Q1(a) Explain how a synapse functions. [9]
(b) Describe the role of glucagon in regulating blood glucose. [6]
[Total: 15]
(a) 1 depolarisation/action potential;
2 of presynaptic membrane/synaptic knob;
3 opening calcium ion channels;
4 calcium ions in;
5 vesicles containing transmitter/acetylcholine;
6 fuse with membrane;
7 contents emptied into synaptic cleft/exocytosis;
8 transmitter/acetylcholine diffuses across synaptic cleft;
9 transmitter/acetychloine binds to receptor; R protein channel
10 on post synaptic membrane;
11 Na+ channels open/NA+ enters;
12 depolarises post synaptic membrane;
13 action potential set up/impulse transmitted
14 breakdown/hydrolysis of transmitter/acetylcholine by enzyme/cholinesterase; [9 max]
(b) 15 when blood glucose levels low;
16 glucagon released from alpha cells (in pancreas);
17 (acts on ) liver (cells);
18 breakdown of glycogen to glucose;
19 use of fatty acides in respiration; R fats
20 production of glucose from other compounds/fats/amino acids/gluconeogenesis;
21 liver releases glucose into blood;
22 glucose levels rise/return to normal;
23 switching off glucagon secretion;
24 antagonistic to insulin; [6 max]
Q 2 (a) Describe why variation is important in natural selection. [6]
(b) Explain the role of isolating mechanisms in the evolution of new species. [9]
[Total: 15]
(a) 1 ref. continuous/discontinuous variation;
2 genetic/inherited variation;
3 variation in phenotype/characteristics/AW;
4 (can be due to) interaction of genotype and environment;
5 e.g. of characteristic that influences survival;
6 ref. intraspecific competition/struggle for existence;
7 those with favourable characteristics survive/AW;
8 pass on favourable characteristics to offspring;
9 those with disadvantageous characteristics die; [6 max]
(b) 10 ref. to definition of species;
11 ref. allopatric;
12 geographical isolation;
13 ref. to examples e.g. islands/lakes/mountain chains/idea of barrier;
14 ref. to example organism;
15 ref. to populations prevented from interbreeding;
16 isolated populations subjected to different selection pressures/conditions;
17 over time sufficient differences to prevent interbreeding;
18 ref. sympatric;
19 ref. to reproductive isolation;
20 ref. behavioural barriers (within a population);
21 e.g. day active/night active;
22 correct ref. to gene pool 23 change to allele frequencies; [9 max] nov 2007[q1&2]
Q3 (a) Describe how the structure of neurones speeds up the transmission of action
potentials. [6]
(b) Explain, using a named example, how sensory receptors in mammals convert energy
into action potentials. [9]
[Total: 15]
a] 1 myelin sheath / schwann cell ;
2 insulates, axon / dendron ;
3 impermeable to Na+ / K+ ;
4 depolarisation only at nodes of Ranvier ;
5 ref. local circuits ;
6 action potentials ‘jump’ from node to node ;
7 saltatory conduction ;
8 speed increased by 50 times / 0.5 ms-1 to 100 ms-1 ;
9 axons with large diameter / giant axon ;
10 reduce resistance ;
11 elongated, axon / dendron / neurone ; 6 max
b] 12 ref. specific example ; e.g. pacinian corpuscle / rod / cone / hair cell
13 correct stimulus ; e.g. touch / pressure light / sound
14 detail of receptor response ; e.g. deformation of pacinian corpuscle membrane
15 stimulus causes Na+ channels to open ;
16 Na+ enters cell ;
17 K+ channels open ;
18 K+ leaves cell ;
19 depolarisation ;
20 receptor / generator potential ;
21 greater than threshold leads to, action potential / impulses ;
22 less than threshold only localised depolarisation ;
23 increased stimulus leads to increased frequency of action potentials ;
24 AVP ;
apply max 8 for points 15 - 24 9 max
Total 15
Q4 (a) Describe the transfer of light energy to chemical energy in ATP during photosynthesis.
