Biology Flashcards

Question

Explain why the concentration of water in cells should be maintained within a narrow range for optimal function

Answer 1

Changes in water concentration lead to corresponding changes in solute concentration in cells Water in cells→ determines osmotic pressure of cells Water moves by osmosis→ water movement into/ out of cells depends on solute concentration inside/ out of cells Water provides necessary medium in which all chemical reactions of metabolism occur: Chemical reactions occur→ only if reactants are dissolved in water; levels must be constant Water concentration; Too much→ cells may burst. Too little→ cell contents shrink Too little water→ increase in solute concentration→ lowers pH (must be maintained→ enzymes) Water accumulates→ may dilute reactants and slow down metabolism

Answer 2

Accumulation of wastes is toxic→ must be removed to maintain homeostasis If build up→ alters conditions→ stops enzyme functioning. Can change pH→ stops enzymes Accumulation that doesn’t alter pH→ alters reaction rates, osmotic imbalance→ affects membrane functioning E.g. Accumulation of Carbon Dioxide→ internal environment becomes too acidic

Answer 3

KIDNEY: Filters blood, remove waste/excess fluids→ turn into urine (excreted) Passive: Glomerular capillaries diffuse wastes through membrane Active: Reabsorption in nephrons, wastes reused into bloodstream 180 L blood filters everyday (entire blood volume filtered 20-25 x per day) Maintains chemical balance in blood RENAL DIALYSIS: Carries out function of failed kidneys (cleans blood) Haemodialysis→ transfers blood to machine to be filtered before returned to body Glucose levels same in fluid (so doesn't diffuse) Passive transport; diffusion of substances in dialysis membrane between blood and fluid Blood filtered for 3-4 hours (2-3 times a week) Removes wastes to stop accumulating; maintains chemical balance in blood

Answer 4

Water accumulates in body→ by eating/drinking, metabolism. Nitrogenous wastes→ metabolism Water potential: Tendency of a solution to lose water by osmosis (typical; high water concentration) Water concentration in environment; Determines organism’s need to conserve or lose water FRESHWATER FISH: Live in rivers/lakes (high water potential) water freely available (few salts) Urinate frequently; water accumulates (osmosis→ high concentration surroundings to low in fish) Too much water in bodies→ Kidneys excrete excess and wastes. Conserve salt MARINE FISH: Live in sea- urinate less (lose body water across gills to surroundings) Salt diffuses into bodies→ main kidney function (remove excess) Kidneys conserve water rather than extract TERRESTRIAL MAMMAL: Water and salt loss from body;respiration ,excretion (sweat, urine) Control mechanism; ensure balance maintained of amount excreted Urine; dilute or concentrated (adjusted depending on body needs) Large amount of salt lost by sweat→ needs replacing for stable osmotic pressure in body

Answer 5

Both are slow (rely on concentration gradient difference; slows as difference is smaller, stops; equal) Solution; combine active transport and osmosis (quick; removes waste even against gradient) Used to pump salts from urine back into kidney (draws water with them by osmosis) PROBLEMS WITH DIFFUSION: Rate of movement is slow Wastes must be dissolved with water when removed→ Concentrations equalise movement slows and stops Not all wastes can be removed by diffusion If concentrations equalise and no further wastes removed→ pH would be altered PROBLEMS WITH OSMOSIS: Too much water may be lost in urine Contains too much nitrogenous wastes, water will be drawn into urine to dilute waste (equalise concentration) → dilute urine (loses too much) Movement of water may make wastes too dilute for excretion by diffusion Slows down excretion by diffusion (lowers concentration gradient)

Answer 6

``` Adrenocortical insufficiency (Addison’s disease) some immune systems cause inflammation in own glands, other causes are tuberculosis and cancer Decreased secretion of aldosterone→ increased sodium loss Clinically; Person is weak, thin, have salt-cravings, faintness, feel light-headed, low blood-sugar Most patients → require treatment with fludrocortisone plus cortisone as a replacement glucocorticoid ```

Answer 7

Passive→ diffusion, osmosis (molecules move along concentration gradient) no energy input Active→ needs cellular energy to move molecules against concentration gradient Diffusion; Particles from region of high concentration to low until equilibrium is reached Osmosis; water molecules from high water concentration to low,through semi permeable membrane PASSIVE TRANSPORT IN KIDNEY: Limitations; relies on difference in concentration gradient (slow) Tubules→ wastes from bloodstream to be excreted as urine Substances needed→ removed from urine and returned to bloodstream Passive moves water (osmosis), some wastes (ammonia, urea) into kidney ACTIVE TRANSPORT IN KIDNEY: Sometimes have to move against gradient Carrier proteins spans membrane and carrier molecule actively move chemicals from low to high concentration using cellular energy Mainly sodium ions, glucose, amino acids across wall of nephron (reabsorbed) Sodium pump in tubules→ transports salts from urine back into kidney (conserve salt and water→ salt draws water)

Answer 8

Urine concentration; depends on need to conserve water. High solute; concentrated. Low solute; dilute FRESHWATER FISH: Only dilute Sources; drinks, osmosis into fish MARINE FISH: Only concentrated Sources; Drinks,osmosis out of fish TERRESTRIAL MAMMAL: Conserve water (concentrated) Consumes water (dilute Source; Drinking, eating

Answer 9

FILTRATION: Occurs between glomerulus, lining of Bowman’s capsule High pressure; blood flowing through glomerulus (small substances squeeze through capillary wall under pressure→ pass through cell layer in Bowman’s capsule→ move into lumen) Pass through; blood cells, proteins, water→ carry dissolved amino acids, glucose, salts, wastes (fluid; glomerular filtrate) Substances body needs; reabsorbed into bloodstream (so not lost with urine) REABSORPTION: Filtrate with molecules needed; amino acids, glucose→ actively reabsorbed into proximal tubule Passed to interstitial fluid, capillaries surrounding nephron→ to renal vein; carried back to general circulation 99% water reabsorbed by osmosis, only 1% excreted as urine Ascending loop→ salts actively pumped into interstitial fluid in medulla (draw water out by osmosis) SECRETION: Toxic substances removed from capillaries, tissues Drugs secreted in proximal tubule, urea in descending loop of Henle

Answer 10

Limited water availability→ must conserve water and excrete waste High water availability→ water conservation not necessary (waste may be dilute) Moth, blowfly→ uric acid as paste (low toxic) high energy needed, but conserve water Spinifex hopping mouse→ concentrated urea; conserve water (moderate toxic) Humans, moth, blowfly→ water not freely available (must be sourced)

Answer 11

ADH Dehydration, blood volume drops→ detected by hypothalamus in brain; stimulates pituitary gland to release ADH→ acts on nephrons to increase reabsorption of water Increases permeability of membranes lining distal, collecting tubule; water reabsorbed (conserved) ALDOSTERONE Decrease in sodium ion concentration in blood→ secreted from adrenal gland cortex (above kidney) Aldosterone via bloodstream reaches kidney; increase permeability of nephron to sodium→ reabsorption into surrounding kidney tissue (less lost by urine)

Answer 12

MANGROVE: Concentrate salt accumulation to certain parts (leaf) → fall off, salt leaves mangrove. Leaves; salt glands secrete salt entering; can be blown or washed away Roots; first line of defense→ filter out incoming salt BLADDER SALTBUSH: alt enters roots, travels to leaves. Stored in vacuole and moves to bladder cell Bladder cell ruptures→ salt released

Answer 13

Enantiostasis: Survival mechanism; organisms cope with extreme fluctuations in environmental conditions Estuary: Water/salt concentrations fluctuate daily→ high tide; salt in river. Low tide; freshwater in Organisms need to maintain normal metabolic functioning (despite fluctuations) OSMOCONFORMERS: Tolerate change; alter internal solute concentration to match external environment E.g. Fiddler crab accumulates additional solutes in high salt, then pumps out excess when low salt OSMOREGULATORS: Avoid change in internal environment; keep solutes at optimal level regardless of environment E.g. Mussels in rock pools close valves when tide it out (keeps salt concentrate same as seawater)

Answer 14

SHEOAKS: Needle like leaves→ reduces surface area, reduces water loss EUCALYPTUS: Waxy cuticle→ reflects sun, reduces water loss by evaporation Leaves hang vertically→ reduces exposure to sun GREVILLEA: Small curled leaves→ Retain more water Hairy leaves→ hair returns water, increases humidity WATTLE: Grey colour→ Light colour to reflect sunlight, reduces evaporation Hair on undersurface→ retains water

Answer 15

Needle-like leaves→ reduces surface area, water loss. E.g.She-oakes Woody fruits→ Less water loss that in fleshy fruits. E.g She-oakes Leaf curling→ Reduce surface area. Traps humid layer of air→ reduced water loss. Hanging leaves→ reduce exposure to sun Hairy/shiny leaves→ hairy undersurface→ reduces air movement, increase humidity→ less water loss. Upper surface, reflects radiation from sun (reduced heat gain) Water directing leaves/stems→ shaped so water runs down to roots. E.g. Acacia

Answer 16

Macro evolution→ Millions of years, arising new species. E.g wolf and dog from common ancestor Micro evolution→Shorter time periods, pop changes but no new species. E.g. Different dog breeds

Answer 17

- Changes in physical conditions in environment Early organisms; water to land habitat→ reduced UV radiation (ozone forming) Aus climate; cool/wet→ hot/dry, rain forests to woodland, Lakes dry up→ evolution to conserve water Ice age→ change in sea levels, temp. Dinosaurs→ meteorite; reduced light, plant life→ no food - Changes in chemical conditions in environment First life; anoxic environment; some produced CO2; led to photosynthetic organisms Increased oxygen levels; evolution of organisms using oxygen (complex-diverse animals today) E.g. Peppered moth; industrial revolution. Black moth protected from soot; white stand out and killed - Competition for resources Comp for light, soil, nutrients, water, shelter, mates, territory Organisms compete; most successful survive and reproduce; pass on genes

Answer 18

Pop begins with 30 moths (10 black, grey, white) → chart works out offspring colours. Spin for predator (colour removed) shuffle cards; repeat until trend recognisable; dominant species?

Answer 19

