Author: Philip Colls
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Homeostasis – Blood glucose control booklet revision questions
Q1. Scientists investigated the control of blood glucose concentration in mice. They kept a group of normal mice without food for 48 hours. After 48 hours, the blood glucose concentrations of the mice were the same as at the start of the experiment.
(a)     Explain how the normal mice prevented their blood glucose concentration falling when they had not eaten for 48 hours.
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The scientists then investigated mice with a mutation that prevents their liver cells making glucose. They kept a group of these mice without food for 48 hours. After 48 hours, the mean blood glucose concentrations of the mutant mice and the normal mice were the same.
The scientists investigated how blood glucose concentration is controlled in these mutant mice. An enzyme required for synthesis of glucose is coded for by a gene called PCK1. The scientists measured the mean amount of mRNA produced from this gene in cells from the kidneys and intestines of normal mice and mutant mice. They did this with mice that had previously been without food for 48 hours.
The scientists’ results are shown in the graph.

(b)     Use information from the graph to suggest how blood glucose concentration is controlled in the mutant mice, compared with the normal mice.
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(c)     The scientists performed statistical tests on the data shown in the graph, to see whether the differences in the amount of mRNA in cells from normal and mutant mice were significant. Both the probability values they obtained were p<0.01. Explain what this means about the differences in the amounts of mRNA produced.
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Q2. Homeostatic mechanisms maintain a constant environment in the body.
(a)     The graph shows changes in plasma glucose concentration that occurred in a person who went without food for some time.
 
Use evidence from the graph to explain the role of negative feedback in the control of plasma glucose concentration.
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(5)
(b)     How does maintaining a constant body temperature allow metabolic reactions in cells to proceed with maximum efficiency?
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(5)
(Total 10 marks)

Q3. (a)     Technicians in a hospital laboratory tested urine and blood samples from a girl with diabetes at intervals over a one-year period. Each time the technicians tested her urine, they also measured her blood glucose concentration. Their results are shown in the graph.
 
(i)      The girl who took part in this investigation was being successfully treated with insulin. The graph shows that on some occasions, the concentration of glucose in her blood was very high. Suggest why.
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(2)

(ii)     Use the graph to evaluate the use of the urine test as a measure of blood glucose concentration.
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(3)
(b)     Diabetic people who do not control their blood glucose concentration may become unconscious and go into a coma. A doctor may inject a diabetic person who is in a coma with glucagon. Explain how the glucagon would affect the person’s blood glucose concentration.
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(2)
(Total 7 marks)
Q4.
(a)     Explain how insulin lowers the concentration of blood glucose.
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(Extra space) ________________________________________________________
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(3)

(b)     Doctors studied a large group of people. They recorded the death rates for non-diabetic people, undiagnosed diabetics and diagnosed diabetics.
They gave the death rates as deaths per 1000 years lived by people.
The graph shows these death rates.
 
(i)      Calculate the ratio of the death rate of diagnosed diabetics to undiagnosed diabetics.

 
Ratio ____________________
(2)
(ii)     People with undiagnosed diabetes were not receiving treatments, such as insulin injections. Suggest one reason for the difference in death rates for undiagnosed and diagnosed diabetics.
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(2)
(Total 7 marks)

Q5.
(a)     Describe how insulin reduces the concentration of glucose in the blood.
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(3)
Some people produce no insulin. As a result they have a condition called diabetes. In an investigation, a man with diabetes drank a glucose solution. The concentration of glucose in his blood was measured at regular intervals. The results are shown in the graph.
 
(b)     Suggest two reasons why the concentration of glucose decreased after 1 hour even though this man’s blood contained no insulin.
1. _________________________________________________________________
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2. _________________________________________________________________
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(2)
(c)     The investigation was repeated on a man who did not have diabetes. The concentration of glucose in his blood before drinking the glucose solution was 80 mg per 100 cm^3. Sketch a curve on the graph to show the results you would expect.
(1)
(d)     The diabetic man adopted a daily routine to stabilise his blood glucose concentration within narrow limits. He ate three meals a day: breakfast, a midday meal and an evening meal. He injected insulin once before breakfast and once before the evening meal.
The injection he used before breakfast was a mixture of two types of insulin. The mixture contained slow-acting insulin and fast-acting insulin.
(i)      Explain the advantage of injecting both types of insulin before breakfast.
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(2)
(ii)     One day, the man did not eat a midday meal. Suggest one reason why his blood glucose concentration did not fall dangerously low even though he had injected himself with the mixture of insulin before breakfast.
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(1)
(Total 9 marks)
Q6.
(a)     Sucrose, maltose and lactose are disaccharides.
(i)      Sucrase is an enzyme. It hydrolyses sucrose during digestion. Name the products of this reaction.
_________________________ and _________________________
(2)
(ii)     Sucrase does not hydrolyse lactose. Use your knowledge of the way in which enzymes work to explain why.
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(2)

(b)     A woman was given a solution of sucrose to drink. Her blood glucose concentration was measured over the next 90 minutes. The results are shown on the graph.
 
