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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.
- Write your answers in the spaces provided.
- The number of marks is indicated in brackets [ ] at the end of each question or part question.
- You may use a calculator for calculations.
Section A: Multiple Choice Questions (Questions 1–5)
Choose the correct answer and write the letter in the box provided.
1. Which of the following correctly describes the movement of substances in the human circulatory system?
| Option | Arteries | Veins | Capillaries |
|---|---|---|---|
| A | Carry blood away from heart | Carry blood to heart | Site of exchange |
| B | Carry blood to heart | Carry blood away from heart | Site of exchange |
| C | Carry oxygenated blood | Carry deoxygenated blood | Thick walls |
| D | Have valves | Have thick elastic walls | One cell thick |
Answer: [ ] [1]
2. A patient has a blockage in the coronary artery. Which of the following is the most likely immediate consequence?
A. Reduced oxygen supply to the heart muscle.
B. Reduced oxygen supply to the brain.
C. Accumulation of urea in the blood.
D. Failure of the liver to detoxify alcohol.
Answer: [ ] [1]
3. The diagram below shows the changes in air pressure in the lungs during breathing.
(Imagine a graph where pressure drops below atmospheric at point X and rises above at point Y)
At which point is the diaphragm contracting and flattening?
A. At the peak of the curve (highest pressure).
B. At the trough of the curve (lowest pressure).
C. When pressure equals atmospheric pressure.
D. During exhalation only.
Answer: [ ] [1]
4. Which row correctly identifies the products of anaerobic respiration in human muscle cells?
| Option | Product 1 | Product 2 |
|---|---|---|
| A | Ethanol | Carbon dioxide |
| B | Lactic acid | Carbon dioxide |
| C | Lactic acid | Energy (ATP) |
| D | Ethanol | Energy (ATP) |
Answer: [ ] [1]
5. In the nephron, where does selective reabsorption of glucose primarily occur?
A. Bowman’s capsule
B. Proximal convoluted tubule
C. Loop of Henle
D. Collecting duct
Answer: [ ] [1]
Section B: Structured Questions (Questions 6–15)
6. The diagram below shows a section of the human heart.
(Diagram description: Label A points to the left ventricle wall. Label B points to the valve between the left atrium and left ventricle.)
(a) Identify structure B.
_________________________________________________________________________ [1]
(b) Explain why the wall at A is thicker than the wall of the right ventricle.
_________________________________________________________________________ [2]
7. Table 1 shows the composition of blood plasma, glomerular filtrate, and urine.
| Substance | Plasma (g/100cm³) | Glomerular Filtrate (g/100cm³) | Urine (g/100cm³) |
|---|---|---|---|
| Protein | 8.0 | 0.0 | 0.0 |
| Glucose | 0.1 | 0.1 | 0.0 |
| Urea | 0.03 | 0.03 | 2.0 |
(a) Explain why there is no protein in the glomerular filtrate.
_________________________________________________________________________ [2]
(b) Explain why the concentration of urea is much higher in urine than in plasma.
_________________________________________________________________________ [2]
8. A student investigated the effect of temperature on the activity of salivary amylase. The results are shown in the graph below.
(Graph description: Rate of reaction increases from 10°C to 37°C, peaks at 37°C, then drops sharply to zero at 60°C.)
(a) Describe the effect of increasing temperature from 10°C to 37°C on the enzyme activity.
_________________________________________________________________________ [2]
(b) Explain why the enzyme activity drops to zero at 60°C.
_________________________________________________________________________ [2]
9. Figure 1 shows a villus from the small intestine.
(a) State two features of the villus that adapt it for absorption of digested food.
-
- _______________________________________________________________________ [2]
(b) Name the blood vessel that carries absorbed glucose away from the villus to the liver.
_________________________________________________________________________ [1]
10. The table below shows the breathing rate and volume of air breathed per minute for a person at rest and after exercise.
| State | Breathing Rate (breaths/min) | Volume of Air Breathed (dm³/min) |
|---|---|---|
| Rest | 12 | 6.0 |
| After Exercise | 20 | 40.0 |
(a) Calculate the volume of air breathed in per breath (tidal volume) after exercise. Show your working.
