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Secondary 3 Biology Human Physiology Quiz
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Questions
Secondary 3 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.
- Diagrams are not drawn to scale unless stated.
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 function of the hepatic portal vein?
A. It carries oxygenated blood from the heart to the liver.
B. It carries deoxygenated blood from the liver to the heart.
C. It carries blood rich in absorbed nutrients from the small intestine to the liver.
D. It carries blood rich in urea from the kidneys to the bladder.
Answer: [ ] [1]
2. A student investigates the effect of temperature on the activity of salivary amylase. At which temperature would the enzyme activity be highest?
A. 0°C
B. 37°C
C. 60°C
D. 100°C
Answer: [ ] [1]
3. The diagram below shows a cross-section of a human alveolus and a capillary.
(Diagram description: Arrow X points from the alveolus into the capillary; Arrow Y points from the capillary into the alveolus.)
Which gases are represented by X and Y?
| Gas X | Gas Y | |
|---|---|---|
| A | Carbon dioxide | Oxygen |
| B | Oxygen | Carbon dioxide |
| C | Oxygen | Nitrogen |
| D | Nitrogen | Carbon dioxide |
Answer: [ ] [1]
4. Which component of tobacco smoke is primarily responsible for reducing the oxygen-carrying capacity of red blood cells?
A. Tar
B. Nicotine
C. Carbon monoxide
D. Carcinogens
Answer: [ ] [1]
5. In the human heart, which structure prevents the backflow of blood from the ventricles to the atria during contraction?
A. Semilunar valves
B. Atrioventricular valves
C. Septum
D. Coronary arteries
Answer: [ ] [1]
Section B: Structured Questions (Questions 6–15)
6. The diagram below shows the human digestive system.
(Diagram description: Labels A, B, C, D point to Mouth, Stomach, Small Intestine, and Large Intestine respectively.)
(a) Identify the organ labelled C.
_________________________________________________________________________ [1]
(b) State one enzyme produced by organ B and the food substance it digests.
Enzyme: __________________________
Food Substance: __________________________ [2]
(c) Explain why physical digestion is important before chemical digestion can occur efficiently.
_________________________________________________________________________ [2]
7. The table below shows the results of food tests performed on three unknown solutions.
| Solution | Iodine Test | Benedict’s Test (heated) | Biuret Test |
|---|---|---|---|
| P | Blue-black | Blue | Purple |
| Q | Brown | Brick-red precipitate | Blue |
| R | Brown | Blue | Purple |
(a) Identify the nutrients present in Solution P.
_________________________________________________________________________ [1]
(b) Describe the procedure for the Benedict’s test on Solution Q.
_________________________________________________________________________ [2]
(c) Solution R contains protein but no reducing sugars or starch. Suggest a possible source for this solution.
_________________________________________________________________________ [1]
8. The diagram shows a villus from the small intestine.
(a) State two structural features of the villus that increase the rate of absorption.
-
- _________________________________________________________________________ [2]
(b) Explain how the structure of the capillary network inside the villus aids in the transport of absorbed glucose.
_________________________________________________________________________ [2]
9. During vigorous exercise, muscle cells may respire anaerobically.
(a) Write the word equation for anaerobic respiration in human muscle cells.
_________________________________________________________________________ [2]
(b) Explain what is meant by "oxygen debt" and how it is repaid after exercise.
_________________________________________________________________________ [3]
10. The graph below shows the change in lung volume during breathing.
(Graph description: Y-axis is Lung Volume (dm³), X-axis is Time (s). The curve rises from 2.5 to 3.5 dm³ between 0-2s, falls back to 2.5 dm³ between 2-4s.)
(a) Calculate the volume of air breathed in during one breath (tidal volume).
__________________________ dm³ [1]
(b) Describe the actions of the diaphragm and intercostal muscles during the interval 0–2 seconds.
_________________________________________________________________________ [3]
11. The human circulatory system is described as a "double circulatory system."
(a) Explain what is meant by a double circulatory system.
_________________________________________________________________________ [2]
(b) State one advantage of having a double circulatory system compared to a single circulatory system.
_________________________________________________________________________ [1]
12. Blood vessels have different structures suited to their functions.
(a) Compare the wall thickness of an artery and a vein.
