OxfordAQA International AS and A-level Biology: Blood glucose and diabetes (9610) – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions follow section 3.4.7 of the OxfordAQA International AS and A-level Biology (9610) specification, Version 5.1: 3.4.7.1 to 3.4.7.4, Hormones and the control of blood glucose concentration. The content sits in Unit 4, which the specification lists as International A-level only.

Links: the study guide, the revision notes, the OxfordAQA A-level Biology hub and the checklist.

Questions

1. Explain why it is important that the concentration of glucose in the blood is kept stable. [4]

2. Name the process in the liver that:

(a) converts glucose to glycogen [1] (b) converts glycogen to glucose [1] (c) produces glucose from glycerol and amino acids [1]

3. Describe how insulin lowers the concentration of glucose in the blood after a meal. [5]

4. A person has not eaten for 14 hours.

(a) Describe how glucagon increases the concentration of glucose in the blood. [3] (b) State one way in which the action of adrenaline on a liver cell is the same as that of glucagon. [1]

5. Adrenaline acts on liver cells through a second messenger.

(a) Describe the sequence of events from adrenaline binding to a liver cell to the release of glucose. [4] (b) Suggest why a very small amount of adrenaline can cause a large release of glucose. [2]

6. Compare the causes and the control of Type 1 and Type 2 diabetes. [4]

7. A boy with untreated Type 1 diabetes has glucose in his urine, passes a large volume of urine and is very thirsty.

(a) Explain why there is glucose in his urine. [2] (b) Explain why he passes a large volume of urine and is thirsty. [3]

8. Adults aged 45 to 64 were followed for several years. The table shows new cases of Type 2 diabetes in groups with different amounts of moderate physical activity.

Activity per week	Under 1 hour	1 to 3.9 hours	4 hours or more
New cases per 1000 people per year	14.2	9.6	6.1

(a) Calculate the percentage by which incidence is lower in the 4 hours or more group than in the under 1 hour group. [2] (b) Calculate how many times greater the incidence is in the least active group than in the most active group. Give your answer to 2 significant figures. [1] (c) Describe the relationship shown by the data. [1] (d) Evaluate the claim that low physical activity causes Type 2 diabetes. [3]

9. Liver cells were kept in a buffer for 15 minutes under different conditions. The glucose released into the buffer was measured.

Treatment	Glucose released / micromol per 100 mg of cells
No hormone	1.5
Glucagon	13.8
Adrenaline	12.0
Glucagon plus an inhibitor of protein kinase	2.4
A form of cAMP that is not broken down, no hormone	12.9
That form of cAMP plus the inhibitor of protein kinase	2.2

(a) Calculate the mean rate of glucose release with glucagon, in micromol per 100 mg per minute, to 2 significant figures. [1] (b) Calculate how many times greater glucose release was with glucagon than with no hormone. Give your answer to 2 significant figures. [1] (c) Explain what the result with glucagon plus the inhibitor shows. [2] (d) Explain what the results with the form of cAMP, with and without the inhibitor, show. [2]

10. A patient and a control subject fasted overnight, then drank a glucose solution at time 0. Blood glucose was measured at intervals.

Time / min	0	30	60	90	120	180
Control / mmol dm⁻³	4.9	9.3	6.8	5.3	4.8	4.7
Patient / mmol dm⁻³	10.4	17.9	19.6	18.8	16.9	14.2

(a) Calculate the percentage fall from the peak to 180 minutes for the control and for the patient. Give each answer to the nearest whole number. [2] (b) Describe two differences between the patient’s results and the control’s. [2] (c) The patient’s blood contained more insulin than normal. Suggest why this points to Type 2 rather than Type 1 diabetes. [2] (d) State one change in lifestyle that could help to control the patient’s blood glucose. [1]

11. An adult with a high body mass has just been diagnosed with Type 2 diabetes. A man with Type 1 diabetes injects his usual insulin dose but then misses a meal.

(a) Suggest how increased exercise could lower the adult’s blood glucose. [3] (b) Explain why the man’s blood glucose may fall too low and how his body could respond. [4] (c) Evaluate the statement “People with Type 2 diabetes never need insulin”. [2]

Answers

1. Low glucose: less glucose for respiration, so less ATP is made [1], and brain cells are affected, for example confusion or loss of consciousness [1]. High glucose: the water potential of the blood falls [1], so water leaves cells by osmosis and they lose water [1]. [4] Examiner insight: “Energy” alone is vague; name respiration and ATP, and link high glucose to water potential and osmosis.

2. (a) Glycogenesis [1]. (b) Glycogenolysis [1]. (c) Gluconeogenesis [1]. [3] Examiner insight: Spell each term carefully; a near-miss such as “glycolysis” names a different pathway.

3. Insulin attaches to receptors on the surface of target cells [1]. Its shape is complementary to the receptor, so only target cells respond [1]. More channel proteins are included in the surface membrane [1]. Glucose uptake into the cell therefore increases [1]. Insulin activates enzymes that convert glucose to glycogen [1]. [5] Examiner insight: Say that insulin “activates enzymes”, not that it converts glucose itself, and link channel proteins to the membrane.

4. (a) Glucagon attaches to receptors on the surface of liver cells [1]. It activates enzymes that convert glycogen to glucose [1]. It also switches on enzymes that make glucose from glycerol and amino acids [1]. (b) Either it attaches to receptors on the surface of the cell, or it activates enzymes that convert glycogen to glucose [1]. [4] Examiner insight: A “state one way” question needs one clear statement; adding a second, contradictory statement weakens the answer.

