Secondary 3 Biology Human Physiology Quiz

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Secondary 3 Biology Quiz - Human Physiology

Name: ___________________________
Class: _________
Date: ____________
Score: _______ / 40

Duration: 50 minutes
Total Marks: 40
Instructions: Answer all 20 questions. Section A is short structured response. Section B requires explanation. Section C uses data and diagrams. Write clearly in the spaces provided.

Section A: Short Structured Questions (Questions 1–8, 1 mark each)

1. Name the enzyme in the human mouth that begins the chemical digestion of starch. [1]

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2. State one function of the hepatic portal vein. [1]

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3. What is the term for the contraction and relaxation of muscles that pushes food along the digestive tract? [1]

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4. Name the tiny air sacs in the lungs where gas exchange occurs. [1]

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5. Which blood vessel carries deoxygenated blood from the heart to the lungs? [1]

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6. State the main nitrogenous waste product removed by the human kidney. [1]

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7. Name the molecule in red blood cells that binds and transports oxygen. [1]

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8. What is the process by which water moves out of the blood into the kidney tubule at the start of urine formation? [1]

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Section B: Explanation and Structured Response (Questions 9–15)

9. Describe how the structure of a villus is adapted for absorption of digested food. [3]

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10. Explain why active transport is needed for the uptake of glucose by the villi of the small intestine. [2]

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11. Trace the pathway of oxygen from the lungs to a muscle cell in the leg, naming the heart chambers and blood vessels involved. [4]

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12. Compare diffusion and active transport in terms of energy requirement and direction of movement. [4]

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13. Explain how the alveoli are adapted for efficient gas exchange. [3]

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14. Describe the role of the kidney in osmoregulation when a person drinks a large amount of water. [3]

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15. A student says: "The heart pumps blood only to the lungs and back." Explain why this statement is incorrect using the double circulation concept. [3]

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Section C: Data and Diagram Interpretation (Questions 16–20)

16. The diagram below shows the human digestive system.

Image pending generation: diagram for Q16.

Identify the organ labelled E and state one digestive function of the gland labelled near the stomach. [2]

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17. The graph shows the volume of oxygen absorbed by the lungs per minute at different exercise intensities.

Image pending generation: graph for Q17.

Describe the trend shown and explain why oxygen uptake increases with exercise. [3]

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18. The table shows blood contents before and after passing through the kidney.

Substance	In renal artery (g/100cm³)	In renal vein (g/100cm³)
Glucose	0.10	0.10
Urea	0.03	0.01
Water	90.0	88.0

State one conclusion from the table about kidney function. [2]

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19. The figure shows a cross-section of an alveolus and capillary.

Image pending generation: diagram for Q19.

Explain how the feature labelled "wall (1 cell thick)" helps gas exchange. [2]

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20. A person has damaged kidney tubules. Suggest one substance that would appear in higher concentration in their urine and explain why. [3]

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Secondary 3 Biology Quiz - Human Physiology (Answer Key)

Total Marks: 40
Topic: Human Physiology (syllabus-first; complements Stage 3 patterns, not past-year derived)

Section A

1. Amylase [1]
   Teaching note: Salivary amylase is secreted by salivary glands in the mouth; it hydrolyses starch into maltose. Common mistake: writing "pepsin" (that is in stomach, acts on protein).

2. Carries blood from the small intestine to the liver [1]
   Teaching note: The hepatic portal vein transports absorbed nutrients (e.g., glucose, amino acids) from gut to liver for processing before entering general circulation.

3. Peristalsis [1]
   Teaching note: Rhythmic wave-like muscle contractions move food bolus along the oesophagus and gut.

4. Alveoli (plural) / alveolus (singular accepted) [1]
   Teaching note: Alveoli are the sites of O₂ and CO₂ exchange with blood capillaries.

5. Pulmonary artery [1]
   Teaching note: Unusual because it is an artery carrying deoxygenated blood (from right ventricle to lungs).

6. Urea [1]
   Teaching note: Formed in liver from deamination of amino acids; filtered by kidneys.

7. Haemoglobin [1]
   Teaching note: Iron-containing protein; each molecule binds up to 4 O₂.

8. Ultrafiltration [1]
   Teaching note: High hydrostatic pressure in glomerulus forces water, ions, glucose, urea into Bowman's capsule.

Section B

9. [3] Mark breakdown: 1 mark each for three distinct adaptations.

   • Villus has thin wall (one cell thick) → short diffusion distance.
   • Rich network of capillaries → maintains concentration gradient.
   • Large surface area / microvilli → more absorption.
     Teaching note: Structure-function link is key; do not just list "absorbs food".

10. [2]

• Glucose absorbed by villi often moves against its concentration gradient (from low in gut lumen to higher in blood). [1]
• Therefore ATP energy is required → active transport. [1]
  Teaching note: Diffusion alone cannot explain uptake when blood glucose is already high.

11. [4] Pathway: lungs → pulmonary vein → left atrium → left ventricle → aorta → femoral artery → leg muscle capillary.
    Marking: 1 mark per correct sequence segment (lungs to heart, heart chamber, artery, capillary).
    Teaching note: Oxygen enters pulmonary vein (oxygenated), not artery. Double circulation: pulmonary then systemic.

12. [4] 2 marks for energy, 2 for direction.

• Energy: Diffusion = passive, no ATP; Active transport = requires ATP. [2]
• Direction: Diffusion = down concentration gradient; Active = against gradient. [2]
  Teaching note: Example not required here but osmosis is diffusion of water.

13. [3]

• Many alveoli → large surface area. [1]
• Thin walls (one cell) → short diffusion path. [1]
• Moist surface / dense capillaries → gas dissolves and gradient maintained. [1]

14. [3]

• High water intake → blood dilute (low solute). [1]
• Hypothalamus detects, pituitary releases less ADH. [1]
• Kidney tubules less permeable → more water lost in urine (dilute urine). [1]
  Teaching note: Osmoregulation keeps water balance via negative feedback.

15. [3]

• Heart has double circulation: pulmonary and systemic. [1]
• Right side pumps deoxygenated blood to lungs; left side pumps oxygenated to body. [1]
• So blood also goes to organs (brain, muscles) not just lungs. [1]

Section C

16. [2]

• E = liver [1]
• Gland near stomach = pancreas; function: secretes digestive enzymes (e.g., lipase) or bicarbonate. [1]
  Teaching note: Diagram must show liver at E; pancreas is behind stomach.

17. [3]

• Trend: oxygen uptake increases with exercise intensity. [1]
• Muscles respire more → need more O₂. [1]
• Heart and breathing rate rise to deliver O₂ faster. [1]

18. [2]

• Conclusion: Kidney removes urea (level drops 0.03→0.01) and reabsorbs water (90→88). [2: 1 each]
  Teaching note: Glucose unchanged shows selective reabsorption works.

19. [2]

• Thin wall = short diffusion distance for O₂/CO₂. [1]
• Speeds up gas exchange between air and blood. [1]

20. [3]

• Substance: glucose or urea (e.g., glucose). [1]
• Damaged tubules cannot reabsorb it. [1]
• So it remains in urine at high concentration. [1]
  Teaching note: Healthy kidneys reabsorb all glucose; tubule damage causes glycosuria.