bio p1

Question 1

humoral response kerboodle

Answer 1

complimentary B cell to antigen in blood engulfs antigen via endocytosis and presents it on its cell surface membrane (clonal selection)

Th cell activates and stimulate division by mitosis into plasma cells or memory cells (clonal expansion)

Question 2

adaptations of aorta

Answer 2

Elastic tissue to allow stretching / recoil / smoothes out flow of blood

(Elastic tissue) stretches when ventricles contract
Recoils when ventricle relaxes;

Muscle for contraction / vasoconstriction;

Thick wall withstands pressure + stop bursting;

Smooth endothelium reduces friction;

Aortic valve / semi-lunar valve prevents backflow.

Question 3

capillary adaptations

Answer 3

1 cell thick - narrow lumen = so short diffusion distance (cells pressed sideways against capillary)

highly branched so large SA

small pores in endothelium allow WBC to leave and fight infection

Question 4

vein adaptations

Answer 4

muscle and elastic layers are relatively thin = thin muscle layer as constriction isn’t needed to control the flow of blood to the tissues as veins take blood back to the heart
thin elastic layer as blood is transported at low pressure so wont burst

veins have valves = low pressure and low flow of blood so no backflow

Question 5

arteriole adaptations

Answer 5

thicker muscle layer = vaso constrict to reduce flow of blood into capillaries

thinner elastic layer as blood pressure is lower

Question 6

adaptations of arteries

Answer 6

thick muscular wall = high pressure so doesn’t burst

elastic wall = stretch and recoil

smooth muscle = reduces friction so blood has less restriction to move

no valves = high pressure and speed so unlikely backwards flow of blood

Question 7

xerophyte adaptations

Answer 7

thick wavy cuticle = impermeable + larger diffusion distance less water loss

sunken stomata = traps moist air - humidity
reduces WP gradient

rolled leaves and hairs = reduce WP gradient

reduced SA:V ratio

Question 8

how to make a temporary mount of a piece of plant tissue to observe starch grains

Answer 8

● Add a drop of water to the slide
● Remove a thin section of tissue and place it onto the slide (flat as possible)
● Add 1 drop of iodine dissolved in potassium iodide to stain the sample if its plant tissue
● Lower a coverslip on top using a mounting needle

Question 9

active vs passive immunity

Answer 9

• active involves memory cells but passive doesnt
• active involves antibody production by plasma cells
• passive involves antibody introduced from external source
• active = long term as antibody is produced in response to antigen
• passive = short term as antibody broken down
• active takes time to develop, passive fast acting

Question 10

founder effect

Answer 10

new population established by a small group of individuals from a larger population
reduced genetic diversity + more inbreeding

Question 11

gas exchange adaptations

Answer 11

many alveoli = provide a large surface area
many capillaries = large SA so fast diffusion
alveoli/capillary epithelium thin = short diffusion distance
flattened squamous epithelial cells = short diffusion distance so fast diffusion
ventilation/circulation maintains diffusion/conc gradient

Question 12

insect adaptations

Answer 12

trachioles = thin wall so short diffusion distance
highly branched = large SA + short diffusion distance
tracheae provide tubes full of air so fast diffusion
fluid in ends of trachiole moves out into tissue during exercise so larger SA forgas exchange / faster diffusion to gas exchange surface
body can be moved by muscles to move air so maintains diffusion conc gradient

Question 13

asthma

Answer 13

smooth muscle of bronchioles contract secreting mucus
airway constricts so air flow reduces ans less oxygen in blood

Question 14

emphysema (smoking)

Answer 14

smoke inflames alveoli attracting phagocytes breaking down elastin so alveoli cant expel air so trapped air destroys alveoli lowering SA

Question 15

fibrosis

Answer 15

formation of scar tissue so thicker and less elastic so slow diffusion
lungs expand less and tidal volume decreases

Question 16

tuberculosis

Answer 16

TB bacteria stimulates immune response killing bacteria but damaged exchange surface so tidal volume decreases

Question 17

community

Answer 17

all populations of different species in the same area at the same time

Question 18

ecosystem

Answer 18

a community and the non living (abiotic) components of an environment

Question 19

how the structure of DNA is related to its function

Answer 19

double stranded / sugar phosphate backbone so stable/strong/protects bases

long/large molecule so stores lots of genetic information

helix/coiled so compact

base sequence codes for amino acid/proteins

double stranded so replication can occur semi conservatively

weak hydrogen bonds between base pairs for replication
or many hydrogen bonds so stable/strong

