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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.
- Write in dark blue or black pen.
- Where diagrams are required, use a sharp pencil.
- Marks for each question are shown in brackets [ ].
- The total mark for this paper is 40.
- You are advised to spend no more than 45 minutes on this paper.
Section A: Multiple Choice Questions (10 marks)
Questions 1–10. Each question is worth 1 mark. Choose the single best answer.
1. Which of the following is the main function of the loop of Henle in the nephron?
(a) Filtration of blood plasma
(b) Reabsorption of glucose
(c) Reabsorption of water to concentrate urine
(d) Secretion of urea into the filtrate
Answer: ________ [1]
2. A person's blood glucose concentration rises after a meal. Which hormone is secreted to bring the blood glucose level back to normal?
(a) Glucagon
(b) Adrenaline
(c) Insulin
(d) Thyroxine
Answer: ________ [1]
3. Which blood vessel carries oxygenated blood away from the heart to the body?
(a) Pulmonary artery
(b) Pulmonary vein
(c) Vena cava
(d) Aorta
Answer: ________ [1]
4. Which of the following is a function of the white blood cell?
(a) Transport of oxygen
(b) Blood clotting
(c) Production of antibodies
(d) Transport of carbon dioxide
Answer: ________ [1]
5. In which part of the human eye are rod cells and cone cells found?
(a) Cornea
(b) Iris
(c) Retina
(d) Lens
Answer: ________ [1]
6. Which part of the brain controls body temperature and hunger?
(a) Cerebellum
(b) Medulla oblongata
(c) Cerebrum
(d) Hypothalamus
Answer: ________ [1]
7. During exercise, the rate and depth of breathing increase. What is the main stimulus for this change?
(a) Decrease in blood oxygen concentration
(b) Increase in blood carbon dioxide concentration
(c) Decrease in blood pH only
(d) Increase in blood glucose concentration
Answer: ________ [1]
8. Which of the following describes the role of bile in digestion?
(a) Breaks down fats into fatty acids and glycerol
(b) Emulsifies fats to increase the surface area for enzyme action
(c) Neutralises hydrochloric acid in the stomach
(d) Digests proteins into amino acids
Answer: ________ [1]
9. Which structure in the heart prevents the backflow of blood from the left ventricle to the left atrium?
(a) Tricuspid valve
(b) Semilunar valve
(c) Bicuspid (mitral) valve
(d) Pulmonary valve
Answer: ________ [1]
10. A person has a damaged receptor in the skin that can no longer detect temperature changes. Which type of receptor is most likely affected?
(a) Mechanoreceptor
(b) Chemoreceptor
(c) Thermoreceptor
(d) Photoreceptor
Answer: ________ [1]
Section B: Short Answer and Structured Questions (20 marks)
Questions 11–16. Answer in the spaces provided.
11. Fig. 11 shows a section through a human heart.
(Diagram description for context: A labelled diagram of the heart showing the four chambers, major vessels, and valves is referenced.)
(a) Identify chamber X, which receives oxygenated blood from the lungs. [1]
(b) Name the blood vessel Y that carries deoxygenated blood from the heart to the lungs. [1]
(c) State one structural feature of the left ventricle that enables it to pump blood to the entire body. [1]
(d) Explain why the wall of the right ventricle is thinner than the wall of the left ventricle. [2]
[4 marks]
12. Table 12 shows the composition of blood plasma, glomerular filtrate, and urea in a healthy person.
| Component | Blood Plasma (g/100 cm³) | Glomerular Filtrate (g/100 cm³) | Urine (g/100 cm³) |
|---|---|---|---|
| Water | 90–93 | 90–93 | 95–97 |
| Glucose | 0.1 | 0.1 | 0.0 |
| Urea | 0.03 | 0.03 | 2.0 |
| Protein | 7.0 | 0.0 | 0.0 |
| Salts | 0.4 | 0.4 | 1.2 |
(a) Explain why protein is present in blood plasma but not in the glomerular filtrate. [2]
(b) Explain why glucose is present in the glomerular filtrate but not in the urine of a healthy person. [2]
(c) The concentration of urea in urine is much higher than in blood plasma. Suggest an explanation for this observation. [2]
[6 marks]
13. Fig. 13 shows a reflex arc.
(Diagram description: A typical reflex arc showing receptor, sensory neurone, relay neurone in the spinal cord, motor neurone, and effector.)
