Biology description questions

a. sarcomere - clearly indicated between Z lines (whether Z lines named or not); b. Z lines - shown at the ends of a sarcomere; c. actin (filaments) - drawn as thin lines attached to Z lines; d. myosin (filaments) - drawn as thick lines interdigitating with thin/actin filaments; e. myosin heads - on both sides of at least one myosin filament; f. light band and dark band - indicating regions of actin only and myosin plus actin

Draw a labelled diagram to show the structure of a sarcomere.

a. each amino acid with a COO-/COOH group at one end AND a NH2/NH3+ at the other b. CH in middle with H or R group attached c. peptide bond correctly drawn between N and C=0 d. COO-/COOH group at one end of dipeptide AND NH2/NH3+ at other end Both needed. e. loss of water

Draw molecular diagrams to show the condensation reaction between two amino acids to form a dipeptide.

a. photophosphorylation is the production of ATP; b. (some of the) light absorbed by chlorophyll / photosystem II; c. photolysis/splitting of water separation of hydrogen ion from its electron; d. the electron transport system moves the electrons through a series of carriers; e. (electron transport system occurs) in the thylakoid membrane; f. electron transport linked to movement of protons into thylakoid space; g. a proton gradient builds up (in the thylakoid space); h. small thylakoid space enhances the gradient; i. hydrogen ions move by diffusion through the ATP synthase; j. ADP + inorganic phosphate (Pi) forms ATP; k. (the kinetic energy from) movement of hydrogen ions (through ATP synthase) generates ATP; l. ATP synthase is a protein complex in the thylakoid membrane; m. formation of proton gradient / ATP synthesis linked to electron transport is chemiosmosis;

Explain chemiosmosis as it occurs in photophosphorylation.

a. DNA is replicated/copied semi-conservatively/from a template; b. mutations can be a source of variation / resulting protein has new or different functions; c. mutations/changes in the DNA may not result in changes in the amino acid for which the triplet codes; d. genetic code is redundant; e. genes occur as paired alleles which can be different; f. crossing-over occurs; g. recombines linked alleles producing new combinations; h. random orientation of bivalents / homologous chromosomes (in metaphase I); i. large genetic variation in (haploid) gametes / 2n / 223; j. random recombination of alleles during fertilization (leads to variation); k. different phenotypes among members of the same population; l. natural selection may lead to enhanced survival of recombinants;

Explain how DNA is used to pass on genetic information to offspring accurately but also produce variation in species.

a. less transpiration/water loss as (atmospheric) humidity rises; b. air spaces inside leaf are saturated/nearly saturated (with water vapour); c. smaller concentration gradient with higher atmospheric humidity; d. more transpiration/water loss as temperature rises/with more heat; e. faster diffusion / more kinetic energy (of water molecules); f. faster evaporation (due to more latent heat available); g. more transpiration/water loss as wind (speed) increases; h. humid air/water vapour blown away from the leaf; i. increasing the concentration gradient (of water vapour); j. more transpiration/water loss in the light; k. light causes stomata to open / stomata closed in darkness; l. low CO2 concentration inside leaf in bright light so stomata open wider

Explain how abiotic factors affect the rate of transpiration in terrestrial plants

a. resting potential is -70 mV / relatively negative inside in comparison to the outside; b. Na+/K+ pumps maintain/re-establish (the resting potential); c. more sodium ions outside than inside (when at the resting potential); d. more potassium ions inside than outside (when at the resting potential); e. nerve impulse is an action potential that stimulates a (wave of) depolarization along the membrane/axon; f. if neuron is stimulated/threshold potential/-50 mV is reached sodium ion channels open; g. sodium ions diffuse/move in; h. (Na+ move in) causing depolarization; i. potassium ion channels open / potassium ions diffuse/move out; j. (K+ move out) causing repolarization; k. local currents / description of Na+ ion diffusion between depolarized region and next region of axon to depolarize

Explain how an impulse passes along the axon of a neuron

a. meiosis / production of male and female gametes b. pollination / transfer of pollen from anther to stigma c. fertilization happens after pollination / fertilisation is joining of gametes d. seed dispersal / spread of seeds to new locations

Outline three processes required for successful reproduction of angiospermophyta.

a. germinal cells / spermatogonia undergo mitosis to keep a supply of germinal cells present; b. some germinal cells / spermatogonia grow larger to become primary spermatocytes; c. primary spermatocytes go through meiosis I; d. to form secondary spermatocytes; e. these secondary spermatocytes go through meiosis II; f. to produce spermatids; g. spermatids differentiate/grow a tail and reduce their cytoplasm h. spermatids associated with nurse cells (Sertoli cells); i. sperm detach from Sertoli cells and enter lumen of the seminiferous tubule; j. testosterone stimulates sperm production;

Accurate transmission of base sequences to offspring depends on successful gamete production. Describe how spermatogenesis occurs in humans.

during inhalation: a. external intercostal muscles contract moving rib cage up and out; b. diaphragm contracts becoming lower/flatter; c. increase in volume and decrease in pressure (of thorax); d. air flows into lungs as atmospheric pressure is higher; during exhalation: e. internal intercostal muscles contract so ribs move in and down; f. diaphragm relaxes and returns to domed shape; g. decrease in volume and (therefore) increase in pressure (of thorax); h. air moves out until pressure in lungs falls/is equal to atmospheric pressure; i. abdominal muscles can be used to make a stronger/forced exhalation;

Active skeletal muscle requires a good supply of oxygen. Outline the mechanism of ventilation in the lungs

a. higher nitrogen/urea as blood enters nephron/Bowman's capsule than when it leaves the nephron (in the renal vein); b. most small soluble molecules/glucose/nutrients/ions are removed from blood in Bowman's capsule; c. through ultrafiltration; d. proteins / blood cells / large molecules remain in the blood; e. as filtrate moves through the nephron (tubule), water is returned to the blood (by osmosis); f. glucose/nutrients is returned to blood by active transport (and diffusion) / selective reabsorption; g. in the proximal convoluted tubule; h. urea / uric acid remain in the filtrate / removed from blood; i. sodium is pumped into the medulla in the loop of Henlé; j. water reabsorption is enhanced by a high sodium gradient (in the medulla); k. permeability of the collecting duct membrane is regulated by hormones / ADH; l. water concentration in urine is variable to maintain homeostasis in the blood; m. more oxygen/less carbon dioxide in blood entering (kidney) than in blood leaving (kidney);

All parts of the body change the composition of the blood. Explain how the nephron changes the composition of blood.

anaerobic respiration: glucose transformed into (two molecules of) pyruvate/pyruvic acid; oxidation reactions using NAD/NAD+ / producing reduced NAD/NADH; smaller amount of energy released/ATP produced than in aerobic; NAD/NAD+ regenerated by reducing pyruvate/transfer of hydrogen to pyruvate; pyruvate to CO2 and ethanol in yeast/in alcoholic fermentation; pyruvate to lactic acid in humans/in lactic/lactate fermentation; aerobic respiration: pyruvic acid/pyruvate fully oxidized/fully broken down; by the link reaction and Krebs cycle; reduced NAD/NADH passes electrons to electron transport chain; proton/H+ gradient generated; oxygen required as terminal electron acceptor; proton gradient used by ATP synthase/synthetase to produce ATP

