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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 for each question is shown in brackets [ ].
- 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 row correctly describes the function of the hepatic portal vein?
| Blood Source | Blood Destination | Primary Function | |
|---|---|---|---|
| A | Heart | Liver | Deliver oxygen for respiration |
| B | Small Intestine | Liver | Transport absorbed nutrients for processing |
| C | Liver | Heart | Remove urea from the blood |
| D | Small Intestine | Heart | Distribute glucose to body cells |
Answer: [ ] [1]
2. A patient has a condition where the alveoli walls become thickened and less elastic. How would this primarily affect gas exchange?
A. Decreased surface area for diffusion.
B. Increased diffusion distance for oxygen.
C. Reduced blood flow to the lungs.
D. Increased production of mucus blocking airways.
Answer: [ ] [1]
3. Which of the following best explains why arteries have thicker walls than veins?
A. Arteries carry deoxygenated blood which is heavier.
B. Arteries need valves to prevent backflow of blood.
C. Arteries must withstand high pressure generated by ventricular contraction.
D. Arteries exchange materials with tissues, requiring thicker walls for protection.
Answer: [ ] [1]
4. In an experiment, a dialysis tubing bag containing starch and glucose solution is placed in a beaker of distilled water. After 30 minutes, which substance(s) will be found in the beaker water?
A. Starch only
B. Glucose only
C. Starch and Glucose
D. Neither Starch nor Glucose
Answer: [ ] [1]
5. Which part of the nephron is responsible for the selective reabsorption of glucose and amino acids?
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. Fig 6.1 shows a section of the human small intestine.
(Imagine a diagram showing a single villus with labels A, B, and C)
- Label A: The outer layer of cells.
- Label B: The central vessel containing lacteals.
- Label C: The network of vessels surrounding the lacteal.
(a) Identify structures B and C. [2] Structure B: __________________________ Structure C: __________________________
(b) Explain how the structure of the villus (specifically Label A) is adapted for efficient absorption of nutrients. [2]
(c) State the specific food substance that is primarily absorbed into structure B. [1]
7. Enzymes are crucial for chemical digestion.
(a) Complete the table below by stating the enzyme, the substrate it acts on, and the end products. [3]
| Enzyme | Substrate | End Products |
|---|---|---|
| Amylase | Starch | (i) __________________ |
| (ii) _________________ | Protein | Amino Acids |
| Lipase | Fats | (iii) Fatty Acids and _________________ |
(b) Explain why enzymes are described as "specific" in their action. Use the "lock and key" hypothesis in your answer. [2]
8. Fig 8.1 shows the changes in pressure inside the thoracic cavity during breathing.
(Imagine a graph showing pressure dropping below atmospheric, then rising above)
(a) Describe the movements of the diaphragm and rib cage during the phase where thoracic pressure decreases. [2]
(b) Explain how these movements cause air to enter the lungs. [2]
9. The heart acts as a double pump.
(a) Explain why the wall of the left ventricle is thicker than the wall of the right ventricle. [2]
(b) State the name of the valve located between the left atrium and the left ventricle. [1]
(c) Why is it important that blood flows in only one direction through the heart? [1]
10. Homeostasis maintains a constant internal environment.
(a) Define homeostasis. [1]
(b) A person enters a very cold room. Describe two physiological responses that occur to maintain body temperature. [2]
11. The liver plays a central role in metabolism.
(a) State the process by which the liver converts excess glucose into glycogen. [1]
(b) Explain why alcohol consumption can lead to liver damage over time. [2]
12. Fig 12.1 shows a nephron.
(Imagine a diagram of a nephron with arrows showing filtration and reabsorption)
(a) Name the process that occurs in the Bowman’s Capsule. [1]
(b) In a healthy person, glucose is present in the blood filtrate but absent in the urine. Explain why. [2]