Question 20

how are epithelial cells adapted to their function in the small intestine

Answer 20

Microvilli provide a large / increased surface area;

2. Many mitochondria produce ATP / release or provide energy (for active transport);
3. Carrier proteins for active transport;
4. Channel / carrier proteins for facilitated diffusion;
5. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose;
6. Membrane-bound enzymes digest disaccharides / produce glucose;

Question 21

how does mitosis produce geneitcally identical cells

Answer 21

DNA replicated in s phase
by complementary base-pairing;

forming two identical sister chromatids;

Each sister chromatid moves to opposite poles of cell

Question 22

membrane fluidity definition

Answer 22

ability of proteins/lipids to diffuse laterally in the plane of the membrane

Question 23

cholesterols role in the membrane

Answer 23

high cholesterol = reduced membrane fluidity as cholesterol fits between fatty acids and phospholipids increasing packing of the membrane and restricting movement of membrane components

Question 24

plasmolysed palisade cells

Answer 24

cytoplasm shrinks and membrane detaches from the wall
in a hypertonic solution causing water to leave by osmosis
(dirupts rigidity by loss of turgor pressure)

Question 25

method to determine water potential of a plant

Answer 25

place plant tissue in different concentrations of solution -dilution series record change in mass plot calibration curve record the solute concentration where there is no change in mass of plant tissue this solute concentration has the same WP As plant tissue

Question 26

why would affecting habitat decrease index of diversity

Answer 26

fewer food SOURCES fewer habitats/niches removes species/types of insects

Question 27

mitosis stages

Answer 27

(During prophase) 1. Chromosomes coil,condense,become visible; and appear as (two sister) chromatids joined at the centromere; (During metaphase) 3. Chromosomes line up on the equator of the cell attached to spindle fibres By their centromere; (During anaphase) 6. The centromere divides; 7. (Sister) chromatids / chromosomes are pulled to opposite poles (During telophase) 8. chromosomes uncoil.

Question 28

Describe the role of the rough endoplasmic reticulum in the formation of chylomicrons?

Answer 28

Proteins are synthesised by ribosomes on the surface of the RER vesicles formed by the RER are then used to transport the chylomicron to the golgi and leaves epithelial cell by exocytosis

Question 29

homologous chromosome

Answer 29

homologous chromosome - a pair of chromosomes (maternal paternal) that have the same gene loci Same shape/size; Carry the same genes; Found at the same loci but carry different alleles

Question 30

definitions of gene allele locus

Answer 30

gene -length of DNA coding for a polypeptide allele - different forms of a gene locus - position of a gene on a chromosome

Question 31

possible chromosome combinations after meiosis

Answer 31

after meiosis without crossing over: 2^n 4 homologous chromosomes = 16 after random fertilisation: (2^n)2 4 homologous chromosomes = 256

Question 32

genetic diversity definition

Answer 32

The number of different alleles of genes in a population

Question 33

ATP adaptations

Answer 33

1.Releases relatively small amount of energy 2. Releases energy instantaneously; 3. Phosphorylates other compounds, making them more reactive; 4. Can be rapidly re-synthesised; 5. Is not lost from/does not leave cells;

Question 34

why is it good to use island populations

Answer 34

Can record all individuals on (small) islands; 2. (So) no / less sampling error; 3. (Maybe) different rates of mutation / different selection pressures / different environmental conditions; 4. Inbreeding / breeding with close relatives (more likely); 5. (Little) gene flow / (more chance of) genetic drift; Accept reference to either of these ideas for this point

Question 35

adaptations of alveolar epithelium

Answer 35

Many alveoli ​ (so) large surface area; Walls of alveoli are one cell thick (so) short diffusion pathway/distance; Walls of alveoli have flattened cells (so) short diffusion pathway/distance; Alveoli are close to capillaries (so) short diffusion pathway/distance; Alveolar wall is permeable to gases (so) ventilation maintains diffusion gradient; .​ Alveolar wall is lined with fluid (so) gases are absorbed.