Carbon dioxide is released during cell respiration. Explain anaerobic and aerobic respiration.

a. mitosis is the division of a nucleus to produce two genetically identical daughter nuclei b. consists of four phases: prophase, metaphase, anaphase, telophase c. cytokinesis occurs after mitosis d. interphase is the metabolically active phase between cell divisions e. the interphase consists of the S phase, G1 and G2 f. DNA replicates in the S phase g. cell growth OR preparation for mitosis OR duplication of organelles in G1 and G2

Cells go through a repeating cycle of events in growth regions such as plant root tips and animal embryos. Outline this cell cycle.

a. myofibrils «in muscle fibers/cells» b. sarcomeres «are the repeating units in muscle/myofibrils» c. sarcomeres arranged end to end / sarcomeres shorten during muscle contraction d. actin and myosin/overlapping protein filaments/diagram to show sarcomere with actin and myosin overlapping e. dark and light bands «in sarcomeres»/diagram to show this/light bands narrower when muscle is contracted f. thick filament is myosin and thin filament is actin/diagram to show this g. nerve impulses stimulate contraction/cause depolarization of sarcolemma/ T-tubules/trigger release of calcium from sarcoplasmic reticulum h. calcium ions released from sarcoplasmic reticulum/bind to troponin i. troponin causes tropomyosin to move/exposes binding sites on actin j. myosin «heads» form cross bridges with/bind to actin k. myosin heads move/change angle/swivel/cock / myosin heads cause the power stroke l. myosin filaments pull actin towards center of sarcomere/more overlap between actin and myosin/Z-lines move closer m. ATP is used «to provide energy»/cause cross-bridges to break/cause movement of myosin heads/cause filaments to slide/cause muscle contraction n. intercostal/abdominal/diaphragm muscles contract «to cough»

Coughing to clear the airways is accomplished by muscle contractions. Explain muscle contraction.

a. in multiple alleles there are more than two alleles of a gene; b. codominant alleles both affect the phenotype (in the heterozygote); c. IA and IB and i are the three alleles controlling blood groups; d. in ABO blood group IA and IB are codominant and i is recessive; e. when A and B both present, both are expressed/will give AB; f. i is recessive to both IA and IB / type A and type B can be heterozygous; g. only homozygous/ii organisms are blood group O; h. example of inheritance of blood groups / Punnett square showing inheritance

Describe codominance and multiple alleles using inheritance of ABO blood groups as an example of them.

a. producers/plants/autotrophs obtain energy from light/sun/inorganic sources b. food contains energy / energy passed in the form of food/carbon compounds (along food chains/between trophic levels) c. consumers obtain energy from other organisms/from previous trophic level d. energy released (in organisms) by (cell) respiration e. ATP produced f. energy/ATP used for biosynthesis/movement/active transport/other valid use of ATP g. less energy available / energy lost at each trophic level

Describe how energy flows through and is used by organisms in ecosystems.

a. (both) atria collect blood (from veins); b. sinoatrial/SA node sends impulses to muscle/fibres initiating contraction; c. blood is pushed to ventricles by contraction of atria/atrial systole; d. AV (atrioventricular) valves are open (as atria contract); e. semilunar valves are closed so that ventricles fill with blood; f. ventricles contract / ventricular systole; g. AV (atrioventricular) valves close ( preventing backflow); h. (blood is pushed through the) semilunar valves/pulmonary artery and aorta; i. when ventricles relax /diastole, semilunar valves close preventing backflow of blood;

Describe the action of the heart in pumping blood.

a. more (offspring) than the environment can support / carrying capacity reached; b. increased mortality/lower life expectancy/more deaths; c. competition (for resources) / struggle for survival; d. food/mates/nest sites/territory/other example of resource shortage / example of greater need; e. variation between members of population / example of variation; f. better adapted more likely to survive / converse; (reject Lamarckian statements such as those who adapt survive) g. better adapted reproduce / pass on (favourable) genes/traits / converse; h. natural selection / (survival of fittest) leads to evolution;

Describe the consequences of the potential overproduction of offspring.

a. spermatogonia «2n» are undifferentiated germ cells b. spermatogonia mature and divide «by mitosis» into primary spermatocytes «2n» c. primary spermatocytes divide by meiosis I into secondary spermatocytes «1n» d. secondary spermatocytes divide by meiosis II into spermatids «1n» e. spermatids differentiate/mature into spermatozoa/sperm f. Sertoli/nurse cells provide nourishment/support to these developing cells g. Leydig/interstitial cells produce testosterone

Describe the different cell types in the seminiferous tubules that are involved in the process of spermatogenesis.

a. «immumoglobulins are/function as» antibodies b. variety of binding sites / variable regions for binding c. specific to antigens on bacteria/viruses/pathogens d. constant region aids destruction of the bacteria/virus/pathogen e. attracts phagocytes/macrophages to engulf pathogen f. bursting pathogen cells/agglutination/neutralizing toxins/other example of the action of antibodies

Describe the functioning of immunoglobulins.

a. coolant in sweat/in transpiration; b. water has a high heat of vaporisation / heat taken when hydrogen bonds break; c. water is cohesive so can pulled up/so can be moved under tension in xylem; d. water is an excellent/universal solvent/dissolves many different substances; e. medium for transport in blood/xylem/phloem; f. medium for metabolic reactions / (metabolic) reactions happen dissolved in water; g. surface tension due to cohesion allows organisms to live on water surface; h. water has high heat capacity so much energy required to change its temperature; i. ice floats so lakes/oceans do not freeze allowing life under the ice; j. high heat capacity so stable habitat/so temperature of water changes slowly; k. used in chemical reactions/photosynthesis/hydrolysis in organisms

Describe the importance of water to living organisms.

enzymes are (globular) proteins that are catalysts/lower activation energy of chemical reactions; lock and key model: explains specificity of enzyme-substrate; the substrate (key) fits into/has complementary shape to the active site (lock) of the enzyme; the active site can be changed by different chemicals/temperatures/pH so substrate cannot bind; induced-fit model: changes in the active site/conformational changes to allow substrate to bind; the substrate induces the active site to change; bonds weakened in the substrate (so easier to break); explain reduction of activation energy/wider substrate specificity

Describe the lock and key model of enzyme activity and how the induced fit model extends it.

a. (plasma) membrane encloses/engulfs solid particles/droplets of fluid/molecules; b. fluidity of the membrane allows endocytosis; c. plasma membrane forms pit/forms indentation/pulled inwards/invaginates; d. membrane pinches off/seals back on itself/edges fuse; e. vesicle/vacuole formed; f. inside of plasma membrane becomes outside of vesicle membrane / converse; g. vesicle breaks away from plasma membrane/moves into cytoplasm; h. active process / endocytosis/vesicle formation requires energy;

Describe the process of endocytosis.