(a) State the function of the relay neurone. [1]
(b) Explain why reflex actions are important for survival. [2]
(c) A student accidentally touches a hot object. Describe the path of the nerve impulse from the receptor to the effector. [3]
[6 marks]
14. (a) Define the term homeostasis. [2]
(b) Explain how the body responds when the body temperature rises above 37 °C during vigorous exercise. Include the roles of the skin and the brain in your answer. [4]
[6 marks]
15. (a) Name the enzyme in the stomach that digests protein. [1]
(b) State the optimum pH for the enzyme named in (a). [1]
(c) Explain why this enzyme would not function well in the small intestine. [2]
[4 marks]
16. Fig. 16 shows the effect of exercise on the breathing rate of a student over a period of 10 minutes.
(Graph description: Time in minutes on the x-axis from 0 to 10. Breathing rate in breaths per minute on the y-axis from 12 to 30. From 0–2 min, breathing rate is 12. From 2–6 min (exercise period), it rises sharply to 28. From 6–10 min (recovery), it gradually decreases back to 12.)
(a) State the breathing rate of the student at the start of the experiment. [1]
(b) Calculate the increase in breathing rate during the exercise period. Show your working. [1]
(c) Explain why the breathing rate remains elevated for some time after exercise has stopped. [2]
[4 marks]
Section C: Data-Based and Extended Response Questions (10 marks)
Questions 17–20. Answer in the spaces provided.
17. A student investigated the effect of different concentrations of sugar solution on the mass of identical pieces of potato tissue. The results are shown in Table 17.
| Sugar solution concentration (mol/dm³) | Initial mass of potato (g) | Final mass of potato (g) | Change in mass (g) | Percentage change in mass (%) |
|---|---|---|---|---|
| 0.0 | 2.0 | 2.3 | +0.3 | +15.0 |
| 0.2 | 2.0 | 2.1 | +0.1 | +5.0 |
| 0.4 | 2.0 | 2.0 | 0.0 | 0.0 |
| 0.6 | 2.0 | 1.8 | −0.2 | −10.0 |
| 0.8 | 2.0 | 1.6 | −0.4 | −20.0 |
(a) At which concentration of sugar solution did no net movement of water occur into or out of the potato cells? Explain your answer. [2]
(b) Explain why the potato tissue lost mass in the 0.8 mol/dm³ sugar solution. [2]
(c) State one variable that should be kept constant in this experiment to ensure a fair test. [1]
[5 marks]
18. Fig. 18 shows a section through the human eye.
(Diagram description: A labelled cross-section of the human eye showing cornea, iris, pupil, lens, ciliary muscle, suspensory ligament, retina, fovea, blind spot, and optic nerve.)
(a) Name the structures responsible for:
(i) Focusing light onto the retina. [1]
(ii) Detecting light and converting it into nerve impulses. [1]
(b) Explain how the eye adjusts to focus on a nearby object. Include the roles of the ciliary muscles, suspensory ligaments, and lens in your answer. [3]
(c) State the function of the blind spot. [1]
[6 marks]
19. A person with Type 1 diabetes cannot produce insulin. Fig. 19 shows the blood glucose concentration of a healthy person and a person with Type 1 diabetes over a 12-hour period, including a meal at 1 hour.
(Graph description: Time in hours on the x-axis (0–12). Blood glucose concentration in mg/100 cm³ on the y-axis (60–200). Both persons start at ~90 mg/100 cm³. After the meal at 1 h, the healthy person's glucose rises to ~140 and returns to ~90 by 3 h. The diabetic person's glucose rises to ~190 and remains elevated at ~170 at 12 h.)
(a) Describe the changes in blood glucose concentration for the healthy person after the meal. [2]
(b) Explain why the blood glucose concentration of the person with Type 1 diabetes remains high after the meal. [2]
(c) Suggest one way in which a person with Type 1 diabetes can manage their condition. [1]
[5 marks]
20. Explain how the human body maintains a constant internal body temperature of approximately 37 °C when the external environment is cold. In your answer, include the roles of the following:
- Thermoreceptors in the skin
- Hypothalamus
- Arterioles in the skin
- Sweat glands
- Skeletal muscles
[5 marks]
END OF QUIZ
Answers
Secondary 4 Pure Biology Quiz - Human Physiology
Answer Key
Section A: Multiple Choice Questions
1. (c) Reabsorption of water to concentrate urine [1]
Marking note: The loop of Henre creates a water potential gradient in the medulla, enabling water reabsorption.