(i)      Describe how the woman’s blood glucose concentration changed in the period shown in the graph.
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(ii)     Explain the results shown on the graph.
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(Total 8 marks)
Q7. (a)     Adrenaline binds to receptors in the plasma membranes of liver cells. Explain how this causes the blood glucose concentration to increase.
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 (2)
(b)     Scientists made an artificial gene which codes for insulin. They put the gene into a virus which was then injected into rats with type I diabetes. The virus was harmless to the rats but carried the gene into the cells of the rats.
The treated rats produced insulin for up to 8 months and showed no side-effects. The scientists measured the blood glucose concentrations of the rats at regular intervals. While the rats were producing the insulin, their blood glucose concentrations were normal.
(i)      The rats were not fed for at least 6 hours before their blood glucose concentration was measured. Explain why.
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(ii)     The rats used in the investigation had type I diabetes. This form of gene therapy may be less effective in treating rats that have type II diabetes. Explain why.
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(iii)    Research workers have suggested that treating diabetes in humans by this method of gene therapy would be better than injecting insulin. Evaluate this suggestion.
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(Total 8 marks) 
Q8. (a)     Give two ways in which people with type 1 diabetes control their blood glucose concentration.
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2. _________________________________________________________________
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(b)     Scientists investigated the effect of diabetes on the control of heart rate in response to changes in blood pressure in rats. The scientists found the mean changes in heart rates of healthy rats and rats with diabetes in response to rises or falls in blood pressure.
The diagram shows their results in the form they were presented.
 
Diabetes can damage the nervous system. The response of the rats with diabetes is different from the response of the healthy rats. Use your knowledge of the control of heart rate by the nervous system to suggest an explanation for these results.
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____________________________________________________(4) (Total 6 marks)
Q9. There are two types of diabetes: type 1 and type 2.
•        People with type 1 diabetes do not produce enough insulin.
•        People with type 2 diabetes do produce insulin but have cells which do not respond to insulin.
Doctors use a glucose tolerance test to help diagnose people with diabetes. They start each test after a person has not eaten overnight. They measure a person’s blood glucose concentration.
The person then drinks a solution containing 75 g of glucose. The doctors measure the person’s blood glucose concentration 2 hours later. During the test, the person remains at rest.
Figure 1 shows three diagnoses that can be made from the results of the test.
Figure 1 – glucose tolerance test results and diagnoses

Blood glucose
concentration after 2 hours
/ mg 100 cm^–3

Diagnosis

Comments

≤ 110 | Non-diabetic | Low risk for future diabetes

Between 140 and 200

Pre-diabetic

High risk for future diabetes.
Some doctors recommend that the
upper value should be lowered to
180 mg 100 cm^–3

≥ 200 | Diabetic | Confirm by doing a second test
A researcher monitored the mean blood glucose concentration of a non-diabetic, a pre-diabetic and a diabetic after they had each eaten a midday meal.
His results are shown in Figure 2.
Figure 2
 
(a)     People with type 1 diabetes are described as being insulin-dependent.
Suggest why they are described as insulin-dependent.
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(1)

(b)     Some people with type 2 diabetes have cells which do not respond to insulin.
Explain how this leads to a reduced ability to regulate blood glucose concentration.
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(c)     During a glucose tolerance test the person remains at rest.
Why is it important that the person remains at rest?
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(d)     Use Figure 2 to calculate how many times the maximum mean blood glucose concentration of the pre-diabetic is greater than the maximum of the non-diabetic person. Show your working.