_________________________________________________________________________ [1]
(b) Explain why veins contain valves while arteries do not.
_________________________________________________________________________ [2]
13. The kidney plays a vital role in excretion and osmoregulation.
(a) Define excretion.
_________________________________________________________________________ [1]
(b) Name the functional unit of the kidney where ultrafiltration occurs.
_________________________________________________________________________ [1]
(c) State two substances that are completely reabsorbed into the blood during selective reabsorption.
-
- __________________________ [2]
14. Homeostasis maintains a constant internal environment.
(a) Define homeostasis.
_________________________________________________________________________ [1]
(b) When body temperature rises above normal, describe two mechanisms the skin uses to cool the body.
-
- _________________________________________________________________________ [2]
15. Type 2 diabetes is a condition affecting blood glucose regulation.
(a) Name the hormone that is either insufficient or ineffective in Type 2 diabetes.
_________________________________________________________________________ [1]
(b) Suggest two lifestyle changes that can help manage Type 2 diabetes.
-
- _________________________________________________________________________ [2]
Section C: Free Response Questions (Questions 16–20)
16. Enzymes are biological catalysts.
(a) Explain the "lock and key" hypothesis of enzyme action.
_________________________________________________________________________ [3]
(b) Explain why high temperatures (above 45°C) cause enzymes to stop functioning.
_________________________________________________________________________ [3]
17. Describe the journey of a molecule of oxygen from the atmosphere to a muscle cell in the leg. Include the structures involved in gas exchange and transport.
_________________________________________________________________________ [4]
18. Compare and contrast arteries, veins, and capillaries in terms of structure and function. Present your answer in a table or structured paragraphs.
_________________________________________________________________________ [4]
19. Explain how the structure of the human heart is adapted to pump blood efficiently to the lungs and the rest of the body. Refer to the thickness of the ventricular walls and the presence of valves.
_________________________________________________________________________ [4]
20. A patient suffers from kidney failure and requires dialysis.
(a) Explain the principle of diffusion used in kidney dialysis.
_________________________________________________________________________ [2]
(b) Why is it necessary for the dialysis fluid to be constantly refreshed or flowed in the opposite direction to the blood?
_________________________________________________________________________ [2]
End of Quiz
Answers
Secondary 3 Biology Quiz - Human Physiology (Answer Key)
Total Marks: 40
Section A: Multiple Choice Questions
1. C
Reasoning: The hepatic portal vein transports nutrient-rich blood from the small intestine to the liver for processing before it enters general circulation.
2. B
Reasoning: Human enzymes have an optimum temperature of approximately 37°C (body temperature).
3. B
Reasoning: Oxygen diffuses from the alveolus (high concentration) into the blood (low concentration). Carbon dioxide diffuses from the blood into the alveolus.
4. C
Reasoning: Carbon monoxide binds to haemoglobin with higher affinity than oxygen, forming carboxyhaemoglobin and reducing oxygen transport.
5. B
Reasoning: Atrioventricular (AV) valves (tricuspid and bicuspid/mitral) prevent backflow from ventricles to atria. Semilunar valves prevent backflow from arteries to ventricles.
Section B: Structured Questions
6.
(a) Small Intestine [1]
(b) Enzyme: Pepsin (or Protease) [1]; Food Substance: Protein [1]
(Note: If student states Amylase, mark 0 as stomach does not produce amylase. If student states Lipase, mark 0 as primary lipase is pancreatic.)
(c) Physical digestion breaks large food particles into smaller pieces [1], increasing the surface area for enzymes to act on [1].
7.
(a) Starch and Protein [1] (Must have both)
(b) Add Benedict’s solution to the sample [1] and heat in a water bath (boil) [1].
(c) Egg white solution / Meat extract / Any protein-rich source without carbs [1]
8.
(a) Any two:
- Thin epithelium (one cell thick) for short diffusion distance [1]
- Large surface area due to finger-like projection [1]
- Rich blood supply (capillary network) to maintain concentration gradient [1]
(b) The capillaries have a large surface area for absorption [1] and blood flow carries away absorbed glucose, maintaining a low concentration in the blood to sustain the diffusion gradient [1].