2. (c) Insulin [1]
Marking note: Insulin is secreted by β-cells of the islets of Langerhans in the pancreas when blood glucose rises.
3. (d) Aorta [1]
Marking note: The pulmonary artery carries deoxygenated blood to the lungs; the pulmonary vein carries oxygenated blood to the heart.
4. (c) Production of antibodies [1]
Marking note: Lymphocytes (a type of white blood cell) produce antibodies. Red blood cells transport oxygen; platelets are involved in clotting.
5. (c) Retina [1]
Marking note: Rod and cone cells are photoreceptor cells located in the retina.
6. (d) Hypothalamus [1]
Marking note: The hypothalamus is the body's thermostat and also regulates hunger, thirst, and osmotic balance.
7. (b) Increase in blood carbon dioxide concentration [1]
Marking note: CO₂ dissolves to form carbonic acid, lowering blood pH, which is detected by chemoreceptors in the medulla oblongata.
8. (b) Emulsifies fats to increase the surface area for enzyme action [1]
Marking note: Bile does not chemically digest fats; it physically breaks large fat globules into smaller droplets (emulsification).
9. (c) Bicuspid (mitral) valve [1]
Marking note: The tricuspid valve is between the right atrium and right ventricle.
10. (c) Thermoreceptor [1]
Marking note: Thermoreceptors detect changes in temperature. Mechanoreceptors detect pressure/touch; chemoreceptors detect chemical stimuli; photoreceptors detect light.
Section B: Short Answer and Structured Questions
11.
(a) Left atrium [1]
(b) Pulmonary artery [1]
(c) The wall of the left ventricle is thick / has thick muscular walls [1]
(d) The right ventricle only pumps blood to the lungs (a short distance), so it does not need to generate as much pressure as the left ventricle, which pumps blood to the entire body [2]
Marking note: Award 1 mark for stating the right ventricle pumps to the lungs (short distance) and 1 mark for linking this to lower pressure / less muscular wall needed.
12.
(a) Protein molecules are too large to pass through the (partially permeable) basement membrane of the glomerulus / the pores in the glomerular capillaries are too small to allow protein molecules through [2]
Marking note: Award 1 mark for "too large" and 1 mark for referencing the glomerulus/filtration barrier.
(b) Glucose is reabsorbed back into the blood in the (proximal) convoluted tubule by (active transport) [2]
Marking note: Award 1 mark for "reabsorbed in the (proximal) convoluted tubule" and 1 mark for "active transport" or "selective reabsorption".
(c) Water is reabsorbed in the collecting duct (and loop of Henle), so urea becomes more concentrated in the remaining fluid / less water remains in the urine, so the concentration of urea increases [2]
Marking note: Award 1 mark for water reabsorption and 1 mark for the resulting concentration effect.
13.
(a) The relay neurone transmits the nerve impulse from the sensory neurone to the motor neurone within the spinal cord / central nervous system [1]
(b) Reflex actions are rapid / automatic / do not require conscious thought, so they protect the body from harm by enabling a quick response to dangerous stimuli [2]
Marking note: Award 1 mark for "rapid/automatic" and 1 mark for linking this to protection from harm.
(c) Receptor → sensory neurone → relay neurone (in spinal cord) → motor neurone → effector (muscle) [3]
Marking note: Award 1 mark for correct start (receptor → sensory neurone), 1 mark for relay neurone in spinal cord, and 1 mark for motor neurone → effector. The sequence must be correct.
14.
(a) Homeostasis is the maintenance of a constant internal environment / the regulation of internal conditions (such as body temperature, blood glucose, water content) within narrow limits [2]
Marking note: Award 1 mark for "constant internal environment" and 1 mark for giving an example or elaboration.
