Control of blood glucose concentration — AQA GCSE Combined Science
Test yourself on Control of blood glucose concentration with AQA GCSE practice questions.
7 days Premium · Then free forever · No card, no charge
Control of blood glucose concentration explained
The pancreas monitors and controls blood glucose concentration.
Read the full explanation
Its cells detect changes in blood plasma glucose and respond by secreting hormones. If glucose rises (e.g. after a carbohydrate meal), the pancreas releases insulin, causing cells to take up glucose. (HT only: If glucose falls, the pancreas releases glucagon, causing glycogen to be converted back into glucose). These hormones travel in the blood to target organs like the liver and muscles. This negative feedback mechanism ensures the corrective response reverses the original change, returning glucose to a set point. The pancreas thus links stimulus detection to an effector response, maintaining a steady energy supply.
If the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes glucose to move from the blood into the cells. In liver and muscle cells excess glucose is converted to glycogen for storage.
After a carbohydrate-rich meal, glucose absorbed from the gut raises blood glucose above the normal range. Pancreas cells detect this rise and secrete insulin into the blood. Insulin travels to cells and increases the rate at which they take up glucose from the blood plasma. In liver and muscle cells, glucose not needed immediately for respiration is converted into glycogen, a storage polysaccharide. This lowers blood glucose back towards the set point, an example of negative feedback. Glycogen acts as a store that can later be broken down to release glucose when blood concentration falls. The liver is especially important because it can both store and release glucose, helping to keep the supply steady between meals.
Students should be able to explain how insulin controls blood glucose (sugar) levels in the body.
Blood glucose must stay within a narrow range to supply cells with fuel without damaging them. After a meal, glucose absorbed from the small intestine raises blood glucose. The pancreas detects this rise and secretes insulin into the blood. Insulin travels to target cells, mainly liver and muscle, where it increases the rate at which glucose is taken up from the blood and converted into glycogen for storage. As cells remove glucose, blood glucose falls, so the pancreas reduces insulin secretion. This is negative feedback: the response cancels the original change. For example, after a carbohydrate-rich meal blood glucose might rise from about 5 mmol/dm³ towards 8 mmol/dm³; insulin restores it towards the set point.
Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin. It is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections.
Type 1 diabetes is a disorder of blood glucose control. The pancreas fails to produce sufficient insulin, so glucose is not removed from the blood efficiently after meals. Blood glucose can remain high, a state called hyperglycaemia, and glucose may appear in the urine. Typical effects include thirst, frequent urination, tiredness and weight loss. These have different causes: thirst and frequent urination follow from glucose and water loss in urine, whereas weight loss occurs mainly because cells cannot use glucose, so the body breaks down fat and protein for energy. Because the body cannot make enough insulin, the usual treatment is insulin injections, often several times a day, alongside monitoring blood glucose and managing diet and exercise. Injecting insulin replaces the missing hormone so that cells take up glucose and store it as glycogen.
In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas. A carbohydrate controlled diet and an exercise regime are common treatments. Obesity is a risk factor for Type 2 diabetes.
Type 2 diabetes develops when body cells become less responsive to insulin, so glucose is not removed from the blood efficiently even though the pancreas still produces insulin. Blood glucose therefore tends to stay too high. Treatment focuses on reducing the glucose load and improving insulin sensitivity: a carbohydrate-controlled diet limits glucose intake, while regular exercise increases glucose uptake by muscles and helps lower blood glucose. Obesity is a major risk factor because excess fat tissue is linked to reduced insulin sensitivity. A student can explain this by comparing a person with Type 2 diabetes who eats a high-sugar meal and does little exercise with one who follows a controlled diet and exercises regularly; the latter usually has lower blood glucose. This links cell response, treatment and risk factors.
Students should be able to compare Type 1 and Type 2 diabetes and explain how they can be treated.
Type 1 and Type 2 diabetes both cause blood glucose to rise too high, but their causes and treatments differ. In Type 1 diabetes, the pancreas produces little or no insulin, so glucose cannot be taken up by body cells effectively. Treatment usually involves insulin injections, alongside diet and exercise. In Type 2 diabetes, the pancreas still produces insulin, but body cells no longer respond well to it. Treatment commonly involves a carbohydrate-controlled diet and an exercise regime, sometimes with medication. A student can compare them by stating the cause, the insulin status and the main treatment for each. For example, a person with Type 1 diabetes needs insulin injections because their pancreas cannot supply enough insulin, whereas a person with Type 2 diabetes may manage their blood glucose by changing diet and increasing exercise.