[6]
(b) Describe the process of oxidative phosphorylation. [9] [Total: 15] [Q3&4 Nov 2006]
1 light absorbed by chlorophyll / AW ;
2 ref. photosystems ;
3 ref. harvesting clusters / accessory pigments ;
4 reaction centre / P680 / P700 ;
5 excitation of electrons / AW ;
6 ETC ;
7 idea of different energy levels ;
8 ADP + Pi . ATP ;
9 cyclic / non-cyclic, photophosphorylation ;
10 chemiosmosis / ATP synthase / description ; 6 max
b]
11 reduced NAD / FAD ;
12 passed to ETC ;
13 hydrogens removed ; R H2
14 split into H+ and e- ;
15 e- passed to carriers ;
16 H+ stays in mitochondrial matrix ;
17 oxygen final e- carrier ;
18 joins with H+ / reduced ; R H2 / hydrogen
19 forms water ;
20 ref. energy levels of carriers ;
21 energy available to convert ADP and Pi to ATP ;
22 occurs three times ( for each reduced NAD ) / ref. total yield ;
23 chemiosmosis / ATP synthase / description ; 9 max
[Total: 15]
Q5(a) Explain the meaning of the term homeostasis with specific reference to the
control of raised blood glucose concentration in mammals. [8]
(b) Describe the role played by ADH in osmoregulation in mammals. [7] [Total: 15]
2
3
4
5
6
7
8
9
10
11
12
13
14
(a1 maintenance of constant / stable, internal environment ;
2 despite changes in external environment ;
3 negative feedback ;
4 receptor and effector ;
5 beta cells ;
6 in islets of langerhans / pancreas ;
7 release insulin (into blood) ;
8alpha cells stop releasing glucagon ;
9 affects liver / muscle cells ;
10 increased permeability to glucose / absorption from blood ;
11 in creased use of glucose in respiration ;
12 increase in conversion of glucose to glycogen ;
13 stored in liver and muscles ;
14 fall in blood glucose concentration / return to normal ; [8 max]
B]1 low blood water content / water potential ;
2 detected by osmoreceptors ;
3 in hypothalamus ;
4 ADH produced / released ;
5 from posterior pituitary gland ;
6 target kidney ;
7 cells of collecting duct ;
8 binds to receptors ;
9 vesicles with water permeable channels ;
10 fuse with cell membrane ;
11 cells more permeable to water / water passes into cells ;
12 urine lower volume ;
13 higher concentration ; [7 max]
[Total: 15]
Q6 (a) Describe the role of natural selection in evolution. [8]
(b) Explain, using named examples, how mutation can affect phenotype. [7]
[Total: 15] [JUNE 2006]
(a)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
individuals in population have great reproductive potential / AW ;
numbers in population remain roughly constant ;
many fail to survive / die ;
do not reproduce ;
due to environmental factors / named factor ;
variation in members of population ;
those best adapted survive ;
reproduce / pass on alleles ; R genes
genetic variation leads to change in phenotype ;
ref: changes in gene pool ;
over time produces evolutionary change ;
new species arise from existing ones [8 max]
(b)
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
gene) example ; (sickle cell / PKU )
change in gene / DNA / base change ;
different amino acid ;
different polypeptide / different protein / non-functional protein ;
AVP ; details
AVP ; details
(chromosome) example ; (Down’s, Turner’s syndromes)
structural changes in chromosomes ;
change in number of chromosomes ;
change in sets of chromosomes / ref. polyploidy ;
23. AVP ; details
24 AVP ; details [7 max] [Total: 15]
Q7 (a) Explain how a synapse functions. [9]
(b) Describe the role of glucagon in regulating blood glucose. [6]
[Total: 15][nov 2005]
(b) 15 when blood glucose levels low;
16 glucagon released from alpha cells (in pancreas);
17 (acts on ) liver (cells);
18 breakdown of glycogen to glucose;
19 use of fatty acides in respiration; R fats
20 production of glucose from other compounds/fats/amino acids/gluconeogenesis;
21 liver releases glucose into blood;