``` HIGH ALTITUDE: Cold, shallow soil, exposed to snow Small and twisted to bend away from elements. Short leaves Large fruit Thin bark More resistance to frost Short trees ``` ``` LOW ALTITUDE: Warm, high precipitation, Tall and straight to receive nutrients and rainfall Long leaves Small fruit Thick bark Less resistance to frost Tall trees ```

Answer 20

PALAEONTOLOGY: Scientific study of fossils and extinct life Fossils→ evidence of past life forms; evolutionary transitions to modern living forms Undisturbed rock fossils; show sequence living things arose; have common features (change over time) E.g. Lobe- finned fish; bones in fin→ dragging from water to land (amphibians evolved from fish) Limitations; fossil record incomplete, bias to fossils with body/environment better suited to fossilisation BIOGEOGRAPHY: Study of geographical distribution of organisms Darwin/Wallace theory; new species; group isolated from rest→ thought species close; similar, far apart; different E.g. Flightless birds/continental drift→ common Gondwana ancestor; different pop evolved on continents. E.g. Emu in Aus, Kiwi in NZ→ share similar features; flat breastbone COMPARATIVE EMBRYOLOGY: Comparison of similarities in vertebrate early embryos Embryos of closely related organisms have homologous parts→ support common ancestor E.g. Fish, bird, mammal, reptile embryos; gill slits, tails (later internal gills in fish) COMPARATIVE ANATOMY: Similarities in organisms structure (similarities; common ancestor, differences; modification) evolution Limitations; fossils often incomplete→ hard to compare with extinct life form E.g. Pentadactyl limb; (homologous structure) same basic sequence of bones in dog, human, bird; BIOCHEMISTRY: DNA hybridisation: Compare DNA sequence of 2 organisms; unzip, zip codes to match E.g. Heat applied to chimpanzee, human DNA→ high temp means more closely related; 83℃ Amino acid sequencing Similarities in protein sequencing→ Similarities; shared ancestor. Differences; evolved over time E.g. Humans. chimps→ identical sequence in haemoglobin. More related than gibbons,humans (3 differences)

Answer 21

DNA in amino acid sequencing, DNA hybridisation→ new biochemical evidence Historically; orangutans, gorillas, chimps→ 1 family, humans another (based on structure of leg, teeth) 60’s→ Chimps, humans→ identical haemoglobin, cytochrome c sequence→ different to gorilla Humans, chimps small DNA difference, (more closely related than orangutans→ diverged earlier) New genetic tree→ humans, chimps diverged more recently from common ancestor

Answer 22

Proposed; variations within species and more offspring produced than can survive and reproduce Some individuals have adaptive characteristics; enable survival better→ passed on to next generation Over time; natural selection→ pop with adaptations most suited to environment Source of variation; gene mutation; phenotypic advantage Isolation; if species pop geographically isolated, interbreeding stops; separate species develop Divergent; one species forms other with adaptations suited to variety of environments E.g. Aus marsupials; evolved from common possum like ancestor; common structure, but dominant differences Convergent; Organisms come to resemble each other; share similar environment, perform same function. E.g. Streamline dolphin/shark body for swimming in sea. Similar but dolphin; mammal, shark; fish

Answer 23

England 1858→ Darwin/Wallace published theory Invention of machinery, people flocked to cities (disease) social changes in class, French revolution New discoveries; people looked to science.