Students should be able to extract information and interpret data from graphs that show the effect of insulin in blood glucose levels in both people with diabetes and people without diabetes.
Blood glucose is controlled by insulin, which lowers glucose when it is too high. On a graph, read the vertical axis for glucose concentration, often in mmol/dm³, and the horizontal axis for time after eating or after an insulin dose. In a person without diabetes, glucose rises after a meal, then insulin is released and glucose falls back to a stable level. In a person with diabetes, the rise may be larger or the fall slower, or injected insulin may cause a sharper fall. To extract information, quote values from the graph. To interpret, link the shape to insulin action: a steeper downward slope shows a faster fall in glucose. Compare curves by giving specific values and times, not by saying one is higher.
(HT only) If the blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood.
When blood glucose falls below the normal level, the pancreas detects this and secretes glucagon into the blood. Glucagon travels to the liver, where it stimulates the breakdown of glycogen into glucose. The glucose then leaves the liver cells and enters the blood, so blood glucose concentration rises back towards normal. This is an example of negative feedback: the original change is reversed. Glycogen is a storage polysaccharide made of many glucose units; glucagon is a hormone, not an enzyme, and it does not directly convert glycogen. Instead, it triggers the cells to carry out the conversion. In a person without diabetes, this response helps keep glucose steady between meals.
(HT only) Students should be able to explain how glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body.
Blood glucose must stay steady for cells to respire reliably. After a meal, rising glucose is detected by the pancreas, which secretes insulin. Insulin causes liver and muscle cells to take up glucose and store it as glycogen, so glucose falls. If glucose falls too low, the pancreas secretes glucagon instead. Glucagon makes liver cells break glycogen down into glucose, which is released into the blood, so glucose rises. Each hormone therefore reverses the other's effect, forming a negative feedback cycle that keeps glucose within a narrow range. For example, after exercise glucose dips, glucagon restores it; after a sugary drink, insulin lowers it.
Your focus
- State that the pancreas monitors blood glucose concentration.
- Describe how the pancreas controls blood glucose using hormones.
- Explain why blood glucose concentration must be kept within a narrow range.
Show all 27 objectives
- Describe how insulin lowers blood glucose concentration.
- Explain the role of liver and muscle cells in converting excess glucose to glycogen.
- Relate the insulin response to the principle of negative feedback.
- Describe the role of the pancreas in detecting changes in blood glucose concentration.
- Explain how insulin increases glucose uptake and glycogen storage in target cells.
- Use the idea of negative feedback to explain how blood glucose concentration is returned towards its normal level.
- State that type 1 diabetes results from the pancreas failing to produce sufficient insulin.
- Describe the characteristic uncontrolled high blood glucose levels and associated symptoms of type 1 diabetes.
- Explain why insulin injections are the normal treatment for type 1 diabetes.
- Describe how body cells respond to insulin in Type 2 diabetes.
- Explain how a carbohydrate-controlled diet and exercise regime help manage Type 2 diabetes.
- Explain why obesity is a risk factor for Type 2 diabetes.
- Compare the causes of Type 1 and Type 2 diabetes.
- Explain how Type 1 and Type 2 diabetes are treated.
- Distinguish between the roles of insulin production and insulin response in the two types of diabetes.
- Read values of blood glucose concentration and time from a graph showing insulin effects.
- Compare the blood glucose patterns of a person with diabetes and a person without diabetes using quoted data.
- Explain how the shape of a graph links to the action of insulin in lowering blood glucose.
- Describe the role of glucagon when blood glucose concentration is too low.
- Explain how glucagon causes glycogen to be converted into glucose and released into the blood.
- Distinguish between the actions of insulin and glucagon in controlling blood glucose.
- State the gland that secretes insulin and glucagon and the conditions that trigger each.
- Describe the effects of insulin on liver and muscle cells, and the effect of glucagon on liver cells.
- Explain how the opposing actions of insulin and glucagon form a negative feedback cycle that stabilises blood glucose.
Control of blood glucose concentration exam tips
Marking Points
- The pancreas contains receptor cells that detect changes in blood glucose concentration.
- The pancreas acts as an endocrine gland by secreting the hormone insulin directly into the blood when glucose levels are too high.