a. phloem transports organic compounds/sucrose b. from sources/leaves/where produced to sinks/roots/where used c. through sieve tubes/columns of cells with sieve plates/perforated end walls d. loading of organic compounds/sucrose into /H+ ions out of phloem/sieve tubes by active transport/using ATP e. high solute concentration causes water to enter by osmosis (at source) f. high (hydrostatic) pressure causes flow (from source to sink) g. companion cells help with loading / plasmodesmata provide a path between sieve tubes and companion cell h. translocation/mass flow

Describe the transport of organic compounds in vascular plants.

cut DNA into fragments using restriction enzymes/endonucleases; satellite DNA/(short) repeated sequences are used; PCR used to amplify/copy many times (satellite) DNA; DNA fragments separated by size / DNA separated by gel electrophoresis; pattern of bands/fragments compared to bands of suspected person/criminal;

Describe the use of DNA profiling in forensic investigations.

a. gas exchange b. oxygen diffuses from air to blood and carbon dioxide diffuses from blood to air c. oxygen binds to hemoglobin in red blood cells d. pressure inside/volume of alveoli increases/decreases / air enters/exits alveoli during inspiration/expiration/ventilation e. blood flow through capillaries / concentration gradients of gases/oxygen/CO2 maintained f. type II pneumocytes secrete fluid/surfactant / secretion of surfactant to prevent sides of alveolus adhering

Describe what happens in alveoli

a. similar structure but different function «in homologous structures» b. pentadactyl limbs/limb with five digits/toes / other example c. similar bone structure/example of similarity of bones «in pentadactyl limbs» but different uses/functions d. two examples of use of pentadactyl limb by a vertebrate group e. suggests a common ancestor «and evolutionary divergence» f. process called adaptive radiation

Describe, using one example, how homologous structures provide evidence for evolution.

Genes a. mutation changes genes/causes genetic differences b. genes can have more than one allele/multiple alleles OR alleles are different forms/versions of a gene c. different alleles «of a gene» give different characters OR variation in alleles between individuals d. eye colour/other example of «alleles of» a gene affecting a character e. alleles may be dominant or recessive OR dominant alleles determine trait even if recessive allele is present f. both alleles influence the characteristic with codominance OR reference to polygenic inheritance g. all members of a species are genetically similar/have shared genes OR certain genes expressed in all members of a species h. reference to epigenetics/methylation/acetylation / not all genes are expressed «in an individual» i. genes are inherited from parents/passed on to offspring/passed from generation to generation Chromosomes j. same locus/same position of genes OR same sequence of genes/same genes on each chromosome «in a species» k. same number of chromosomes «in a species»/all humans have 46 chromosomes/differences in chromosome number between species l. some individuals have an extra chromosome/Down syndrome/other example of aneuploidy OR polyploidy divides a species/creates a new species m. X and Y/sex chromosomes determine the sex/gender of an individual n. meiosis/independent assortment/fertilization/sexual reproduction give new combinations «of chromosomes/genes»

Discuss the role of genes and chromosomes in determining individual and shared character features of the members of a species.

a. metabolism is all enzyme-catalyzed reactions in a cell/organism/is anabolism plus catabolism b. anabolism is synthesis of polymers/complex/larger molecules/larger substances «from smaller molecules/monomers» c. catabolism is breaking down «complex» molecules/substances «into simpler/smaller ones/into monomers»

Distinguish between anabolism, catabolism and metabolism.

a. chlorophyll is the main photosynthetic pigment; b. high levels of absorption in red light and blue light; (both needed) c. greatest absorption in blue light; d. least/low absorption in green light; e. green light is reflected; f. other pigments absorb other wavelengths/colours;

Distinguish between the absorption of red light, blue light and green light by plants.

a. less urea/excretory waste products/creatinine in renal vein b. less oxygen in the renal vein c. more carbon dioxide in renal vein d. less glucose in renal vein e. concentration of sodium ions/chloride ions/pH at normal level in the renal vein whereas it is variable in renal artery f. solute concentration/osmolarity/water balance at normal level in the renal vein whereas it is variable in renal artery

Distinguish between the composition of the blood of the renal artery and the blood of the renal vein.

a. cell wall shown with two continuous lines to indicate the thickness b. plasma membrane/cell membrane shown as a single continuous line c. nuclear membrane/nucleus shown with double membrane and nuclear pores d. vacuole «membrane»/tonoplast shown as a single continuous line e. chloroplast/plastid shown with a double line to indicate the envelope and thylakoids/grana f. mitochondrion shown with double membrane/cristae

Draw a labelled diagram of a eukaryotic plant cell as seen in an electron micrograph.

a. haploid nucleus; b. cytoplasm - with nucleus-to-membrane distance >4 times nucleus diameter; c. centrioles - two must be shown but only one needs to be labelled; d. cortical granules - needs to be drawn in vicinity of plasma membrane; e. plasma membrane - shown as a single line and approximately circular overall; f. polar cell / (first) polar body - needs to be drawn outside the egg cell; g. zona pellucida / layer of gel (outside the cell membrane); h. follicle cells / corona radiata (outside the cell membrane); i. size shown as 100 µm/0.1 mm

Draw a labelled diagram of a mature human egg.

a. «crossing over/chiasmata shown between» homologous chromosomes b. centromere drawn and labelled It is likely that more than one c. single strand break «SSB»/DNA cut between homologous chromosomes d. non-sister chromatids labelled OR sister chromatids labelled e. chiasma between homologous chromosomes labelled «shown forming after SSB»

Draw a labelled diagram of the formation of a chiasma by crossing over.

a. phospholipid bilayer drawn and labelled with at least one protein labelled and drawn embedded either in one or both halves of the bilayer b.integral/ intrinsic/ transmembrane/ carrier/pump/channel/pore protein labelled and shown crossing the membrane c. extrinsic/peripheral protein labelled and shown on membrane surface/not embedded in bilayer d. glycoprotein labelled and shown integral and with a clear carbohydrate region projecting out on one side of the membrane

Draw a labelled diagram that shows the positions of proteins within the cell membrane.

a. NAD/FAD carries/is reduced by gaining «two» H «atoms»/«two» electrons b. reduced NAD produced in glycolysis/link reaction/Krebs cycle c. reduced NAD/FAD delivers electrons/hydrogen «atoms» to ETC d. ETC is in mitochondrial inner membrane/cristae e. electrons release energy as they flow along the chain/from carrier to carrier f. electrons from ETC accepted by oxygen/oxygen is the final electron acceptor g. proteins in the inner mitochondrial membrane/electron carriers act as proton pumps h. protons pumped into intermembrane space/proton gradient across inner mitochondrial membrane/proton concentration higher in intermembrane space than in matrix i. energy «from electrons» used to pump protons into intermembrane space/generate a proton gradient / high H+ concentration is a store of «potential» energy j. ATP synthase in inner mitochondrial membrane/cristae k. energy released as protons pass down the gradient/through ATP synthase l. ATP synthase converts ADP to ATP/phosphorylates ADP m. oxidative phosphorylation «is ATP production using energy from oxidizing foods»

Explain how chemical energy for use in the cell is generated by electron transport and chemiosmosis.

