothalamus

Question 358

what is the sinoatrial node, how does it work

Answer 358

- special group of cardiac muscle cells in wall of right atrium - accts as pacemaker for heartbeat - signal from medulla: sympathetic nerve causes inc in HR, vagus nerve causes dec. in HR

Question 359

what do baroreceptors do, wherea re they found

Answer 359

monitor BP, found in carotid arteries, and lungs

Question 360

what do chemoreceptors do, where are they found

Answer 360

monitor blood pH, O2 and CO2 concentration - medulla of brain, carotid arteries

Question 361

how is heart rate controlled

Answer 361

- cardiovascular centre (in medulla) receives sensory input from baroreceptors and chemoreceptors - low BP = inc in HR vv. - low O2 or pH = inc in HR vv. - negative feedback loop

Question 362

how is ventilation rate controlled

Answer 362

- chemoreceptors monitor blood pH in aorta/carotid arteries - low pH (high CO2) triggers inc in VR which will dec CO2 conc in alveoli - allows for more diffusion of CO2 from capillaries to lungs, increasing pH

Question 363

how does the ENS play a role in peristalsis in the digestive system | examples

Answer 363

- muscles can exert continuous moderate force for short periods - circular muscles: contract behind food, pushing it forward - longitudinal muscles: contracts along food - esophagus: peristalsis occurs only downwards in one continuous wave

Question 364

what is the ENS

Answer 364

- enteric nervous system - part of the PNS - extensive and complex, basically allows control of stomach and intestine w/o inputs from CNS

Question 365

examples of voluntary movements of digestive system controlled by CNS

Answer 365

- initiation of swallowing as tongue is composed of striated muscles - defecation

Question 366

what is a disease, what is it caused by

Answer 366

- particular kind of illness with characteristic symptoms - main types of causes are genetic, environmental, infection w/ a pathogen

Question 367

what are pathogens, how do they work

Answer 367

- organisms that cause disease - passed from one infected organism to another, enter organism and multiply

Question 368

skin as primary defence against pathogens

Answer 368

- outermost layer, provides physical barrier - tough layer of dead cells containing a lot of keratin (protein) - sebaceous glands release sebum to maintain low pH on skin, inhibits bacterial/fungal growth

Question 369

mucous membrane as primary defence against pathogens

Answer 369

- thin, softer skin that secretes mucous (sticky solution of glycoproteins) - traps pathogens and harmful particles (swallowed or expelled) - antiseptic properties

Question 370

outline how cuts on skin are sealed by blood clotting

Answer 370

1. platelets cluster at site, release clotting factors, triggers clotting process 2. clotting factors produce enzyme thrombin 3. thrombin rapidly converts fibrinogen in blood to insoluble fibrin 4. fibrin forms mesh in cuts, traps more platelets and blood cells to form clot

Question 371

innate immune system vs. adaptive immune system

Answer 371

innate: responds to broad categories of pathogen, doesn't change during life of organism (ex. phagocytes) adaptive: responds a certain way to certain pathogens, builds memory of pathogens that have been encountered, immune system becomes more effective (ex. antibody-producing lymphocytes)

Question 372

how do phagocytes control infections

Answer 372

- squeeze thru pores in capillaries to move to site of infection where they recognize pathogens - engulf thru endocytosis, digest using enzymes from lysosomes - forms pus

Question 373

what are lymphocytes, where are they found

Answer 373

- cells in adaptive immune system that work together to rpoduce antibodies - circulates in blood and lymph nodes

Question 374

how do lymphocytes work to fight infection

Answer 374

- we have large amounts of B-lymphocytes that each make specific antibody - little bit of each lymphocytes for each antibody - when pathogen infects body, needed lymphocytes multiply and create large volumes

Question 375

antibody structure

Answer 375

hypervariable region: recognizes+binds to specific molecules on pathogen constant region: helps body fight pathogen by making it more recognizable to phagocytes to engulf them

Question 376

structure of antigens

Answer 376

- glycoproteins or other proteins or some large polysaccharides - usually located on surface of pathogen

Question 377

what happens when someone is transfused the wrong blood type

Answer 377

- antibodies are produced to respond to foreign molecules (ex. transplanted organs or blood) - antigens on wrong blood type trigger antibody production

Question 378

how do we fight off pathogens (general process)

Answer 378

1. macrophage ingests pathogen and displays its antigens 2. helper T-cell specific to antigen activated by macrophage 3. B-cell specific to antigen activated by proteins from helper T-cell 4. B-cell divides repeatedly to produce antibody-secreting plasma cells 5. antibodies produced by clones of plasma cell are specific to antigen of pathogen, helps destroy it

Question 379

what does activation of a B-cell require

Answer 379

- direct interaction with specific antigen and contact w helper T-cell that has been activated by same antigen

Question 380

what occurs after B-cells have been activated

Answer 380

- don't immediately start producing antibody, too few of them and may not have needed organelles yet - instead, divide repeatedly thru mitosis to form many clones - golgi apparatus, ER develops allowing for rapid production of antibodies by protein synthesis - B-cells that have grown+differentiated are plasma B-cells

Question 381

how are helper T-lymphocytes/cells activated

Answer 381

- have antibody-like receptor in plasma membrane to help it bind to macrophage - helper T-cells are specific to 1 antigen and bind w/ + activated by macrophage

Question 382

what do activated helper T-cells do

Answer 382

- bind to B-lymphocytes - B-cells are specific to one antigen and are activated by helper T-cells via binding + signalling protein

Question 383

immunity from retaining memory cells

Answer 383

- most B-cells produced by mitosis become active B-cells but some become memory B-cells - remain inactive until same pathogen infects body again -> activates+ responds rapidly

Question 384

how is HIV transmitted

Answer 384

- thru blood and body fluid - sex w/o condom where abrasions to mucous membrane can cause minor bleeding - sharing of hypodermic needles - transfusion of infected blood - childbirth and breastfeeding

Question 385

how does HIV work in the body

Answer 385

- invades and destroys helper T-cells leading to progressive loss of capacity to produce antibodies - retrovirus w genes made of RNA - uses reverse transcriptase to produce DNA copies of its genes in host

Question 386

when does HIV become AIDS

Answer 386

- when conditions cause by HIV are combined in a person, its called AIDS

Question 387

how can HIV be combatted

Answer 387

- using antiretroviral drugs that inhibit reverse transcriptase

Question 388

what are antibiotics

Answer 388

- chemicals that inhibit growth of microorganisms - block processes that occur in prokaryotes (bacteria) but not eukaryotes

Question 389

when are antibiotics ineffective

Answer 389

- control bacterial infections but not viruses - using it on viral infections will not work and will contributes to antibiotic resistance

Question 390

antibiotic resistance

Answer 390

- since antibiotic discovery, more bacteria have become resistant - more resistance = more antibiotics needed - when antibiotic has multiple resistances, can lead to widespread strains <- public health concern

Question 391

ways to avoid antibiotic resistance

Answer 391

- only prescribe antibiotics for serious bacterial infections and for min period - hospitals maintain high standards of hygiene to prevent cross infection - farmers avoid use of antibiotics in animals feeds - pharm companies must develop new classes of antibiotics

Question 392

what is zoonoses

Answer 392

an infection disease that can transfer from other species to humans or vv

Question 393

what can a vaccine contain

Answer 393

- weakened, live version of pathogen - killed pathogen - subunits (proteins) of pathogen that acts as antigens - mRNA coding protein that acts as antigen then humans can translate to make protein

Question 394

how do vaccines work

Answer 394

- al vaccines contain antigens that allow pathogen to be recognized - antigens stimulate primary immune response by activation of T-cells, B-cells and plasma cells - pathogen will be destroyed by secondary immune response if enters body in future

Question 395

how is herd immunity achieved, how does it prevent epidemics

Answer 395

- when significant proportion of population have contracted disease or been vaccinated - spread of pathogen is impeded as it mostly encounters immune people

Question 396

what is a population

Answer 396

group of individual organisms of the same species living in a given area

Question 397

characteristics of a population

Answer 397

- normally interbreeds with each other - diff populations often separated by a geographical barrier - can be distinguished thru reproductive isolation

Question 398

importance of random sampling

Answer 398

- not possible to determine exact size of population, random sampling is a good estimate - every individual in population should have equal chance of being included in sample to limit bias, more accurate rep

Question 399

what can random quadrant sampling be used for, how does it work

Answer 399

- estimates population size of sessile organisms - repeatedly places quadrant frame in random positions in habitat and recording # organisms present each time - randomly generated #s to represent location of quadrant (x and y axis)

Question 400

assumptions made for capture-mark-release-recapture method of estimating population size

Answer 400

- no migration occurs in or out of population - no deaths or births - marked individuals have same chance of being captured as unmarked ones - marks remain visible - marks don't threaten survival

Question 401

what is carrying capacity

Answer 401

the maximum size of a population that an environment can support

Question 402

what factor limits carrying capacity

Answer 402

- competition for limited resources plants: water, light, soil nitrogen animals: water, breeding space, food, dissolved O2

Question 403

what factors impact size of populations

Answer 403

density-independent factors (having same effect however large population is) density-dependent factors (having increasing effect as population increases) - population usually remains relatively stable due to negative feedback loops

Question 404

the 3 groups of density dependent factors

Answer 404

competition: for limited resources predation: becomes more intense as prey becomes denser and vv infectious disease/parasitism: increase with population density as pathogens spread easier | more predation as denser prey? is it cus theres more predators?