 
 
Answer =____________________
(2)
(e)     Give three differences between the method used by the researcher to obtain the results in Figure 2 and the method doctors use to carry out a glucose tolerance test.
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2. _________________________________________________________________
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3. _________________________________________________________________
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(3)
(f)     Some doctors have recommended that the upper value used in the glucose tolerance test should be lowered to 180 mg 100 cm^–3. Using information from Figure 1 and Figure 2, suggest why.
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(Total 14 marks)
Q10. (a)     When insulin binds to receptors on liver cells, it leads to the formation of glycogen from glucose. This lowers the concentration of glucose in liver cells.
Explain how the formation of glycogen in liver cells leads to a lowering of blood glucose concentration.
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People with type II diabetes have cells with low sensitivity to insulin. About 80% of people with type II diabetes are overweight or obese. Some people who are obese have gastric bypass surgery (GBS) to help them to lose weight. Doctors investigated whether GBS affected sensitivity to insulin. They measured patients’ sensitivity to insulin before and after GBS. About half of the patients had type II diabetes. The other half did not but were considered at high risk of developing the condition. The table below shows the doctors’ results. The higher the number, the greater the sensitivity to insulin.

Patients

Mean sensitivity to insulin /
arbitrary units
(± SD)

| Before gastric bypass surgery | 1 month after gastric bypass surgery

Did not have
diabetes

0.55
(± 0.32)

1.30
(± 0.88)

Had type II
diabetes

0.40
(± 0.24)

1.10
(± 0.87)

(b)     The doctors concluded that many of the patients who did not have type II diabetes were at high risk of developing the condition.
Use the data in the table to suggest why they reached this conclusion.
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(c)     The doctors also concluded that GBS cured many patients’ diabetes but that some were not helped very much.
Do these data support this conclusion? Give reasons for your answer.
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(Total 7 marks)
Q11. Some mice have diabetes. The diabetes causes the blood glucose concentration to become very high after a meal. Scientists investigated the use of an inhibitor of amylase to treat diabetes.
The scientists took 30 mice with diabetes and divided them into two groups, A and B.
•        Group A was given yoghurt without the inhibitor of amylase each day.
•        Group B was given yoghurt with the inhibitor of amylase each day.
Apart from the yoghurt, all of the mice were given the same food each day.
The scientists measured the blood glucose concentration of each mouse, 1 hour after it had eaten. This was done on days 1, 10 and 20 after the investigation started.
The following figure shows the scientists’ results.
 
        Days after the investigation started
(a)     Group A acted as a control in this investigation.
Explain the purpose of this group.
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(b)     Apart from the yoghurt, it was important that all of the mice were given the same food each day.
Give two reasons why it was important that all of the mice were given the same food each day.
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2. _________________________________________________________________
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(c)     The scientists’ hypothesis was that adding the inhibitor of amylase to the food would lead to a lower blood glucose concentration.
Use your knowledge of digestion to suggest how the addition of the inhibitor could lead to a lower blood glucose concentration.
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(d)     Give one reason why these results may not support the use of the inhibitor of amylase to treat diabetes in mice.
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(2)
(Total 8 marks)
Q12.
(a)     Each year, a few people with type I diabetes are given a pancreas transplant. Pancreas transplants are not used to treat people with type II diabetes.
Give two reasons why pancreas transplants are not used for the treatment of type II diabetes.
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2. _________________________________________________________________
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(2)
(b)     The pancreas produces the hormone insulin.
Put a tick (✔) in the box next to the statement which describes incorrectly the action of insulin.
 
Activates enzymes involved in the conversion of glucose to glycogen. |
Controls the uptake of glucose by regulating the inclusion of channel proteins in the surface membranes of target cells. |
Attaches to receptors on the surfaces of target cells. |
Activates enzymes involved in the conversion of glycerol to glucose. |
(1)

(c)     Scientists investigated the use of induced pluripotent stem cells (iPS cells) to treat type I diabetes in mice. The scientists used four transcription factors to reprogramme skin cells to form iPS cells. The scientists then stimulated the in vitro differentiation of iPS cells into pancreatic cells.
The scientists set up three experimental groups:
•   Group A – 30 mice with type I diabetes received pancreatic cell transplants derived from iPS cells.
•   Group B – 30 mice with type I diabetes were left untreated.
•   Group C – 30 mice without diabetes were left untreated.
The scientists measured the blood glucose concentration of all the mice on a weekly basis for 12 weeks. The results the scientists obtained are shown in the graph.
 