5. (a) Adrenaline binds to its receptor on the cell surface membrane [1]. This activates adenyl cyclase [1], which converts ATP to cAMP [1]. cAMP activates protein kinase, which activates enzymes that convert glycogen to glucose [1]. (b) One adrenaline molecule leads to many cAMP molecules being made [1]. Each activated enzyme catalyses many reactions, so the signal is amplified at each stage [1]. [6] Examiner insight: List the molecules in order and name all three: adenyl cyclase, cAMP and protein kinase. For “suggest why”, an amplification point must say that numbers increase at a stage.

6. Type 1: the immune system destroys the insulin-secreting cells, so little or no insulin is made [1]. Type 2: target cells respond poorly to insulin (fewer or less responsive receptors) [1]. Type 1 is controlled by injecting insulin with attention to diet [1]. Type 2 is controlled first by regulating diet, losing weight and exercising [1]. [4] Examiner insight: A “compare” question is rewarded when each point sets the two types side by side. Two unconnected descriptions leave the comparing to the reader.

7. (a) The glucose concentration of the filtrate is too high [1]. Carrier proteins in the kidney tubule are saturated, so not all of the glucose is reabsorbed [1]. (b) Glucose left in the filtrate lowers its water potential [1], so the kidney recovers less water and more urine is produced [1]. The water loss lowers the water content of the blood, so he is thirsty [1]. [5] Examiner insight: Saying only “he has diabetes” repeats the question. Name the water potential change and the reduced reabsorption.

8. (a) (14.2 − 6.1) ÷ 14.2 × 100 [1] = 57% [1]. (b) 14.2 ÷ 6.1 = 2.3 times [1]. (c) As activity increases, incidence falls (negative correlation) [1]. (d) A correlation does not prove cause [1]. Other variables, such as body mass, diet or age, may differ between the groups [1]. A plausible mechanism exists, as active muscle uses more glucose, but the data do not show it, and the number of people followed is not given [1]. [7] Examiner insight: An evaluation needs a judgement based on reasons. “Not proven, because other variables may differ” scores better than a list of unconnected criticisms. Show your working for percentages.

9. (a) 13.8 ÷ 15 = 0.92 micromol per 100 mg per minute [1]. (b) 13.8 ÷ 1.5 = 9.2 times [1]. (c) Release fell to 2.4, close to the control value [1], so glucagon needs protein kinase to cause the release [1]. (d) The cAMP form alone gave a release similar to glucagon, so no hormone is needed once cAMP is present [1]. The inhibitor removed that effect, so cAMP acts through protein kinase [1]. [6] Examiner insight: Quote the figures when you interpret a table, and compare each result with the control.

10. (a) Control: (9.3 − 4.7) ÷ 9.3 × 100 = 49% [1]. Patient: (19.6 − 14.2) ÷ 19.6 × 100 = 28% [1]. (b) The patient started higher (10.4 compared with 4.9) [1]. The patient’s peak was higher and later (19.6 at 60 minutes compared with 9.3 at 30 minutes), and glucose fell far less by 180 minutes [1]. (c) In Type 1 diabetes little or no insulin is made, so a high insulin level suggests the insulin-making cells work [1]. Glucose stays high because target cells respond poorly to insulin, as in Type 2 [1]. (d) Lose weight, increase exercise or reduce refined sugar in the diet [1]. [7] Examiner insight: For “describe two differences”, pair values from both rows. A difference quoted with only one subject’s data does not show a comparison.

11. (a) Active muscle cells use more glucose in respiration [1]. Glucose is taken up from the blood, so its concentration falls [1]. Exercise may help weight loss, which could improve the response of cells to insulin [1]. (b) The injected insulin still acts: glucose uptake into cells rises and glucose is converted to glycogen [1], but no new glucose is absorbed from a meal, so blood glucose falls [1]. Low glucose means less respiration and ATP, affecting brain cells [1]. Glucagon and adrenaline could raise glucose by activating enzymes that convert glycogen to glucose [1]. (c) Many can be controlled by diet, weight loss and exercise [1], but insulin may be needed if these fail, because target cells respond poorly or insulin production falls [1]. [9] Examiner insight: A statement containing “never” invites a counter-example. Name a case where the claim fails and give the reason it fails.

Where marks are usually lost

• Saying insulin or glucagon “converts” substances instead of activating enzymes.
• Omitting water potential when explaining why high glucose or the glucose in urine matters.
• Confusing glycogen (the store) with glucagon (the hormone).
• Missing one or more of adenyl cyclase, cAMP and protein kinase, or putting them in the wrong order.
• Giving the same cause for both types of diabetes.
• Concluding that a correlation in risk-factor data proves cause.
• Giving a percentage change calculated from the wrong starting value.
• Quoting no figures when asked to interpret a table.

Next steps

• Condense with the revision notes and revisit the study guide.
• Tick off the topic on the checklist and return to the course hub.
• Try all the free 10-minute diagnostics.
• Book a free trial class.

Official syllabus

OxfordAQA, International AS and A-level Biology (9610), Version 5.1, for International A-level exams May/June 2018 onwards: section 3.4.7, Hormones and the control of blood glucose concentration.