Question 405

why does exponential phase of population growth curve occur

Answer 405

- when species have spread to new area, found new ecological niche - resources are abundant - initially, no predators, pathogens, pasts that target population

Question 406

what is a community

Answer 406

groups of populations living together in an area and interacting with each other

Question 407

competition as an intraspecific relationship

Answer 407

- individuals of population are likely same species, need same resources - unless abundant, competition will occur - causes natural selection - ex. for light in plants, for pollinators in flowering plants, for food+breeding sites in animals

Question 408

cooperation as an intraspecific relationship

Answer 408

- occurs more in social animals rather than plants - strong advantages as all individuals benefit - ex. communal roosting+feeding+defense against predation+parental care in animals

Question 409

herbivory as an interspecific relationship within communities

Answer 409

- primary consumer feeding on producers which may or may not be killed - ex. bison grazing on grass

Question 410

predation as an interspecific relationship within communities

Answer 410

- one consumer species kills and eats another consumer species -ex. anteaters feeding on ants

Question 411

interspecific competition as an interspecific relationship within communities

Answer 411

- two or more species using the same resource with amount taken by one reducing amount available to other - ex. ivy climbing up oak tree and competing for light

Question 412

mutualism as an interspecific relationship within communities

Answer 412

- two species living in close association, both benefiting - ex. zooxanthellae living on cells of hard corals and exchanging materials

Question 413

parasitism as an interspecific relationship within communities

Answer 413

- one species (parasite) living inside/outside of host and obtaining food from them, harms host benefits parasite - ex. ticks living on deer, sucking their blood

Question 414

pathogenicity as an interspecific relationship within communities

Answer 414

- one species (pathogen) living inside host and causing disease - ex. tuberculosis bacterium infecting badgers

Question 415

mutualism b/w fabaceae family (pea/bean plants) and rhizobium bacteria

Answer 415

f->r: growing root nodules where bacteria can live and be protected, maintains low O2 for rhizobium, supplies sugar r->f: produces and supplies ammonium, prevents nitrogen deficiency giving plant advantage

Question 416

mutualism b/w zooxanthellae and hard corals

Answer 416

z->c: supplied carbon compounds and oxygen c->z: provides safe environment, gives algae reliable source of light as coral grows near water surface, supplied CO2

Question 417

how do invasive species affect endemic species

Answer 417

- invasive species not effectively regulated by density-dependent factors - if alien and endemic species have same ecological niche-> competition for resources, endemic species can result in smaller realized niche, population decline

Question 418

how can one test for interspecific competition

Answer 418

- presence/absence of species can show association b/w them - chi-squared test, field manipulation (see effects of having 1 species removed), lab experiments (species growth tgt vs. apart)

Question 419

predator-prey relationships as density-dependent control of population size

Answer 419

- overall predator population should remain stable if prey population is stable - could have cyclical oscillation patterns - prey # inc = more food for predators = more predators=more predation=less prey= no food for predators = less predators = les predation = more prey

Question 420

how are top-down and bottom-up control present in populations of communities

Answer 420

- top down: acts from higher trophic level to lower one - bottom up: acts from lower trophic level to higher one - communities can experience both types of control, but typically one is more dominant than the other

Question 421

what is allelopathy

Answer 421

- allelopathy: when allopathic agents are secreted into soil by plants to kill/deter growth of neighbouring plants - a secondary metabolite, like antibiotics

Question 422

what is an ecosystem

Answer 422

composed of all organisms in an area and their abiotic environment

Question 423

open vs closed ecosystem

Answer 423

open: resources and enter or exit, includes both chemical substances and energy closed: energy can enter or exit, chemical resources cannot

Question 424

what is the principle source of energy that sustains most ecosystems

Answer 424

- sunlight as producers can harvest energy by photosynthesis - percentage of light harvested is different depending on ecosystem (ex. sahara desert has high intensity of light, but little producers to harvest)

Question 425

flow of chemical energy thru food chains

Answer 425

- producers convert sunlight into chemical energy used to make carbs, lipids (other carbon compounds) - consumers obtain energy from the carbon compounds in the organisms which they feed on

Question 426

why are food chains part of webs

Answer 426

- many consumers feed on more that one species and fed upon by 1+ species - represents complex relationships b/w organisms

Question 427

how to decomposers (saprotrophs) obtain energy

Answer 427

- secrete digestive enzymes into dead matter (faeces, dead organisms) and digest externally - absorbs products of digestion

Question 428

why are decomposers so important

Answer 428

- helps to break complex insoluble carbon compounds into simple soluble ones, causing breakdown of solid structures - prevents build up of dead organic matter - recycles energy

Question 429

what are autotrophs

Answer 429

organisms that use external energy sources to synthesize carbon compounds from simple inorganic substances

Question 430

what do autotrophs need to make carbon compounds

Answer 430

- need carbon source and a simple inorganic substance (nitrate, phosphate etc) - need energy source to perform anabolic rxns to build carbon compounds

Question 431

external energy source of chemoautotrophs

Answer 431

- exothermic inorganic chemical rxns - thru oxidation of a substrate, energy released which synthesizes carbon compounds - used by many prokaryotes

Question 432

how do heterotrophs obtain carbon compounds

Answer 432

- digest carbon compounds (proteins, AA) of other organisms so it can pass thru cell membrane - use products of digestion to build the carbon compounds they need - digestion can occur internally or externally

Question 433

what is assimilation

Answer 433

- absorbing carbon compounds into cells and making them part of body

Question 434

how is ATP produced in autotrophs and heterotrophs

Answer 434

- by cell respiration - carbon compounds are oxidized to release energy which is used to phosphorylate ADP, producing ATP

Question 435

what is there less energy available higher up in food chain

Answer 435

- large energy losses b/w trophic levels cause by incomplete consumption, incomplete digestion and cell respiration

Question 436

incomplete consumption as a source of energy loss

Answer 436

- organisms are usually not entirely consumed by organisms in next trophic level - energy is then passed to saprotrophs instead of next trophic level, leaving the food chain

Question 437

incomplete digestion as a source of energy loss

Answer 437

- not all food ingested in digested and absorbed, egested in faeces and passes to saprotrophs and detritus feeders - ex. some animals don't digest tough plant matter

Question 438

cell respiration as a source of energy loss

Answer 438

- substrates are oxidized to CO2 and water which are waste products and cannot supply energy for next trophic level - only unoxidized compounds can be passed - smaller amount of energy to each trophic level as # of energy-containing substances dec.

Question 439

heat loss as a source of energy loss

Answer 439

- energy transformations are never 100% efficient - not all energy from oxidation of carbon compounds in cell respiration is transferred into ATP, some converted to heat - heat released in production of ATP in cell respiration, and when it's used

Question 440

why are number of trophic levels in food chain restricted

Answer 440

- energy losses bw levels - animals in higher trophic levels don't need to eat more food as prey contains large energy per unit mass, just not much prey available (less biomass)

Question 441

how does biomass accumulate

Answer 441

- when living organisms grow and reproduction as it inc. # of growing organisms - biomes vary in capacity to accumulate biomass depending on rates of photosynthesis

Question 442

gross primary production vs. net primary production

Answer 442

GPP: total biomass of carbon compounds made by plants in photosynthesis NPP: GPP minus biomass lost due to respiration of plant (aka amount of biomass available to consumers)

Question 443

secondary production vs. primary production

Answer 443

- sp: accumulation of carbon compounds in biomass of animals and heterotrophs - pp: accumulation of carbon compounds in biomass of autotrophs - will always be lower per unit area than primary production as loss of biomass in every trophic level - declines w each successive trophic level

Question 444

pool vs. flux in the carbon cycle

Answer 444

pool: reserve of an organic or inorganic element flux: transfer of an element from one pool to another

Question 445

what are the 3 main types of carbon flux due to living organisms in ecosystems

Answer 445

- photosynthesis - feeding - respiration

Question 446

when is an ecosystem a carbon sink or source

Answer 446

- if photosynthesis exceeds respiration, ecosystem acts as carbon sink - if respiration exceeds photosynthesis, ecosystem acts as carbon source

Question 447

what is sequestration

Answer 447

when carbon is stored in the natural environment and removed from the carbon cycle

Question 448

what is natural gas and oil

Answer 448

- formed 550M years ago - deep burial of partially decomposed organic matter where high temps caused chem changes and oil + gas production

Question 449

what is coal

Answer 449

- formed 325-250M years ago - wood+ other plant matter in swamps buried under other sediments

Question 450

what is peat

Answer 450

- formed 10,000 years ago - incomplete decomposition of dead plant matter cus acidic and anaerobic conditions

Question 451

how is CO2 released in combustion of biomass, peat, coal and oil

Answer 451

- carbon can be sequestered in them for indefinite amounts of time - can be combusted naturally (volcanic activity or lightning strikes) - human activity has increased rate (burning)

Question 452

what causes the annual fluctuations of keeling curves

Answer 452

- CO2 inc. b/w october and may then falls from may to october - due to global imbalances in rates of CO2 fixation by photosynthesis and cell respiration (ex. photosynthesis higher in northern hemisphere during summer, less CO2)

Question 453

what causes the long-term trend in keeling curves

Answer 453

- CO2 conc for one year shows that inc in not completely reversed by dec so overall inc in CO2 - from 1959 onwards in keeling curve, steady inc in conc of CO2 in atmosphere - largly due to burning fossil fuels and anthropogenic factors (deforestation)