- (HT only) The pancreas secretes the hormone glucagon when blood glucose levels are too low, interacting with insulin in a negative feedback cycle.
- Hormones travel in the blood plasma to target organs, primarily the liver and muscle cells, to regulate glucose uptake and storage.
- Blood glucose must be maintained within a narrow range to provide a constant supply of respiratory substrate for cells.
- A rise in blood glucose concentration is detected by the pancreas, which releases insulin into the blood.
- Insulin causes glucose to move from the blood plasma into cells, including liver and muscle cells.
- Inside liver and muscle cells, excess glucose is converted into glycogen for storage.
- Glycogen is an insoluble storage polysaccharide made from many glucose units joined together.
- The removal of glucose from the blood and its conversion to glycogen lowers blood glucose concentration towards the normal range.
- This is negative feedback because the response reverses the original rise in blood glucose.
- The pancreas detects a rise in blood glucose concentration and secretes insulin into the bloodstream.
- Insulin is a hormone that travels in the blood plasma to target cells such as liver and muscle cells.
- Insulin increases the uptake of glucose from the blood into cells and increases the conversion of glucose to glycogen for storage.
- As glucose is removed from the blood, blood glucose concentration falls, which reduces insulin secretion.
- The fall in blood glucose is an example of negative feedback because the response reverses the original increase.
- Glycogen is the storage polysaccharide in liver and muscle; it is not the same as the hormone glucagon.
- In type 1 diabetes the pancreas fails to produce sufficient insulin, so blood glucose is not regulated effectively.
- Uncontrolled high blood glucose levels are a characteristic feature and can be detected by monitoring blood or urine.
- Thirst and frequent urination are linked to glucose remaining in the blood and being excreted in urine, which draws water out with it.
- Weight loss in type 1 diabetes occurs mainly because cells cannot use glucose for energy, so the body breaks down fat and protein instead.
- Insulin injections are the normal treatment because they replace the insulin the pancreas cannot produce.
- Injected insulin allows cells to take up glucose and store it as glycogen, lowering blood glucose.
- Management also involves monitoring blood glucose concentration and adjusting diet and exercise, but insulin injection is the defining treatment.
- Type 2 diabetes involves body cells no longer responding normally to insulin, so glucose uptake from the blood is reduced.
- The pancreas still produces insulin in Type 2 diabetes, but the cells have become less sensitive to it.
- A carbohydrate-controlled diet reduces the amount of glucose entering the blood from digestion, helping to lower blood glucose concentration.
- Regular exercise increases glucose uptake by muscles and can improve the body's response to insulin.
- Obesity is a risk factor for Type 2 diabetes because excess body fat is associated with reduced insulin sensitivity.
- Treatment aims to manage blood glucose concentration and reduce the risk of long-term health problems.
- Type 1 diabetes: pancreas produces little or no insulin; Type 2 diabetes: pancreas produces insulin but cells respond less well.
- Type 1 diabetes is treated with insulin injections; Type 2 diabetes is commonly treated with a carbohydrate-controlled diet and exercise regime.
- Both types result in high blood glucose if untreated, and both require management to reduce health risks.
- Lifestyle factors such as obesity are linked to Type 2 diabetes but not to Type 1 diabetes.
- Comparison should include at least one similarity and one difference between the two types.
- Treatment explanations should link the treatment to its effect on blood glucose concentration.
- Read the vertical axis as blood glucose concentration, commonly in mmol/dm³, and the horizontal axis as time, so that each point gives a glucose value at a stated time.
- Describe the pattern in a person without diabetes: glucose rises after a meal, then falls back towards a stable level as insulin causes cells to take up glucose and store it as glycogen.
- Describe the pattern in a person with diabetes: the glucose rise may be greater or the return to the stable level slower, or an injected insulin dose may produce a more rapid fall.
- Compare curves using data, for example the peak glucose value in mmol/dm³ and the time taken to return to the starting value, rather than using vague words such as higher or faster alone.
- Interpret a downward slope as insulin lowering blood glucose, and a smaller or absent fall as reduced insulin action or insufficient insulin.
- Use the graph to support a conclusion about how well blood glucose is controlled, quoting at least one value from each curve.
- State that a fall in blood glucose concentration is detected by the pancreas, which acts as the receptor and coordinator.
- State that the pancreas produces and secretes the hormone glucagon into the blood when blood glucose is too low.
- State that glucagon causes glycogen to be converted into glucose; glycogen is the storage form of glucose in the liver.