a. double circulation / pulmonary and systemic circulations b. b. heart is a double pump / heart has separate pumps for lungs and other systems / left and right sides of heart are separate / no hole in heart (after birth) c. deoxygenated blood pumped to the lungs and oxygenated to other organs/tissues/whole body (apart from lungs) d. each side of the heart has an atrium and a ventricle e. left ventricle/side pumps blood to the systems/tissues and right ventricle/side pumps blood to the lungs f. left atrium receives blood from the lungs and right atrium receives blood from systems/tissues g. left ventricle pumps blood via the aorta and right ventricle pumps blood via the pulmonary artery h. left atrium receives blood via the pulmonary vein and right atrium receives blood via the vena cava i. lungs require lower pressure blood / high pressure blood would damage lungs j. high pressure required to pump blood to all systems/tissues apart from lungs k. pressure of blood returning from lungs not high enough to continue to tissues / blood has to be pumped again after returning from lungs l. oxygenated blood and deoxygenated blood kept separate / all tissues receive blood with high oxygen content/saturation

Explain how circulation of the blood to the lungs and to other systems is separated in humans and what the advantages of this separation are.

a. variation in population; b. (variation is) due to mutation/sexual reproduction; c. valid example of variation in a specific population; d. more offspring are produced than can survive / populations over-populate; e. competition / struggle for resources/survival; f. example of competition/struggle for resources; g. survival of fittest/best adapted (to the changed environment)/those with beneficial adaptations / converse; h. example of changed environment and adaptation to it; i. favourable genes/alleles passed on / best adapted reproduce (more) /converse; j. example of reproduction of individuals better adapted to changed environment; k. alleles for adaptations to the changed environment increase in the population; l. example of genes/alleles for adaptations increasing in a population; m. evolution by natural selection; n. evolution is (cumulative) change in population/species over time / change in allele frequency

Explain how evolution may happen in response to environmental change with evidence from examples.

a. minerals bound to soil particles; b. examples of three nutrients from: phosphate, nitrate, magnesium, iron, calcium, potassium, sodium, magnesium; c. minerals dissolve in water; d. mass flow causes movement of minerals with movement of water through soil; e. minerals diffuse down a concentration gradient towards roots (as the mineral concentration next to the roots is continuously decreasing); f. minerals enter the plant through roots; g. by active transport / use of ATP; h. branching of roots increases surface area for absorption of minerals; i. root hairs increase surface area (for the absorption of minerals); j. hypha of (mutualistic) fungi may enhance movement of selected ions into roots / increase surface area; k. root hairs have many mitochondria to provide energy/ATP for active transport; l. export of H+ creates electrochemical gradient / displaces ions bound to soil/clay; m. that causes positive mineral ions to diffuse into (root) cells; n. negative mineral ions cross membrane linked to H+ ions moving down (H+) gradient;

Explain how minerals move into plants

a. minerals bound to soil particles; b. examples of three nutrients from: phosphate, nitrate, magnesium, iron, calcium, potassium, sodium, magnesium; c. minerals dissolve in water; d. mass flow causes movement of minerals with movement of water through soil; e. minerals diffuse down a concentration gradient towards roots (as the mineral concentration next to the roots is continuously decreasing); f. minerals enter the plant through roots; g. by active transport / use of ATP; h. branching of roots increases surface area for absorption of minerals; i. root hairs increase surface area (for the absorption of minerals); j. hypha of (mutualistic) fungi may enhance movement of selected ions into roots / increase surface area; k. root hairs have many mitochondria to provide energy/ATP for active transport; l. export of H+ creates electrochemical gradient / displaces ions bound to soil/clay; m. that causes positive mineral ions to diffuse into (root) cells; n. negative mineral ions cross membrane linked to H+ ions moving down (H+) gradient;

Explain how minerals move into plants.

impulse/message/action potential/depolarization reaches the pre-synaptic membrane; calcium channels open; calcium diffuses into/calcium ions enter (pre-synaptic) neuron; vesicles of neurotransmitter fuse with membrane (of pre-synaptic neuron); release of neurotransmitter by exocytosis; diffusion of neurotransmitter across cleft/synapse; neurotransmitter binds to receptor in (post-synaptic) membrane/neuron; ion channels open and sodium/positively charged ions enter; depolarization/action potential/impulse in post-synaptic neuron/membrane; neurotransmitter broken down by enzymes;

Explain how nerve impulses pass from one neuron to another neuron.

a. sliding filament model / filaments/actin and myosin slide past each other; b. action potential/depolarisation/nerve impulse arrives at end of motor neurone; c. neurotransmitter/acetylcholine released causing action potential (in muscle fibre); d. sarcoplasmic reticulum releases calcium ions; e. calcium ions cause binding sites on actin/for myosin to be exposed; f. myosin heads bind to sites on actin/form cross-bridges; g. myosin (head) moves actin filament using energy from ATP; h. actin moved towards the centre of sarcomere/M line/M band; i. sarcomeres shortened; j. (binding of) ATP causes release of myosin head from actin; k. conversion of ATP to ADP and Pi causes myosin heads to change angle; l. cycle (of events) repeated (during muscle contraction);

Explain how skeletal muscle contracts

a. leaf has large surface area for absorption of light; b. upper epidermis (thin) allowing light to pass; c. (waxy translucent) cuticle to (allow light in and) prevent water loss; d. palisade mesophyll contains many (cells with) chloroplasts; e. palisade mesophyll close to upper layer to receive more light; f. spongy mesophyll contains chloroplasts which allow photosynthesis; g. spongy mesophyll (cells loosely packed) allows gaseous exchange; h. stoma allow CO2 for photosynthesis to diffuse in; i. stoma allow O2 produced in photosynthesis to diffuse out; j. xylem brings water (for reactions); k. phloem carries away products of photosynthesis/sucrose; l. guard cells open and close stoma (for gas exchange);

Explain how the distribution of tissues in the leaf of a dicotyledonous plant is adapted to production and distribution of products of photosynthesis.

a. transport facilitated by proximity of mother and embryo blood vessel; b. chorionic villi increase surface area for exchange; c. oxygen and food reach embryo; d. carbon dioxide and waste matter carried from embryo to mother; e. immune system of mother protects embryo; f. barrier function as bloods do not mix; g. endocrine function as it secretes hormones; h. human chorionic gonadotropin/HCG prevents degeneration of corpus luteum; i. production of estrogen maintains endometrium; j. estrogen increases mammary gland growth; k. progesterone maintains endometrium; l. progesterone prevents uterine contractions;

Explain how the structure and functions of the placenta maintain pregnancy.