22 glucose levels rise/return to normal;
23 switching off glucagon secretion;
24 antagonistic to insulin; [6 max]
Total: 15
Q8 (a) Describe why variation is important in natural selection. [6]
(b) Explain the role of isolating mechanisms in the evolution of new species. [9]
[Total: 15][nov 2005]
(a) 1 ref. continuous/discontinuous variation;
2 genetic/inherited variation;
3 variation in phenotype/characteristics/AW;
4 (can be due to) interaction of genotype and environment;
5 e.g. of characteristic that influences survival;
6 ref. intraspecific competition/struggle for existence;
7 those with favourable characteristics survive/AW;
8 pass on favourable characteristics to offspring;
9 those with disadvantageous characteristics die; [6 max]
(b) 10 ref. to definition of species;
11 ref. allopatric;
12 geographical isolation;
13 ref. to examples e.g. islands/lakes/mountain chains/idea of barrier;
14 ref. to example organism;
15 ref. to populations prevented from interbreeding;
16 isolated populations subjected to different selection pressures/conditions;
17 over time sufficient differences to prevent interbreeding;
18 ref. sympatric;
19 ref. to reproductive isolation;
20 ref. behavioural barriers (within a population);
21 e.g. day active/night active;
22 correct ref. to gene pool;
23 change to allele frequencies; [9 max]
Total: 15
Q9(a) Describe how the structure of a dicotyledonous leaf is related to its functions in
photosynthesis. [7] (a) thin / flat to give large surface area to volume ratio ;
held at right angles to sun to allow max. light absorption ;
ref. to arrangement of cells in palisade mesophyll ;
ref. to spongy mesophyll large surface area for CO2 uptake / gaseous exchange
;
ref. to stomata / guard cells and entry of CO2 ;
ref. to moist surfaces ;
ref. to xylem and supply of water / mineral ions ;
and support ;
ref. to phloem and translocation of products of photosynthesis ;
ref. to cuticle on upper surface ;
avp ; [8 max]
Total [15]
(b) Discuss the effects that variations in carbon dioxide concentration and light intensity
have on the rate of photosynthesis. [8]
[nov 2005]
(b) carbon dioxide 0.03% ;
most likely limits / major limiting / implied low in atmosphere ;
increase in carbon dioxide concentration and increase in rate ;
during day when light and warm ;
ref. to variations in conc. e.g., within canopy / at soil surface ;
avp ;
light intensity
ref. to wavelengths of light ;
light saturated below full sun ;
idea of limiting and saturation, with other key factor limiting ;
light and stomatal aperture ;
and temperature of leaf ;
day length and season / morning and evening ;
high light and damage to pigments ;
ref. to light exciting electrons in chlorophyll ;
avp ; [7 max]
Q10 (a) Describe how nitrogenous waste products are formed and explain why they
need to be removed from the body. [6]
(Q11) Describe how the kidney removes metabolic wastes from the body. [9] [nov 2005]
(a) Explain the source and importance of removing nitrogenous waste products
from the body. [6]
(b) Describe how the kidney removes metabolic wastes from the body. [9]
(a) deamination;
ref. to ornithine cycle ;
ref. to not all urea / produced each day / always some present ;
ref. to urea ;
ref. to creatinine and uric acid ;
and ammonium ions ;
produced in liver ;
continuously / from excess amino acids ;
toxic ;
if allowed to accumulate ;
ref. to potential damage to tissues ;
ref. to not all urea / that produced each day ; [6 max]
(b) ultrafiltration ;
of blood in glomerulus ;
forming filtrate in Bowman’s capsule ;
of kidney tubule ;
soluble molecules ;
including urea ;
and ammonium ions pass into filtrate ;
concentrated by removal of water (in collecting ducts) ;
ref. to formation of ammonium ions in distal convoluted tubule ;