Answer 24

``` Heredity in garden peas; pure bred (consistent characteristics) Deliberately crossed one variety with another→ observed next generation Removed stamens (so no self pollination) repeated experiments, kept records Monohybrid cross; Offspring of cross (F1) Crossbred tall x short (all offspring tall) Tall then grew (F2) F2 most tall, some short (3:1) Law of segregation; 2 genes that control each characteristic; segregate during reproduction; 1 factor each in a gamete→ factors recombine at fertilisation (match together) Law of Independent assortment; Pairs segregate independently of other pairsof factors Reproductive cells combine at fertilisation; offspring had one factor for tallness and one for shortness→ only tallness observed (dominated shortness) ```

Answer 25

Cross pollinated by hand, studied large number of characteristics Used quantitative data, studied characteristics one at a time By chance→ characteristics he studied carried out on different chromosome Studied separately characterises occurring in pairs (tall or short) previously; whole plant studied

Answer 26

Check for dominance and assign symbols Write down parents phenotype and genotype Write down parents gametes gametes, noting only one allele for characteristic in gamete Make punnett square and write down all possible crosses underneath

Answer 27

2 different parents→ F1 generation only has dominant trait | F1 crossed→ F2 generation has dominant trait, recessive trait in (3:1)

Answer 28

Hybridisation; Crossbreeding two genetically non-identical individuals Parents with desirable traits selected; offspring reflecting desired traits further breed; hybrid offspring E.g. Hybridisation within species: Labradoodle (Labrador x Poodle) → successful hybridisation leads to hybrid vigour (increased strength, better health, greater fertility) ADVANTAGES: Increases genetic variety Combine best features of each parent→ hybrid vigour DISADVANTAGES: May combine weaker features of parents→ offspring have less stamina, resistance to disease etc Very expensive (especially if no hybrid vigour) Sometimes offspring are infertile or reduced fertility

Answer 29

Homozygous→ Identical alleles of a particular gene for a characteristic. E.g. TT, tt, HH, hh Heterozygous→ Two different alleles of a particular gene for a characteristic. E.g. Aa, Bb, Ee

Answer 30

Gene→ Smallest unit of hereditary. Codes for a particular characteristic E.g. Eye colour gene Allele→ Variations of a gene E.g. Brown, blue, green, black eye colour

Answer 31

Dominant alleles→ Form of gene expressed in heterozygous condition, masking the other (recessive) form of same gene. Written in UPPERCASE letters. E.g. T Recessive alleles→ Form of gene expressed in homozygous condition. Written in lowercase letters. E.g. t

Answer 32

Paper only presented to small group; work suddenly appeared (may not have been noticed) Work radically different to previous; may not have been understood and little known about cels He wasn’t recognised scientist; more likely to have been noticed if was serious scientist

Answer 33

SUTTON: (1877-1916) Meiosis of grasshopper cells→ observed chromosomes occur in visible pairs in meiosis (paternal and maternal) During meiosis; chromosome number is halved, chromosome in each pair separate; gamete receives one chromosome from each pair→ fertilisation resotes full number in zygote Concluded that: Chromosomes carriers of hereditary units;arrange themselves independently in middle of cell before divides Chromosomes units involved in inheritance; believed that several Mendelian factors present in one chromosomes; therefore inherited as unit BOVERI (1896-1904) Sea urchin egg experiment→ behaviour of cell nucleus and chromosomes (in meiosis and fertilisation) Already known→ organisms has set number of chromosomes and in fertilisation (egg and sperm fuse) Found nucleus of egg and sperm contribute 50% of chromosomes to zygote Experiments: Egg and sperm fuse; resulting offspring have characteristics of parents. If only one parent nucleus; abnormalities→ showed that complete set of chromosomes needed for normal; inheritance factors on chromosomes in nucleus Before→ Hereditary factors found in nucleus and cytoplasm; After→ Nucleus only Before→ Proteins store hereditary info. After→ full set of paired chromosomes Before→ gametes transport factors to pass onto next generation. After→ random assortment during meiosis Before→ Chromosomes believed to disappear and reappear. After→ Occur in set numbers, in pairs

Answer 34

Chromosome→ made of DNA, proteins Proteins→ histone proteins bind to DNA to form chromatin (in nucleus) DNA→ Double helix structure, basic building block of nucleotide (base, sugar, phosphate) 4 bases; Adenine (A) and Thymine (T), Cytosine (C ) and Guanine (G) Diagram of Nucleotide 2 nucleotides linked by covalent bonds between sugar and phosphate DNA tightly wrapped around histone→ protect from damage, allow long DNA length to be packaged so it doesn't move around cell in cell division

Answer 35

DNA contains info in specific sequence of nucleotides (sugar, phosphate, base) Spiral double helix (rungs of ladder→ hydrogen bonds linking (A,T) and (C,G)

Answer 36

Radishes grown in 2 petri dishes; one kept in light. Other kept in dark In dark: grew taller faster; but had yellow leaves → In light: shorter height Radishes in dark moved into light→ leaves became green; gene undamaged, but not expressed in dark

Answer 37

In meiosis; genetic variation from crossing over, random segregation, independent assortment Meiosis; One cell (2 divisions) → 4 haploid cells (genes in each; new combo of parent genes) Independent assortment; paternal and maternal chromosomes sort out independently of one another Maternal don’t all move into one gamete and paternal into another→ random where it ends up→ mixes paternal and maternal (genetic variation) Chromosomes in pair separate→ ensures chromosomes number in gametes is half of original

Answer 38

Variability→ Different forms of a gene within a population (from genes, environment or both) Sexual reproduction increases variability→ increasing gene recombination Greater variability improves pop’s ability to adapt to changes in environment Meiosis and fertilisation→ when gametes form, cross over, random segregation→ results in genetic recombination of paternal and maternal genes within each gamete

Answer 39

Mendelian ratios→ only when similar conditions to Mendel; if genes don’t assort independently,or show dependence→ Mendel's ratios not obtained Cells; 23 chromosome pairs (22 x autosomes, 1x sex chromosomes) Female genotype XX, Male; XY Offspring;equal chance of male or female; determined during meiosis; transfer 1 sex chromosome to each gamete; fusion of gametes in fertilisation Meiosis; Females (44 autosomes plus XX) → halved egg gets 22 autosomes and X. Males→ Half get 22 autosomes and X, half get 22 autosomes and Y X from mother and father→ will be female (XX) X from mum, Y from dad→ will be male (XY) Mendel's experiments; no sex-specific effects; sex-linked inheritance is deviation from Mendel's ratios

Answer 40

At time; Unknown why number of traits that separate in meiosis exceeds number of chromosomes Sutton/Boveri→ more than one trait is present on each chromosomes (didn’t demonstrate) 1910→ Morgan experiments on gene eye colour in fruit flies; located on X chromosome→ heredity factors exchanged between X chromosomes Drosophila Melanogaster (normally red eyes, but found mutant white eyed male) → crossed to see if white eyed gene would show Mendel ratio CROSS 1: Pure bred parents o obtain F1 hybrid offspring White eyed male and red eyed female CROSS 2: Crossed F1 hybrid offspring to obtain F2 generation Expecting Mendelian 3:1 ratio but more than 80% had red eyes and less than 20% white eyes Most white eyed were male. Thought females couldn’t have white eyes CROSS 3: Typical cross to investigate hypothesis → crossed white eyed male with heterozygous red eyed female Results shown in F2 generation,both males and females had white eyes Next (and correct) hypothesis→ white eyed characteristic is ‘sex-limited’. Genetic crosses proved red eyes were sex limited (carried on sex chromosome)

Answer 41

Doesn’t show Mendelian pattern (pairs of alleles don’t show dominance over the other) Heterozygote where 2 different alleles for same gene; both expressed separate (both dominant) E.g. Cattle have red or white→ Heterozygous may have red and white coat→ roan (not in patches but interspaced red and white hairs)

Answer 42

Genotype + environment= phenotype E.g. (TT)plant may end up same size as (tt), if grew in unfavourable conditions (lack of water) E.g. Temp can affect phenotype of animals: or effect of soil pH on colour of hydrangea flowers; Pink flowers in alkaline or blue flowers in acidic Identical twin; differences due to environmental rather than genetics→ One may have freckles (sun exposure) other may not Environmental factors influencing humans; smoking, physical activity levels, diet, nutrition

Answer 43

DNA replication→ DNA copied; produce new molecules with same base sequence STAGE 1: DNA double helix unwound, separated into strands (hydrogen bonds broken) STAGE 2: Strands act as templates→ Nucleotides and bases form bonds with bases on parent strand STAGE 3: Daughter DNA molecules rewind in double helix; identical in base sequence to parent (due to complementary base pairing) Each of new strands is complementary to template it was made on and identical to other template