13. Coronary Heart Disease (CHD) is a major health concern.
(a) Identify the blood vessels that supply the heart muscle with oxygenated blood. [1]
(b) Describe how a diet high in saturated fats contributes to the development of CHD. [2]
14. Compare aerobic and anaerobic respiration in humans.
(a) Write the word equation for anaerobic respiration in human muscle cells. [1]
(b) Explain what is meant by "oxygen debt" after vigorous exercise. [2]
15. The skin plays a role in temperature regulation.
(a) Describe the role of sweat glands in cooling the body. [2]
(b) Explain how vasodilation of blood vessels in the skin helps lose heat. [2]
Section C: Free Response Questions (Questions 16–20)
16. Describe the journey of a protein molecule from ingestion to assimilation into a muscle cell. Include the roles of the stomach, small intestine, and liver in your answer. [4]
17. Explain how the structure of the alveoli and the capillaries surrounding them facilitates efficient gas exchange. Refer to surface area, diffusion distance, and concentration gradients. [4]
18. Discuss the differences between arteries, veins, and capillaries in terms of structure and function. [4]
19. Explain the mechanism of blood glucose regulation after a person consumes a meal rich in carbohydrates. Include the roles of the pancreas, insulin, and liver. [4]
20. Kidney failure can be treated by dialysis. Explain the principles of dialysis and how the dialysis machine mimics the function of the kidney. [4]
*** End of Quiz ***
Answers
Secondary 3 Biology Quiz - Human Physiology (Answer Key)
Section A: Multiple Choice Questions
1. B
Reasoning: The hepatic portal vein carries nutrient-rich blood from the small intestine to the liver for processing (e.g., deamination, storage) before it enters general circulation.
2. B
Reasoning: Thickened walls increase the diffusion distance, slowing down the rate of gas exchange according to Fick's Law.
3. C
Reasoning: Arteries carry blood away from the heart under high pressure generated by ventricular systole. Thick muscular and elastic walls withstand this pressure and help maintain flow.
4. B
Reasoning: Glucose molecules are small enough to pass through the semi-permeable dialysis tubing via diffusion. Starch molecules are too large to pass through the pores.
5. B
Reasoning: The proximal convoluted tubule is the site where 100% of glucose and amino acids, along with most water and ions, are selectively reabsorbed back into the blood.
Section B: Structured Questions
6. (a) Structure B: Lacteal [1]; Structure C: Blood Capillary / Capillary Network [1] (b) The outer layer (epithelium) is one cell thick [1]. This provides a short diffusion distance for nutrients to pass into the blood/lacteal [1]. (c) Fatty acids and Glycerol (or Fats/Lipids) [1]
7. (a) (i) Maltose [1] (ii) Protease (or Pepsin/Trypsin) [1] (iii) Glycerol [1] (b) Enzymes have a specific active site shape [1]. Only substrates with a complementary shape can fit into the active site to form an enzyme-substrate complex (Lock and Key) [1].
8. (a) The diaphragm contracts and flattens/moves downwards [1]. The external intercostal muscles contract, pulling the rib cage upwards and outwards [1]. (b) These movements increase the volume of the thoracic cavity [1]. This causes the pressure inside the thorax to drop below atmospheric pressure, causing air to rush in [1].
9. (a) The left ventricle pumps blood to the entire body (systemic circulation) which requires higher pressure [1]. The right ventricle only pumps blood to the lungs (pulmonary circulation) which is a shorter distance/lower resistance [1]. (b) Bicuspid valve (or Mitral valve) [1] (c) To ensure efficient circulation and prevent mixing of oxygenated and deoxygenated blood / to maintain pressure gradients [1].
10. (a) The maintenance of a constant internal environment within narrow limits despite changes in the external environment [1]. (b) Any two of: Shivering (muscle contraction generates heat) [1]; Vasoconstriction of skin arterioles (reduces heat loss) [1]; Hair erector muscles contract (traps insulating air layer) [1].
11. (a) Glycogenesis [1] (b) The liver detoxifies alcohol [1]. Excessive alcohol consumption causes liver cells to die and be replaced by scar tissue (cirrhosis), reducing liver function [1].