a. osmoregulation/excretion of nitrogenous waste/urea «is a function of the» kidney b. ultrafiltration in the glomerulus/smaller molecules filtered out in the glomerulus OR capillary walls/glomerulus permeable to smaller molecules c. basement membrane/filtration slits/podocytes act as filter/prevent loss of «large» «proteins»/prevent loss of blood cells d. high «blood» pressure in glomerulus due to larger afferent than efferent arteriole e. «selective» reabsorption of glucose/useful substances in proximal convoluted tubule f. microvilli/coiling/convolutions give large surface area pump proteins to reabsorb specific solutes «in proximal convoluted tubule» g. water reabsorbed in descending limb «of loop of Henle» OR descending limb permeable to water h. active transport/active pumping of sodium ions/Na+ out of ascending limb «from filtrate to medulla» i. ascending limb is impermeable to water j. loop of Henle creates solute gradient/high solute concentration/hypertonic conditions in medulla k. distal convoluted tubule adjusts pH/adjusts concentration of Na+/K+/H+ l. water reabsorbed in collecting duct m. collecting duct permeability to water varies due to number of aquaporins/ADH n. osmoregulation by varying the amount of water reabsorbed «in the collecting duct»

Explain how the structure of the nephron and its associated blood vessels enable the kidney to carry out its functions.

pancreatic cells monitor the blood glucose concentrations; alpha and beta cells are in the islets of Langerhans; negative feedback mechanisms; send hormones (through bloodstream) to target organs; if too high, β cells (in pancreas) produce insulin; insulin stimulates liver/muscle cells to take up glucose; glucose is converted into glycogen (stimulated by insulin); lowering blood glucose level; other cells are stimulated to absorb glucose and use it in cell respiration; if glucose levels too low, α cells (in pancreas) produce glucagon; glucagon stimulates liver/muscle cells to break down glycogen;

Explain the control of blood glucose concentrations in humans

a. mRNA conveys genetic information from DNA to the ribosomes «where it guides polypeptide production» b. gene expression requires the production of specific mRNA «through transcription» c. most genes are turned off/not being transcribed at any one time/regulated OR some genes are only expressed at certain times d. some genes are only expressed in certain cells/tissues OR «cell» differentiation involves changes in gene expression e. transcription factors/proteins can increase/decrease transcription f. hormones/chemical environment of cell can affect gene expression g. example of cell environment eg: auxin/insulin/cytoplasmic gradient in embryo h. transcription factors/proteins may prevent or enhance the binding of RNA polymerase i. nucleosomes limit access of transcription factors to DNA/regulate gene expression/transcription OR activate or silence genes j. DNA methylation/acetylation appears to control gene expression «as epigenetic factor» OR methylated genes are silenced k. «some» DNA methylation patterns are inherited l. introns may contain positive or negative gene regulators OR gene expression can be regulated by post-transcriptional modification/splicing/mRNA processing

Explain the control of gene expression in eukaryotes.

glucose filtered out of blood (plasma) in glomerulus; glucose reabsorbed from filtrate in proximal convoluted tubule; by active transport; reference to specific pumps for glucose / limited capacity for glucose uptake; in diabetic patients glucose concentration in plasma is high; not all glucose can be reabsorbed (in PCT) /capacity for reabsorption exceeded; no glucose reabsorption after the proximal convoluted tubule; glucose still present at end of nephron/collecting duct/in the ureter/bladder; type I diabetes treated with insulin; insulin reduces the glucose concentration of blood/plasma/filtrate; all glucose reabsorbed from filtrate in Type I diabetics if treated;

Explain the presence of glucose in the urine of a diabetic person and its absence in the urine of a person with type I diabetes that is being successfully treated.

a. translation involves initiation, elongation/translocation and termination; b. ribosome slides along the mRNA to the start codon; c. translation takes place in 5 3 ′ ′ → direction; d. start codon is AUG/ codes for methionine; e. tRNA activating enzymes; f. link amino acids to a specific tRNA; g. ribosome binds the tRNA with the mRNA; h. anticodon of tRNA pairs with codon on mRNA; i. using complementary base pairing; j. second tRNA binds (to the codon) at the adjacent/next binding site; k. peptide bond forms between amino acids; l. translocation occurs moving the tRNA into the next site; m. reference to A, P and E sites; n. tRNA that has lost its amino acid detaches; o. this proceeds until stop codon is reached;

Explain the process of translation

a. plants/producers/autotrophs convert light to chemical energy by photosynthesis. b. chlorophyll/photosynthetic pigments absorb light c. electrons are excited/raised to higher energy level d. excited electrons pass along chain of electron carriers e. energy from electrons used to pump protons across thylakoid membrane/into thylakoid space f. chemiosmosis/proton gradient used to make ATP g. ATP synthase generates ATP h. pigments arranged in photosystems i. electrons from Photosystem II flow via the electron chain to Photosystem I j. electrons from Photosystem I are used to reduce NADP k. ATP and reduced NADP used in the light independent reactions/Calvin cycle l. carbohydrate/glucose/carbon compounds produced containing energy

Explain the processes by which light energy is converted into chemical energy.

Krebs cycle only occurs in aerobic conditions; the Krebs cycle occurs in the mitochondria; acetyl CoA from the link reaction releases an acetyl group; NADH+H+ and CO2 are formed (with each decarboxylation); decarboxylation/removal of CO2 involves oxidation/oxidative decarboxylation; and the release of energy; acetyl group is joined to a 4-carbon molecule/C4/oxaloacetate to form a 6-carbon molecule/citrate; (decarboxylation changes citrate) to 5-carbon molecule/C5; (decarboxylation changes glutamate) to a 4-carbon molecule/C4; then converted into the original 4-carbon molecule/C4/oxaloacetate and the cycle repeats; one (molecule) of ATP is made during this step; reduced H-carriers/ NADH and FADH2 and carbon dioxide are end-products of Krebs cycle;

Explain the processes involved in the Krebs cycle.

a. each antibody corresponds to a specific antigen b. antibodies are necessary for immunity/resistance to «infectious» disease c. macrophage/phagocyte ingests/engulfs pathogen d. macrophage/phagocyte digests pathogen e. macrophage/phagocyte displays antigen from pathogen f. antigens of a pathogen correspond to a specific T lymphocytes/cells OR T lymphocytes/cells are activated by antigen binding g. T lymphocytes/cells activate B lymphocytes/cells h. «B cells» divide by mitosis to form many/clones of plasma cells i. plasma cells secrete specific antibody j. some «activated» B lymphocytes/cells act as memory cells

Explain the production of antibodies

a. ultrafiltration in the glomerulus produces (large volumes of) filtrate; b. 80 %/most of water in filtrate is (always) (re)absorbed in proximal convoluted tubule; c. water reabsorbed from filtrate in descending loop of Henle; d. pituitary gland secretes ADH if blood solute concentration is too high; e. ADH makes the collecting duct/distal convoluted tubule more permeable to water; f. ADH moves aquaporins into the membranes (of cells in the tubule wall); g. more water reabsorbed from filtrate/into blood due to ADH; h. blood becomes more dilute / small volume of urine with high solute concentration; i. with low/no ADH less water is reabsorbed in the collecting duct; j. blood becomes more concentrated / large volume of dilute urine; k. water reabsorption in collecting duct due to high solute concentration of medulla; l. active transport of Na+ ions from filtrate in ascending limb of loop of Henle

Explain the role of the nephron in maintaining the water balance of the blood in the human body.