Answer 44

Polypeptide synthesis; uses RNA→ single stranded nucleic acid (bases A, C, G and Uracil→ replaces Thymine; T) Three types of RNA: mRNA (messenger RNA) tRNA (Transfer RNA) and rRNA (ribosomal RNA) DNA to polypeptide; DNA code determines amino acid sequencing in polypeptide chain→ DNA info transcribed to mRNA from template strand 3 nucleotides on mRNA→ codon for particular amino acid TRANSCRIPTION STAGE: Copy of gene is made (RNA not DNA) → carries info for making polypeptide (mRNA) Double helix unwinds; RNA nucleotides assemble use one DNA strand as template; mRNA separates from DNA and double helix reforms TRANSLATION STAGE: Ribosomes move along mRNA molecule→ transfer RNA molecules present around ribosomes (bind to them→ only bind to anticodon that is complementary to codon on mRNA) Codon and anticodon base link (form hydrogen bonds) tRNA molecules carry amino acids→ bonded by peptide linking; dipeptide formed→ upper tRNA detaches, another one binds→ chain of 3 amino acids forms These stages are repeated until a polypeptide is formed

Answer 45

1941→ mutants of fungus→ led to discovery of genes provide instructions for making proteins Hypothesis; gene controls production of one enzyme→ evidence needed Designed experiment to attempt to mutate genes of mould→ evidence led to hypotheses; genes affect enzyme productivity→ Breakthrough! (At time; ongoing debate; heredity material protein or DNA?) EXPERIMENT: Irradiated bread mould with X-rays (induce mutations) → showed some mutants no longer produced amino acid (implies particular enzyme no longer functions) Tested; If loss of function had genetic basis→ crossed mutant with normal mould; found offspring shared mutant phenotype→ inability to produce amino acid is inherited (due to mutation) Found different enzymes in different mutants altered or missing; proved gene determines structure of enzyme→ proposed one gene-one enzyme hypothesis Changed to one-gene-one protein when demonstrated other proteins besides enzymes encoded by gene Found one gene not necessarily responsible for structure of entire protein; but for each polypeptide chain making up protein (currently accepted)

Answer 46

Proteins: Amino acid chain joined by peptide bonds; may be from many polypeptide subunits Polypeptide: Molecule consisting of many joined amino acids→ aa joined by peptide bonds To make particular polypeptide, amino acids must be linked up in a precise sequence Genes store info needed for making polypeptides→ info is stored in coded form Precise sequence of bases in gene codes for the sequence of amino acids in a polypeptide

Answer 47

Mutagens are environmental agents that cause mutations; Chemical (asbestos), Biological (HIV), Mutagenic radiation (UV, nuclear reaction) Changes to genetic material arise during DNA replication Mutations alter genes; change nucleotide sequence in DNA→ One or more genes may be altered from original form (Allele 1, Allele 2) 2 variations of gene is formed→ new allele formed One or more genes may be altered from original. E.g, Allele 1→ altered polypeptide→ new protein Most new proteins have little effect on organism, but some lead to genetic disorders, inherited diseases Effect of new proteins on next generation: If mutation in a somatic cell→ individual may be affected but no effect on future generations If mutation is in germline cell (gametic mutation) → alleles can be inherited and have significant effects on population→ result in evolution Changes to genetic material arise during DNA replication→ result in Change to single gene (gene mutation) or rearrangement of blocks of whole chromosomes (chromosomal mutations)

Answer 48

During late 1800’s and early 1900’s, many scientists were involved in studying radiation Harmful effects of radiation were unknown→ scientists such as Marie Curie who were exposed to large amounts of radiation over a prolonged periods of time, developed various illnesses Marie Curie worked with ionising radiation for most of career; died from leukemia (overexposure) Survivors of Hiroshima bomb→ suffer physical mutations (radioactive output of nuclear explosion)

Answer 49

Mutation; basic source of variation Mutations affect base sequence of DNA→ understand how can be passed from one generation to next→ supports Darwin’s theory of evolution (Explains how heritable variation arises) Mutation will result in change in phenotype, may not do anything, or may confer advantages disadvantage to organism Mutations provide diversity of genetic material that results in variation in phenotype If mutations can be inherited→ provide variation on which natural selection acts Evolutionary purposes, mutation can be redefined as heritable change in genetic material

Answer 50

Majority of mutations; detrimental to or have no significant effect on environment; some beneficial INSECTICIDE RESISTANCE: Some organisms→ developed resistance; most killed, some naturally resistant survive and reproduce (pass genes→ resistant pop develops) E.g. Sheep blowfly lay eggs in wet wool; burrow into skin→ loss of production → developing resistant to agricultural insecticides If insecticides rotate, effectiveness increased ANTIBIOTIC RESISTANCE: Many bacterial infections treated with antibiotics. Interfere with protein synthesis Many bacteria become resistant to wide range of antibiotics Animals given antibiotics to grow faster and not have disease→ if humans eat or drink milk from animals, then resistant bacteria could be transferred to humans Encouragement of doctors to restrict general use of some selected antibiotics

Answer 51

Theory; Evolution occurs in short bursts of rapid change, followed by longer periods of stability If evolutional change is gradual, could be predicted; fossilised remains showing these ongoing changes Darwinists use traditional forms to support perspective of gradualism→ gradual change over an extremely long period of time Many fossilised remains show millions of years with no noticeable evolutionary change to species E.g. Soft bodied organisms dominates seas for hundred of millions of years and in period of million years disappeared and were replaced by organisms with shells and skeletons Supporters of punctuated equilibrium argue if evolution occurs gradually, as proposed by Darwinists there should be greater diversity among living organisms that exist Fossil records is incomplete so difficult to come to an agreement on evolutionary change

Answer 52

Scientists associated with double helix discovery; Rosalind given no recognition Franklin; find out structure of DNA molecule (X-ray crystallography) → Identified A and B form Work provided without knowledge or consent to Cambridge competitors through Wilkins; used her data to build model Maurice Wilkins→ studied diffraction images and discovery of patterns to guess molecular DNA structure Wilkins, Franklin diffraction images→ discovery of 3D helical nature Crick and Watson analyse Franklin/Watson crystallography; realised DNA structure was helix Processed infor from other, manipulated model→ Watson and Crick discovered fmoud double helix Watson, Crick and Wilkins won Nobel Prize (1962) for work in DNA→ Franklin wasn’t honoured and appropriately acknowledged→ already dead

Answer 53

ARTIFICIAL INSEMINATION: Sperm taken from chosen male; inserted into selected females Cost effective; frozen sperm transported; not animals(reduce injury danger) Sire several offspring with different females; conservation of species→ but reduces genetic diversity Bred selectively; alleles increase in gene pool selected by breeder not nature Survival and reproduction in pop→ depends on alleles that are useful to humans, not environment ARTIFICIAL POLLINATION: Remove stamens; dust pollen onto stigmas of another flower or same flower; E.g. Mendel pea plants Greater degree over breeding process; ensures pure breeding→ but less genetic diversity; species vulnerable to sudden environment change CLONING: Reproductive cloning: Genetically identical fully developed organism using cell from other organisms Therapeutic cloning: Cells from individual to produce cloned early embryo Gene cloning: Producing identical copies of a gene E.g. Dolly the sheep, Bananas, twins Characteristics can be precisely bred→ conservation; reintroduce extinct genes, endangered animals Reduces genetic diversity; increases risk of being wiped out from sudden environmental change Not natureal→ need to ‘switch on” genes and most experiments fail Organisms; genetically identical→ reduced variability

Answer 54

Somatic Cell Nuclear Transfer→ SCNT→ 3 animals; nucleus donor, egg donor, surrogate mother Somatic cell nucleus transferred to egg without nucleus; reprogrammed to become zygote and grows E.g. Dolly the sheep; cell from 6 yr old ewe udder→ injected into enucleated second sheep cell; fused with electricity→ grow and develop normally→ injected into third sheep uterus Sheep born dentic twin to sheep donating egg

Answer 55