Question 454

how do autotrophs and heterotrophs depend on each other for O2 and CO2

Answer 454

- CO2 conc. limit rate of photosynthesis so autotrophs rely on heterotrophs to supply - oxygen only exists in atmosphere because it's produced by photosynthesis so respiring heterotrophs depend on photosynthesizing autotrophs - huge fluxes, shows major interaction bw auto and hetero

Question 455

recycling of chemical elements in ecosystem

Answer 455

- limited quantities of each chemical element on earth, can be recycled endlessly hence why we havent run out - key role: decomposers break carbon compounds containing chemical elements to be reused

Question 456

what is DNA replication, what is it needed for

Answer 456

- production of new strands of DNA with base sequences identical to existing strands - need: reproduction and growth+tissue replacement in multicellular organisms

Question 457

what is the semi-conservative nature of DNA replication

Answer 457

- 2 strands of double helix separate, both og strands used as templates - new strands formed on og strands - new DNA molecule has one og strand and one new strand

Question 458

how does complementary base paring allow high degree of accuracy in copying base sequences

Answer 458

- only nucleotide carrying base complementary to template strand can be hydrogen bonded to each other - ensures two DNA molecules from replication are identical to parent - makes checking for mispairing and fixing it possible in DNA

Question 459

role of helicase in DNA replication

Answer 459

- ring-shaped protein - separates two strands of DNA by unwinding and breaking hydrogen bonds b/w bases

Question 460

role of DNA polymerase in DNA replication

Answer 460

- moves along template strands adding one nucleotide to assemble new strands of DNA - brings nucleotide to position where hydrogen bonds can form

Question 461

what does PCR need

Answer 461

thermal cycler, primers, free DNA nucleotides, taq DNA polymerase

Question 462

steps of PCR

Answer 462

1. denaturation at 95C, DNA is heated to separate into two strands –> all H bonds broken 2. annealing at 45C, small DNA primers attach to opposite ends of target sequence –> DNA cooled 3. elongation at 72C, heat-tolerant taq DNA polymerase copies strands

Question 463

steps of gel electrophoresis

Answer 463

1. DNA samples amplified w PCR 2. DNA cut at specific base sequences 3. fluorescent marker binds to DNA fragments 4. samples added to gel electrophoresis chamber where electric current is passed through, separating DNA molecules by length (longer = moves less) 5. DNA is dyed to be more visible 6. banding pattern shows up that can be analyzed and compared

Question 464

how is used DNA to analyze DNA in paternity testing/forensic analysis

Answer 464

- 13 short tandem repeats (STRs) (2-7 bases repeated each) that is unique to individual - use PCR to amplify and gel electrophoresis to separate fragments of DNA - band will be unique to person

Question 465

how is PCR and gel electrophoresis used in testing of COVID 19

Answer 465

1. acquire DNA sample from nose/throat 2. use reverse transcriptase to convert viral RNA to DNA 3. use PCR to amplify specific viral sequence that are markers of COVID 4. fluorescent markers attach to target DNA, if threshold is met, positive test reuslt

Question 466

pros and cons of PCR test for covid

Answer 466

pros: sensitive, and specific cons: expensive, delayed results

Question 467

how can DNA profiling be make more reliable

Answer 467

- by increasing number of measurements in experiment (ex. increasing # of markers used reduces probability of false match)

Question 468

what is transcription

Answer 468

- synthesis of RNA using DNA template

Question 469

what does RNA polymerase do during transcription

Answer 469

- binds to site on DNA at start of gene that is being transcribed - unwinds DNA double helix separating it into 2 single strands, moving along it - positions correct RNA nucleotides on template strand - links RNA nucleotides by covalent sugar-phosphate bonds - detaches RNA from template, allowing DNA to reform

Question 470

differences of RNA and DNA | in terms of transcription and translation

Answer 470

DNA: has thymine, double stranded RNA: has uracil, single stranded

Question 471

sense vs antisense strands

Answer 471

sense: DNA strand w base sequence to be copied into RNA (coding strand) antisense: has complementary base sequence to sense strand (template strand)

Question 472

what strand of DNA is RNA transcribed from

Answer 472

- the antisense (template) strand - results in a strand of RNA with same base sequence as sense strand of DNA but RNA has uracil not thymine

Question 473

what is stability of DNA templates, importance?

Answer 473

- refers to how DNA base sequence doesn't change after transcription - DNA strands link up again after transcription to prevent any mutation - DNA may be transcribed many times throughout life, instability would mean RNA would accumulate many mutations over time, translated proteins would work less

Question 474

importance of transcription in the expression of genes

Answer 474

- first stage of gene expression - not all genes in cell are always expressed, transcription is key stage where genes are turned on and off - controls proteins produced from transcription to determine observable characteristics of individuals

Question 475

what is translation

Answer 475

process of polypeptide synthesis from mRNA

Question 476

roles of mRNA in translation

Answer 476

- hold information in form of genetic code - single stranded - has site which ribosome can bind - sequence of codons that specifies AA sequence with start and stop codon - mRNA can be translated many time until it is damaged or polypeptide not required

Question 477

roles of tRNA in translation

Answer 477

- translates base sequence of mRA into AA sequence of polypeptide - has anticodon consisting of 3 bases on one end and attachment point for wanted AA on other end - each tRNA molecule has distinctive shape recognized by dedicated activating enzyme to attaches right AA to tRNA

Question 478

roles of ribosomes in translation

Answer 478

- consists of small and large subunits - small: binding site for mRNA - large: three binding sites for tRNA, however only 2 tRNA can bind at any given time - large subunit has catalytic site that makes peptide bonds bw AA to assemble polypeptide

Question 479

relationship bw anticodon vs. codon

Answer 479

anti: the 3 nucleotides forming unit of genetic code on tRNA codon: sequence of 3 nucleotides forming unit of genetic code on mRNA - bases of anticodon must be complementary to codon for tRNA to bind to ribosome and deliver AA

Question 480

why do living organisms used triplet code

Answer 480

- two bases would only form 16 combos, not enough for 20 AA - three bases form 64 combos, enough for 20 AA

Question 481

what does it mean by the genetic code is degenerate

Answer 481

- different codons can code for the same amino acid

Question 482

what does it mean by the genetic code is universal

Answer 482

- genetic code used by all living organisms and viruses, with rare minor changes

Question 483

process of translation

Answer 483

1. activating enzyme that fits tRNA binds to it, attaches specific AA corresponding to anticodon 2. tRNA carrying AA bind to A site on ribosome, complementary base pairing of anticodon to next codon 3. AA of tRNA linked to growing polypeptide with peptide bond, tRNA now holding whole chain 4. tRNA moves from A to P site as result of ribosome moving along mRA by 1 codon 5. polypeptide transferred to new tRNA in A site 6. tRNA moves to E site causing anticodon and codon + tRNA and ribosome to separate 7: cycle repeats

Question 484

affects of gene mutation

Answer 484

- a change to the base sequence of gene - even a single base substitution can change codon to different one - may not affect structure of protein or may affect a lot

Question 485

how is gene mutation present in sickle cell disease

Answer 485

- example of radical change due to single base substitution - mutated gene codes for beta-globin polypeptide in hemoglobin - mutation converts 6th codon of gene from GAG to GTG and allele goes from HbA to HbS

Question 486

consequences of the gene mutation in sickle cell disease

Answer 486

- affects hemoglobin molecules when they are in tissues w low O2 conc - hemoglobin link into chains and distort blood cells into sickle shape - can get trapped in capillaries and damaging tissues, shorter lifespan of RBCs (4 days) - body cannot replace RBC fast enough, leads to anemia

Question 487

what are gene mutations

Answer 487

- random structural changes to genes at the molecular level - should be distinguished from gene editing done by humans

Question 488

what is substitution, how does it occur?

Answer 488

substitution: one base in coding sequence is replace by another - can happen by chemical changes or mispairing during DNA replication

Question 489

what is insertion, how does it occur?

Answer 489

insertion: a nucleotide is inserted, extra base in sequence - requires a break in the sugar-phosphate backbone of DNA

Question 490

what is deletion, how does it occur?

Answer 490

deletion: a nucleotide is removed, one less base in sequence - requires two breaks in sugar-phosphate backbone

Question 491

same sense vs. nonsense vs. mis-sense mutations

Answer 491

same sense: change one codon for an AA to another codon of the same AA nonsense: changes a codon that codes for AA into stop codon mis-sense: changes a codon into one that codes for a different AA

Question 492

are base substitution mutations beneficial or dangerous

Answer 492

- beneficial mutations are outnumbered by deleterious mutations, but more significant - beneficial mutations create new alleles that can be inherited by offspring and inc. genetic diversity

Question 493

what are SNPs

Answer 493

- single nucleotide polymorphisms - position in gene where one base is altered, can lead to new allele - each person has 4000-5000, makes us unique - can be associated with diseases

Question 494

are insertions/deletion mutations beneficial or dangerous

Answer 494

- less likely to be beneficial compared to substitutions - insertions/deletions almost always results in non-functioning polypeptide - result of frameshift mutation

Question 495

what is a frameshift mutation

Answer 495

when a mutation (insertion/deletion) changes the reading frame for every codon onwards in direction of transcription and translation

Question 496

what causes and increases likelihood of gene mutations?