Question 36

explain how a phylogenetic system differs from a simple hierarchy

Answer 36

(phylogenetic) based on evolutionary history; shows points of divergence e.g. reptiles and birds separated after mammals and birds more closely related than mammals; (hierarchical) based on shared characteristics (seen today);

Question 37

evidence to classify different animals as different species

Answer 37

fossil record evolutionary history / phylogeny biochemical differences e.g. DNA / proteins homologous features (characteristics in different species that share a common evolutionary origin, meaning they were inherited from a common ancestor) karyotype / number and form of chromosomes;

Question 38

population

Answer 38

all the individuals of the same species living in a specific area at a particular time, who can potentially interbreed

Question 39

isolating mechanisms of sympatric speciation

Answer 39

temporal − different breeding seasons / feeding times / ecological / behavioural − different courtship displays / different niches / habitats / feeding areas / mechanical − mismatch of reproductive parts gamete incompatibility − sperm killed in female’s reproductive tract / hybrid inviability / hybrid infertility;

Question 40

structure and function of starch

Answer 40

1. Coiled / helical 2. (So) compact 3. Insoluble; 4. so does not affect water potential; 5. Large molecule / long chain; 6. (So) does not leave cell / contains large number of glucose units; 7. Branched chains; 8. (So) easy to remove glucose;

Question 41

how does increase in harmful lipids affect risk of developing coronary heart disease

Answer 41

more harmful lipids increase risk of ATHEROMA (a build-up of fatty deposits, within the walls of arteries) leads to blockage of coronary artery atheroma is the plaque buildup, and a myocardial infarction is the damage caused by a blockage resulting from that plaque oxygen cant reach heart

Question 42

assumptions of mark release recapture

Answer 42

marking doesn't affect survival no immigration/emigration no losses to predation birth rate = death rate all belong to one population

Question 43

glycolipid vs glycoprotein

Answer 43

Glycoprotein (carbohydrate chain attached to protein) Important in cell signaling eg receptors or hormones Glycolipid (carbohydrate chain attached to phospholipid) For cell recognition in immune system

Question 44

When you need to find the concentration of the solution that has the SAME water potential as the vegetable/fruit you are investigating you:

Answer 44

a. Plot data on a graph (give titles of the x and y axis) b. Draw a line of best fit c. From the graph either: (depending on question) i. Find when the ratio is 1 (there is no change in mass/length) ii. extrapolate the line of best fit and read off iii. Find where it crosses the x axis

Question 45

binary fission of bacteria

Answer 45

Binary Fission ● Circular DNA and plasmids replicate ● Circular DNA attaches to opposite ends of cell membrane ● Bacterial cell grows ● The cell membrane pinches inwards in the middle of the cell ● cytoplasm divides to form two daughter cells (each has a variable number of plasmids) ● A cell wall is formed around each daughter cell.

Question 46

vaccination

Answer 46

1. A vaccine is made from dead or weakened bacteria or antigens from them. 2. B cells with complementary receptors bind to the antigen 3. Specific T helper cells, activate these B cells. 4. B cells divide by mitosis to produce B-plasma cells. 5. The B plasma cells release antibodies, which are complementary to the bacterial antigens 6. Some B plasma cells become B memory cells 7. If the person is exposed again to the antigen or pathogen, the B memory cells become active and divide by mitosis to produce B plasma cells , which produce more antibodies more quickly. 8. These antibodies lead to the destruction of the pathogen before symptoms appear 9. Vaccinating a large proportion of the population results in the herd immunity effect

Question 47

(indirect) Elisa test

Answer 47

1. Antibodies complementary to the antigen are bound to the test plate 2. The sample containing antigens is added 3. The first antibody binds to the antigen 4. The plate is washed 5. Second antibody is added. This antibody is complementary to the first antibody AND has an enzyme attached to it. 6. The second antibody attaches to the primary antibody. 7. The plate is washed again and any unbound antibody is removed 8. A substrate is added and it will change colour if the antigen is present

Question 48

2 ways monoclonal antibodies stop cancer

Answer 48

E.g. 1 - direct ● The monoclonal antibody is complementary to a receptor protein on cancer cells ● When the monoclonal antibody is present it binds to the receptor so the growth factor doesn’t bind and the cell doesn’t divide E.g. 2 - indirect ● Use a monoclonal antibody that is complementary to an antigen on the cancer cell ● Bind a drug to the monoclonal antibody ● The monoclonal antibody will bind to the cancer cell and thus take the drug to the cell which causes the cell to be killed

Question 49

HIV replication

Answer 49

The HIV’s attachment proteins binds to the CD4 receptor proteins on the surface of the Th cell. 2. The virus’s lipid envelope fuses with the cell membrane of the Th cell. 3. The protein capsid breaks down 4. RNA and enzymes (e.g. reverse transcriptase) of the virus are now released into the cytoplasm of the host cell. 5. Reverse transcriptase converts the viral RNA to DNA. 6. The viral DNA is incorporated into the cell’s DNA. 7. The viral DNA can now be transcribed into mRNA 8. Viral mRNA passes through the nuclear pore and attaches to a ribosome 9. Viral mRNA is translated into viral proteins that can be assembled into new HIV particles. 10. HIV particles bud off the Th cell (so that the Th cell’s membrane forms the lipid envelope of the virus).