Transgenic species: A species that has genes transferred into its genetic code from another species E.G: Gene from bacteria has been transferred to cotton called BT cotton→ Gene codes for bacterial protein called BT toxin that kills Helicoverpa moth→ major pest of cotton crop Use of less insecticide on BT cotton crop→ benefits farm workers and wildlife Increase in crop yield FOR: DNA and proteins of transgenic organisms unlikely to cause any problems as digested in human gut Research suggests transgenic species don’t survive long in natural ecosystems and if genes transfer to wild species, natural selection acts against them Transgenic techniques will reduce cost of food production, which benefits producer and consumer Transfer of genes between species is natural phenomenon. AGAINST: Impossible to be certain about long-term health effects of genes in GMO foods or proteins made using genes Genes could escape and be transferred to wild plants or animals. E.g. Possibly creating superweeds Will allow multinational companies that develop them to become too powerful Infringement of rights of every species to independently exists and could cause suffering in animals

Answer 56

PRONUCLEAR INJECTION: DNA can be introduced directly into an animal cell by microinjection Multiple copies of desired transgene are injected via a glass micropipette into a recently fertilised egg cell→ then transferred to surrogate mother Not efficient; many don’t survive GENE GUN: Foreign DNA into living tissues literally shoots directly into organism using “gene gun” Microscopic particles of gold or tungsten are coated in DNA and propelled by burst of helium into skin and organs of animals and tissues of intact plants Some of cells express introduced DNA as if it were their own. TRANSFER USING BACTERIA TO CARRY DNA OF GENE: E.g. Insulin Messenger RNA coding for insulin is extracted from human pancreas cells that make insulin DNA copies of messenger RNA made and sticky ends are made by adding extra G nucleotides to gene ends Plasmids are small loops of DNA found in bacteria→ cut open using restriction enzymes and sticky ends made by adding C nucleotides at ends of cut plasmid Insulin gene and plasmid are mixed. Link by complementary base pairing (G-C) between sticky ends Plasmid with human insulin gene inserted is called recombinant plasmid Suitable host cell is chosen to receive gene. E.g. E. Coli bacteria Recombinant plasmid are mixed with host cells.Host cells absorb them Genetically modified E. Coli are cultured in fermenter E. coli bacteria start to make human insulin which is extracted, purified and used by diabetics.

Answer 57

CLONING Decreased genetic diversity;only one parent; identical to one parent Desired characteristics evident;individual control and reproduced in short time All identical→ less likely to survive sudden environmental change, foreign pathogens May be used in conservation with endangered or extinct animals

Answer 58

Health; “State of physical, social and mental wellbeing, not just absence of disease” WHO Hard to achieve all 3 areas at once, different opinions about what is healthy Disease: “Condition adversely affecting normal functioning of any part of living thing” Broad, conditions not normally classed as disease (pregnancy, broken arm)

Answer 59

Gene expression; Cell ‘switched on’ and DNA code converted to polypeptides controlling structure and function of cell Expressed as should be→ cell functions normally, tissues maintained and repaired Polypeptides make up proteins; some responsible for mitosis and cell cycle, or replace damaged cells Effective gene expression needed for ongoing maintenance/repair of tissue→ if altered mutations and cells can’t function Tumour suppressor gene→ limits cell division, encourages cell death of too many cells BRCA1 gene→ Codes for proteins repairing PTEN gene, PTEN gene→ limits cell divisions, encourages cell death; regulates cell cycle, prevents excessive cell production

Answer 60

Cell differentiation→ Cells mature, take on different structural features to suit for specific function Cell specialisation→ Specific genes ‘switched on’ → perform particular body function Enable cells to work together to carry out coordinated complex functions to maintain, repair tissue Genes control production of polypeptides (make up cell proteins)→ responsible for cell growth, repair Gene malfunction→ cells can't function, onset of disease Mitosis; cell division→ growth, repair damaged tissues, worn out cells→ can cause mutations; uncontrolled production of cells, prevents cell death Mutations→ tumour suppression genes halt protein production Disruption of cell cycle; uncontrolled cell replication→ cells don’t differentiate; forms tumours

Answer 61

People of Mesopotamia Drains→ carry away waste Aware of insects carrying disease, isolated the sick Egyptians Performed surgery and had over 700 drugs Specific rules for cleanliness→ house cleaning, frequent bathing, pure water Chinese Personal hygiene and classified diseases Immunity→ if exposed to tissue of person with smallpox→ gain protection against more infection Hebrews Personal hygiene by washing and keeping clean Water supplies kept clean, free of wastes, dead animals and people Isolated sick and burnt used bandages

Answer 62

Infectious; disease caused by organism, infectious agent→ Ebola, Zika Non-infectious; not caused by pathogen, can’t be passed on→ Down Syndrome, lung cancer

Answer 63

Petri dish; innoculate bacterial colonies (e-coli) wipe in cultivated agar plate, attach antibiotic; seal Heat, observe next day how much bacteria grown→ antibiotic with least bacteria (effective)

Answer 64

Hygiene→ decreases spread and growth of pathogens→ controls spread of disease HYGIENE: Personal hygiene Keep body and openings clean→ reduce risk of pathogens entering Wash hands with soap before eating, after using toilet→ prevents spread of disease Body, hair, teeth regularly cleaned→ prevent buildup of bacteria Cough or sneeze into handkerchief→ prevents airborne droplets spreading Community hygiene Sewerage, garbage disposal→ reduces increase of pathogens Sterilisation, disinfection of equipment in hospitals, dentists→ reduces pathogen spread City planning-- reduces overcrowding→ reduce transmission of disease through pop CLEANLINESS IN FOOD: Pathogens transferred from person to person, or environment to person via food Increased incidence of foodborne disease→ due to eating out on regular basis, consume takeaway Guidelines; hair tied back, cuts covered, hands washed, utensils washed, raw veg washed, meat cooked thoroughly, food covered before stored CLEANLINESS IN WATER: Domestic water→ comply with strict standards and guidelines Water contaminated with faces→ could contain unsafe pathogens Treatment→ destroys pathogens and multiplication→ reduce transmission

Answer 65

Water treated before distribution→ ensure no health risk Coagulation/flocculation/sedimentation/filtration→ remove matter harbouring pathogens, disinfect Testing to ensure water meets guidelines Water should be clear→ virtually colour free Tested; bacteria associated with faecal contamination→ killed by chlorine Cryptosporidium, Giardia→ may infect animals in intestines; in water through faces or animal carcass Chlorine→ added t water to kill pathogens Fluorine→ added to tap water to help dental health

Answer 66

Any organism or infectious agent living in another organism and causing disease Microorganisms can become one if not in normal location (E.g. good bacteria on skin if enters blood) Methods of infectious transmission Person to person; (blood→ HIV, Ebola) Environment to person (common cold) Vector; person to person via organism (Zika)

Answer 67

19th century→ revolution in microbiology (pasteur and Koch) → previously spontaneous generation P disproved theory; germ theory→ all germs cause disease, microorganisms come from pre- existing Koch→ all disease caused by specific microorganism

Answer 68

PASTEUR: Discovered microorganisms were cause of beer, wine spoilage→ Heat them to kill (pasteurisation) Discovered rotting food due to living organism, (refuted spontaneous generation) proposed germ theory of disease Investigated cause of anthrax and developed successful vaccine→ also vaccine or rabies, cholera in chickens Swan necked flask experiment Drawn out necked flask→ meat inside and air drawn in→ microorganisms from air trapped in curved neck No growth in curved neck, but growth in flask with broken off neck Proved organisms contaminating broth carried in air, not spontaneously generated KOCH: Agar plate technique for growing microorganisms→ cultured bacteria; determined each disease caused by specific microorganism Anthrax→ bacteria inserted into healthy sheep; showed spores obtained could cause disease→ evidence for germ theory→ microorganism grown outside body caused disease Breakthrough→ discovery of bacteria responsible for Tuberculosis, bacteria for cholera Postulates (principles for identifying microorganisms responsible for disease) Same microorganism present in every diseased host Microorganism must be isolated, cultured Sample inoculated into host→ must display symptoms as original host Must be able to isolate microorganisms from second host and culture and identify as original species

Answer 69