<br> <br> Answer: ____________________ dm³ [2](b) Explain why the volume of air breathed per minute increases after exercise.
_________________________________________________________________________ [2]
11. Insulin and glucagon are hormones involved in homeostasis.
(a) Name the organ that secretes insulin and glucagon.
_________________________________________________________________________ [1]
(b) Describe how insulin lowers blood glucose levels after a meal.
_________________________________________________________________________ [2]
12. Figure 2 shows a reflex arc involving a hand touching a hot object.
(Diagram description: Receptor in skin -> Sensory Neurone -> Relay Neurone in Spinal Cord -> Motor Neurone -> Effector in arm muscle)
(a) Identify the effector in this reflex arc.
_________________________________________________________________________ [1]
(b) Explain the survival advantage of a reflex action compared to a voluntary action.
_________________________________________________________________________ [2]
13. Tobacco smoke contains tar, nicotine, and carbon monoxide.
(a) State the effect of carbon monoxide on the blood’s ability to transport oxygen.
_________________________________________________________________________ [2]
(b) Explain how tar contributes to the development of lung cancer.
_________________________________________________________________________ [1]
14. A patient suffers from kidney failure and undergoes dialysis.
(a) Define the term excretion.
_________________________________________________________________________ [1]
(b) Why must the dialysis fluid contain glucose and salts at the same concentration as normal blood plasma?
_________________________________________________________________________ [2]
15. The human eye adjusts to changes in light intensity.
(a) Name the part of the eye that controls the amount of light entering.
_________________________________________________________________________ [1]
(b) Describe the changes that occur in the iris muscles when a person moves from a dark room into bright sunlight.
_________________________________________________________________________ [2]
Section C: Free Response Questions (Questions 16–20)
16. Compare the structure and function of arteries and veins.
_________________________________________________________________________ [4]
17. Explain how the structure of the alveoli is adapted for efficient gas exchange.
_________________________________________________________________________ [4]
18. Describe the process of ultrafiltration in the kidney.
_________________________________________________________________________ [4]
19. Explain the role of the liver in maintaining blood glucose levels when a person has not eaten for 24 hours.
_________________________________________________________________________ [4]
20. Discuss the differences between nervous coordination and hormonal coordination in humans.
_________________________________________________________________________ [4]
*** End of Quiz ***
Answers
Secondary 4 Pure Biology Quiz - Human Physiology (Answer Key)
Total Marks: 40
Section A: Multiple Choice Answers
1. A
Marks: [1]
Reasoning: Arteries carry blood away from the heart, veins to the heart, and capillaries are the site of exchange.
2. A
Marks: [1]
Reasoning: Coronary arteries supply the heart muscle itself. Blockage leads to ischemia (lack of oxygen) in the heart muscle.
3. B
Marks: [1]
Reasoning: Diaphragm contraction increases thoracic volume, decreasing pressure (Boyle's Law). Lowest pressure corresponds to maximum inhalation effort.
4. C
Marks: [1]
Reasoning: Human anaerobic respiration produces lactic acid and a small amount of ATP. No CO2 is produced in human muscle anaerobic respiration.
5. B
Marks: [1]
Reasoning: Glucose is selectively reabsorbed in the proximal convoluted tubule via active transport.
Section B: Structured Answers
6.
(a) Bicuspid valve (or Mitral valve). [1]
(b) The left ventricle pumps blood to the whole body (systemic circulation), which requires high pressure to overcome resistance in distant vessels. The right ventricle only pumps to the lungs (pulmonary circulation), which is a shorter distance with lower resistance. [2]
7.
(a) Protein molecules are too large to pass through the pores of the glomerular capillaries / Bowman’s capsule filter. [2]
(b) Water is reabsorbed from the filtrate back into the blood (in the Loop of Henle and collecting duct), but urea is not reabsorbed (or only partially). This concentrates the urea in the remaining fluid (urine). [2]
8.
(a) As temperature increases, kinetic energy of enzyme and substrate molecules increases. This leads to more frequent successful collisions between the enzyme active site and substrate, increasing the rate of reaction. [2]
(b) At 60°C, the high heat energy breaks the bonds holding the enzyme's tertiary structure. The enzyme denatures, changing the shape of the active site. The substrate can no longer fit into the active site, so no reaction occurs. [2]
9.