Question 50

calibrating a stage micrometer

Answer 50

1) Find out the length of the stage micrometer? e.g. 10mm long = 10000μm 2) Find out how many divisions there are? e.g 100 divisions 3) Work out how big each division is in μm? e.g 10000/100 = 100μm = 1 division 4) Place the stage micrometer on the stage 5) Line up the divisions on the eyepiece graticule with those of the micrometer 6) Lets say 100 units on the eyepiece graticule fit 30 units of the stage micrometer 7) Now work out the length of one eyepiece graticule unit in μm

Question 51

cohesion tension theory

Answer 51

 water evaporates from the leaves;  this reduces water potential in the mesophyll cells in the leaf  so water moves out of the xylem down a water potential gradient by osmosis  this creates tension (negative pressure) in the xylem  so water is pulled up the xylem as a continuous column  there is cohesion between water molecules due to H-bonding  the column doesn’t break because of adhesion between the water molecules and the xylem walls

Question 52

absorption

Answer 52

1. Monoglycerides and fatty acids associate with bile salts to form micelles 2. Micelles transport fatty acid and glycerol to the lining of the ileum 3. Micelles release monoglycerides and fatty acids when they come into contact with epithelial cells 4. Monoglycerides + fatty acids diffuse across the phospholipid bilayer and enter epithelial cells 5. Enter the smooth endoplasmic reticulum and are converted back into triglycerides 6. A vesicle buds off the SER and moves to the golgi apparatus and fuses with it 7. Triglycerides associate with proteins to form lipoprotein before combining with cholesterol to form a chylomicron (which are wrapped in a vesicle – from the golgi) 8. Chylomicrons leave epithelial cells by exocytosis in lacteals 9. Chylomicrons enter the lymphatic capillaries 10. The lymphatic vessels transport the chylomicrons to the blood

Question 53

mRNA vs tRNA

Answer 53

linear vs folded clover leafe shape no hydrogen bonds vs H bonds no amino acid binding site vs specific amino acid binding sites length varies and more nucleotides vs same length codons vs anticodons

Question 54

translation process

Answer 54

1. mRNA leaves (nucleus) through nuclear pore 2. mRNA associates with a ribosome;
 3. Ribosomes moves to find the start codon 4. tRNA brings a specific amino acid; 5. The anticodon on tRNA is complementary to the codon on mRNA 6. Ribosome moves along to the next codon on mRNA 7. Another tRNA binds to the 2 nd binding site in the ribosome (bringing another specific amino acid) 8. The process continues and a peptide bond forms between the amino acids in a condensation reaction (using energy from ATP) to form a polypeptide chain 9. the tRNA detaches and collects another amino acid and the process continues 10. The sequence of codons determines the order of amino acids in the polypeptide

Question 55

properties of triglycerides related to their function

Answer 55

high H to O ratio so acts as a water source when oxidised high ratio of energy storing C-H bonds compared to C atoms so are an excellent source of energy low mass to energy ratio so good storage molecules with more energy being stored in a smaller volume large non polar molecules, triglycerides are insoluble in water storage does not affect water potential

Question 56

properties of phospholipids related to their function

Answer 56

polar molecule - hydrophilic phosphate head and hydrophobic tail = forms a hydrophobic bilayer between inside/outside of cells hydrophilic phosphate heads help hold at the surface of the cell membrane forms glycolipids by combining with carbohydrates involved in cell recognition

Question 57

A student prepared a plant root to observe cells undergoing mitosis. He put the root in a small bottle of hydrochloric acid in a 40 °C water bath. Why did he put the plant root in acid?

Answer 57

To break down links between cells/cell walls To separate cells/cell walls To break down/hydrolyse cellulose/cell wall Allowing the stain to pass/diffuse into the cells Allowing the cells to be (more easily) squashed To stop mitosis

Question 58

Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise.