Beef stock cubes (make broth) and conical flasks with glass tubing bent into S (replace swan neck) Filtered broth added to flask with straight piping and one with curve Boil broth, leave in sub and check every few days→ scum, cloudiness, fungus, bubbles Few weeks→ straight tubing should show signs of decay

Answer 70

Prions Protein capable of causing disease→ no genetic material Multiply in contact with normal prion proteins; alter structure and change them to infectious prions Can’t be destroyed by heating or chemicals E.g. Kuru disease→ through cannibalism Viruses Non cellular pathogens, contain genetic material, not composed of cells (30-300 nm) Only can replicate in host cells→ enters and makes copies of itself Cell becomes too full with copies; bursts→ releases them to repeat in other host cells E.g. Influenza, herpes, glandular fever Bacteria Single celled organism (0.5-100um) → reproduce by binary fusion Found everywhere (classified on basis of shape) → many beneficial E.g. Cause food poisoning, anthrax, pneumonia Protozoans Single celled eukaryotic→ cell membrane, membrane-bound nucleus and organelles (1-300um) E.g. Malaria, African sleeping sickness Fungi Eukaryotic organisms; have cell wall but different to plant cell wall Microscopic to macroscopic→ no chlorophyll (can’t produce own food) Most live on dead plant, animal material (decomposers) E.g. Athlete's foot (tinea) or black spot on rose plants Macro-parasites Visible to naked eye; larger than other pathogens; multicellular eukaryotic Tiny louse→ long tapeworm Some transmit disease directly or act as vectors Live outside host body (suck blood-mosquitos) or live inside body (tapeworm) E.g. Flea is vector for bacteria causing plaque, plant disease→ aphids transmitting Banana Bunchy Top

Answer 71

1000 CE→ Chinese recognised disease 2000 YA→ Greeks described symptoms. Built drains to take away stagnant water 1880→ Charles Laveran discovered malaria causing pathogen 1897→ Ronald Ross discovered main stages of transmission, identified mosquito as vector 1898→ Grassi and Bastianelli→ showed human malaria is transmitted in the same way as malaria in birds 1898→ Draining stagnant water, spraying oil onto water to stop breeding, wearing protective clothes 1930→ Antimalarial drug (Atabrine) used. Discontinued due to side effects 1970’s→ Use of drugs as prophylactics to try and prevent the disease, Incidence of malaria decreased 1980’s→ Incidence of malaria increases 2000- present→ Combination drug therapy that includes highly effective aertesminsimin,. Netting treated with long term insecticide and other protective measures

Answer 72

MALARIA: Cause Protozoa Plasmodium→ anopheles mosquito is vector Transmission and life cycle Female mosquito picks up gametes of parasite from blood of host→ fertilise in mosquito gut Zygote matures, form sporozoites (move to salivary gland) injected into another host when feeding Sporozoites move to liver cells; grow and multiply→ cells burst→ released into blood Transferred back to feeding mosquito Host response In liver cells; isolated from immune system, but in RBC→ antibodies produced Plasmodium avoids immune response as surface antigens change weekly→ not recognised by antibodies already produced by host Major symptoms Cells burst→ parasite, toxins, haemoglobin breakdown released into plasma Creates shivering, high fever, headache, sweating Anemia→ from breakdown of RBC, haemoglobin Treatment Antimalarial drugs→ reduce temp or cure infection Some resistant strains→ oral quinine instead Prevention Travellers to malaria areas→ drugs prior to departure and after come back→ kill any from liver Protective clothing, insect repellent, mosquito nets No donating blood if been recently to infected area Ships, planes, vehicles from areas→ sprayed with insecticides Control Insecticides→ DDT spraying, or draining standing water Vaccine being trialled

Answer 73

Antibiotics; chemicals destroy or stop growth of bacteria causing disease (without destroying host) Destroy cell membrane, or accumulate in bacteria cells preventing them forming new cell wall Natural selection→ evolve resistant strains. Some bacteria possess natural resistance, survive and reproduce to build up population resistant to antibiotic

Answer 74

Many no longer effective→ resistant strains forming→ dont respond to first line antibiotics; need 2nd or 3rd line (take longer to cure, more severe) Superbugs→ virtually resistant to all; only treated with experimental drugs Current trends→ in future, some diseases have no treatment due to resistant strains Strategies: Prescription only for bacterial infections, and taken for entire course (not just until symptoms stop) Cleaning products with antimicrobial ingredients should not be used

Answer 75

Skin Prevents entry of pathogens→ microorganisms rarely penetrate intact skin Certain bacteria on skin→ destroys incoming pathogens Lack of moisture→ limits growth of microorganisms Mucous membrane Membranes line nasal passages, digestive, respiratory tracts→ secrete mucus Mucus traps pathogens until body disposes Prevents membranes drying → provides moist surface for normal microflora Cilia Fine,mucus coated, hair like→ line nasal, respiratory surfaces Beating of cilia→ moves mucus layer along (with any trapped microorganisms) in throat Chemical barriers Lysozyme (enzyme) → in tears, saliva, mucus, sweat, tissue fluid→ breaks up bacteria membrane Stomach acid (pH 1-2) → lethal environment for pathogens Bile and acidic urine fluid→ inhibits pathogen growth Other body secretions Tears→ wash surface of eye when blink→ prevents settling of microorganisms Perspiration→ any microorganism in sweat glands washed away Saliva→ washes microorganisms from teeth, into stomach lining (digestive enzymes, stomach acid destroy) Urine→ cleans urinary tract,flushes out microorganisms

Answer 76

Disease/pathogen Fungus Candida albicans → causes Thrush Symptoms Itching/burning sensation when urinating or sexual intercourse Thick, white discharge Splits in skin, redness or swelling Treatment/ Prevention Treatment→ vaginal creams, tablets Prevention→ women wipe from front to back when using toilet (avoids spreading yeast from anus) Conditions under which disease develops Usually kept low by competition from other micro-organisms→ but if balance upset, increase in C Albicans→ disease develops Balance upset by suppression of immune system, drug use, diabetes antibiotics treating bacterial infection→ reduced number of bacteria

Answer 77

Antigen→ molecule recognised as foreign→ triggers immune response Surface of cells in body→ markers identify as belonging to self→ protects from immune system attack Pathogens have chemical markers (antigens) immune recognises as not belonging to body→ activate immune response (foreign particles)

Answer 78

New organ→ marker molecules on cell surface→ antigens different to markers on own cells Organ identified as foreign→ immune response activated to attack and defend body More number of matching macromolecules→ less foreign antigen molecules to fight

Answer 79

Inflammation response Response brought by infected/injured cells→ release chemicals for fluid containing phagocytes to enter tissues→ destroy invaders Damage to tissue triggers response (characterised by pain, heat, swelling→ increased temp inhibits pathogen activity) Destroys cause of infection or confines infection to small area. Replaces/ repairs damaged tissue Phagocytosis Phagocytes (macrophages, neutrophils) surround, enclose foreign particle→ then bathed in enzyme lysozyme (destroys it) Neutrophils→ Immune cell, ingest bacteria in bloodstream, (then digested by lysozyme) Macrophage→ Larger cell, wander around tissue collecting microorganisms or other foreign bodies Lymph system Responsible for filtering lymph fluid, (remove pathogens, dead cells, debris) Lymph nodes contain phagocytes (destroy foreign material brought by tissue fluid) Lymphoid organs defend body→ fight infections in spleen, bone marrow, thymus gland Cell death to seal off pathogens If area badly infected, other responses can’t control pathogens→ layer of dead cells forms around infection site→ followed by layer of macrophages Seals off and contains pathogens→ eventually die and consumed by macrophages

Answer 80

Antibodies Proteins (produced by plasma cells) → in response to antigen Antibodies seek out antigen and bind to part of it (forms antigen-antibody complex) → deactivates antigen Antigens destroyed by antigen-antibody complex clumping together (easier to eliminate by phagocytosis) T cells Lymphocytes produced in bone marrow and mature in thymus gland→ released into blood, lymph nodes Each T cell→ particular surface receptor protein (recognises specific antigen) Encounter antigen, matching receptor→ activate and clone killer T cells→ move to infection; destroy infected cell B cells Lymphocytes produced and mature in bone marrow→ released into blood, lymph nodes, tonsils On surface→ different antibody specific to antigen→ encounter antigen (makes copies of itself) → forms plasma cells that produce specific antibodies Antibodies move to infection site→ form antigen-antibody complex (deactivate antigen

Answer 81