(a) Any two of:
- Wall is one cell thick (short diffusion distance).
- Large surface area (due to finger-like projection/microvilli).
- Rich blood supply (capillary network) maintains concentration gradient. [2]
(b) Hepatic portal vein. [1]
10.
(a) Working: Volume per breath = Total Volume / Breathing Rate
Answer: 2.0 dm³ [2]
(b) During exercise, muscles respire more aerobically to produce energy (ATP). This requires more oxygen and produces more carbon dioxide. The increased breathing rate and volume allow for greater gas exchange to meet these demands. [2]
11.
(a) Pancreas. [1]
(b) Insulin causes glucose to be converted into glycogen in the liver and muscle cells. It also increases the uptake of glucose by body cells for respiration. This lowers blood glucose concentration. [2]
12.
(a) Arm muscle (or biceps). [1]
(b) Reflex actions are involuntary and bypass the brain (processed in spinal cord), resulting in a much faster response time. This minimizes tissue damage from harmful stimuli. [2]
13.
(a) Carbon monoxide binds to haemoglobin with a higher affinity than oxygen, forming carboxyhaemoglobin. This reduces the amount of haemoglobin available to carry oxygen. [2]
(b) Tar contains carcinogens (cancer-causing chemicals) that damage the DNA of lung cells, leading to uncontrolled cell division (tumors). [1]
14.
(a) Excretion is the removal of toxic metabolic waste products (such as urea and carbon dioxide) from the body. [1]
(b) To prevent the loss of useful substances from the blood by diffusion. If the concentration in the dialysis fluid were lower, glucose/salts would diffuse out of the blood. If higher, they would diffuse into the blood. Equilibrium ensures no net movement. [2]
15.
(a) Iris. [1]
(b) Circular muscles of the iris contract. Radial muscles of the iris relax. This causes the pupil to constrict (become smaller), reducing the amount of light entering the eye to prevent damage to the retina. [2]
Section C: Free Response Answers
16.
Structure: Arteries have thick, elastic walls and a small lumen. Veins have thinner walls, a larger lumen, and contain valves.
Function: Arteries carry blood away from the heart under high pressure; elasticity helps withstand pressure surges. Veins carry blood to the heart under low pressure; valves prevent backflow of blood.
[4 marks: 2 for structure comparison, 2 for function link]
17.
- Large Surface Area: Millions of alveoli provide a vast surface area for gas exchange.
- Thin Walls: Alveolar walls and capillary walls are one cell thick, providing a short diffusion distance for oxygen and carbon dioxide.
- Moist Surface: The lining is moist, allowing gases to dissolve before diffusing.
- Rich Blood Supply: Dense capillary network maintains a steep concentration gradient for efficient diffusion.
[4 marks: 1 mark per point explained]
18.
- Blood enters the glomerulus under high pressure (due to wider afferent arteriole than efferent arteriole).
- This high pressure forces small molecules (water, glucose, urea, salts) out of the blood.
- These molecules pass through the porous capillary walls and the basement membrane into the Bowman’s capsule.
- Large molecules like blood cells and plasma proteins remain in the blood as they are too large to pass through the filter.
[4 marks: 1 mark per step]
19.
- After 24 hours, blood glucose levels drop below normal.
- The pancreas detects this low level and secretes glucagon.
- Glucagon travels to the liver via the blood.
- It stimulates the conversion of stored glycogen into glucose (glycogenolysis).
- Glucose is released into the bloodstream, raising blood glucose levels back to normal.
[4 marks: Logical sequence of homeostatic mechanism]
20.
Nervous Coordination:
- Signals are electrical impulses along neurones.
- Transmission is very fast.
- Response is short-lived.
- Effectors are muscles or glands.
- Localized response.
Hormonal Coordination:
- Signals are chemicals (hormones) transported in blood.
- Transmission is slower.
- Response is long-lasting.
- Effectors are specific target organs.
- Widespread response.
[4 marks: 2 distinct differences clearly explained]