- State that the glucose produced is released into the blood, so blood glucose concentration increases.
- Explain that this is negative feedback because the response reverses the original fall in blood glucose.
- Distinguish glucagon from insulin: insulin lowers blood glucose, whereas glucagon raises it, and both are hormones secreted by the pancreas.
- Insulin is secreted by the pancreas when blood glucose concentration is too high.
- Insulin increases the uptake of glucose by cells and stimulates the conversion of glucose to glycogen in the liver and muscles.
- Glucagon is secreted by the pancreas when blood glucose concentration is too low.
- Glucagon stimulates the liver to convert stored glycogen back into glucose, which is released into the blood.
- The two hormones have opposite effects, so each corrects a deviation and restores the set point, which is negative feedback.
Examiner Tips
- 💡Name the pancreas as the receptor and control centre, and explicitly name the liver and muscles as the target effector tissues.
- 💡(HT only) When explaining negative feedback, clearly link each hormone (insulin or glucagon) to the specific direction of change in blood glucose.
- 💡Use the sequence: high blood glucose → pancreas detects → insulin released → glucose enters cells → excess converted to glycogen → blood glucose falls.
- 💡Name both liver and muscle as storage sites when the question asks where glycogen is made.
- 💡Distinguish clearly between glycogen (storage molecule) and glucagon (hormone) in written answers.
- 💡Link the response to negative feedback so the examiner sees that the original change is reversed.
- 💡Use the sequence stimulus, hormone, target, response, negative feedback when explaining the control pathway.
- 💡Name the pancreas, insulin, liver or muscle, glucose and glycogen explicitly, because vague terms such as 'it controls sugar' do not show understanding.
- 💡Link the fall in blood glucose back to reduced insulin secretion to demonstrate negative feedback rather than describing only a one-way process.
- 💡Link each feature of the disorder to its cause: insufficient insulin leads to high blood glucose, which leads to the symptoms.
- 💡Use the phrase 'uncontrolled high blood glucose levels' when describing the characteristic state, and avoid saying simply 'too much sugar in the blood' without qualification.
- 💡When asked about treatment, state that insulin is injected because it is a protein hormone and would be digested if swallowed.
- 💡When asked about Type 2 diabetes, always state that cells no longer respond to insulin, not that insulin is absent.
- 💡Link each treatment to its effect on blood glucose: diet reduces glucose intake, exercise increases glucose uptake.
- 💡Use the term 'risk factor' correctly: obesity increases the chance of developing Type 2 diabetes but does not guarantee it.
- 💡Use a table or clear sentences to compare Type 1 and Type 2 diabetes, covering cause, insulin production and treatment.
- 💡Always link treatment to the underlying problem: insulin injections replace missing insulin in Type 1; diet and exercise reduce insulin resistance in Type 2.
- 💡Avoid vague statements like 'diabetes is when you have too much sugar'; specify the type and the mechanism.
- 💡Before answering, label each curve, for example 'without diabetes' and 'with diabetes', and note the units on both axes.
- 💡When asked to compare, use the phrase 'at X minutes, the person without diabetes had Y mmol/dm³, whereas the person with diabetes had Z mmol/dm³'.
- 💡If asked to suggest why a curve differs, link your answer to insulin: less insulin released, insulin not working effectively, or injected insulin acting at a different time.
- 💡Check that every value you quote has a unit and a time, and that your conclusion follows from the data you have quoted.
- 💡Use the sequence: low blood glucose → pancreas detects → glucagon secreted → glycogen converted to glucose → glucose released into blood → blood glucose rises.
- 💡Name the hormone and the storage molecule precisely; do not use 'sugar hormone' or 'glycogen hormone'.
- 💡If asked to explain negative feedback, state the original change and how the response reverses it.
- 💡Link the site of action to the liver, where glycogen is broken down to release glucose into the blood, rather than saying glucagon acts everywhere.
- 💡Use the phrase 'blood glucose concentration' rather than just 'sugar' so your answer is precise.
- 💡Structure longer answers as a cycle: stimulus, detector, hormone, target organ, effect, correction.
Common Mistakes
- Saying the pancreas 'makes' glucose or 'filters' blood; correction: the pancreas detects glucose concentration and releases hormones that change how cells handle glucose.
- Confusing hormones with enzymes; correction: insulin (and glucagon for HT) are hormones released into the blood, not digestive enzymes released into the gut.