9.
(a) Glucose → Lactic Acid (+ Energy) [2] (1 mark for reactants/products, 1 mark for correct spelling of lactic acid)
(b) Oxygen debt is the amount of oxygen required to oxidize the accumulated lactic acid after exercise [1]. It is repaid by continuing to breathe deeply and rapidly after exercise [1], which supplies oxygen to convert lactic acid back to glucose/pyruvate in the liver [1].
10.
(a) 1.0 dm³ (3.5 - 2.5) [1]
(b) Diaphragm contracts and flattens [1]; External intercostal muscles contract [1]; Rib cage moves up and out [1]. (This increases thoracic volume, decreasing pressure, causing air to rush in).
11.
(a) Blood passes through the heart twice for every complete circuit of the body [1]. Once to the lungs (pulmonary) and once to the body (systemic) [1].
(b) Blood can be pumped at higher pressure to the body tissues [1], ensuring faster delivery of oxygen/nutrients.
12.
(a) Arteries have thicker walls than veins [1].
(b) Veins carry blood at low pressure [1], so valves are needed to prevent backflow of blood due to gravity [1]. Arteries carry blood at high pressure from the heart, so backflow does not occur.
13.
(a) The removal of metabolic waste products from the body [1].
(b) Nephron [1]
(c) Glucose [1] and Amino Acids [1] (Order does not matter)
14.
(a) The maintenance of a constant internal environment within narrow limits [1].
(b) Any two:
- Sweating: Evaporation of sweat removes heat from the skin [1].
- Vasodilation: Blood vessels near the skin surface dilate [1], allowing more blood flow and heat loss by radiation/convection.
15.
(a) Insulin [1]
(b) Any two:
- Reduce sugar/carbohydrate intake [1]
- Exercise regularly [1]
- Lose weight [1]
Section C: Free Response Questions
16.
(a) The enzyme has an active site with a specific shape [1]. The substrate has a complementary shape [1]. The substrate fits into the active site like a key into a lock, forming an enzyme-substrate complex [1].
(b) High temperatures break the bonds holding the enzyme's structure together [1]. The active site changes shape (denaturation) [1]. The substrate can no longer fit into the active site [1].
17.
- Oxygen enters through the nose/mouth and travels down the trachea and bronchi to the alveoli [1].
- In the alveoli, oxygen diffuses across the thin alveolar wall and capillary wall into the blood [1].
- Oxygen binds to haemoglobin in red blood cells to form oxyhaemoglobin [1].
- Blood is pumped by the heart to the leg muscles via arteries [1].
- In the muscle capillaries, oxygen dissociates from haemoglobin and diffuses into muscle cells for respiration [1].
(Max 4 marks. Must mention diffusion, haemoglobin, and transport pathway.)
18.
Arteries: Thick muscular/elastic walls to withstand high pressure; carry blood away from heart; no valves (except semilunar at base) [1].
Veins: Thinner walls, less elastic; carry blood to heart; contain valves to prevent backflow; large lumen [1].
Capillaries: Walls one cell thick for diffusion; connect arteries and veins; very narrow lumen (RBCs fit single file) [1].
Comparison: Arteries have highest pressure, capillaries lowest surface area for exchange, veins lowest pressure [1].
(Award marks for clear distinction of structure-function relationship for all three.)
19.
- Left ventricle has the thickest wall [1] because it pumps blood to the entire body (systemic circulation) against high resistance [1].
- Right ventricle has a thinner wall [1] because it only pumps blood to the lungs (pulmonary circulation) which is a shorter distance/lower resistance [1].
- Valves (AV and semilunar) ensure one-way flow [1], preventing mixing of oxygenated and deoxygenated blood and ensuring efficient pumping [1].
(Max 4 marks. Must link wall thickness to destination/pressure.)
20.
(a) Dialysis uses a semi-permeable membrane [1]. Waste products (urea, excess salts) diffuse from the blood (high concentration) into the dialysis fluid (low concentration) down the concentration gradient [1].
(b) To maintain a steep concentration gradient [1]. If the fluid became saturated with waste, diffusion would stop or reverse [1]. Counter-current flow maximizes efficiency.