Endocrine system and blood glucose control – GCSE Biology exam questions with mark scheme

1Grade 1–3Foundation3 marks

The endocrine system is made up of glands that secrete hormones.

Draw one line from each gland to the hormone it secretes.

Gland	Hormone
Pancreas	Oestrogen
Testes	Thyroxine
Ovary	Insulin
	Testosterone

[3]

Pancreas → insulin(1)
Testes → testosterone(1)
Ovary → oestrogen
(if more than one line is drawn from a gland, no mark for that gland)(1)
Answer: Pancreas – insulin; testes – testosterone; ovary – oestrogen.
Examiner tip: Oestrogen comes from the ovaries and testosterone from the testes – students often swap them.

2Grade 6–76 marks

The graph shows the blood glucose concentration of a healthy person before and after eating a meal.

(a) Use the graph to find the increase in blood glucose concentration from when the meal was eaten to the highest value. [1]

(b) Calculate the percentage increase in blood glucose concentration from 30 minutes to 60 minutes. Give your answer to 3 significant figures. [2]

(a) 50 (mg per 100 cm³)(1)
(b) $\frac{50}{90}\times 100$
allow ecf from (a)(1)
(b) 55.6 (%)
must be 3 significant figures for this mark; 55.56 or 55.5555… scores mark 1 only
correct answer with no working scores 2(1)
(c) (rise in glucose detected by pancreas) insulin is released / secreted (into the blood)
ignore references to glucagon(1)
(c) (insulin) causes glucose to move from the blood into cells(1)
(c) (in liver and muscles) excess glucose is converted to glycogen (for storage)
do not accept 'glucagon' for 'glycogen'(1)
Answer: (a) 50 mg per 100 cm³ (b) 55.6% (c) Pancreas secretes insulin; glucose moves into cells; liver/muscle convert glucose to glycogen.
Examiner tip: Spelling matters: writing 'glucagon' when you mean 'glycogen' loses the storage mark.

3Grade 6–76 marks

Type 1 diabetes and type 2 diabetes both cause blood glucose concentration to be too high.

Compare type 1 and type 2 diabetes.

In your answer you should refer to the causes and the treatment of each type. [6]

Type 1: pancreas produces little or no insulin / fails to produce enough insulin(1)
Type 1: often starts in childhood / is not linked to lifestyle(1)
Type 1: treated with insulin injections(1)
Type 1: insulin dose matched to diet and exercise / blood glucose monitored(1)
Type 2: body cells no longer respond to insulin (pancreas still makes insulin)(1)
Type 2: obesity is a risk factor / linked to diet and lack of exercise(1)
Type 2: treated with a carbohydrate-controlled diet and an exercise regime(1)
Type 2: may also be treated with drugs/medication (if diet and exercise are not enough)(1)
Similarity: both result in uncontrolled/high blood glucose; both need blood glucose monitoring(1)

Level	Marks	What it looks like
Level 3	5–6	Detailed, linked comparison of both causes and both treatments, with clear direct comparisons between the two types.
Level 2	3–4	Describes causes and treatments of both types with some comparison, or one type in detail and the other partly.
Level 1	1–2	Simple relevant statements about one or both types; little or no comparison.
No relevant content	0	Nothing worthy of credit.

Answer: Type 1 – no insulin made, treated with insulin injections; type 2 – cells stop responding to insulin, linked to obesity, treated with diet and exercise.
Examiner tip: To reach Level 3 you must compare directly (e.g. 'whereas') and cover both causes and treatments for both types.

4Grade 1–3Foundation6 marks

The diagram shows the positions of five endocrine glands, A to E, in a woman's body.

(a) Name glands A, B and D. [3]

(b) Which letter, A to E, shows the gland that secretes insulin? [1]

Suggest why. [1]

(d) How are hormones carried from a gland to their target organ? [1]

(a) A – pituitary (gland); allow phonetic spelling; do not accept pineal / hypothalamus(1)
(a) B – thyroid (gland); do not accept thymus(1)
(a) D – adrenal (gland); do not accept kidney(1)
(b) C(1)
(c) it secretes (several) hormones that act on / control / stimulate other glands (to release their hormones); ignore 'controls the body' / 'most important gland' alone(1)
(d) in the blood / bloodstream; allow in (blood) plasma; do not accept 'along nerves / neurones'(1)
Answer: (a) A pituitary, B thyroid, D adrenal (b) C (c) its hormones stimulate other glands to secrete hormones (d) in the blood
Examiner tip: In (c) 'it controls everything' scores nothing — say that its hormones act on OTHER GLANDS and make them release hormones.

5Grade 4–54 marks

The nervous system and the endocrine system both coordinate responses in the body.

(a) Complete the table to compare the two systems. [3]

	Nervous system	Endocrine system
Type of signal	electrical impulses	chemicals (hormones)
How the signal travels	along neurones	……………………
Speed of the response	very fast	……………………
How long the effect lasts	a short time	……………………

(b) Growth during puberty is controlled by hormones, not by the nervous system.