Suggest how transcription factors can reprogramme cells to form iPS cells.
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(d)     Using all the information provided, evaluate the use of iPS cells to treat type I diabetes in humans.
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___________________________________________________ (4) (Total 9 marks)

Mark schemes
Q1.
(a)     1.      Release of glucagon;
2.      Leads to formation of glucose in liver (cells);
Reject: glucagon breaks down glycogen, or any other biological molecule
3.      From non-carbohydrates / amino acids / fatty acids.
Accept: gluconeogenesis / references to glycogen as source of glucose
3
(b)     1.      Mutant mice (mRNA suggests) make a lot of (the) enzyme;
Accept: PCK1 made (for enzyme made)
2.      Mutant mice use kidney / intestine (cells) to make glucose;
Accept: use other organ (than liver)
3.      Normal mice do this much less / normal mice use liver cells.
3
(c)     1.      Differences significant;
Reject: references to results being significant once
2.      Probability of difference being due to chance less than 0.01 / 1% / 1 in 100 / probability of difference not being due to chance more than 0.99 / 99% / 99 in 100.
Ignore: references to 0.05 / 5% / 5 in 100
2
[8]
Q2.
Quality of Communication
The answers to all sections of this question require the use of continuous prose.
Quality of language should be considered in crediting points in the scheme. In order to gain credit, answers should be expressed logically and unambiguously, using scientific terminology where appropriate.
(a)     1.      Deviation of a value from norm initiates corrective mechanisms;
2.      fluctuations in plasma glucose concentration detected by hypothalmus / islet cells in pancreas;
3.      initial decrease, no food given (in plasma glucose) stimulates (increased) secretion of glucagon;
4.      increases (in plasma glucose) stimulate (increased) secretion of insulin from β cells as secretors;
5.      correct ref. to interconversion of glycogen / glucose / increased / decreased uptake of glucose by cells (as appropriate) / correct ref to change in membrane permeability;
5
(b)     1.      Body temp. / 37 °C  is optimum temp for enzymes;
2.      excess heat denatures enzymes / alters tertiary structure / alters shape of active site / enzyme so substrate cannot bind / eq;
3.      reactions cease / slowed;
4.      too little reduces kinetic energy of molecules / moleculesmove more slowly;
5.      fewer collisions / fewer ES complexes formed’
5
[10]
Q3.
(a)     (i)      Eaten;
Containing carbohydrate / sugar;
Glucose absorbed from intestine / into blood;
Long time after insulin injection / needs more insulin / has not taken insulin;
Does not convert glucose to glycogen / glucose not taken up from blood;
2 max
(ii)     Shows positive correlation / directly proportional;
A range of results for a particular value / values (for different colours) overlap;
Urine test only an arbitrary scale / not directly related to concentration / colour is subjective / few colour values;
Accept description
3
(b)     Glycogen to glucose / glycogenolysis by activating enzymes;
If name incorrect this disqualifies.
Gluconeogenesis;
Allow explanation in terms of glucose from a non-carbohydrate / named non-carbohydrate source.
2
[7]
Q4.
(a)     Binds to receptor on target/liver/muscle cell;
Reject reference to insulin as an enzyme
Causes more transport/carrier proteins to become active/
move to (plasma) membrane;
Glucose (diffuses) into cells (and lowers blood glucose);
(Enzymes in cells) convert glucose to glycogen;
Stimulates fatty acids/lipid/fat formation (from glucose);
Raises rate of respiration (in cells), using more glucose;
3 max
(b)     (i)      27 : 39;
1 : 1.44;
2 marks for 1 : 1.44
Accept 0.69 : 1
Accept 9 : 13
2
(ii)     One suitable reason; with explanation;
e.g. undiagnosed
Diabetic coma/brain cells not enough respiration;
Due to low blood glucose/acidosis/dehydration;
Heart attacks/coronary heart disease;
Due to faster atheroma formation/damage to arteries;
Kidney failure;
Due to damage to blood vessels;
2 max
[7]
Q5.
(a)     insulin binds to specific receptors (on membranes);
insulin activates carrier proteins / opens channels / causes more
channels to form;
insulin increases the permeability of liver / muscle cells / tissues to glucose;
insulin action results in glucose conversion to glycogen / glycogenesis;
3 max
(b)     glucose is used in cell respiration / as energy source / in metabolism;
(must qualify how glucose is used)
glucose enters cells / converted to glycogen in cells;
glucose is excreted / in urine;
(do not credit no reabsorption of glucose in kidneys)
2 max
(c)     line from 80 mg, increasing but keeping below line for diabetic,
dropping to 80 mg;