Answer 496

- errors in DNA replication and DNA repair also mutagens - radiation if it has enough energy to chemically change DNA - chemical substances like mustard gas

Question 497

randomness in mutations

Answer 497

- cannot be directed in organism to achieve an intended outcome - no natural mechanisms have been found to change a particular base to a certain trait

Question 498

where can gene mutations occur

Answer 498

- anywhere in base sequences of genome - some bases and positions in genome have higher probability of mutating

Question 499

mutations in somatic cells vs. germ-line cells

Answer 499

somatic: mutations that occur in body cell of someone, cannot be passed to offspring, even if its beneficial germ-line: mutations that occur in testes/ovaries can be passed to offspring, create new allele and may cause genetic disease - determines what the consequences of mutation are

Question 500

what is an allele

Answer 500

a variant of a gene, differing in one or more bases from other alleles

Question 501

how does mutation create genetic variation

Answer 501

- increases # of alleles in gene in population, inc. genetic variation - although most mutations are harmful/neutral it's needed for natural selection

Question 502

how are new cells generated

Answer 502

- a mother cell divides and produces 2 daughter cells thru process of cell division - all cells come from pre-existing cells

Question 503

how does cytokinesis occur in animal cells

Answer 503

- plasma membrane pulled inwards->cleavage furrow - done using ring of contractile proteins (actin and myosin) - when cleavage furrows reaches middle, cell pinched apart

Question 504

how does cytokinesis occur in plant cells

Answer 504

- microtubules at equator assemble vesicles which ruse to from plate-shaped structures - creates 2 layers of membrane at equator which connect to pre-existing plasma membrane to divide cytoplasm - cellulose+pectins+others brought in vesicles and exocytosis bw two new membranes forming cell walls

Question 505

division of organelles in cytokinesis

Answer 505

- all daughter cells must receive one mitochondrion and one of every organelle that can only be made by dividing a pre-existing structure

Question 506

budding of yeast as unequal cytokinesis

Answer 506

- nucleus divides, small outgrowth of mother cell receives one nucleus but only a small bit of cytoplasm - dividing wall constructed, separating cells, leaving scar on mother cell - repeats, do not need to double in size bw each division

Question 507

oogenesis in humans as unequal cytokinesis

Answer 507

- development of female gamete (egg) - meiosis first division produces one large cell w almost all the cytoplasm and a small polar body - second division, results in one large cell and 3 small polar body - large cell develops into oocyte

Question 508

what is the main goal of mitosis and meiosis

Answer 508

- nuclear division to ensure that both daughter cells have a nucleus - anucleate cells cannot synthesize polypeptides, cannot grow/maintain selves

Question 509

role of mitosis in eukaryotes

Answer 509

- produce genetically identical cells (promotes continuity) - daughter cells have same # chromosomes as parent cell - daughter cells have same gene as parent, ensures all cells in organism has all required genes - allows successful genome to be inherited by offspring in asexual reproduction

Question 510

role of meiosis in eukaryotes

Answer 510

- to generate genetic diversity (promotes change) - daughter cells have half as many chromosomes as parent (diploid become haploid) - pairs of genes in diploid mother dealt randomly to daughter cells, variation in genes

Question 511

importance of nuclear division

Answer 511

to prevent the production of anucleate cells

Question 512

what needs to occur before mitosis and meiosis

Answer 512

- DNA replication to ensure each daughter cell receives all gene

Question 513

structure of DNA before and after DNA replication | in relation to cell division

Answer 513

before: DNA exists in nucleus as long single molecules call chromosomes after: pair of identical DNA molecules (chromatids) held together by cohesin loops (still considered same chromosome)

Question 514

condensation of chromosomes

Answer 514

- condensing occurs by wrapping double helix of DNA around histone proteins to form nucleosomes - nucleosomes are linked together - process still not fully understood

Question 515

movement of chromosomes

Answer 515

- kinetochores assembled at centromere of each chromatid - microtubules link with kinetochores at equator of cell and poles at opposite ends - as cohesin loops cut, shortening of spindle microtubules by kinetochores cause sister chromatids to move to opposite poles

Question 516

phases of mitosis

Answer 516

G1, S, G2, PMAT, C

Question 517

interphase before mitosis

Answer 517

- all DNA is replicated and each chromosome consist of two elongated chromatids containing identical DNA held together by cohesin loops

Question 518

prophase of mitosis

Answer 518

- chromosomes condense by packing DNA thicker and shorter - microtubules grow from structure at poles (MTOCs) - nuclear membrane breaks down - kinetochore attached to centromere of chromatid

Question 519

metaphase of mitosis

Answer 519

- microtubules grow from poles, attach to centromere of each chromatid - chromosomes align at equator of cells

Question 520

anaphase of mitosis

Answer 520

- cohesin loops cut, chromatids become separate chromosomes - microtubules and kinetochores work together to bring chromosome to pole - chromosomes reach pole at end of anaphase

Question 521

telophase/cytokinesis of mitosis

Answer 521

- nuclear membrane forms around chromosomes - chromosomes decondense into chromatin - cell divides its cytoplasm (cytokinesis)

Question 522

interphase after mitosis

Answer 522

- gene in decondensed chromosome can be transcribed and mRNA translated to synthesize proteins - cell grows

Question 523

meiosis results in cells that have half the number of chromosomes as its parent, this is called….

Answer 523

reduction division

Question 524

what occurs during interphase in meiosis

Answer 524

- diploid cell - DNA = chromatin G1: synthesis of cell components + growth S phase: DNA replication–> 2 identical strands w centromere held tgt until anaphase II G2: cell prepares for meiosis

Question 525

what occurs during prophase I of meiosis

Answer 525

- nuclear membrane breaks down - spindle fibres form - DNA condenses into chromosomes - synapsis - crossing over

Question 526

what occurs during synapsis of meiosis

Answer 526

where homologous chromosomes pair up into tetrads - genes of chromatids of homologous chromosomes align and attach with each other

Question 527

what occurs during crossing over in meiosis

Answer 527

sections of chromosomes(chiasma) cut + exchanged b/w homologous chromosomes - new combos of alleles created–> combos different from parent

Question 528

what occurs during metaphase I in meiosis

Answer 528

- homologous chromosomes align at cell equator - independent assortment: orientation of each homologous pair is random

Question 529

what occurs during anaphase I in meiosis

Answer 529

- tetreds separate into homologous chromosomes and moves towards opposite side of cell - kinetochores attach chromosomes to spindle fibre *sister chromatids NOT separated

Question 530

what occurs during telophase I and cytokinesis in meiosis

Answer 530

- occurs simultaneously - new nuclei forms around chromosomes DNA uncoils: chromosomes–>chromatin - spindle fibres break apart - left with 2 unique haploid cells

Question 531

what occurs during prophase II in meiosis

Answer 531

- cells are haploid - DNA condenses - nuclear membrane breaks apart - spindle fibres form

Question 532

what occurs during metaphase II in meiosis

Answer 532

- chromosomes align at equator in single file

Question 533

what occurs during anaphase II in meiosis

Answer 533

- sister chromatids pull apart from each other and move to opposite pole of the cell - moved by microtubules

Question 534

what occurs during telophase II and cytokinesis in meiosis

Answer 534

- occurs simultaneously - spindle fibres break apart DNA uncoils: chromosomes–> chromatin END with 4 unique haploid gamete cells

Question 535

what are homologous chromosomes

Answer 535

chromosomes in pairs: one maternal one paternal - Two chromosomes with the same set of genes, in the same sequence, sometimes with different alleles

Question 536

what are tetrads

Answer 536

- aka bivalent chromosomes - pair of homologous chromosomes

Question 537

what do homologous chromosomes have in common

Answer 537

size, centromere location, order of genes

Question 538

what is non-disjunction

Answer 538

errors in chromosome separation during anaphase I or II - results in wrong # of chromosomes

Question 539

what happens if nondisjunction occurs in anaphase I

Answer 539

- one gamete receives 2 copies of chromosome while other gamete receives none -all resulting gametes after meiosis will have incorrect # of chromosomes

Question 540

what happens if nondisjunction occurs in anaphase II

Answer 540

- half of the final 4 gametes will have an incorrect # of chromosomes - other half will be unaffected

Question 541

non-disjunction causing down syndrome

Answer 541

- when someone have 3 copies of chromosome 21instead of 2 - rare case where non-disjunction isn't lethal

Question 542

how does meiosis promote genetic diversity using independent assortment

Answer 542

- bivalents (tetrads) are oriented in random directions (independent assortment) during metaphase I and II - orientation of one bivalent doesn't affect others - allows daughter cells to have variety of genes

Question 543

how does meiosis promote genetic diversity by crossing over

Answer 543

- two non-sister chromatids brought together at same point along gene sequences and parts of DNA are swapped - at least one crossover occurs in each bivalent - creates chromatids with new combos of alleles

Question 544

what is solvation

Answer 544

combination of a solvent with molecules/ions of a solute

Question 545

how does solvation in water occur

Answer 545

- polar solutes dissolve as + charged ions attracted to -O pole and - charges ions attracted to +H2 pole - attractions cause hydrogen bonds where water forms shells around ions, preventing them from precipitating (now dissolved)

Question 546

water movement bw solutions of different concentrations

Answer 546

- attraction b/w solute and water is stronger than water-water, restricts movement of water molecules - water always moves in both directions however net movement from less concentrated (hypotonic) solutions to more concentrated (hypertonic) solutions

Question 547

hypotonic vs. hypertonic vs. isotonic solutions

Answer 547

hypo: less concentrated hyper: more concentrated iso: equally concentrated

Question 548

water movement bw solutions of same concentration

Answer 548

- moves both ways equally rather than not move at all

Question 549

properties of plasma membranes

Answer 549

- made of phospholipids - thin (5nm or less) - liquid state, allows changes of position - very low tensile strength - semi-permeable