- Treating the pancreas as the effector; correction: the effector cells are mainly liver and muscle cells that change their glucose uptake or release.
- Foundation students discussing glucagon; correction: Foundation tier only requires knowledge of insulin lowering high blood glucose. (HT only: remember glucagon raises low blood glucose).
- Writing that insulin 'destroys' glucose; correction: insulin causes glucose to enter cells, where it is used in respiration or stored as glycogen.
- Confusing glycogen with glucagon; correction: glycogen is the storage carbohydrate, while glucagon is the hormone that raises blood glucose.
- Saying glucose is stored as glycogen in all cells; correction: the main storage sites are liver and muscle cells.
- Stating that insulin is an enzyme; correction: insulin is a hormone that alters cell behaviour, not a catalyst that digests glucose.
- Writing that insulin is an enzyme that digests glucose; correction: insulin is a hormone that changes cell activity, and glucose is not digested in the blood.
- Stating that insulin converts glucose into glucagon; correction: glucose is stored as glycogen, while glucagon is a separate hormone that raises blood glucose.
- Saying the liver produces insulin; correction: the pancreas produces insulin, and the liver is a target organ that stores glucose as glycogen.
- Confusing type 1 and type 2 diabetes; correction: type 1 involves insufficient insulin production by the pancreas, whereas type 2 involves cells becoming less responsive to insulin.
- Stating that type 1 diabetes is treated with diet alone; correction: diet and exercise help management, but insulin injections are normally required.
- Attributing weight loss to glucose being excreted in urine; correction: weight loss is mainly due to fat and protein breakdown when cells cannot use glucose for energy.
- Writing that insulin injections cure diabetes; correction: they treat and control the condition but do not restore the pancreas's ability to produce insulin.
- Error: stating that the pancreas does not produce insulin in Type 2 diabetes. Correction: in Type 2 diabetes the pancreas usually still produces insulin, but body cells respond less well to it.
- Error: saying that Type 2 diabetes is caused by eating too much sugar alone. Correction: obesity is a risk factor, but the condition involves reduced cell response to insulin and multiple risk factors.
- Error: confusing treatment of Type 2 diabetes with insulin injections as the first treatment. Correction: common treatments are a carbohydrate-controlled diet and an exercise regime; insulin may be used in some cases but is not the standard first approach described here.
- Error: saying Type 1 diabetes is caused by obesity. Correction: Type 1 diabetes is an autoimmune condition where the pancreas produces little or no insulin; obesity is a risk factor for Type 2 diabetes.
- Error: stating that both types are treated with insulin injections. Correction: Type 1 diabetes requires insulin injections, while Type 2 diabetes is commonly treated with diet and exercise, though medication may be used.
- Error: describing Type 2 diabetes as the pancreas not producing insulin. Correction: in Type 2 diabetes the pancreas produces insulin, but body cells no longer respond to it properly.
- Reading the axes the wrong way round, for example treating time as glucose concentration. Correction: always state the quantity and unit on each axis before quoting any value.
- Confusing the roles of insulin and glucagon. Correction: insulin lowers blood glucose; glucagon raises it, and only insulin is the focus of these graphs.
- Describing a curve as going up or down without giving values. Correction: quote a glucose concentration and its time, such as 7.0 mmol/dm³ at 60 minutes, to support each comparison.
- Assuming all people with diabetes show identical graphs. Correction: describe the general pattern shown by the data, and note that individual responses and treatments vary.
- Saying that glucagon is an enzyme that digests glycogen. Correction: glucagon is a hormone that stimulates cells to break down glycogen; enzymes such as glycogen phosphorylase carry out the reaction inside cells.
- Confusing glucagon with glycogen. Correction: glucagon is a hormone; glycogen is a storage carbohydrate made of glucose units.
- Saying that glucagon is released when blood glucose is too high. Correction: glucagon is released when blood glucose is too low; insulin is released when it is too high.
- Writing that glucose is converted into glycogen when glucagon acts. Correction: glucagon causes glycogen to be converted into glucose, the opposite direction.
- Saying insulin and glucagon are secreted by the liver; correction: both are secreted by the pancreas, and the liver is the main target organ.
- Stating that glucagon is released when glucose is too high; correction: glucagon is released when glucose is too low, while insulin is released when it is too high.
- Describing the cycle as positive feedback; correction: because the response reverses the original change and returns glucose towards normal, it is negative feedback.