Suggest why hormones are better suited to controlling growth. [1]

(a) (carried) in the blood / bloodstream; allow in blood plasma; ignore 'through the body'(1)
(a) slower / slow; allow takes longer / not as fast(1)
(a) longer / for a long time; allow 'long-lasting'(1)
(b) growth happens over a long time / years so a long-lasting effect is needed; allow hormones (in the blood) can reach many / all parts of the body at once; ignore 'hormones control growth' (restates stem)(1)
Answer: (a) in the blood; slower; longer (b) growth needs a long-lasting effect (over years)
Examiner tip: Fill each blank for the endocrine system using comparison words – 'slower' and 'lasts longer' – and say hormones travel 'in the blood'; 'through the body' does not score.

6Grade 4–5Foundation7 marks

Scientists studied adults in one country. The bar chart shows the percentage of adults with type 2 diabetes in four groups with different body mass index (BMI).

A BMI of 30 or more is classed as obese.

(a) Describe the relationship shown by the bar chart. [1]

(b) How many times greater is the percentage of adults with type 2 diabetes in the '35 and over' group than in the 'under 25' group? [2]

Use the bar chart to estimate how many of these adults have type 2 diabetes. [1]

(d) A student says, 'This proves that obesity causes type 2 diabetes.'

Give one reason why the student is not correct. [1]

(e) Give two ways type 2 diabetes is usually treated. [2]

(a) as BMI increases, the percentage of adults with type 2 diabetes increases; allow positive correlation; allow 'higher BMI, more (people with) type 2 diabetes'(1)
(b) 21 and 3 read from chart / 21 ÷ 3(1)
(b) 7 (times); 7 with no working scores 2(1)
(c) 768; allow 770; allow ecf for 6400 × (their reading for 30.0–34.9) ÷ 100(1)
(d) any one from: correlation does not show cause / a link is not proof; other factors may be involved, e.g. age / diet / lack of exercise / genetics; not all obese people have type 2 diabetes / some people with BMI under 25 have it; ignore 'only one country was studied' (limits how far the results apply, not whether obesity is the cause)(1)
(e) any two from: a carbohydrate-controlled diet / eat less sugar / carbohydrate; (regular) exercise; lose weight; allow medication / drugs (to lower blood glucose) — first way; ignore 'healthy diet' / 'balanced diet' unqualified(1)
(e) second different way from the list above; do not accept insulin injections as the usual treatment; two diet answers (e.g. 'eat less sugar' and 'eat less carbohydrate') count as one way only(1)
Answer: (a) higher BMI, higher % with type 2 diabetes (b) 7 (c) 768 (d) correlation is not causation / other factors (e) carbohydrate-controlled diet; exercise
Examiner tip: In (e) do not say 'insulin injections' — that is the treatment for TYPE 1; type 2 is treated with a carbohydrate-controlled diet and exercise.

7Grade 6–7Higher6 marks

The diagram shows how blood glucose concentration is controlled when it falls below normal.

(a) Name hormone X. [1]

(b) Name substance Y. [1]

(d) During a long run, a person's muscles use a lot of glucose.

Explain why the person's blood glucose concentration could fall to a dangerously low level if their pancreas could not secrete hormone X. [2]

(a) glucagon; do not accept glycogen / glucose / insulin; misspellings that could be glycogen = 0(1)
(b) glycogen; do not accept glucagon(1)
(c) a change / fall (in blood glucose) is detected (by the pancreas)(1)
(c) the response reverses the change / brings the level back to normal; ignore 'keeps it constant' alone(1)
(d) (glucose used in) respiration (by the muscles) removes glucose from the blood(1)
(d) (no glucagon so) glycogen (in the liver) is not converted to glucose / released into the blood, so the glucose used is not replaced; allow glucose stores cannot be released(1)
Answer: (a) glucagon (b) glycogen (c) a fall in glucose is detected and the response returns it to normal / reverses the change (d) glucose used in respiration is not replaced because glycogen is not converted back to glucose
Examiner tip: Glucagon and glycogen are the most confused pair in the spec — glucagon is the hormone (it ends in -gon, like 'glucose gone'), glycogen is the stored carbohydrate.

8Grade 6–77 marks

A glucose tolerance test was done on three people, A, B and C. Each person did not eat for 10 hours and then drank a solution of glucose.

Their blood glucose concentration and blood insulin concentration were measured every 30 minutes.

Time in minutes	Blood glucose in mmol/dm³			Blood insulin in arbitrary units
Time in minutes	A	B	C	A	B	C
0	7.5	6.9	5.0	2	25	8
30	13.2	11.8	8.6	3	95	60
60	16.0	13.9	7.1	3	120	45
90	16.8	13.5	5.9	3	110	25
120	16.4	12.6	5.0	2	95	10

One person does not have diabetes, one has type 1 diabetes and one has type 2 diabetes.

(a) Which person, A, B or C, has type 1 diabetes?