Question 550

properties of cell walls

Answer 550

- made of cellulose - thick (250nm-5μm) - solid state, changes in position limited - high tensile strength, stronger than steel - freely permeable unless impregnated w waterproof material

Question 551

what happens to cells that lack a cell wall in isotonic, hypertonic, and hypotonic solutions

Answer 551

iso: stays normal hyper: water leave thru osmosis, cell shrinks and develops crenations (indentations) from water loss hypo: water enters thru osmosis, cell swells, easily can burst

Question 552

how do freshwater unicellular organisms perform osmoregulation

Answer 552

- water moves from freshwater->cell - use contractile vacuoles to remove excess water from cytoplasm to prevent cell from bursting

Question 553

what happens to cells with a cell wall in isotonic, hypertonic, and hypotonic solutions

Answer 553

iso: stays normal hyper: pressure in cell decreases, no longer pushes against cell wall, plasma membrane pulls away from cell wall (plasmolysis) hypo: high pressures of water can build up and cell can become turgid<- normal state of plant cells as it provides support to plant

Question 554

importance of isotonic solutions in medical environments

Answer 554

- allows water molecules to pass in and out thru plasma membrane at same rate, preventing dehydration and swelling of human cells

Question 555

when are isotonic solutions used in medical environments

Answer 555

- intravenous drip - rinse off wounds - keep areas of damaged skin moist before skin grafts - basis for eyedrops - stores donor organs

Question 556

features of asexual reproduction

Answer 556

- one parent needed - mitosis to make genetically identical offspring - existing gene combos maintained - no genetic variation generated - organisms adapted to unchanging environment produced adapted offspring

Question 557

features of sexual reproduction

Answer 557

- tow parents needed - meiosis to made genetically different offspring - new gene combos produces - genetic variation created - offspring may be better adapted to changing environment

Question 558

role of meiosis and fusion of gamete in sexual lifecycle

Answer 558

- fusion of gametes = fertilization - fertilization doubles # of chromosomes, meiosis halves it to maintain correct # - meiosis makes parental combos of genes break and form new combos

Question 559

male gametes vs. female gamtes

Answer 559

male: travel to female, smaller, small food reserves, produced in a large # female: sessile, larger, big food reserves to develop embryo, few produced

Question 560

follicular phase of menstrual cycle

Answer 560

- first half of ovarian cycle - group of follicles develops on ovary, egg stimulated to grow in each - most developed follicle breaks open, releasing egg into oviduct (ovulation) - other follicles degenerate

Question 561

luteal phase of menstrual cycle

Answer 561

- second half of ovarian cycle - wall of follicle that released egg develops into corpus luteum - if fertilization doesn't occur, corpus luteum breaks down and ovary returns to follicular phase

Question 562

uterine cycle of menstrual cycle

Answer 562

- changes that occur to endometrium (lining of uterus) during menstrual cycle - menstruation marks beginning of uterine cycle - from there, endometrium becomes thicker in prep for embryo - no embryo, endometrium starts breaking down and shed

Question 563

where are the hormones that regulate the menstrual cycle produced

Answer 563

pituitary gland: FSH (follicle stimulating hormone), and LH (luteinizing hormone) wall of follicle (ovarian steroid hormones): oestradiol, progesterone

Question 564

when does hormone FSH peak

Answer 564

- towards the beginning and middle of the cycle - stimulates development of follicles, each containing oocyte and follicular fluid - stimulates secretion of oestradiol

Question 565

when does hormone oestradiol peak

Answer 565

- near end of follicular phase (day 14) - stimulates repair and thickening of endometrium - increases FSH receptors, making follicles more receptive to FSH, boosting oestradiol production (pos. feedback loop) - at high levels, oestradiol inhibits secretion of FSH (neg. feedback loop), stimulates LH secretion

Question 566

when does hormone LH peak

Answer 566

- sharp peak at end of follicular phase (day 14) - stimulates completion of meiosis in oocyte, makes follicle wall burst open at ovulation - promotes development of follicle wall into corpus luteum which secretes oestradiol and progesterone causing them to peak (day 21)

Question 567

when does hormone progesterone peak

Answer 567

- rise at start of luteal phase, peak at day 21, drop by end of luteal phase - promotes thickening and maintenance of endometrium - inhibits FSH and LH secretion by pituitary gland (neg. feedback loop_

Question 568

how does sperm reach egg in fertilization

Answer 568

- plasma membrane of sperm have receptors to detect chemical released by egg - directional swimming towards egg

Question 569

how do sperm and egg fuse

Answer 569

- sperm binds to egg plasma membrane, sperm nucleus enters egg cell <- moment of fertilization - immediately after, glycoprotein around egg hardens, preventing entry of more sperm - sperm tail +mitochondria doesn't penetrate or broken down in zygote

Question 570

what happens after sperm and egg fuse

Answer 570

- nuclei kept separate until zygote's first mitosis when nuclear membranes break down - participate jointly in mitosis, results in 2 genetically identical diploid nuclei each w 46 chromosomes

Question 571

how are hormones used in IVF

Answer 571

- normal secretion of hormones suspended, artificial doses of FSH given to stimulate superovulation <- allows control over timing of egg production - eggs can be harvested and fertilized in petri dish

Question 572

production of pollen (male gametes)

Answer 572

- in anther, diploid cells go thru meiosis to produce haploid pollen grains in each pollen grain, the haploid nucleus creates 3 copies of self - 2 are male pollen gametes - 1 used for gene expression during pollen development and fertilization

Question 573

production of plant eggs (female gametes)

Answer 573

- in carpel (pistil) ovary and stigma connected by style (hollow tube) - ovary has 1+ ovules, and cell in center of ovule goes thru meiosis to produce 4 haploid nuclei - each one divides 3 times by mitosis = 8 total - 1 becomes egg - others help embryonic development + fertilization

Question 574

pollination vs. fertilization in plant

Answer 574

p: transfer of pollen from anther to stigma by wind/animals etc. f: pollen grains go thru tube to an ovule in ovary where pollen grains are released to fertilize egg

Question 575

what does it mean if a flower is hermaphrodite

Answer 575

- aka "perfect flowers" - it contains both male and female parts - still sexual reproduction

Question 576

what is a cotyledon

Answer 576

an embryonic seed leaf - typically first leaves to appear from germinating seed - can be one (monocotyledon) or 2 (dicotyledon)

Question 577

features of insect-pollinated flowers

Answer 577

- large, bright petals +scent to appeal and to be landing stage - large, spiky pollen grains to stick onto insects - stick stigma to collect pollen - glands secrete nectar to attract insects as fuel<- deep in flower so insect must brush past anthers and stigma

Question 578

what is cross-pollination, importance

Answer 578

transfer of pollen from an anther on one plant to the stigma of another plant - promotes genetic variation and evolution

Question 579

strategies of plants to promote cross pollination

Answer 579

- separation of anthers and stigma on same plant (ex. diff heights) - separation of anthers and stigma on different plants (only male parts or female) - anthers and stigmas maturing at different times - use of outside agents to transfer pollen to different plants

Question 580

why could self pollination be a problem

Answer 580

- no genetic diversity - recessive traits are amplified - inbreeding depression (rare recessive genes paired together) - heritable characteristics are amplified, less healthy

Question 581

self-incompatibility mechanism

Answer 581

- pollen can fail to germinate or pollen tube stops growing before reaching ovary due to rejection of self-proteins or cells (opposite of human immune system)

Question 582

what is protandry vs. protogyny

Answer 582

protandry: when anthers of plant mature first protogyny: when stigma of plant matures first

Question 583

seed dispersal vs. pollination

Answer 583

sd: seeds transferred from female parent to germination site by wind/animals/explosion p: pollen transferred from anther to stigma by wind/animals

Question 584

common ways of seed dispersal

Answer 584

- dry and explosive - fleshy+attractive for animals to eat - feathery+winged to catch wind - covered in hook to catch coats of animals

Question 585

how does seed germination work, what does it require

Answer 585

- requires: oxygen, water, warmth - food reserves (starch) are mobilized, digested then transferred to the growing embryo

Question 586

inheritance in eukaryotes with a sexual life cycles | gametes -> zygotes

Answer 586

- haploid gamete produced in parents and fused to form a diploid zygote - zygote has two copies of each autosomal gene (one from each parent)

Question 587

method of creating genetic crosses in flower plants

Answer 587

- paint brush can brush anther to get pollen then dabbed onto stigma - anthers must be cut off, and flower in an enclosed area to prevent other pollen from reaching it

Question 588

P vs. F1 vs. F2 generation

Answer 588

P: parents F1: offspring in seeds inside of parent F2: offspring of F1

Question 589

what is a genotype

Answer 589

combination of alleles inherited by an organism

Question 590

homozygous vs. heterozygous genotypes

Answer 590

homo: ex. DD, dd, as all gametes that can be produced will have this allele of the gene hetero: ex. Dd, as all gametes will have different alleles of the gene

Question 591

what is a phenotype

Answer 591

- observable traits of an organism resulting from genotype and environmental factors

Question 592

traits affected by genotype/phenotype and both

Answer 592

genotype only: eye colour, haemophilia, ABO blood groups phenotype only: languages, scars, body art both: skin colour, height, diabetes

Question 593

what is phenotypic plasticity

Answer 593

- capacity to develop traits suited to the environment experienced by an organism - occurs by varying patterns of gene expression

Question 594

how does phenotypic plasticity work

Answer 594

- genes are switched on and off, not changed to new alleles - typically is reversible