(line must stablise at, or fluctuate around 80 mg)
1
(d)     (i)      fast acting insulin reduces blood glucose from breakfast;
slow acting insulin reduces blood glucose from other meals
before the evening meal / eliminates the need to inject at lunch;
(must be a reference to the meals)
(one mark if neither of the above but a clear reference is 
made to glucose conversion to glycogen);
2
(ii)     glucagon is still active; 
glycogen converted to glucose / glycogenolysis; 
insulin injected at breakfast causes cells to take up glucose
too slowly for levels to become dangerously low;
person is not active so little glucose used in respiration;
(do not credit statements about consuming large breakfasts)
1 max
[9]
Q6.
(a)     (i)      Glucose;
Fructose;
Any order.
2
(ii)     Lactose has a different shape / structure;
Does not fit / bind to active site of enzyme / sucrase;
Only allow a second mark if reference is made to the active site.
Max 1 mark if active site is described as being on the substrate.
OR
Active site of enzyme / sucrase has a specific shape / structure; Does not fit / bind to lactose;
Do not accept same shape.
2
(b)     (i)      Rose and fell;
Peak at 45 (minutes) / concentration of 6.6 (mmol dm^–3);
2
(ii)     Glucose (produced by digestion) is absorbed / enters blood;
Decrease as used up / stored;
2
[8]
Q7.
(a)     1.      Adenylate cyclase activated / cAMP produced / second messenger produced;
2.      Activates enzyme(s) (in cell so) glycogenolysis / gluconeogenesis occurs / glycogenesis inhibited;
2. Neutral: ‘glucose produced’ as given in the question stem
      Accept: correct descriptions of these terms
2
(b)     (i)     1.      Glucose / sugar in food would affect the results;
1. Accept references to starch / carbohydrate
Or
2.      Food / eating would affect blood glucose (level);
Or
3.      (Allows time for) blood glucose (level) to return to normal;
3. Neutral: allows time for insulin to act
1 max
(ii)     Type 2 diabetes is a failure to respond to insulin / still produces insulin / is not insulin-dependent;
1
(iii)    (For) – 3 max
A maximum of three marks can be awarded for each side of the argument
1.      Avoids injections / pain of injections;
2.      Long(er) lasting / permanent / (new) cells will contain / express gene;
Ignore references to methodology e.g. sample size not known
3.      Less need to measure blood sugar / avoids the highs and lows in blood sugar;
4.      Less restriction on diet;
(Against) – 3 max
5.      Rats are different to humans;
6.      May have side effects on humans;
6. Accept: virus may be harmful / disrupt genes / cause cancer
7.      Long(er) term effects (of treatment) not known / may have caused effects after 8 months;
8.      (Substitute) insulin may be rejected by the body;
4 max
[8]
Q8.
(a)     1.      Treat with insulin (injection/infusion);
2.      (Control) diet/control sugar intake;
2. Accept ‘(regular) exercise’
2
(b)     1.      Damage to autonomic (nervous) system in diabetic rats;
2.      (Could be) pressure receptors/baroreceptors (in arteries/aorta/carotid body) don’t work as well;
3.      Damage to medulla
OR
Change in (number of) impulses to/from medulla;
4.      (When pressure drops damage to) sympathetic system, so doesn’t speed up (enough);
5.      (When pressure rises damage to) parasympathetic system, so doesn’t slow down (enough);
Accept answers in terms of what happens in healthy rats only if then qualified by statement these things don’t happen/happen less in rats with diabetes
1. Accept damage to ANS
2. Ignore reference to chemoreceptors
4 and 5. Appropriate system and effect on heart rate both needed
4 max
[6]
Q9.
(a)     Treatment requires person receiving insulin (in some way);
Accept descriptions e.g. insulin injection
Reward idea that insulin must be received, not that it isn’t being produced
1
(b)     1.      No / fewer / abnormal receptors on (cell) membrane;
2.      (So) fewer (glucose) transport proteins;
3.      (So) less glucose can enter (cells);
4.      (So) less glucose converted to glycogen;
Accept no / fewer enzymes (for this conversion) are activated
5.      (So, without treatment) blood glucose concentration not lowered when high / above normal;
Accept converse
3 max
(c)     1.      Movement uses muscles;
2.      Movement increases (rate of) respiration;
3.      Respiration uses glucose / respiration reduces blood glucose concentration;
2 max
(d)     1.      Identification of 195 ± 2 and 113 ± 2;
2.      Answer within range of 1.67 to 1.77 (times greater);
Ignore numbers after two decimal places
Correct answer = 2 marks
2
(e)     1.      Meal / uncontrolled intake v 75 g glucose / controlled intake;
Must have both sides of the story for each point. Marking guidance shows researcher’s method first
Idea of could eat anything in meal as against just glucose