a. «DNA» gyrase/topoisomerase «II» prepares for uncoiling/relieves strains «in the double helix» b. helicase uncoils/unwinds the DNA/double helix c. helicase separates/unzips/breaks hydrogen bonds between the two strands of DNA d. «DNA» primase adds an RNA primer/short length of RNA Accept RNA primase. e. DNA polymerase III adds «DNA» nucleotides/replicates DNA/synthesizes complementary strand in a 5' to 3' direction f. DNA polymerase III starts replication/adding nucleotides at the primer g. DNA polymerase I removes the primer OR replaces RNA with DNA h. «DNA» ligase seals the nicks OR links sections of replicated DNA OR links Okazaki fragments i. DNA polymerase I/DNA polymerase III proofreads for mistakes

Explain the roles of specific enzymes in prokaryote DNA replication

a. anterior pituitary/hypophysis secretes FSH which stimulates ovary for follicles to develop b. follicles secrete estrogen c. estrogen stimulates more FSH receptors on follicle cells so respond more to FSH d. increased estrogen results in positive feedback on «anterior» pituitary e. estrogen stimulates LH secretion f. estrogen promotes development of endometrium/uterine lining g. LH levels increase and cause ovulation h. LH results in negative feedback on follicle cells/estrogen production i. LH causes follicle to develop into corpus luteum OR follicle cells produce more progesterone j. progesterone thickens the uterus lining k. high progesterone results in negative feedback on pituitary/prevents FSH/LH secretion l. progesterone levels drop and allow FSH secretion m. falling progesterone leads to menstruation/degradation of uterine lining

Explain the roles of specific hormones in the menstrual cycle, including positive and negative feedback mechanisms.

a. growth phase/G-1: synthesis of proteins/cytoplasm/organelles; b. synthesis phase/S-phase: replication of DNA; c. second growth phase/G-2: continued growth of cytoplasm/molecular synthesis/ duplication of organelles; d. prophase: chromosomes super-coil to prepare for mitosis / nuclear envelope disappears / spindle fibres form; e. metaphase: chromosomes line up at equatorial/metaphase plate / spindle fibres attach to centromeres/chromosomes; f. anaphase: chromatids move along microtubules/spindle fibres move chromatids toward opposite poles; g. telophase: nuclear membranes form around each cluster of chromosomes; h. cytokinesis: new plasma membrane forms between the nuclei / cell plate forms; i. a new cell wall forms; j. (mitosis) results in two cells with identical nuclei

Following germination of seeds, plants undergo a rapid increase in the number of cells. Describe stages in the cell cycle that result in this increase of cells.

a. helicase unwinds the double helix b. gyrase/topoisomerase relieves strains during uncoiling c. helicase separates the two strands of DNA/breaks hydrogen bonds d. each single strand acts as a template for a new strand / process is semi-conservative e. DNA polymerase III can only add nucleotides to the end of an existing chain/to a primer f. (DNA) primase adds RNA primer/short length of RNA nucleotides. g. DNA polymerase (III) adds nucleotides in a 5' to 3' direction. h. complementary base pairing / adenine to thymine and cytosine to guanine. i. DNA polymerase (III) moves towards the replication fork on one strand and away from it on the other strand j. continuous on the leading strand and discontinuous/fragments formed on the lagging strand k. DNA polymerase I replaces primers/RNA with DNA l. ligase joins the fragments together/seals the nicks

Growth in living organisms includes replication of DNA. Explain DNA replication.

a. evaporation of water «in leaf/mesophyll» creates tension/low pressure/negative pressure «potential»/pulling force/transpiration pull b. water drawn through cell walls/out of xylem «in leaf» by capillary action/adhesion «to cellulose» c. low pressure/tension/suction/pulling force in xylem d. hydrogen bonds make water cohesive/allow water to be pulled up under tension/allow the transpiration pull «to move water» e. xylem resists tension/low pressure/collapse with thickened/lignified walls f. water travels from the roots to the leaves in xylem g. water absorbed in roots by osmosis h. active transport of ions/solutes into roots «enabling osmosis» i. deep/wide ranging/extensive root systems/taproots/many root hairs j. thick/waxy cuticle reduces transpiration/water loss/evaporation k. small/no leaves/reduced surface area of leaves/thorns instead of leaves l. few stomata/stomata in pits/rolled leaves m. hairs on leaf surface «to reduce air flow near the leaf/reflect sunlight» n. stomata open at night/CAM physiology to reduce water loss

In hot, dry conditions plants lose water rapidly due to transpiration. Explain how the structures and processes of the plant allow this water to be replaced

actin and myosin filaments are the proteins involved in muscle contraction; (a motor neuron stimulates the) release of calcium ions; from the sacroplasmic reticulum; calcium reveals the binding sites on actin; myosin heads form cross-bridges with binding sites on actin; ATP binds to myosin heads; breaking cross bridges to actin; ATP hydrolyzed to ADP (+phosphate); causing myosin heads to change angle/become cocked with energy from ATP; myosin heads bind to new sites on actin further from centre of sarcomere; ADP is released; actin filaments slide inwards to centre of sarcomere/power stroke;

Muscle contraction is a chemical process involving proteins. Explain how skeletal muscle contracts.

a. plasmid used for gene transfer/removed from bacteria; b. plasmid is a small/extra circle of DNA; c. restriction enzymes/endonucleases cut/cleave DNA (of plasmid); d. each restriction enzyme cuts at specific base sequence/creates sticky ends; e. same (restriction) enzyme used to cut DNA with (desired) gene; f. DNA/gene can be added to the open plasmid/sticky ends join gene and plasmid; g. (DNA) ligase used to splice/join together/seal nicks; h. recombinant DNA/plasmids inserted into host cell/bacterium/yeast;

Outline a technique used for gene transfer.

a. receptor/binding site for hormone/neurotransmitter b. cell-to-cell communication / cell recognition c. channels «for passive transport» / facilitated diffusion d. pumps / active transport e. cell adhesion f. «immobilized» enzymes/enzymes embedded in the membrane g. electron transport / electron carriers

Outline four different functions of membrane proteins.

a. protect against/kill/inhibit growth of microorganisms/bacteria/prokaryotes b. bacteria/prokaryote processes blocked but not processes in eukaryotes/other organisms c. block metabolic pathways/DNA replication/DNA transcription/translation/ribosome functioning/cell wall formation d. do not protect against viruses as they have no metabolism/are non-living e. antibiotics fail to protect if bacteria have resistance f. can be used in humans/animals because antibiotics do not affect eukaryotic cells/bacterial metabolism is different

Outline how antibiotics offer protection from certain forms of infectious disease.

a. different alleles for proteins exist in nature / a gene for a protein shows variations; b. selection pressure acts on organisms / change in external environment / example of selection pressure (eg: use of antibiotic); c. organisms expressing one allele/protein have advantage over those expressing others; d. organisms expressing one allele/protein have greater chances of survival / by natural selection the better adapted organisms survive; e. organisms expressing one allele/protein can reproduce more / leave more descendants; f. expression of the given allele/protein is inherited by these organisms; g. population expressing the given allele/protein increases (while the ones expressing the other protein decreases); h. after a few generations, the characteristic of the species gradually changes;