Smallpox Before vaccine→ millions of deaths worldwide 1967 WHO introduces mass immunisation and follow up vaccines Highly successful→ eradicated disease worldwide Diphtheria Before vaccine→ Thousands worldwide (1900’s) 1974 WHO expanded immunisation program→ aim to decrease children with disease Still present today, but effective→ drop in global incidence to 8000 cases in 2005 Polio Before vaccine→ Thousands of cases worldwide 1955→ Spain developed safe vaccine → 1997 Global Polio Eradication Initiative 70% reduction of cases→ rare in developed countries; but still concern in developing nations

Answer 82

Macrophage engulfs foreign particle with antigen→ antigen on surface moved to macrophage surface Macrophage presents antigen to helper T cell in lymph nodes (has receptor corresponding to antigen) Helper T activates→ release cytokine chemicals activating production of B clones (antigen specific) Also activate production of cytotoxic T clones (have particular antigen receptor on surface) Immune response defeated→ suppressor T stops B and cytotoxic cell activity

Answer 83

System in place to identify cells both belonging to body→ stop them attacking each other Surface of cells; MHC molecules allow recognition in body and identify foreign cells MHCI molecules present on all nucleus cells→ recognise antigens for T cell to destroy MHCII molecules on B cells→ recognition of antigens by B cells, helps helper T cell activate B and T Antibody- mediated immunity B cells presenting antigens→ move to lymph nodes, inspected by helper T cells T cells stimulate cloning of millions of B cells (specific to antigen presented) B cells produce plasma cells→ secrete specific antibodies→ move via blood, lymph to infected area Antigens, antibodies combine→ antigen-antibody complex (inactivates pathogens) Cell mediated immunity Foreign material engulfed by macrophages→ then moves to lymph nodes; inspected by helper T Helper T activate cloning of cytotoxic and memory T cells (specific to antigen) Cytotoxic cells go to infection→ antigen, antibody bind → release chemicals to destroy cells Chemicals increase inflammation, attract macrophages for phagocytosis Infection defeated→ suppressor T cells release chemicals; stop production and action of cytotoxic

Answer 84

Memory T cell Remain in body→ respond quickly to future invasions Suppressor T cell Stop immune response when infection defeated Cytotoxic T cell Activate and move to site of infection→ chemicals destroy infected cells Helper T cell Recognise antigen→ release chemicals activating cloning of T and B cells

Answer 85

Vaccine→ preparation containing dead or weakened pathogens→ can’t cause disease but act as antigens; stimulate immune response and memory Causes multiplication of B and T cells without symptoms → vaccinated person gains immunity; when actual disease occurs→ body undergoes immune response and produces antibodies for that antigen

Answer 86

Donor organ→ marker molecules act as antigens (seen as foreign material) immune response initiated Cytotoxic T cells activated→ attack cells, reject organ To reduce severity of immune response; tissue of donor and recipient need to be closely matched Drugs to suppress immune system to lower risk of rejection Drugs reduce activity of T cells (main cells attacking) → advantage; whole immune system not suppressed, can still defend the body→ but not as effective Much greater risk of infection (anti-rejection drugs needed for rest of life)

Answer 87

Study of patterns of disease occurrence in human pop, hypothesises cause and strategies to control Results used by public health authorities to develop strategies and evaluate ones already in place Descriptive studies→ frequency of disease, geographical location, time period, who is affected Analytical studies→ Statistics on mortality rates, incidence and prevalence Intervention studies→ Test effectiveness of treatment or campaign LUNG CANCER Data collected on age, sex, smoking habits of smokers and nonsmokers Case studies compare lung cancer and those without→ look for exposure (suggests smoking) Cohort studies compare non smokers and smokers to establish link between lung cancer→ greater number of cigarettes smoked daily; greater chance of dying from lung cancer Look at effectiveness of Quit campaign

Answer 88

Cancer council→ 1 in 8 cancers from smoking (most common; lung cancer) 1 in 5 cancer deaths from smoking→ smoking biggest factor for preventable cancer High risk of developing when exposed to cigarettes→ more smoked; greater risk of cancer

Answer 89

Inherited diseases Genetically transmitted; errors in genetic infi May be change in chromosome number or defect in single gene (mutation) E.g. Cystic fibrosis→ mutation to gene causes secretion of thick mucus Blocks passageways into lungs, digestive tract→ problems with breathing, nutrient absorption. No cure. Nutritional deficiencies Unbalanced diet,or physiological conditions leading to poor diets (anorexia) E.g. Scurvy from not getting enough vit C, or anemia from missing iron Environmental diseases Lifestyle related (substance abuse) or physical environment (exposure to uv rays) Disease caused from exposure to chemicals→ e.g. asbestos causes mesothelioma Cancer of cells in membrane on outside of lung→ asbestos fibres penetrate lining and damage cells causing mutations→ mesothelioma

Answer 90

SCURVY Occurrence Rare in developed countries→ mainly in developing where fresh fruit and veg not freely available Occur in all age groups→ alcoholics, elderly, infants Symptoms Swollen, purplish gums Swelling, painful legs If left untreated; gangrene, haemorrhaging, death Cause Nutritional deficiency→ lack of vit C (needed for connective tissues, bones) Deficiency weakens blood capillary wall→ bleeding, bruising Treatment/management Increase amount of vit C in diet→ or vit C supplements Prevention→ eat foods rich in vit C (orange, lemons,cranberries)

Answer 91

Quarantine→ isolation of organisms to control spread of disease All animals coming into Australia→ required to spend time in quarantine (ensure free of disease) Policy protects health of humans, environment→ reduced rate of disease incursion Prevents introduction, establishment or spread of disease/pests E.g. Rhinos from Africa commonly have internal parasites; could transfer to native fauna

Answer 92

Lemon plant Pest→ insect leaf miner Insect eats leaf layers→ causes leaf to curl Rose bush Fungal pathogen→ Black spot Yellowing of leaves, black powdery mildew Rose bush Pest→ Aphid Small leaves, stunted leaf growth

Answer 93

Govt regulations; Sterilising hospital equipment, cook/prepare food→ prevents spread of pathogens Govt regulations; garbage disposal, drinking water and sewerage treatment→ prevents occurrence Laws for reporting diseases→ allows early detection and strategies to be implemented Encourage regular screening for disease; e,g women check breast for lumps (cancer detection) Childhood immunisation program→ prevent disease incidence (e.g. whooping cough) Education programs; awareness of lifestyle risk factors (E.g. Quit campaign→ images of side effects)

Answer 94

Many plant species refused entry; or allowed in if treated to ensure no pests Some restrictions on movement of fruit → prevents spread to disease free areas Quarantine checkpoints on main roads leading to each state (prevents risk material entering) If disease enters Aus; quarantine, control of movements, slaughter or vaccination of infected animals Observation and decontamination→ establish disease free areas E.g. Swine Flu 2007→ horse movement banned, equipment decontaminated, → no swine Flu 2008

Answer 95

TREATMENT AND CONTROL OF DISEASE: Use of pesticides Controls spread of vectors and pests; E.g DDT to kill mosquito (malaria) Harms environment and can lead to resistant strains developing Use of antibiotics Treats many type of bacterial infections; destroys bacteria and cures person Overuse and wrongful use → development of resistant strains Medical intervention procedures E.g. Cancer treatment by surgery radiation, chemotherapy→ if successful cures patient Side effects of treatment severe and increase suffering of patient PREVENTION AND MANAGEMENT OF DISEASE: Vaccination Prevents person from contracting the disease; decreases prevalence of disease E.g. vaccination against diphtheria; only small percentage suffer side effects Quarantine Prevents entry into Aus; management procedures prevent spread around country Decreases incidence of disease and protects agricultural industry allowing them entry to export markets with disease free products Genetic engineering Plants and animals produced that are resistant to pathogens/pests→ prevents occurrence of disease Reduces need for spraying crops with pesticides Effects on biodiversity unknown; could be harmful E.g. Bt cotton that produces natural insecticide to kill caterpillar larvae Public health programs Reduces incidence of disease in population E.g. public education programs; no smoking to prevent lung cancer

Answer 96

Stimulus→ Change in internal or external environment; detected by receptors, response triggered Receptors: single cells or concentrated in areas to form sense organs (eye, ear) E.g. Touch hot plate, receptors in skin detect heat and pain cause to withdraw fingers→ coordination needs link between receptors and effectors (muscles or glands that respond) Link carried out by nervous system Photoreceptor→ sensitive to light energy (visible light, UV light) Mechanoreceptors→ Mechanical energy (touch, pressure, Gravity) Thermoreceptors→ respond to heat and cold (changes in temp)

