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Secondary 4 Pure Biology Human Physiology Quiz
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Questions
Secondary 4 Pure Biology Quiz - Human Physiology
Name: _________________________ Class: _________________________ Date: _________________________ Score: ______ / 40
Duration: 45 minutes Total Marks: 40
Instructions:
- Answer ALL questions in the spaces provided.
- The number of marks is given in brackets [ ] at the end of each question or part question.
- Show all working for calculation questions.
- Diagrams should be drawn with a sharp pencil.
Section A: Short Answer & Identification (Questions 1–5)
Answer all questions in this section.
1. Name the blood vessel that carries deoxygenated blood from the heart to the lungs. ___________________________________________________________________________ [1]
2. State the function of platelets in the blood. ___________________________________________________________________________ [1]
3. Identify the part of the nephron where ultrafiltration occurs. ___________________________________________________________________________ [1]
4. Name the hormone that stimulates the conversion of glycogen to glucose in the liver. ___________________________________________________________________________ [1]
5. State the role of the hepatic portal vein in the transport system. ___________________________________________________________________________ [1]
Section B: Structured Response (Questions 6–12)
Answer all questions in this section.
6. The diagram below shows a cross-section of an artery and a vein.
> Image pending generation for this question.
(a) Identify which vessel (A or B) is the artery. Give one reason for your answer.
___________________________________________________________________________ [2]
(b) Explain how the structure of an artery is related to its function of carrying blood away from the heart.
___________________________________________________________________________ [2]
7. A student investigated the effect of exercise on heart rate. The table below shows the results.
| Time after exercise (min) | Heart rate (beats per min) |
|---|---|
| 0 (immediately after) | 140 |
| 2 | 120 |
| 4 | 105 |
| 6 | 95 |
| 8 | 88 |
| 10 | 85 |
| Resting (before exercise) | 82 |
(a) Describe the trend shown by the data.
___________________________________________________________________________ [1]
(b) Explain why the heart rate remains elevated for several minutes after exercise has stopped.
___________________________________________________________________________ [2]
(c) Calculate the percentage decrease in heart rate from 0 minutes to 10 minutes after exercise. Show your working.
___________________________________________________________________________ [2]
8. The graph below shows the changes in blood glucose concentration after a meal in a healthy person and a person with Type 2 diabetes.
[Graph: X-axis = Time after meal (hours), Y-axis = Blood glucose concentration (mmol/L).
Healthy person: rises from 5 to 7 at 1 hour, returns to 5 by 3 hours.
Diabetic person: rises from 7 to 12 at 1.5 hours, slowly decreases to 9 by 3 hours.]
(a) Compare the blood glucose response of the healthy person and the diabetic person after the meal.
___________________________________________________________________________ [2]
(b) Explain the role of insulin in regulating blood glucose concentration in a healthy person.
___________________________________________________________________________ [2]
(c) Suggest why the blood glucose concentration of the diabetic person does not return to the normal resting level within 3 hours.
___________________________________________________________________________ [1]
9. Describe the process of peristalsis and explain its importance in the digestive system.
___________________________________________________________________________ [3]
10. A patient with kidney failure undergoes dialysis treatment. The dialysis fluid contains the same concentration of glucose and mineral salts as normal blood plasma, but contains no urea.
(a) Explain why the dialysis fluid contains no urea.
___________________________________________________________________________ [1]
(b) Explain how urea is removed from the patient's blood during dialysis.
___________________________________________________________________________ [2]
11. The diagram below shows the structure of a villus.
> Image pending generation for this question.
(a) Name structure C and state its function.
___________________________________________________________________________ [2]
(b) Explain two ways in which the structure of a villus is adapted for efficient absorption of digested food.
___________________________________________________________________________ [2]
12. Explain why a person who has been sprinting breathes heavily for some time after the race has ended.
___________________________________________________________________________ [3]
Section C: Data Interpretation & Analysis (Questions 13–20)
Answer all questions in this section.
13. The table below shows the composition of inspired air and expired air.
| Gas | Inspired air (%) | Expired air (%) |
|---|---|---|
| Oxygen | 21 | 16 |
| Carbon dioxide | 0.04 | 4 |
| Nitrogen | 79 | 79 |
| Water vapour | Variable | Saturated |
(a) Explain why the percentage of oxygen is lower in expired air than in inspired air.
___________________________________________________________________________ [1]
(b) Explain why the percentage of carbon dioxide is higher in expired air than in inspired air.
___________________________________________________________________________ [1]
(c) State why the percentage of nitrogen remains unchanged. ___________________________________________________________________________ [1]
14. The diagram below shows a reflex arc.
*Generated diagram for this question.*
(a) State the function of the relay neurone in the reflex arc. ___________________________________________________________________________ [1]
(b) Explain the importance of a reflex action in protecting the body from injury.
___________________________________________________________________________ [2]
(c) Suggest why a reflex action is faster than a voluntary action.