from ammonia and protons ;
ref. to removal of metabolic water (as a waste product) ;
and osmoregulation ;
by collecting ducts ;
ref. formation of urine ;
ref. to distal convoluted tubule excrete excess acid ; [9 max]
Total [15]
Q12(a) Describe the role of auxins in apical dominance. [6]
(b) Explain the role of gibberellins in the germination of wheat or barley. [9]
[Total: 15] [june2005] 1
2
3
4
5
6
7
8
9
10
auxin = IAA
auxin produced in apical bud / AW ;
diffuses down stem ;
active transport (cell to cell) ;
role of plasmodesmata ;
also in phloem ;
(auxin) inhibits growth of lateral buds ;
plant grows up instead of branching out ;
removal of apical bud allows lateral buds to grow ;
AVP ; e.g. auxin concentrated in lateral bud / auxin in low amounts in lateral bud
AVP ; e.g. correct ref to effect of ABA / cytokinins 6 max
(b) 11 seed absorbs water ;
12 by osmosis ;
13 gibberellin produced by embryo plant ;
14 passes to aleurone layer ;
15 switches on / activation, transcription enzyme genes / AW ;
16 storage proteins broken down to amino acids ;
17 stimulates synthesis / release of amylase ;
18 amylase diffuses / moves into endosperm ;
19 breaks down / hydrolyses starch to maltose ;
20 maltose to glucose ;
21 glucose diffuses / moves into embryo plant ;
22 provides source of energy for growth of embryo plant ; 9 max
Total: 15
Q13 (a) Describe why variation is important in natural selection. [6]
(b) Explain the role of isolating mechanisms in the evolution of new species. [9]
[Total: 15] [june 2005]
(a) 1
2
3
4
5
6
7
8
9
ref. continuous / discontinuous variation ;
genetic / inherited variation ;
variation in phenotype / characteristics / AW ;
(can be due to) interaction of genotype and environment ;
e.g. of characteristic that influences survival ;
ref. intraspecific competition / struggle for existence ;
those with favourable characteristics survive / AW ;
pass on favourable characteristics to offspring ;
those with disadvantageous characteristics die ; 6 max
(b) 10 ref. to definition of species ;
11 ref. allopatric ;
12 geographical isolation ;
13 ref. to examples e.g. islands / lakes / mountain chains / idea of barrier ;
14 ref. to example organism ;
15 ref. to populations prevented from interbreeding ;
16 isolated populations subjected to different selection pressures / conditions ;
17 over time sufficient differences to prevent interbreeding ;
18 ref. sympatric ;
19 ref. to reproductive isolation ;
20 ref. behavioural barriers (within a population) ;
21 e.g. day active / night active ;
22 correct ref. to gene pool ;
23 change in allele frequencies ; 9 max
Total: 15(a) 1 matrix;
15 AVP; 9 max
Q14(a) Describe the main features of the Krebs Cycle. [9]
(b) Explain the role of NAD in aerobic respiration. [6] [nov 2004]
(a) 1 matrix;
2 of mitochondrion;
3 acetyl CoA combines with oxaloacetate;
4 to form citrate;
5 4C to 6C;
6 decarboxylation/produce CO2;
7 dehydrogenation/oxidation;
8 2CO2 released;
9 reduced NAD produced; accept reduced coenzyme for one mark - annotate 9/10
10 reduced FAD produced;
11 ATP produced;
12 series of steps/intermediates;
13 enzyme catalysed reactions;
14 oxaloacetate regenerated;
15 AVP; 9 max
(b) 16 coenzyme;
17 for dehyrogenase;
18 reduced;
19 carries electrons;
20 and protons/H+/H/hydrogen; R H2/hydrogen molecules
21 from Krebs cycle;
22 and from glycolysis;
23 to cytochromes/electron transfer chain;
24 reoxidised/regenerated;
25 ATP produced;
26 3/2.5 (molecules of ATP) per reduced NAD; 6 max
Total 15
Q15 (a) Describe the use of recombinant DNA technology in the synthesis of human
insulin by
bacteria. [9]
(b) Explain the advantages of treating diabetics with human insulin produced by genetic
engineering. [Nov 2004]
1 mRNA coding for insulin/isolate gene for human insulin;