Outline how evolution through natural selection can lead to the expression of one version of a protein rather than another.

a. low light intensity affects light-dependent reactions; b. fewer electrons are excited / less photolysis occurs; c. less NADPH and ATP produced at low light intensities; (both needed) d. rate-limiting step is the reduction of G3P/glycerate 3-phosphate/ PGA phosphoglycerate; e. graph showing: effect of light intensity on rate of photosynthesis; f. low carbon dioxide concentration affects the Calvin cycle/light-independent stage; g. fixation of CO2 is decreased; h. less ribulose bisphosphate joins to CO2 to form G3P/glycerate 3-phosphate /PGA phosphoglycerate; i. graph showing: effect of CO2 concentration on rate of photosynthesis;

Outline how light intensity and concentration of carbon dioxide affect photosynthesis.

a. can be sympatric or allopatric 3 max b. temporal isolation by members of difference populations reproducing at different times c. behavioural isolation by difference in courtship behaviours d. geographic isolation by a population being separated by river/mountain/barrier to contact e. polyploidy

Outline how reproductive isolation can occur in an animal population.

a. only a small proportion/20 %/10 % «of energy» can pass from one trophic level to the next OR large proportion/80 %/90 % lost between one trophic level and the next b. energy released by respiration AND lost as heat c. energy losses due to uneaten parts/undigested parts/feces/egestion d. not enough energy for 4th/5th/later stages of a food chain OR more energy available if feeding at an earlier stage in a food chain

Outline how the energy flow through food chains limits their length.

a. (high blood glucose levels) detected by pancreas islet cells/beta cells; b. insulin secreted in response (to high blood glucose/glucose above threshold level); c. insulin stimulates cells to absorb glucose; d. glucose used in cell respiration (rather than lipids); e. glucose converted to glycogen (in liver/muscle cells); f. glucose converted to fatty acids/triglycerides/fat; g. negative feedback process

Outline how the human body responds to high blood glucose levels

heart cells can contract on their own / myogenic (muscle contraction); contractions/heart beat controlled by/starts at pacemaker/sinoatrial node; pacemaker/sinoatrial node is in the wall of the right atrium; signal to contract transmitted from across the atria/heart muscle/heart wall; nerves/impulses from medulla (of brain) to heart; fone nerve increases rate and another nerve decreases it; epinephrine/adrenalin increases rate;

Outline how the rate at which the heart beats is controlled

a. complete human DNA/chromosomes sequenced; b. identification of all human genes / find position/map (all) human genes; c. find/discover protein structures/functions; d. find evidence for evolutionary relationships/human origins/ancestors; e. find mutations/base substitutions/single nucleotide polymorphisms; f. find genes causing/increasing chance of/develop test for/screen for diseases; g. develop new drugs (based on base sequences) / new gene therapies; h. tailor medication to individual genetic variation / pharmacogenomics; i. promote international co-operation/global endeavours

Outline outcomes of the human genome project.

a. catalyse/speed up reactions b. substrate-specific c. lower the activation energy «of a chemical reaction» d. substrate collides with/binds to active site e. enzyme-substrate complex formed OR transition state formed OR bonds in substrate weakened

Outline the action of enzymes.

a. water to rehydrate the seed / activate metabolic processes; b. oxygen for aerobic respiration as seed germinates; c. suitable temperature for enzyme activity; d. each type of seed has specific temperature requirements / temperature requirements ensure that seeds germinate at the correct time of year;

Outline the conditions needed for the germination of a typical seed.

no photosynthesis at very low/no CO2 concentration; positive correlation between increasing amount of CO2 and photosynthesis rate; at high CO2 concentration (rate of photosynthesis) reaches a plateau; carbon dioxide used in the light independent reactions/Calvin cycle; oxygen release measured by counting/measuring volume of bubbles in water; (changes in) oxygen concentration measured using oxygen probe/electrode; oxygen is a product of light dependent reactions so it is a measure of the rate;

Outline the effect of carbon dioxide on the rate of photosynthesis and how this can be measured by oxygen release.

DNA changes from GAG to GTG/CTC to CAC / mRNA changes from GAG to GUG; affecting the process of translation/causes different primary structure of polypeptide; causing glutamic acid to be replaced by valine; changing the form of hemoglobin; changes the shape of the red blood cells / red blood cells become sickle shaped; transport oxygen less efficiently/less oxygen gets to tissues; sickled cells block capillaries; muscular pain/severe anemia/slow growth; correlated with protection against malaria in heterozygotes;

Outline the effects of a base substitution mutation in the case of sickle-cell anemia.

a. hypertonic solution has more solutes/higher solute concentration «than the tissue/cells/cytoplasm» b. water moves out of the cells/tissue by osmosis «into the hypertonic solution» c. water moves from lower solute concentration to higher solute concentration/up the solute concentration gradient d. pressure inside cell drops OR cell no longer turgid OR cell becomes flaccid e. volume of cytoplasm drops OR «plasma» membrane retracts from the cell wall OR cell is plasmolysed

Outline the effects of putting plant tissue in a hypertonic solution.

(original) source of energy in a food chain is from (sun)light; captured by plants/autotrophs/producers/first trophic level; by means of photosynthesis/converted to chemical energy/organic molecules; plants use part of energy for own energy requirements/lost through cell respiration; consumers use energy for own requirements from organisms in previous trophic level; energy travels between trophic levels/producer to 1st consumer/1st consumer to 2nd consumer/2nd consumer to 3rd consumer; not all material is assimilated/consumed/not digested/lost in faeces; only a small amount of energy/(approximately) 10-20% is passed between trophic levels / most/80-90%/a large amount of the energy of a trophic level is lost (and not transferred); loss of energy from organisms in form of heat; energy is not recycled in an ecosystem (but nutrients are);

Outline the energy flow between trophic levels in a food chain.

primary structure is the (number and) sequence/order of amino acids in a polypeptide; secondary structures are regularly repeating structures/β-pleated sheets/α-helices (held together by H-bonds); tertiary structure is the (specific) 3-dimensional structure of the polypeptide (held by bonds/ionic bonds/H-bonds/hydrophobic interactions/disulfide bridges/interactions between R groups); quaternary structure links two or more polypeptides (to form one protein)/and/or describes non protein groups associated with the polypeptide;

Outline the four levels of protein structure.

water must be absorbed by the seed (to become metabolically active); gibberellin is produced (in the embryo); stimulates production of amylase; which catalyses digestion of starch to maltose; maltose diffuses to the growing embryo root and shoot/growth regions; maltose is converted to glucose for (aerobic) cell respiration (to release energy); or to synthesize materials/cellulose for plant growth;

Outline the metabolic processes during germination of a starchy seed

a. (at the start) drugs/hormones given to stop ovulation; b. ovarian hyperstimulation / fertility drugs/hormones/named drug injected in mother; c. development of multiple follicles; d. induction of egg maturation; e. retrieval of eggs through (minor) surgery; f. sperm collected (in vitro); g. fertilization in vitro of egg and sperm; h. (if sperm count is low) intracytoplasmic sperm injection (ICSI) is performed; i. fertilized egg is grown in medium; j. fertilized egg is introduced/implanted in uterus