___________________________________________________________________________ [1]
15. A student set up an experiment to investigate the effect of temperature on the rate of respiration in yeast. The volume of carbon dioxide produced was measured every 5 minutes at different temperatures. The results are shown in the table below.
| Temperature (°C) | Volume of CO₂ produced in 10 minutes (cm³) |
|---|---|
| 10 | 2 |
| 20 | 8 |
| 30 | 18 |
| 40 | 22 |
| 50 | 5 |
| 60 | 0 |
(a) Describe the relationship between temperature and the rate of respiration between 10°C and 40°C.
___________________________________________________________________________ [1]
(b) Explain why the volume of CO₂ produced decreases at temperatures above 40°C.
___________________________________________________________________________ [2]
(c) State the word equation for aerobic respiration. ___________________________________________________________________________ [1]
16. The diagram below shows the human urinary system.
*Generated diagram for this question.*
(a) State the function of structure R. ___________________________________________________________________________ [1]
(b) Describe the role of the kidney in excretion.
___________________________________________________________________________ [2]
(c) Explain why it is important to remove urea from the body.
___________________________________________________________________________ [1]
17. A person accidentally touches a hot object and immediately withdraws their hand.
(a) Name the type of neurone that carries the impulse from the receptor to the spinal cord. ___________________________________________________________________________ [1]
(b) Explain why the person withdraws their hand before feeling the pain.
___________________________________________________________________________ [2]
18. The table below shows the ABO blood groups and the antigens present on the red blood cells.
| Blood group | Antigens on red blood cells |
|---|---|
| A | Antigen A |
| B | Antigen B |
| AB | Antigens A and B |
| O | None |
(a) Explain why a person with blood group O can donate blood to a person with blood group AB, but a person with blood group AB cannot donate blood to a person with blood group O.
___________________________________________________________________________ [2]
(b) State why it is important to match blood groups before a blood transfusion.
___________________________________________________________________________ [1]
19. The diagram below shows the structure of the heart.
> Image pending generation for this question.
(a) State the letter of the blood vessel that carries oxygenated blood to the heart. ___________________________________________________________________________ [1]
(b) Explain why the wall of chamber Z is thicker than the wall of chamber X.
___________________________________________________________________________ [2]
(c) Describe the function of the valves in the heart.
___________________________________________________________________________ [1]
20. Explain how the body maintains a constant internal temperature on a hot day.
___________________________________________________________________________ [4]
END OF QUIZ
Answers
Secondary 4 Pure Biology Quiz - Human Physiology — Answer Key
Total Marks: 40
Section A: Short Answer & Identification
1. Pulmonary artery. [1]
2. Platelets are involved in blood clotting / help to clot blood at wound sites. [1]
3. Bowman's capsule / glomerulus. [1]
4. Glucagon. [1]
5. It transports absorbed nutrients (e.g., glucose, amino acids) from the small intestine directly to the liver for processing / before they enter general circulation. [1]
Section B: Structured Response
6. (a) Vessel A is the artery. Reason: It has a thicker muscular wall / narrower lumen compared to vessel B. [2]
(b) Arteries have thick, muscular, and elastic walls to withstand and maintain the high pressure of blood pumped from the heart. The elastic fibres allow the artery wall to stretch and recoil, helping to push blood along and maintain blood pressure between heartbeats. [2]
7. (a) As time after exercise increases, the heart rate decreases / heart rate falls from 140 bpm to 85 bpm over 10 minutes. [1]
(b) After exercise, the body needs to continue delivering extra oxygen to muscles to repay the oxygen debt (remove lactic acid produced during anaerobic respiration). The elevated heart rate maintains increased blood flow to remove waste products and restore normal conditions. [2]
(c) Decrease = 140 – 85 = 55 bpm. Percentage decrease = (55 ÷ 140) × 100 = 39.3% (accept 39.3% or 39%). [2] Marking: 1 mark for correct working, 1 mark for correct answer with units.
8. (a) In the healthy person, blood glucose rises to a lower peak (~7 mmol/L) and returns to resting level within 3 hours. In the diabetic person, blood glucose rises to a higher peak (~12 mmol/L), takes longer to peak, and does not return to resting level within 3 hours / remains elevated. [2]
(b) When blood glucose rises after a meal, the pancreas releases insulin. Insulin stimulates the liver and muscle cells to take up glucose and convert it to glycogen for storage, thereby lowering blood glucose back to normal. [2]
(c) The diabetic person's body cells are resistant to insulin / the pancreas does not produce enough insulin, so glucose uptake by cells is reduced. [1]
9. Peristalsis is the rhythmic, wave-like contraction and relaxation of circular and longitudinal muscles in the wall of the alimentary canal. It pushes food along the digestive tract from the oesophagus to the anus. It is important because it ensures food is mixed with digestive enzymes and moved through the gut for digestion and absorption. [3] Marking: 1 mark for describing muscle contraction/relaxation, 1 mark for movement of food, 1 mark for importance in digestion/absorption.