2.      (Concentration) measured over 6 hours / 6+ hours / longer v measured at 2 hours;
3.      (After intake) regular monitoring / several measurements v only measured once / at 2 hours only;
4.      No fasting v fasting before test;
Credit other descriptions of fasting e.g. went without food as opposed to didn’t have to
5.      Not (necessarily) at rest v remained at rest;
6.      Tested during afternoon v tested in morning;
Accept idea of tested at different times of the day
3 max
(f)     1.      Pre-diabetics are at risk of developing diabetes / some pre-diabetics reach a concentration of 180 (mg 100 cm^−3) after a meal;
2.      Some pre-diabetics will now be classed as diabetic;
3.      Detection leads to treatment (sooner);
4.      Diabetes damages the body / is life-threatening;
Accept examples of damage e.g. blindness, heart disease
3 max
[14]
Q10.
(a)     (Formation of glycogen)
1.      Glucose concentration in cell / liver falls below that in blood (plasma) which creates / maintains glucose concentration / diffusion gradient;
2.      Glucose enters cell / leaves blood by facilitated diffusion / via carrier(protein) / channel (protein);
Not just diffusion
2
(b)     1.      Insulin sensitivity similar to / not (significantly) different from those with diabetes;
No values for non-obese, so comparisons with ‘normal’ not possible
2.      Overlap of SDs;
Accept SE
3.      Their sensitivity (to insulin also) improved by GBS;
2 max
(c)     1.      Sensitivity (to insulin) does increase;
This part of the question concerns spread of data, not overlap of SDs
2.      But large SD / large variation (after GBS);
Accept use of figures / use of SD values to make this point.
Ignore ref to SE
3.      (So) some showing no / little change / get worse;
4.      Do not know what sensitivity to insulin is of non-diabetics (who are not obese);
Accept ‘normal’ as non-diabetic
3 max
[7]
Q11.
(a)     1.      To show the effect of the inhibitor / drug;
2.      To show the effect of yoghurt (on its own does not affect blood
glucose);
2
(b)     1.      Food is a factor affecting blood glucose / different foods contain 
different amounts of starch / glucose / sugar / carbohydrate;
Accept converse
2.      To keep starch / fibre intake the same / similar;
Accept something in food which affects the inhibitor
2
(c)     1.      Fewer E-S complexes formed;
2.      (With inhibitor) less / no starch digested to maltose ;
Require knowledge that maltose comes from starch
3.      (So) less / no glucose from maltose;
Require knowledge that glucose comes from maltose
Accept no glucose
4.      (So) less absorption of glucose (from gut);
2 max
(d)     Suitable reason; with explanation;
Paired responses – do not mix and match
Ignore references to correlation does not prove causation, 
it could be due to other factors
Examples,
1.      Need larger sample / only 30 mice / only 15 mice in each group;
Accept small sample size
2.      Might not be representative / anomalies might have a bigger or smaller effect;
Accept mean not reliable
OR
3.      Investigation only lasted 20 days;
Experiment was not long enough
4.      Can’t see what longer term effects are;
OR
5.      Fall in blood glucose is small / numbers from graph;
6.      Mice with inhibitor still have a large rise in blood glucose / so don’t know if differences significant;
Accept differences are due to chance
OR
7.      No stats / SDs / SEs;
8.      So don’t know if differences significant;
OR
9.       Blood glucose could continue to fall;
10.     which could be harmful;
OR
11.     No group without yoghurt;
12.     So cannot compare to other groups;
2 max
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Q12.
(a)     1.      (Usually)Type II produce insulin;
2.      Cells / receptors less sensitive / responsive (to insulin)
OR
Faulty (insulin) receptors;
3.      (Treated / controlled by) diet / exercise;
2.      Accept: cells / receptors do not respond.
2.      Accept: ‘fewer receptors’
3.      Accept: (Treated / controlled by) weight loss / medication / drugs.
3.      Ignore: diabetes is caused by diet / exercise.
2 max
(b)     Tick in box 4
1
(c)     1.      Attach to gene / DNA / promoter region;
2.      Stimulate / inhibit transcription / RNA polymerase;
Note: Genes being expressed / inhibited or switched on / off is not enough on its own.
2
(d)     1.      (Effective as) group A / with iPS / treated lower than group B / with diabetes;
2.      (Effective as) group A similar to group C / without diabetes;
3.      (Investigation) done on mice not humans;
4.      Only shows results for 12 weeks / short-time period / long-term effects not known;
Ignore: Only one study / not repeated / sample size.
2.      Accept: ‘healthy’ or ‘normal’ or control for group C.
4
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