Outline the process of in vitro fertilization

a. speciation is the splitting of a species «into two species» b. reproductive isolation/lack of interbreeding c. isolation due to geography/«reproductive» behavior/«reproductive» timing d. polyploidy can cause isolation e. gene pools separated f. differences in/disruptive selection cause traits/gene pools to change/diverge g. gradualism / speciation/changes accumulating over long periods h. punctuated equilibrium / speciation/changes over a short time period

Outline the process of speciation.

a. (consists of) prophase, metaphase, anaphase and telophase; b. chromosome number halved/reduced/(diploid) to haploid; c. homologous chromosomes pair up/form a bivalent/synapsis in prophase; d. crossing over between non-sister chromatids/chromatids of different homologues; e. nuclear envelope breaks down (at end of prophase/start of metaphase); f. tetrads/bivalents/homologous pairs move to/align on equator/cell centre/on metaphase plate in metaphase; (accept homologous chromosomes without pairs if pairing has already been described) g. attachment of spindle fibres/microtubules to centromeres/kinetochores; h. (homologous) chromosomes separate/pulled to opposite poles in anaphase; i. nuclear envelopes reform/do not reform (because of meiosis II) in telophase;

Outline the processes that occur during the first division of meiosis.

a. A, P and E binding sites are on the large subunit of the ribosome b. initiation of translation starts with binding of met-tRNA to the start codon c. large sub-unit binds with «start» tRNA in the P site d. A binding site holds the tRNA with the next amino acid to be added e. peptide bond is formed between the amino acids of the A site and the polypeptide at the P site f. polypeptide is transferred to the tRNA in the A site g. the tRNA «with polypeptide» in A site then moves to P site OR P binding site holds the tRNA attached to the growing polypeptide h. E binding site «exit» is where the tRNA «from P site without amino acid» leaves the ribosome

Outline the roles of the different binding sites for tRNA on ribosomes during translation

a. (increase in) light (intensity) increases rate (of photosynthesis); b. until a plateau is reached at higher light intensities/when another factor is limiting; c. light needed for light dependent reactions/example of light dependent reaction; d. (increase in) temperature/heat increases the rate (of photosynthesis); e to an optimum temperature above which the rate drops; f. temperature/heat affects rate of Calvin cycle/enzyme activity/rubisco activity; g. (increase in) carbon dioxide (concentration) increases rate (of photosynthesis); h. until a plateau is reached at higher CO2 levels/when another factor is limiting; i. CO2 needed for light independent reactions/Calvin cycle/carboxylation of RuBP/production of glycerate phosphate;

Outline two factors that affect the rate of photosynthesis.

excess glucose in blood / hyperglycemia; symptoms are excessive thirst / frequent urination / dehydration / fatigue; unresponsive to insulin / insulin resistance / not enough insulin produced; linked to/risk factor is obesity/diets high in sugar/fat; late onset / onset is usually adulthood/after childhood; insulin not required (usually) / insulin ineffective as a treatment; treated with low sugar diets/low GI/glycemic index foods

Outline type II diabetes.

a. DNA replication is semi-conservative; b. each (molecule formed) has one new strand and one from parent molecule; c. helicase uncoils DNA; d. helicase separates the two strands by breaking hydrogen bonds between bases; (reject unzips as an alternative to uncoils but accept as alternative to separates if breakage of hydrogen bonds is included) e. RNA primase adds primer / primase adds (short) length of RNA; f. DNA polymerase III binds to/starts at (RNA) primer; g. DNA polymerase (III) adds nucleotides/bases in a 5' → 3' direction; h. bases according to complementary base pairing / A-T and C-G; i. (leading strand) built up continuously (towards the replication fork); j. (lagging strand) built up in pieces/short lengths/Okazaki fragments; k. DNA polymerase I removes RNA/primers and replaces them with DNA; l. ligase seals gaps between nucleotides/fragments/makes sugar-phosphate bonds;

Prior to cell division, chromosomes replicate. Explain the process of DNA replication in prokaryotes.

a. by photosynthesis / using energy from light b. attached to carbon compounds c. phosphates used to make phospholipids/nucleotides/nucleic acids/DNA/RNA/ATP d. nitrates are used to make amino acids/proteins/nucleotides/nucleic acids/DNA/RNA/ATP e. transported from roots to leaves (in xylem)

Producers extract phosphates and nitrates from soil. Outline how these ions are used in the synthesis of organic molecules.

a. (therapeutic cloning) is the creation of an embryo to supply embryonic stem cells for medical use; b. transfer of nucleus from somatic cell into an (anucleated) egg; c. stimulated by shock to begin cell division; pros: d. stem cells from embryos have greater flexibility; e. pluripotent cells can give rise to all cells in the body / new organ could be grown as needed; f. no (danger of) rejection of the transplant because the organ DNA would match the patient's DNA (exactly); g. elimination of pain/inconvenience/shortened life span of organ recipient; h. would eliminate organ and tissue shortages; i. no need for immunosuppressive drugs; cons: j. manipulation/destruction of human embryos not ethically acceptable; k. the process of extracting stem cells involves killing the embryo; l. many attempts before success is attained

Research is being undertaken by scientists in some countries to develop methods of therapeutic cloning. Discuss the ethical issues of therapeutic cloning in humans.

a.transport: eg: hemoglobin; transport of molecules across membrane: eg: sodium potassium pump; structure: eg: collagen; catalysis: eg: amylase; immunity/protection: eg: IgA / antibodies (named antibody not required); movement: eg: myosin; regulation/homeostasis: eg: insulin; binding sites for hormones (named)/neurotransmitters (name not needed)

State four functions of proteins, giving a named example of each.

a. epidermis - shown and labelled on either the upper or lower surface or both; b. upper and lower epidermis - both labelled; c. palisade layer / palisade mesophyll; d. spongy layer / spongy mesophyll; e. xylem (in upper part of a major or minor vein); f. phloem (in a major or minor vein); g. guard cells

The leaves of plants are adapted for photosynthesis. Draw a labelled plan diagram of a leaf to show the distribution of tissues in a leaf

a. (chlorophyll/pigments/antenna complex) in photosystem II absorb light; b. light/photoactivation produces an excited/high energy/free electron; c. electrons pass from carrier to carrier/along electron transport chain/e.t.c.; d. protons pumped across thylakoid membrane/into thylakoid space; e. ATP produced (by the light dependent reactions); f. ATP production by chemiosmosis/by ATP synthase/ATP synthetase; g. electrons from photosystem II passed to photosystem I; h. light/photoactivation excites electrons in photosystem I (to higher energy level); i. production of NADPH/reduction of NADP(+) (using electrons from photosystem I); j. electrons from photolysis (needed) for photosystem II; k. oxygen from photolysis is a waste product/by-product/passes out/excreted; l. in cyclic photophosphorylation electrons from photosystem I return to it;

The light-dependent reactions in photosynthesis take place on the thylakoid membranes. Explain the light-dependent reactions