Give two reasons for your answer using data from the table. [3]

(b) Explain how the data show that person B has type 2 diabetes. [2]

Give the unit. [2]

(a) A; if B or C is chosen, no marks for (a)(1)
(a) (blood) glucose rises highest / to 16.8 (mmol/dm³) and stays high / does not return to normal (5.0); allow use of figures(1)
(a) (blood) insulin is (very) low / hardly changes / stays at 2–3 (units), so the pancreas produces (very) little insulin(1)
(b) insulin concentration is high / higher than C / rises to 120 (units)(1)
(b) but blood glucose stays high / does not return to 5.0 / normal, so the (body) cells do not respond to insulin; allow cells are resistant to insulin(1)
(c) (8.6 − 5.0) ÷ 90 = 0.04(1)
(c) mmol/dm³ per minute; allow mmol/dm³/min or mmol dm⁻³ min⁻¹; allow 2.4 mmol/dm³ per hour for both marks(1)
Answer: (a) A — glucose stays high (16.8); insulin stays very low (b) insulin high (up to 120) but glucose stays high, so cells don't respond to insulin (c) 0.04 mmol/dm³ per minute
Examiner tip: For type 2 you must use BOTH columns — high insulin AND high glucose together is the evidence that cells are not responding to insulin.

9Grade 8–9Higher6 marks

A student eats a breakfast high in sugar at 8 am.

She does not eat again until 2 pm.

Between 11 am and 1 pm she plays in a football match.

Explain how the student's blood glucose concentration is kept within normal limits between 8 am and 2 pm. [6]

after breakfast, glucose is absorbed (from the small intestine) into the blood so blood glucose concentration rises(1)
the pancreas monitors / detects the rise in blood glucose(1)
the pancreas secretes insulin into the blood(1)
insulin causes (body) cells to take up glucose from the blood(1)
in liver and muscle cells, glucose is converted to glycogen (for storage)(1)
blood glucose falls back to normal (and less insulin is secreted)(1)
during the match, muscles respire faster so they use more glucose; blood glucose falls(1)
the pancreas detects the fall and secretes glucagon(1)
glucagon causes glycogen (in the liver) to be converted into glucose, which is released into the blood(1)
blood glucose rises back to normal(1)
insulin and glucagon act as a negative feedback cycle — each response reverses the change(1)

Level	Marks	What it looks like
Level 3	5–6	A detailed, logically ordered explanation of BOTH the response after breakfast (insulin, uptake of glucose, glycogen stored in liver/muscle) AND the response during the match (glucagon, glycogen converted to glucose), each linked to the correct part of the day. Correct use of glucagon and glycogen.
Level 2	3–4	Explains one response in detail, or both responses with some gaps or minor confusion (e.g. no mention of where glycogen is stored, or glucagon/glycogen confused once). Some linking to the timeline.
Level 1	1–2	Simple, mostly unlinked statements, e.g. 'insulin lowers blood sugar' or 'the pancreas controls blood glucose'. Little or no reference to the timeline.
No relevant content	0	Nothing worthy of credit.

Answer: After breakfast: rise detected by pancreas → insulin → cells take up glucose, liver/muscle store it as glycogen → level falls. During football: respiration uses glucose → fall detected by pancreas → glucagon → liver converts glycogen to glucose → level rises. Insulin and glucagon interact by negative feedback.
Examiner tip: Match each hormone to the right part of the timeline — insulin after breakfast, glucagon during the match — and say what happens to glycogen in each case.

10Grade 4–56 marks

A person with type 1 diabetes injects insulin before each meal.

(a) Explain why a person with type 1 diabetes needs to inject insulin. [2]

(b) The person injects 1 unit of insulin for every 10 g of carbohydrate in a meal.

Their meal is:

180 g of cooked pasta, which contains 30 g of carbohydrate per 100 g
250 cm³ of orange juice, which contains 10 g of carbohydrate per 100 cm³.

Calculate the number of units of insulin the person should inject.

Give your answer to the nearest whole unit. [3]

Suggest why they may need to inject fewer units of insulin than you calculated in (b). [1]

(a) the pancreas does not produce (enough) insulin; allow cells in the pancreas that make insulin are damaged / destroyed(1)
(a) so blood glucose concentration would be too high / uncontrolled (as cells would not take up glucose from the blood); ignore 'to control blood sugar' alone(1)
(b) pasta: 180 × 30 ÷ 100 = 54 (g) and juice: 250 × 10 ÷ 100 = 25 (g)(1)
(b) total = 79 (g) (carbohydrate) ÷ 10 = 7.9; allow ecf from one incorrect carbohydrate value(1)
(b) 8 (units); 8 with no working scores 3; 7.9 with working scores 2(1)
(c) (during exercise) muscles use more glucose in respiration, so blood glucose will fall anyway / risk of blood glucose becoming too low; allow 'exercise lowers blood glucose'(1)
Answer: (a) pancreas makes too little insulin, so blood glucose would be too high (b) 79 g carbohydrate → 7.9 → 8 units (c) exercise uses glucose in respiration, so blood glucose falls anyway (risk of it going too low)
Examiner tip: Read the carbohydrate content 'per 100 g' carefully — 180 g of pasta is NOT 30 g of carbohydrate; scale it: 180 × 30 ÷ 100 = 54 g.

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