A Level · 100 marks · 2h. Each generated paper follows the 9700 Paper 4 · A Level Structured Questions format, with the same number and style of questions as the real exam, and comes with a Cambridge-style mark scheme.
Generate Paper 4 · A Level Structured Questions →Plants respond to their environment using hormones.
Explain the role of abscisic acid in the closing of stomata.
| Part | Answer and marking points | Marks |
|---|---|---|
| ABA binds guard cells; K⁺ leave; water leaves; flaccid ABA binds receptors on guard cells B1 K⁺ ions leave, raising water potential B1 water leaves by osmosis and guard cells become flaccid, closing the stoma B1 | 3 |
The numbers of individuals of four species found in a quadrat survey were 25, 12, 8, 3.
Calculate Simpson’s index of diversity, D = 1 − Σ(n/N)2.
In a mark–release–recapture study, 40 beetles were marked; later 45 were caught, of which 5 were marked. Estimate the population size and state two assumptions.
Explain why conserving biodiversity is important.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 0.635 N = 48 B1 Σ(n/N)2 calculated M1 0.635 A1 | 3 |
| (b) | 360; no migration/births/deaths, marks not lost, marking does not affect survival, random mixing c1 × c2 ÷ m M1 360 A1 two valid assumptions B2 | 4 |
| (c) | ecological stability/food webs; source of drugs/genes; economic (tourism) and ethical reasons any three valid reasons B3 | 3 |
This question is about the control of body temperature and blood glucose.
Explain the role of the hypothalamus in thermoregulation.
Describe how insulin lowers blood glucose concentration.
Explain why type 1 diabetes is treated with insulin injections rather than insulin tablets.
Explain why urine is tested for glucose as an indicator of diabetes.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | thermoreceptors detect blood temperature; receives skin receptor input; coordinates responses via nerves/hormones contains thermoreceptors that detect blood temperature B1 receives impulses from skin thermoreceptors B1 sends impulses to effectors (sweat glands, arterioles, muscles) to correct changes B1 | 3 |
| (b) | binds receptors; GLUT4 vesicles fuse with membrane; more glucose uptake; glycogenesis activated insulin binds to receptors on muscle and liver cells B1 vesicles containing GLUT4 transporter proteins fuse with the cell membrane B1 glucose uptake by facilitated diffusion increases B1 enzymes converting glucose to glycogen (glycogenesis) are activated B1 | 4 |
| (c) | insulin is a protein; digested by proteases in gut insulin is a protein B1 it would be digested by proteases in the gut before absorption B1 | 2 |
| (d) | high blood glucose exceeds reabsorption capacity in PCT; glucose appears in urine when blood glucose is very high the carrier proteins in the proximal convoluted tubule are saturated B1 not all glucose is reabsorbed so some appears in the urine B1 | 2 |
This question is about the control of gene expression in the bacterium E. coli.
Describe the structure of the lac operon in E. coli.
Explain how the presence of lactose leads to production of β-galactosidase.
Explain why it is an advantage to E. coli to make the enzymes coded for by the lac operon only when lactose is present.
Distinguish between structural genes and regulatory genes.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | regulatory gene for repressor; promoter; operator; structural genes for lactose permease and β-galactosidase a regulatory gene coding for a repressor protein B1 a promoter and an operator B1 structural genes lacZ (β-galactosidase) and lacY (permease) B1 | 3 |
| (b) | lactose binds repressor; repressor changes shape, leaves operator; RNA polymerase binds promoter; structural genes transcribed lactose binds to the repressor protein B1 changing its shape so it cannot bind the operator B1 RNA polymerase can bind to the promoter B1 the structural genes are transcribed and translated B1 | 4 |
| (c) | saves energy and resources avoids wasting energy and amino acids making enzymes that are not needed B2 | 2 |
| (d) | structural code for proteins with a function in the cell; regulatory code for proteins controlling other genes structural genes code for proteins used by the cell (enzymes, structural proteins) B1 regulatory genes code for proteins that control the expression of other genes B1 | 2 |
This question is about synapses and drugs.
Explain why synapses ensure one-way transmission of impulses.
Explain how summation at synapses allows integration of information.
Nicotine has a similar shape to acetylcholine. Suggest its effect at cholinergic synapses.
Some insecticides inhibit acetylcholinesterase. Explain why this kills insects.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | neurotransmitter vesicles only presynaptic; receptors only postsynaptic vesicles of neurotransmitter are only in the presynaptic knob B1 receptors are only on the postsynaptic membrane B1 | 2 |
| (b) | temporal: repeated impulses add; spatial: several neurones add; excitatory and inhibitory inputs combine to decide threshold several impulses arriving in quick succession (temporal summation) or from several neurones (spatial summation) add up B1 to reach the threshold in the postsynaptic neurone B1 excitatory and inhibitory synapses combine so the neurone integrates inputs B1 | 3 |
| (c) | binds ACh receptors, causes depolarisation; not broken down by acetylcholinesterase binds to acetylcholine receptors and opens Na⁺ channels, depolarising the postsynaptic membrane B1 it is not broken down by acetylcholinesterase so the effect is prolonged B1 | 2 |
| (d) | ACh not broken down; continuous stimulation, muscles cannot relax (paralysis) acetylcholine is not hydrolysed so it stays bound to receptors B1 postsynaptic neurones / muscles are continuously stimulated, causing paralysis B1 | 2 |
Table 6.1 shows the results of a glucose tolerance test. Two people drink a solution containing 75 g of glucose after fasting overnight. Their blood glucose concentration is then measured every 30 minutes. Person X does not have diabetes; person Y has type 1 diabetes.
| time / min | 0 | 30 | 60 | 90 | 120 |
|---|---|---|---|---|---|
| person X / mmol dm⁻³ | 4.8 | 8.0 | 6.8 | 5.6 | 5.1 |
| person Y / mmol dm⁻³ | 7.0 | 12.6 | 14.2 | 14.0 | 12.4 |
Calculate the percentage increase in blood glucose concentration of person X between 0 and 30 minutes.
Explain the changes in the blood glucose concentration of person X between 30 and 120 minutes.
Compare the results for person Y with those for person X.
Explain the results for person Y.
Explain why the people fasted overnight before drinking the glucose solution.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 66.7 % (8.0 − 4.8) ÷ 4.8 × 100 C1 66.7 % A1 | 2 |
| (b) | β cells detect rise; insulin secreted; GLUT4 uptake into muscle/liver; glycogenesis Any 4 of: β cells in the islets of Langerhans detect the high glucose concentration; they secrete insulin; insulin binds to receptors on muscle (and adipose) cells, so vesicles containing GLUT4 fuse with the cell surface membrane and more glucose enters by facilitated diffusion; liver cells convert glucose to glycogen (glycogenesis); glucagon secretion from α cells decreases B4 | 4 |
| (c) | Y higher at start; rises more and for longer; does not return to fasting level Y has a higher fasting concentration B1 Y’s concentration rises higher and peaks later (60 min rather than 30 min) B1 Y’s does not return to the starting value by 120 min (data quoted) B1 | 3 |
| (d) | no insulin produced; glucose not taken up by cells β cells do not produce (enough) insulin B1 so liver and muscle cells do not take up glucose / convert it to glycogen B1 | 2 |
| (e) | baseline not affected by recent meal so that the starting concentration is not raised by a recent meal / all start from a comparable baseline B1 | 1 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in