10. (a) The dialysis fluid contains no urea so that a concentration gradient for urea exists between the patient's blood (high urea) and the dialysis fluid (no urea), allowing urea to diffuse out of the blood. [1]
(b) The patient's blood flows on one side of a partially permeable membrane, and dialysis fluid flows on the other side. Urea diffuses from the blood (high concentration) across the membrane into the dialysis fluid (low concentration) down the concentration gradient. The dialysis fluid is continually replaced to maintain the gradient. [2]
11. (a) Structure C is the lacteal. Its function is to absorb fats / fatty acids and glycerol / lipids into the lymphatic system. [2]
(b) Two adaptations:
- The epithelium is one cell thick, providing a short diffusion distance for absorbed nutrients to reach the blood capillaries.
- The villus has a dense network of blood capillaries to rapidly transport absorbed glucose and amino acids away, maintaining a steep concentration gradient. (Accept: large surface area due to finger-like shape; presence of microvilli on epithelial cells.) [2]
12. During sprinting, muscles carry out anaerobic respiration due to insufficient oxygen supply, producing lactic acid. This creates an oxygen debt. After the race, heavy breathing continues to supply extra oxygen to the muscles to oxidise / break down the accumulated lactic acid into carbon dioxide and water (or convert it back to glucose in the liver). The increased breathing rate also helps remove excess carbon dioxide produced during respiration. [3] Marking: 1 mark for anaerobic respiration/lactic acid, 1 mark for oxygen debt, 1 mark for removal/breakdown of lactic acid.
Section C: Data Interpretation & Analysis
13. (a) Oxygen is absorbed from the alveoli into the blood and used by body cells for aerobic respiration, so less oxygen remains in expired air. [1]
(b) Carbon dioxide is a waste product of aerobic respiration in body cells. It diffuses from the blood into the alveoli and is exhaled, increasing its concentration in expired air. [1]
(c) Nitrogen is an inert gas that is not used or produced by the body, so its concentration remains unchanged. [1]
14. (a) The relay neurone connects the sensory neurone to the motor neurone within the spinal cord / central nervous system. [1]
(b) Reflex actions are rapid, automatic responses that occur without conscious thought. They protect the body by quickly withdrawing from harmful stimuli (e.g., heat, sharp objects) before serious tissue damage occurs. The speed of the response minimises injury. [2]
(c) A reflex action involves fewer synapses / a shorter neural pathway (only through the spinal cord, not the brain), reducing the time taken for impulse transmission. [1]
15. (a) As temperature increases from 10°C to 40°C, the rate of respiration increases / more CO₂ is produced. [1]
(b) Above 40°C, the enzymes involved in respiration begin to denature. The active site of the enzymes changes shape, so the substrate can no longer bind, and the rate of respiration decreases. At 60°C, the enzymes are completely denatured and respiration stops. [2]
(c) Glucose + Oxygen → Carbon dioxide + Water (+ Energy released). [1] Accept: correct chemical equation.
16. (a) Structure R (bladder) stores urine temporarily before it is expelled from the body. [1]
(b) The kidney filters blood, removing urea (a toxic nitrogenous waste produced from the breakdown of excess amino acids) and excess water and salts. It forms urine, which is then passed to the bladder for excretion. This process maintains the correct water and solute balance in the blood. [2]
(c) Urea is toxic. If it accumulates in the blood, it can damage cells and organs, leading to serious illness or death. [1]
17. (a) Sensory neurone. [1]
(b) The reflex arc involves the impulse travelling from the receptor to the spinal cord and directly to the motor neurone, causing immediate muscle contraction. The impulse for pain travels separately to the brain for conscious sensation, which takes longer. The withdrawal occurs before the brain processes the pain signal. [2]
18. (a) A person with blood group O has no antigens on their red blood cells, so their blood will not trigger an immune response in a recipient with blood group AB (who has both A and B antigens). However, a person with blood group AB has both A and B antigens, which would be recognised as foreign by a person with blood group O (who has anti-A and anti-B antibodies), causing agglutination / clumping of red blood cells. [2]
(b) If incompatible blood groups are mixed, the recipient's antibodies will attack the donor's red blood cells, causing agglutination, which can block blood vessels and be fatal. [1]
19. (a) R (pulmonary vein). [1]
(b) Chamber Z is the left ventricle, which pumps blood to the entire body (systemic circulation). This requires high pressure to overcome the resistance of the long systemic circuit. Chamber X is the right ventricle, which pumps blood only to the nearby lungs (pulmonary circulation), requiring lower pressure. The thicker muscular wall of the left ventricle generates the greater force needed. [2]
(c) Valves prevent the backflow of blood, ensuring that blood flows in one direction through the heart. [1]
20. On a hot day:
- Thermoreceptors in the skin and hypothalamus detect the rise in blood temperature.
- The hypothalamus sends signals to effectors.
- Sweat glands increase sweat production; evaporation of sweat from the skin surface removes heat, cooling the body.
- Arterioles in the skin dilate (vasodilation), allowing more blood to flow near the skin surface, increasing heat loss by radiation and convection.
- Hair erector muscles relax, so hairs lie flat, reducing insulation and allowing more heat to escape.
- Metabolic rate may decrease to reduce internal heat production. [4] Marking: 1 mark for detection (thermoreceptors/hypothalamus), 1 mark for sweating/evaporation, 1 mark for vasodilation, 1 mark for hair/other mechanism. Accept any four valid points.
END OF ANSWER KEY
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