12. (a) Ultrafiltration [1] (b) Glucose is small enough to be filtered into the Bowman's capsule [1]. However, it is actively reabsorbed (or selectively reabsorbed) in the proximal convoluted tubule back into the blood [1].
13. (a) Coronary arteries [1] (b) Saturated fats can lead to high cholesterol levels in the blood [1]. Cholesterol deposits form plaques in the coronary arteries, narrowing the lumen and restricting blood flow to the heart muscle [1].
14. (a) Glucose → Lactic Acid (+ Energy) [1] (b) Oxygen debt is the amount of oxygen required to oxidize the lactic acid accumulated in muscles during anaerobic respiration [1]. This oxygen is used to convert lactic acid back to glucose/pyruvate in the liver [1].
15. (a) Sweat glands secrete sweat onto the skin surface [1]. As sweat evaporates, it absorbs latent heat from the body, cooling the blood/skin [1]. (b) Arterioles near the skin surface dilate (widen) [1]. This increases blood flow to the skin surface, allowing more heat to be lost to the environment via radiation/convection [1].
Section C: Free Response Questions
16.
- Ingestion/Digestion: Protein is mechanically broken down in the mouth/stomach. In the stomach, pepsin breaks protein into peptides. In the small intestine, trypsin/peptidases break peptides into amino acids [1].
- Absorption: Amino acids are absorbed into the blood capillaries of the villi via active transport [1].
- Transport: Blood carries amino acids via the hepatic portal vein to the liver [1].
- Assimilation: The liver regulates amino acid levels. Excess amino acids may be deaminated. Remaining amino acids enter general circulation and are taken up by muscle cells to build new proteins (growth/repair) [1].
17.
- Surface Area: Alveoli are numerous and spherical, providing a very large total surface area for gas exchange [1].
- Diffusion Distance: Alveolar walls and capillary walls are both one cell thick, creating a very short diffusion distance for oxygen and carbon dioxide [1].
- Concentration Gradient: Continuous blood flow in capillaries and ventilation in alveoli maintain a steep concentration gradient (high O2 in alveoli, low in blood; high CO2 in blood, low in alveoli) [1].
- Moisture: Alveoli are lined with moisture, allowing gases to dissolve before diffusing [1].
18.
- Arteries: Thick muscular/elastic walls to withstand high pressure; narrow lumen; no valves (except semi-lunar); carry blood away from heart [1].
- Veins: Thinner walls with less muscle/elastic tissue; wide lumen; contain valves to prevent backflow; carry blood to heart under low pressure [1].
- Capillaries: Walls are one cell thick; very narrow lumen (RBCs pass single file); no valves; site of exchange of materials between blood and tissues [1].
- Comparison: Arteries have the thickest walls, capillaries the thinnest. Veins have valves, arteries (mostly) do not [1].
19.
- Detection: After a meal, blood glucose levels rise. Beta cells in the Islets of Langerhans (pancreas) detect this increase [1].
- Secretion: The pancreas secretes the hormone insulin into the bloodstream [1].
- Action: Insulin travels to the liver (and muscle cells). It stimulates the liver to convert glucose into glycogen (glycogenesis) [1].
- Result: Blood glucose levels decrease back to normal. If levels drop too low, glucagon would be secreted to convert glycogen back to glucose [1].
20.
- Principle: Dialysis uses the principles of diffusion and ultrafiltration across a semi-permeable membrane [1].
- Process: Patient's blood is pumped through tubes made of semi-permeable membrane, surrounded by dialysis fluid [1].
- Diffusion: Waste products like urea and excess salts diffuse from the blood (high concentration) into the dialysis fluid (low/zero concentration) down the concentration gradient [1].
- Selectivity: Glucose and essential proteins are too large to pass through the membrane or are balanced in the dialysis fluid, so they remain in the blood. The cleaned blood is returned to the patient [1].