(b) When body temperature rises above 37 °C:
- Thermoreceptors in the skin and hypothalamus detect the increase in temperature [1]
- The hypothalamus (acting as the thermostat) sends nerve impulses to effectors [1]
- Arterioles in the skin dilate (vasodilation), increasing blood flow to the skin surface, so more heat is lost by radiation [1]
- Sweat glands produce more sweat; as sweat evaporates from the skin surface, heat is lost, cooling the body [1]
Marking note: Award 1 mark for each valid point, up to 4 marks. Must include the role of the hypothalamus and at least two skin responses.
15.
(a) Pepsin [1]
(b) pH 2 (or pH 1.5–2.0) [1]
(c) The small intestine has a higher pH (alkaline/neutral) because bile and pancreatic juice neutralise the stomach acid. Pepsin works best in acidic conditions and would be denatured / would lose its active site shape in alkaline conditions [2]
Marking note: Award 1 mark for stating the small intestine is alkaline/neutral and 1 mark for explaining denaturation or loss of enzyme activity.
16.
(a) 12 breaths per minute [1]
(b) 28 − 12 = 16 breaths per minute [1]
Marking note: Award 1 mark for the correct calculation. Accept 16 even if working is not shown, but working should be shown for full credit.
(c) During exercise, lactic acid accumulates in the muscles (from anaerobic respiration). After exercise, the elevated breathing rate supplies more oxygen to oxidise the lactic acid / to repay the oxygen debt [2]
Marking note: Award 1 mark for lactic acid / anaerobic respiration and 1 mark for oxygen debt / oxidising lactic acid.
Section C: Data-Based and Extended Response Questions
17.
(a) 0.4 mol/dm³ [1]. At this concentration, there was no change in mass, meaning the water potential inside the potato cells was equal to the water potential of the sugar solution, so there was no net movement of water by osmosis [1]
(b) The 0.8 mol/dm³ sugar solution had a lower water potential (more negative / more concentrated) than the cell sap of the potato cells [1]. Water moved out of the potato cells into the sugar solution by osmosis, causing the potato tissue to lose mass [1]
(c) Any one of: temperature, volume of sugar solution, size/surface area of potato pieces, type of potato, duration of experiment [1]
Marking note: Do not accept "mass of potato" alone — the initial mass was controlled, but the variable to keep constant should be something else.
18.
(a)(i) Lens (and cornea) [1]
(a)(ii) Retina (rod and cone cells / photoreceptors) [1]
(b) When focusing on a nearby object:
- The ciliary muscles contract [1]
- The suspensory ligaments become slack / slacken [1]
- The lens becomes thicker / more convex / more rounded (due to its elastic nature), increasing its refractive power to focus the near object on the retina [1]
Marking note: All three points required for 3 marks. Award partial credit if the sequence is partially correct.
(c) The blind spot is the point where the optic nerve leaves the eye; there are no rod or cone cells at this point, so no image is detected [1]
Marking note: Award 1 mark for either "where the optic nerve leaves the eye" or "no photoreceptors present".
19.
(a) After the meal, the blood glucose concentration rises (from ~90 to ~140 mg/100 cm³) as glucose is absorbed from the small intestine into the blood [1]. It then decreases and returns to the normal level (~90 mg/100 cm³) after about 2 hours as insulin promotes the uptake of glucose by cells and its conversion to glycogen in the liver [1]
(b) The person with Type 1 diabetes cannot produce insulin [1]. Without insulin, glucose cannot be taken up by cells or converted to glycogen, so blood glucose remains elevated [1]
(c) The person can inject insulin / use an insulin pump / monitor blood glucose levels regularly and adjust diet [1]
Marking note: Accept any valid management strategy.
20.
When the external environment is cold:
- Thermoreceptors in the skin detect the drop in temperature and send nerve impulses to the hypothalamus [1]
- The hypothalamus acts as the thermostat and coordinates heat-conserving responses [1]
- Arterioles in the skin constrict (vasoconstriction), reducing blood flow to the skin surface, so less heat is lost to the surroundings by radiation [1]
- Sweat glands reduce / stop sweat production, reducing heat loss by evaporation [1]
- Skeletal muscles contract rapidly (shivering), generating heat through increased respiration [1]
Marking note: Award 1 mark for each valid point, up to 5 marks. The response must include all five specified structures for full marks. Partial credit for fewer points.
Total: 40 marks