Question 595

normal vs. diseased allele in phenylketonuria

Answer 595

normal: codes for functioning phenylalanine hydroxylase, an enzyme that converts AA phenylalanine to another AA called tyrosine diseased: codes for non-functioning phenylalanine hydoxylase so phenylalanine from diet is not processed efficiently

Question 596

what occurs in phenylketonuria

Answer 596

- phenylalanine isnt processed, accumulates, tyrosine is deficient - nerve cells in developing brain are very sensitive to phenylalanine levels so excessive amounts lead to brain damage

Question 597

current treatment for phenylketonuria

Answer 597

- prevent foods with high phenylalanine content from entering diet from birth - PKU no longer causes intellectual and developmental disabilities in infants

Question 598

what is a gene pool, how does it relate to evolution

Answer 598

- all the genes of all the individuals in a sexually reproducing population - every individuals gets max of 2 genes from gene pool - changes in gene pool = evolution

Question 599

how is the S-gene an examples of multiple alleles

Answer 599

- system that prevents inbreeding in apples - 32 different S-alleles discovered - each apple tree has 2 copies of S-gene and pollen grains each contain one of these (ex. if S2S3 genotype, 50% of pollen will be S2 and 50% S3) - when pollen germinates stigma of another flower/tree, rejected if S-alleles are the same

Question 600

6 genotypes of 4 phenotypes of blood type

Answer 600

type A: IAIA, IAi type B: IBIB, IBi type O: ii type AB: IAIB

Question 601

how do IA, IB, i alter the blood cell

Answer 601

IA: adds acetylgalactosamine into glycoprotein IB: adds galactose onto glycoprotein i: doesn't cause any alteration to basic glycoproteins

Question 602

what antibodies will type A, type B, type AB and type O blood have

Answer 602

A: anti-B B: anti-A AB: none O: anti-A and anti-B

Question 603

what is the rhesus factor

Answer 603

- a protein on RBC that creates positive and negative blood types controlled by D+ or D- alleles pos: have rh antigens neg: do not have rh antigens

Question 604

what is incomplete dominance

Answer 604

- when heterozygous alleles blend and offspring has a combo/mixture of both alleles (intermediate phenotype) - ex. 4 o'clock flower can be red or white when homozygous and pink when heterozygous

Question 605

what is codominance

Answer 605

- when heterozygous alleles exist independently but with each other (dual phenotype) - ex. AB blood type will have blood cells with A structure and some with B structure

Question 606

sex in humans

Answer 606

- by 23rd pair of chromosomes (X and Y) - all humans have an X chromosome which has 900 genes, needed for female and male development - males have Y chromosome which has genes only needed for male development

Question 607

how is the sex of a baby determined

Answer 607

- all females will pass down an X chromosome, doesnt affect sex of offspring - males will pass down either X (female offspring) or Y (male offspring) chromosome in sperm

Question 608

how do males develop in the womb

Answer 608

- SRY gene (testis determining factor, TDF) on Y chromosome causes embryonic gonads to develop into testes - tests start secreting testosterone, develops other male organs

Question 609

how doe females develop in womb

Answer 609

- gonads develop into ovaries by default - ovaries start secreting oestradiol, causes female reproductive system to develop

Question 610

sex linkage as an inheritance pattern

Answer 610

- where a trait/disorder is linked to genes located on X or Y chromosomes - more commonly linked onto X chromosome as its larger - leads to males more likely to get sex linked recessive traits as they only have 1 X chromosome

Question 611

sex linkage vs gene linkage

Answer 611

sex: trait/disorder linked to gene located on sex chromosomes gene: two or more genes being located close together and tend to be inherited together - two genes can be gene-linked and sex-linked if located close together on X chromosome

Question 612

how are alleles carried on X chromosomes shown

Answer 612

as a superscript on the X

Question 613

haemophilia as a sex-linked genetic disorder | what is the mutation

Answer 613

haemophilia - where blood doesn't clot properly - has defective form of factor VIII, located on X chromosome - females may be carrier of allele but don't show symptoms as they have another X chromosome

Question 614

why is inbreeding in humans harmful

Answer 614

- many genetic disorders are caused by rare recessive alleles, both parents must have allele to pass onto offspring - chances of this are much higher during incest

Question 615

continuous vs. discrete variation

Answer 615

cont: range is possible, no distinct categories, influenced by environment and multiple genes if there's genetic cause dis: separate categories of variation, no intermediates, influenced by 1 or few genes if there's genetic cause, usually not affected by environment

Question 616

how is skin colour an example of continuous variation

Answer 616

- partly due to environment/sunlight which affect amount of melanin produced - shows evolution in humans, ancestors had developed skin colours based on how much sunlight they were exposed to + in order to get vitamin D

Question 617

what is polygenic inheritance

Answer 617

traits determined by multiple genes, leading to continuous phenotypes

Question 618

what is homeostasis

Answer 618

the maintenance of the internal environment of an organisms to keep variables as close to optimal as possible

Question 619

feedback loops in homeostasis

Answer 619

- positive feedback loops create change rather than stability, not used for homeostasis - negative feedback loops maintains gap bw original and new levels - uses a lot of energy but keeps internal environment in narrow limits, allowing organisms to survive

Question 620

what is involved in blood glucose regulation

Answer 620

- kept within narrow limits, must balance glucose removed/added to blood - set point ~5mmol/L - regulated by insulin and glucagon <- secreted by cells in pancreas “isle of langerhans”

Question 621

what must happen when blood glucose levels drop in order to maintain homeostasis

Answer 621

- pancreas detects it - alpha cells make+secrete glucagon hormone which signals liver to convert stored glycogen into glucose which is then released into blood - blood glucose levels increase

Question 622

what must happen when blood glucose levels rise in order to maintain homeostasis

Answer 622

- pancreas detects it - beta cells make+secrete insulin which allow skeletal muscle cells + liver to store glucose and convert it to glycogen - blood glucose levels decrease - insulin broken down by target cells which means secretion must be ongoing

Question 623

what occurs when someone has type 1 diabetes

Answer 623

- body cannot produce enough insulin because of destructions of beta cells in isle of Langerhans by immune system - autoimmune disease - sudden onset

Question 624

treatments for type 1 diabetes

Answer 624

- test blood glucose level regularly - inject insulin when too high/before eating - implant devices to release insulin - stem cell treatment to create new beta cells (in development!)

Question 625

what occurs when someone has type 2 diabetes

Answer 625

- cannot respond to insulin bcus lack of insulin receptors or glucose transporters on target cells - slow onset risk factors: unhealthy diets, prolonged obesity, genetic factors

Question 626

treatments for type 2 diabetes

Answer 626

frequent, smaller meals to avoid peaks of glucose avoid sugary foods eat food w/ low glycemic index and high fibre (slower digestion) exercise and weight loss to improve insulin uptake

Question 627

what is diabetes, what does it do, what are the symptoms?

Answer 627

- consistently elevation blood glucose levels - damages tissues+proteins - prevents water reabsorption in kidneys symptoms: constant thirst/urination/tiredness/sugar cravings/glucose in urine

Question 628

how is body temp monitored

Answer 628

- by thermoreceptors which are free nerve endings of specialized sensory neurons - sensory inputs from peripheral/central thermoreceptors to hypothalamus - initiates response if hypothermia or hyperthermia

Question 629

tissues as effectors of temperature change

Answer 629

- muscles contract to release heat - subcutaneous adipose tissue (insulation) prevents heat loss - brown adipose tissue generated heat at rapid rate

Question 630

how is heat generated by cells for thermoregulation

Answer 630

- by metabolism - hypothalamus secretes thyrotropin releasing hormone (TRH) - goes to pituitary gland which releases thyroid stimulating hormone (TSH) - TSH is a glycoprotein that stimulates thyroxin secretion in thyroid gland - thyroxin increases metabolic rate of cells

Question 631

vasoconstriction as a bodily response to cold

Answer 631

- constriction of arterioles in skin - less blood flow to skin preventing heat loss

Question 632

shivering as a bodily response to cold

Answer 632

muscles contract involuntarily to cause movement to generate heat

Question 633

uncoupled respiration as a bodily response to cold

Answer 633

- when energy from mitochondria doesn’t produce ATP but rather heat - brown adipose tissue has a lot of mitochondria (gives it the brown colour) - mitochondria oxidizes fat and converts all energy to heat

Question 634

hair erection as a bodily response to cold

Answer 634

- thick coat allows air b/w hairs which acts like thermal insulator - erector muscles move hairs to increase insulating effect

Question 635

vasodilation as a bodily response to heat

Answer 635

- circular muscles relax, arterioles dilate - more blood flow to skin encouraging heat loss

Question 636

sweating as a bodily response to heat

Answer 636

- sweat secreted by glands in skin <- controlled by hypothalamus - water is evaporated, solutes remain, giving salty taste - water has high latent heat of vapourization, cooling effect

Question 637

types of thermoreceptors

Answer 637

- there are cold and warm receptors - peripheral thermrec. are located near skin to sense outside temp - central thermrec. located in body to sense core temp

Question 638

how is natural selection achieved

Answer 638

- organisms produce more offspring then environment can support - offspring are variated, ones better suited for environment will live "survival of the fittest" - successful offspring will produce more offspring - occurs over many years

Question 639

what is a paradigm shift, ex

Answer 639

- when observations accumulate and are more easily explained by a new paradigm/theory than an existing one - ex. lamarkism -> darwinism

Question 640

role of mutations in natural selection

Answer 640

- creates new alleles, enlarging gene pool - original source of variation - only source of variation in non-sexual reproducing organisms