Answer 58

Arteriole; (Circular/smooth) muscle relaxes; Vasodilation increases blood flow

Question 59

cytokinesis vs telophase

Answer 59

nuclear membrane reforms in telophase cell surface membrane reforms in cytokinesis and pinches

Question 60

uncertainty

Answer 60

absolute uncertainty = 1/2 smallest division on scale % uncertainty = absolute uncertainty/measurement x 100

Question 61

percentage cover formula

Answer 61

divide total % by num of quadrats (Number of squares/points where the species occupies over half the square/point) / (Total number of squares/points in the quadrat) x 100

Question 62

properties of water

Answer 62

(a) 1. A metabolite in condensation/hydrolysis/ photosynthesis/respiration; 2. A solvent so (metabolic) reactions can occur 3. High (specific) heat capacity so buffers changes in temperature; 4. Large latent heat of vaporisation so provides a cooling effect (through evaporation); 5. Cohesion (between water molecules) so supports columns of water (in plants); 6. Cohesion (between water molecules) so produces surface tension supporting (small) organisms; - pondskaters

Question 63

UPDATED cardiac cycle

Answer 63

diastole: atria and ventricles relaxed and AV valves closed pressure in vena cava exceeds atria and blood fills atria passively when pressure in atria exceed ventricles AV valves open blood flows into ventricles passively atrial systole: atria contract to empty remainder of blood into ventricles pressure in ventricles exceeds atria and AV valves close ventricular systole: ventricles contract so pressure in ventricles exceeds aorta/pulmonary artery semi lunar valves open blood leaves ventricles pressure decreases and semi lunar valves close

Question 64

adaptations due to natural selection

Answer 64

anatomical - physical structures eg fur physiological - internal changes eg: hydrolysing fat for water behavioural eg migration

Question 65

3 domains

Answer 65

bacteria, archaea, eukarya

Question 66

loading of sucrose in phloem

Answer 66

hydrogen ions actively transported out of companion cells into intermembranal space hydrogen ions facilitatedly diffuse back into companion cells via cotransport bringing in sucrose into companion cells sucrose diffuses from companion cells into sieve cells of phloem

Question 67

direct vs indirect elisa

Answer 67

direct = antigen - one antibody with enzyme attached indirect = antigen - primary antibody - secondary antibody with enzyme attached

Question 68

role of B cells in producing antibodies after vaccine

Answer 68

1. virus contains antigen; 2. virus engulfed by phagocyte / macrophage; 3. presents antigen to B-cell; 4. memory cells / B-cell becomes activated; 5. (divides to) form clones; 6. by mitosis; 7. plasma cells produce antibodies; 8. antibodies specific to antigen;

Question 69

stretch / recoil linked to ventricles

Answer 69

(Aorta wall) stretches because ventricle contracts 2. (Aorta wall) recoils because ventricle relaxes 3. Maintain smooth flow

Question 70

cardiac output

Answer 70

volume of blood pumped by the heart per unit of time fitter individuals have a higher CO litres per minute

Question 71

heart rate

Answer 71

the number of times a heart beats per minute (num of cardiac cycles) bpm

Question 72

stroke volume

Answer 72

volume of blood pumped out of the left ventricle during one cardiac cycle max - min volume no matter what second it happens

Question 73

how fish maintain flow of water on gills

Answer 73

1. mouth opens, operculum / opercular valve shuts; 2. floor of mouth lowered; 3. water enters due to decreased pressure / increased volume; 4. mouth closes, operculum / opercular valve opens; 5. floor raised results in increased pressure / decreased volume; 6. high / increased pressure forces / pushes water over gills;

Question 74

how structure of gas exchange is efficient

Answer 74

1. alveoli provide a large surface area; 2. walls of alveoli thin to provide a short diffusion pathway 3. walls of capillary thin / close to alveoli provides a short diffusion pathway; 4. walls (of capillaries / alveoli) have flattened cells; 5. cell membrane permeable to gases; 6. many blood capillaries provide a large surface area; 7. intercostal / chest muscles / diaphragm muscles / to ventilate lungs / maintain a diffusion / concentration gradient; 8. wide trachea / branching of bronchi / bronchioles for efficient flow of air; 9. cartilage rings keep airways open;

Question 75

tidal volume vs vital capacity

Answer 75

TV = volume of air in and out of lungs at rest VC = volume of air in and out of lungs during exercise

Question 76

pulmonary ventilation rate

Answer 76

PVR = Breathing rate x tidal volume air moved in and out of lungs per minute