Answer 97

Communication: sending and receiving meaningful info Communicator (sending info) needs to have signalling device. E.g. Human voice box for sound production Recipient (receiving signal) needs sensory structure to detect signal. E.g. Human ears to detect sound Animals use all 5 senses→ communication relies on corresponding visual, acoustic, tactile (touch) and chemical (smell and taste) receptors. Sight→ Lion; Hairs on mane stand up (larger); when another male in environment Sound→ Lion; Roar to intimidate other male lion; aggressive warning Taste→ Ants follow pheromone markers left by others to indicate location of food Smell→ Fish emit odours to establish rank in a social group Touch→ Humans hug and shake hands to greet

Answer 98

CNS triggers response to stimulus; receptors connected by nerves Receptors change stimuli into electrochemical signals (nerve impulses) Travel along nerves, transmit messages to CNS from receptors→ processed and interpreted as info and response initiated CNS sends impulses along nerves to effector organs (carry out response) Brain and spinal cord interpret and make sense of messages (take into account past experiences or as inherited reflex)

Answer 99

Conjunctiva Thin transparent membrane (continuous with inner layer of eyelid)→ protects front of eye Cornea Transparent; allows light to enter eye. No blood vessels Curvature→ helps bend/refract incoming light rays to converge and land at back of eyeball Nerve fibres sensitive to touch and pain Sclera Outermost layer of eye→ protects inner layers (non-elastic, tough tissue) Site of attachment for external muscles; enables eye movement in socket Maintains shape of eye; transparent at front, opaque at back forming white part of eye Choroid Middle coat of eyeball→ most of blood vessels in layer Back layer is black; reduce scattering/reflection of light within eye Front layer continues to form ciliary body and lens ``` Retina Thin, delicate, contains several layers of nerve cells Contains photoreceptors (rods, cones) → respond to light, convert light energy into nerve impulses ``` Iris Coloured part of eye; made of connective tissue, smooth muscle→ muscles control size of pupil Lens Transparent, biconvex in shape (bulges outwards) → refracts light rays. Directs them onto retina (where focused image will be formed) Elasticity; vary from round to flatter surface; eye accommodates near and far vision Aqueous and vitreous humour Transparent watery liquid (like blood plasma) Contains dissolved nutrients Aqueous; Provides nutrients for cornea and lens that don’t have own supply Vitreous; Material fills remainder of eyeball; helps maintain shape and provide nutrients Ciliary body Muscles and ligaments; help adjust curvature of lens Ciliary muscles relax; lens flat (distant vision) Muscles contract: lens rounder (near vision) Optic nerve Nerves pass through skull via opening in eye socket→ carry electrochemical signals from retina to brain

Answer 100

HUMANS 380-760nm→ all colours in visible light (no uv range) Active during day→ need to distinguish colours in environment INSECTS Bee→ 300-650nm→ uv range, blue, green (not red) UV patterns on flowers to attract bees to pollen and nectar Ant→ 320-630nm→ uv, blue, green. yellow range Maximum sensitivity; discriminate between colours in environment, when gathering food VERTEBRATE Snake→ 400-850 nm→ blue, green, red, uv→ relies on infrared to locate prey in dark burrows Pigeon→ 460-700 nm→ blue, green, red→ distinguish environment when flying

Answer 101

Visible light; small part of electromagnetic spectrum seen by humans; (rods, cones) Humans visible wavelength: 380-760nm Objects absorb some wavelengths, reflect other→ objects look coloured because of light they reflect E.g. Green lead; green light reflected. Other colours (red, blue etc) absorbed; can’t be detected by eye Humans can’t detect ultraviolet part of spectrum; sensitive to light in red, green, blue. (see all colours) Insects see ultraviolet range; sensitive cells for shorter wavelengths Birds see ultraviolet range, detect most efficiently in red and green ranges Some flying animals detect polarised light; used for navigation in flight

Answer 102

Refraction: bending of light as it travels from one medium to another (air to water) Light rays move through more dense medium, it slows down and bends towards normal Light passes through biconvex (eye lens) → light rays refracted to focal point (focus point) Refracted light through biconvex lens converge at focus point Convex lens→ converge. Concave lenses→ diverge Lens in eye changes shape→ allows eye to form focused image of near and far objects Light refracted at cornea, aqueous humour, lens and vitreous humour→ curvature of cornea and lens refracts the light rays to converge and form an image on the retina at the back of the eye

Answer 103

Light box and different focal lengths from concave and convex Convex lens → light rays from box converges Concave lens→ light rays from box diverges

Answer 104

Density of cornea, aqueous humour, lens and vitreous humour→ all similar and close to water All structures refract light passing through eye to a greater or lesser degree Refractive power of air: much lower than refractive power of eye parts Light oases from air into refractive surfaces Therefore→ Greatest degree of refraction in human eye occurs at boundary of air and cornea→ difference between air and cornea is greater than the difference between internal eye structures

Answer 105

Distant vision→ flat curvature (ciliary muscles relax and pull suspensory ligaments taut) Near vision → increased curvature (ciliary muscles contract and suspensory ligaments slacken) Lens becomes rounded; greater refraction

Answer 106

CATARACTS Clouding of lens; obstructs path of light into eye and transmission of clear signals Part of lens becomes opaque; blurred vision, looking through ‘veil’ Form when proteins build up in lens; new cells form outside lens and old cells compacted into centre Due to ageing or injury to eye TECHNOLOGY Phacoemulsification: Probe inserted via tiny incision; breaks cataract into pieces; then suctioned out Lens implant permanently inserted into eye; focuses light rays on surface of retina. No stitches needed Extracapsular extraction: Large incision; removes centre of cataract in one piece; stitches needed IMPLICATIONS FOR SOCIETY Millions have vision restored; ends avoidable blindness Rarely have any complications; majority return to daily activities Increases life expectancy, gives more independence, patients see shaper focus, brighter colours Patients can return to work, regain self sufficiency→ allows caretakers (family) to return to work Previously→ removal of entire lens, have to wear thick glasses

Answer 107

Change in curvature of lens→ accommodation (used at looking at near or far objects) Degree of lens curvature determines degree of light refraction Increased lens curvature (thicker lens) decreases focal length (increased refraction) Decreased curvature (thinner lens) increases focal length (decreased refraction) Refractive power changes from low (thin, flat lens) when at rest (distant objects) to high (round lens) at maximum accommodation (near objects) Distant vision→ flat curvature (ciliary muscles relax and pull suspensory ligaments taut) Near vision → increased curvature (ciliary muscles contract and suspensory ligaments slacken) Lens becomes rounded; greater refraction

Answer 108

MYOPIA Short sightedness→ distant objects unclear, but close up objects seen well Distant objects image fall in front of retina; not on it→ light rays bent incorrectly; blurred vision Occurs when eyeball too long for lens, or cornea/lens too curved for eyeball length HYPEROPIA Long sightedness→ close up objects unclear but distant objects seen well Image falls behind retina; not on it→ light rays not bent to single focus→ blurred vision Occurs when eye too rounded, or lens too flat to alter light adequately CORRECTIVE TECHNOLOGIES Corrective lenses from glasses or contact lenses→ shaped to fit eyeball curvature Myopia: Concave lens (thicker outwards, thinner inwards) bends light outwards→ light diverges before meets eye; extends focal length Hyperopia: Convex lens (thinner outwards, thicker inwards) bends light inwards → light converges before meets eye; shortens focal length Laser eye surgery to change cornea curvature and alter refraction PRK→ Outer cornea surface removed; laser shapes uppermost surface of cornea LASIK→ Cut and lift flap of cornea and reshape using lasers before replacing flap Orthokeratology→ Wear special lens at night to reshape cornea while asleep; in morning temporarily retains new shape; people can seen without glasses

Answer 109

Depth perception; Ability to determine distances between objects and see the world in 3D Judge distances→ from 2 forward facing eyes; brain interprets the 2 images from each eye (by superimposing them to produce a single binocular vision) Brain uses slight differences in the 2 images to create 3D vision allowing calculate depth DP also occurs from previous experience of the size of an object When moving the head; the distant objects move less compared to close objects

Biology Flashcards

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