Question 641

role of sexual reproduction in natural selection/variation

Answer 641

- meiosis produces new combos of alleles thru crossing over and independent orientation of bivalents - fusion of male and female gametes creates new combos of alleles, bringing mutations of diff individuals tgt

Question 642

how does overproduction of offspring and competition for resources promote natural selection

Answer 642

- breeding rate higher than available resources to support - only the organisms that have the most successful adaptations will survive and reproduce, allows more offspring to inherit the adaptation

Question 643

how are abiotic factors selection pressures

Answer 643

- differences in tolerance to abiotic factors is basis of selection - ex. cold temps affects all organisms in area, but only ones tolerant to it will remain/live in area

Question 644

how does intraspecific competition affect natural selection

Answer 644

- fitness: how well-adapted individual is - fitness influences lifespan, if they're able to reproduce, number of offspring - fitter individuals live long enough to have offspring, and have many allowing them to contribute more to gene pool of next generation

Question 645

what kind of traits are not heritable

Answer 645

- traits developed during lifetime (acquired traits) bcus they don't alter genes - typically genes inherited from environment are not heritable as they don't change base sequence - doesn't support evolution

Question 646

how is sexual selection a selection pressure

Answer 646

- if both mates are well adapted, offspring is likely to survive, if one mate is not well adapted, offspring more likely to die - differences in physical/behavioural traits can be used as signs of fitness of mate, attracts mate, driving evolution - ex. thru courtship

Question 647

sexual selection in birds of paradise, why do females like exaggerated traits?

Answer 647

- males have elaborate plumage and carry out vigorous dances, indicating it can obtain enough nutrition to grow and make energy - males being able to survive in rainforest with elaborate plumage shows it's survival skills and how well it's adapted - females are more likely to choose males w these traits, more offspring will have these traits too

Question 648

conclusions from endler's guppy experiment

Answer 648

- investigated effect of predation on physical traits of guppies colouration: more attractive to females but more visible to predator - therefore, fewer predators = more colourful guppies, more predators = less colourful guppies

Question 649

what does an ecosystem being stable mean

Answer 649

- that it can continue indefinitely because of the sustainable mechanisms within - ex. daintree rainforest in australia has lasted 180M years <- contains ancient plant famillies

Question 650

requirements for stability in an ecosystem

Answer 650

- steady supply of energy - nutrient cycling with no leakages - individual species must have high genetic diversity to survive selection pressures (high biodiversity typically means stable ecosystem)

Question 651

what interferes with ecosystem stability

Answer 651

- harvesting/removal of materials from environment - erosion (results in loss of nutrients) - eutrophication can cause population inbalances - removal of species by epidemics/poaching, especially if keystone

Question 652

what is eutrophication

Answer 652

- nutrient enrichment in a body of water due to run off from land - causes overgrowth of algae and plants, disrupting ecosystem

Question 653

what is a tipping point

Answer 653

- an ecological threshold that's difficult to reverse - creates abrupt change in ecosystem if reached

Question 654

how is deforestation of amazon rainforest a potential tipping point in ecosystem stability

Answer 654

- deforestation-> decrease in forest cover -> reduces amount of transpiration from plants ->decrease in cloud formation -> reduces rainfall - can leads to droughts which can lead to fires and more loss of ecosystem - unsure when the ecosystem will stop being able to sustain itself and pass tipping point

Question 655

what are mesocosms

Answer 655

- small experimental areas set up as ecological experiments - can vary one or more variables to examine outcome

Question 656

what is required for a mesocosm to work

Answer 656

- clear jars so that energy(sunlight) and enter - decomposers to recycle energy from dead matter - autotrophs to create carbon compounds and oxygen

Question 657

what is a keystone species

Answer 657

- when one species has a disproportionate effect of the structure of an ecological community - risk ecosystem collapse if removed

Question 658

requirements for sustainability in an ecosystem

Answer 658

- nutrient availability-> nutrients recycled and never a lack of chemical elements in which life is based - detoxification of waste products -> used up by another organisms before they become toxic in environment - energy availability -> energy cannot be recycled, needs energy supply (sun)

Question 659

sustainable harvesting of brazil nuts

Answer 659

- grow in trees of amazon <- over harvesting will lead to no new young trees - in order to be sustainable, some nuts are left behind in order to germinate and grow into new trees

Question 660

sustainable harvesting of atlantic cod

Answer 660

- overfished in 1990s <- population almost went extinct - fish are open access resource so conservation was limited - in order to be sustainable now, fish must stay in range of max. sustainable yield (fishing must occur slower that rate of population growth)

Question 661

tillage as an example of unsustainable agricultural practices

Answer 661

- the process of preparing soil for a crop - soil becomes degraded and erodes quickly

Question 662

nutrient depletion as an example of unsustainable agricultural practices

Answer 662

- when crops are removed, nutrients are depleted (desertification) - when there are no nutrients, farmers use chemical fertilizers which leach into water sources and cause eutrophication

Question 663

monocultures as an example of unsustainable agricultural practices

Answer 663

- same crop grown year after year in large areas - increases pests, weeds and causes nutrient loss in soil

Question 664

mechanical tillage as an example of unsustainable agricultural practices

Answer 664

use of diesel oil in tractors/heating greenhouses - high carbon footprint

Question 665

what happens to a body of water when eutrophication occurs

Answer 665

1. nutrients (nitrate and phosphate fertilizers) go from land to water 2. aquatic plants grow rapidly 3. algae grows rapidly 4. algae bloom blocks sunlight from aquatic plants = water O2 levels fall 5. decomposition rate increases, aerobic respiration of decomposers reduce O2 further 6. greater biochemical oxygen demand (BOD) 7. death of organisms that require oxygen

Question 666

what is bioaccumulation

Answer 666

- build up of toxins in tissue of organisms over time (ex. mercury) - toxins that are fat soluble are not easily excreted, stay in adipose tissue

Question 667

what is biomagnification

Answer 667

increase in chemical concentration in individual organisms going up the food chain - predators consume large quantities of prey which have bioaccumulation in their tissues

Question 668

why are macroplastics and microplastics dangerous to the oceans

Answer 668

- can cause entanglement, accidental ingestion, accumulation of toxins - degrade very slowly, releasing toxic carbon compounds into ocean

Question 669

what is rewilding, what is done during this process

Answer 669

practice of returning natural ecosystems to their original state - stop human resource harvesting in area - allow natural processes to restore habitat - interventions may be taken to speed up restoration

Question 670

what are some possible rewilding interventions

Answer 670

- distribute seeds of missing plants - reintroduce apex predators and keystone species - connect ecosystems broken by fragmentation - control invasive species

Question 671

hinewai reserve as successful example of rewilding

Answer 671

- 1250 hectors of farmland returned to natural forest - alien mammals controlled w/ little interference by humans - invasive species eliminated by better adapted native species - however climate change and extreme weather are still threats

Question 672

how do humans contribute to CO2 and methane production, causing climate change?

Answer 672

- CO2: combustion and biomass and fossil fuels, cell respiration - methane: emitted from marches/waterlogged habitats, landfill sites

Question 673

snow/ice melting as positive feedback cycle in global warming

Answer 673

- snow/ice = high albedo<- reflects solar radiation - water = low albedo - as polar/sea ice melts, more water exposed, darker and absorbs more radiation, further accelerates polar ice cap melting

Question 674

melting of permafrost as positive feedback cycle in global warming

Answer 674

- permafrost: ground that remains frozen year round - contains frozen detritus when begins to decay as permafrost melts (cus global warming) - decay releases more methane, contributing to GHG, accelerating global warming

Question 675

rising ocean temps as positive feedback cycle in global warming

Answer 675

- solubility of gas in water decreases as temp increases - as temp of ocean rises, more CO2 released into atmosphere, raising global temp

Question 676

melting of frozen hydrated methane cap as positive feedback cycle in global warming

Answer 676

- stores of methane can have frozen cap so methane can’t escape - as ocean warms, cap may dissolve, releasing large amounts of methane which leads to more warming

Question 677

increase in forest fires/droughts as positive feedback cycle in global warming

Answer 677

- higher temps -> decreased humidity -> dry plants - increases risk of forest fires which emit a lot of CO2 and kill trees - reduced carbon capture in trees leads to more warming

Question 678

why do boreal forests act as carbon sinks how may it reach its tipping point and shift to a carbon source

Answer 678

colder temps reduce cellular respiration and decay rate - may shift into carbon source when tipping point is reached - with increasing temps, forest fires increase <- after fires, boreal forests may be replace w more temperate forests with less trees

Question 679

pack ice vs landfast ice

Answer 679

moves with the wind and ocean currents vs. "fastened" to the shore and doesn't move

Question 680

how does a loss of ice affect emperor penguins

Answer 680

- breeds on landfast ice away from the shore (flatter, easier to move on) - landfast ice becoming unpredictable-> breeding locations cannot be safely found - breeding too close to shore=more predation, breeding too far from shore = difficult to return to shore for feeding

Question 681

how does a loss of ice affect walruses

Answer 681

- uses pack ice to rest b/w feeding and shelter from sea and predators - sea ice of preferred for breeding becus of space and feeding range pack ice is melting = walruses now must travel further from land to feed/expend more energy keeping warm in cold waters

Question 682

what does it mean that ocean is stratified

Answer 682

- made up of layers - warmer less salty water floats on top of cooler saltier water

Question 683

how does climate change affect ocean stratification

Answer 683

- warmer climate = surface of ocean warms and expands volume <- causes ice to melt adding freshwater and decreasing salinity - creates larger diff in density=slower mixing = inhibits transport of heat, oxygen, CO2 throughout ocean