2 from beta cells of islets of Langerhans/pancreas;
3 reference to reverse transcriptase;
4 to cDNA;
5 reference PCR/DNA polymerase/double strand;
6 reference sticky ends/AW;
7 use of vector/virus/plasmid;
8 reference endonuclease/restriction enzymes;
9 to cut plasmid;
10 reference DNA ligase to join DNA;
11 inserted into suitable host cell/E.coli/bacteria;
12 reference method of insertion;
13 identification of modified bacteria;
14 reference growth/culture of engineered bacteria in fermenters; 9 max
(b) 15 constant/reliable supply all year round/unlimited supply;
16 less risk of contamination/infection;
17 identical to insulin produced in the body;
18 less/no risk of allergic reaction;
19 does not stimulate the immune system;
20 fewer side effects;
21 can be produced without the killing of animals/ethical reason;
22 cheaper/easier to extract and purify;
23 more available/large amount;
24 more rapid response; 6 max
Total 15
Q16(a) Explain how a synapse functions. [9]
(b) Describe the role of glucagon in regulating blood glucose. [6]
[Total: 15] [june 2004]
(a)
1 depolarisation/action potential ;
2 of presynaptic membran,/synaptic knob ;
3 opening calcium ion channels ;
4 calcium ions in ;
5 vesicles containing transmitter / acetylcholine ;
6 fuse with membrane ;
7 contents emptied into synaptic cleft / exocytosis ;
8 transmitter / acetylcholine diffuses across synaptic cleft ;
9 transmitter / acetylcholine binds to receptor ; R protein channel
10 on post synaptic membrane ;
11 Na+ channels open / Na+ enters ;
12 depolarises post synaptic membrane ;
13 action potential set up / impulse transmitted ;
14 breakdown / hydrolysis of transmitter / acetylcholine by enzyme /
cholinesterase ;
9 max
(b)
15 when blood glucose levels low ;
16 glucagon released from alpha cells (in pancreas) ;
17 (acts on) liver (cells) ;
18 breakdown of glycogen to glucose ;
19 use of fatty acids in respiration ; R fats
20 production of glucose from other compounds / fats / amino acids /
gluconeogenesis ;
21 liver releases glucose into blood ;
22 glucose levels rise / return to normal ;
23 switching off glucagon secretion ;
24 antagonistic to insulin ;
6 max
Total : 15
Q17 (a) Outline the main features of the Calvin Cycle. [9] [without mark sch.]
(b) Explain the role of NADP in photosynthesis. [6]
[Total: 15] [june 2004]
(a)
1 RuBP 5C ;
2 combines with carbon dioxide ;
3 rubisco ;
4 to form an unstable 6C compound ;
5 which forms 2 X GP (PGA) ;
6 ATP;
7 energy source
8 and reduced NADP ;
9 forms TP (GALP) ;
10 TP used to form glucose / carbohydrates 1 lipids / amino acids ;
11 TP used in regeneration of RuBP
12 requires ATP ;
13 as source of phosphate ;
14 light independent ;
9 max
(b)
15 coenzyme ;
16 reduced ;
17 carries protons ;
18 and (high energy) electrons ;
19 from photosystem7light stage ; R photosystem II
20 on thylakoid membrane grans ;
21 to stroma / Calvin cycl~
22 ref. regeneration of NADP ;
6 max
Total : 15
Q 18
(a) Discuss
(i) the benefits and [6]
(ii) the disadvantages
of donor insemination using sperm from a sperm bank. [6]
(iii) Describe how seeds are stored in seed banks. [8]
[Total : 20]
Or
(b) (i) Explain the techniques used in enzyme immobilisation. [7]
(ii) Discuss the advantages of enzyme immobilisation in the manufacturing industry. [7]
(iii) Describe an experiment to demonstrate the use of immobilised enzymes. [6]
[Total : 20]
3 Either
(a) Describe and explain the role of microorganisms in
(i) sewage disposal; [8]
(ii) composting; [6]
(iii) extraction of heavy metals. [6]
[Total : 20]
Or
(b) (i) Explain what is meant by the terms monoclonal antibody and biosensor. [6]
(ii) Discuss the uses of monoclonal antibodies in the diagnosis and treatment of
diseases.
[8]
(iii) Describe how a biosensor can monitor blood glucose. [6]
[Total : 20]