Question 684

how is ocean stratification and climate change a positive feedback loop

Answer 684

- warm water on top cannot absorb as much CO2-> more CO2 in atmosphere->more warming - warm water cant absorb as much O2 and it’s harder to mix with deeper cooler layers

Question 685

how does climate change affect nutrient upwelling

Answer 685

- most active biological zone at top 100m of ocean, where sunlight penetrates and photosynthesis occurs - warmer surface water can prevent nutrient upwelling to surface decreasing ocean primary production and energy flow thru marine food chains

Question 686

how does climate change affect ocean currents

Answer 686

- deep water currents approach continental shelves and are forced upwards carrying nutrients (upwelling of nutrients) providing important nutrient cycling - warming of ocean=more stratification=decreased currents=reduces upwelling-> disrupts ecosystems

Question 687

upslope range shifts as result of climate change

Answer 687

- as temps rise, species migrate upslope to cooler temps that match their optimal temp - species at highest points cannot move higher can become threatened and extinct - competitive exclusion occurs as new competition arrives

Question 688

poleward range shifts as result of climate change

Answer 688

- warmer temps lead to shift of latitude range of populations - not migration, due to relative deaths and colonizations at northern and southern boundaries of range (ex. net extinction @ S boundary and net colonization @ N boundary will make shift up)

Question 689

how does ocean acidification affect corals

Answer 689

- increased CO2 conc. cause ocean acidification which suppresses calcification in corals as inc. CO2 levels make Ca levels very low due to interrelated chemical reactions - coral bleaching (expelling zooxanthallae) as result of rising ocean temps - keystone species, extinction could collapse ecosystem

Question 690

how does climate change affect coral-zooxanthellae relationship

Answer 690

- algae benefits from access to sunlight from coral, coral benefit from carbs from algae - loss of mutualistic symbiosis with zooxanthellae (algae) due to temp increase<- water too warm = algae ejected from coral leading to coral bleaching and death

Question 691

what is carbon sequestration

Answer 691

the storage of carbon dioxide from the atmosphere and removal of CO2 from carbon cycle

Question 692

what is afforestation as an approach to carbon sequestration

Answer 692

planting trees in an area where they currently don't exist - approach to address climate change - trees naturally store carbon for photosynthesis

Question 693

peat-forming wetlands as an approach to carbon sequestration

Answer 693

- wetlands are the world's largest carbon sink - dry peat is major fire hazard, must be monitored well - monitoring includes restoration of water levels, blocking drainage, re-establishing native species

Question 694

structure of polysaccharides (cellulose)

Answer 694

- 710,000 beta glucose monomer - 1,4 glycosidic bonds oriented n alternating directions - straight, unbranched chains (can be packed tightly) - not soluble in water

Question 695

properties/function of polysaccharides (cellulose)

Answer 695

- high tensile strength (ability to be stretched) - bundles of microfibrils (often made of cellulose) compose cell wall, preventing it from bursting

Question 696

structure of polysaccharides (amylose)

Answer 696

- thousands of alpha glucose - 1,4 glycosidic bonds oriented in same direction - curved, unbranched chains - hydrophilic, however too large to be soluble in water (doesn’t affect osmotic balance)

Question 697

properties/function of polysaccharides (amylose+amylopectin)

Answer 697

- only made by plant cells - molecules vary in size, easy to add/remove glucose units - useful for glucose/energy storage, glucose can be converted to starch for storage then hydrolyzed when needed (amylopectin more ideal, more free ends)

Question 698

structure of polysaccharides (glycogen)

Answer 698

- 10,000 alpha glucose - chain of 1,4 glycosidic bonds w 1,6 bonded branches - curved and branched chains - lower solubility than glucose, doesn’t affect osmotic balance

Question 699

properties/functions of polysaccharides (glycogen)

Answer 699

- compact, easy to add/remove - good for storage since doesn’t affect osmotic balance (insoluble) - stored in liver and muscles of human

Question 700

structure of polysaccharides (amylopectin)

Answer 700

- 100,000 alpha glucose - 1,4 chain, 1,6 branches - oriented in same way throughout curved + branched chains - hydrophilic, but too big to be soluble in water (doesn’t affect osmotic balance)

Question 701

function of testes

Answer 701

to produce sperm and testosterone

Question 702

function of scrotum

Answer 702

holds testes at lower than core body temp

Question 703

function of epididymis

Answer 703

stores sperm until ejaculation

Question 704

function of sperm duct

Answer 704

transfers sperm during ejaculation

Question 705

function of seminal vesicle and prostate gland

Answer 705

secrete fluid containing alkali, proteins and fructose that is added to sperm to make semen

Question 706

function of urethra

Answer 706

transfers semen during ejaculation and urine during urination

Question 707

function of penis

Answer 707

penetrates the vagina for ejaculation of semen near the cervix

Question 708

function of ovary

Answer 708

produces eggs, oestradiol and progesterone

Question 709

function of oviduct

Answer 709

collects eggs at ovulation, provides a site for fertilization then moves the embryo to uterus

Question 710

function of uterus

Answer 710

provides for the needs of the embryo and foetus during pregnancy

Question 711

function of cervix

Answer 711

protects foetus during pregnancy and then dilates to provide birth canal

Question 712

function of vagina

Answer 712

stimulates penis to cause ejaculation and provides birth canal

Question 713

function of vulva

Answer 713

protects internal parts of female reproductive system

Question 714

what is tidal volume (TV)

Answer 714

amount of air that can be inhaled or exhaled during one respiratory cycle

Question 715

what is vital capacity (VC)

Answer 715

total air exhaled after max. inhalation and vice versa

Question 716

what is residual volume (RV)

Answer 716

volume of air remaining in lungs after max. exhalation

Question 717

what is total lung capacity (TLC)

Answer 717

max volume of air lungs can accommodate TLC = VC +RV

Question 718

what is inspiratory reserve volume (IRV)

Answer 718

air forcibly inhaled after normal tidal volume (after normal inhale)

Question 719

what is expiratory reserve volume (ERV)

Answer 719

air forcibly exhaled after exhalation of normal tidal volume

Question 720

what is inspiratory capacity (IC)

Answer 720

max volume of air inhaled following resting state (normal exhale)

Question 721

what is functional residual capacity (FRC)

Answer 721

amount of air remaining in lungs after normal exhalation

Question 722

structure of transverse section of dicot root

Answer 722

- star in middle (xylem) with circles around it (phloem) surrounded by a thin layer of cells (endodermis) - layer of unspecialized cell to bulk out root (cortex) surrounded by another layer of cells (epidermis)

Question 723

plant plan diagram of stem

Answer 723

- has area in middle (pith) with a ring (cambium) - on the inside of the ring, protrudes (xylem) and on the outside protrudes (phloem) - surrounding the phloem is the (cortex) surrounded by the (epidermis)

Question 724

plant plan diagram of a leaf

Answer 724

- from up to down: upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis - vascular bundle b/w mesophyll with xylem on top and phloem under it - guard cells/stomata in lower upidermis

Question 725

positive vs negative vs no association in chi-squared test

Answer 725

pos: species are found in same habitat neg: species occur separately in different habitats no: species occur as frequently apart as together

Question 726

what is the BRCA1 gene

Answer 726

- a proto-oncogene that codes for BRCA1 in humans - tumor suppressor gene-> works in DNA repair, mends double strand breaks+fixes mispairings

Question 727

consequences of mutation in BRCA1 gene

Answer 727

- increased risk of other mutations bcus lack of DNA repairs - increases risk of breast/ovarian/prostate cancers - >20,000 variants, some benign (same-sense) some inc. risk of cancer by +80% in women

Question 728

how can cancer develop

Answer 728

- proto-oncogenes are normal genes involved in cell growth and division - mutations in proto-oncogenes can convert them to oncogenes - oncogenes are genes that can cause uncontrolled division of cells -> can develop into cancer

Question 729

chromosomes in eukaryotes vs. prokaryotes

Answer 729

euk: linear (straight) structure, multiple, tightly bound to histone proteins, located in nucleus prok: circular, usually only one, found within the nucleoid

Question 730

purine vs. pyramidines

Answer 730

purine: double ring structure (adenine, guanine) pyramidine: single ring structure (cytosine, thymine)

Question 731

endothermic vs. exothermic

Answer 731

endo: absorb energy, typically heat, from their surroundings->decrease in the temperature of the surroundings exo: release energy, typically heat, into the surroundings ->temperature of the surroundings increases

Question 732

endocrine vs. exocrine glands (+examples)

Answer 732

endocrine: secretes hormones into bloodstream influencing organs (ex. pituitary, thyroid) exocrine: secretes substances thru ducts on body's surface or into organs (ex. sweat, salivary)

Question 733

what does plasmolysis mean

Answer 733

- water leaving plant cells, allowing the cytoplasm and plasma membrane to shrink away from the cell wall

Question 734

what is biochemical oxygen demand

Answer 734

- amount of oxygen consumed by bacteria and other microorganisms while they decompose excess organic matter under aerobic conditions - depletes O2 levels

Question 735

what is leptin

Answer 735

- hormone produced by fat cells playing crucial role in regulating energy balance and signalling to brain abt appetite - satiety signal helping to regulate hunger and food intake

Question 736

what is leptin resistance

Answer 736

- leptin constantly stimulates brain, dont get sensation of being full - causes body to enter starvation mode, using less calories, but consuming more - leads to obesity