Secondary 3 Biology Human Physiology Quiz

Secondary 3 Biology Quiz - Human Physiology (Answer Key)

1. Hepatic portal vein function

• Transports absorbed nutrients (glucose, amino acids) from the small intestine directly to the liver for processing/regulation. [1]

2. Peristalsis

• Description: Rhythmic contractions and relaxations of the smooth muscles in the wall of the gut. [1]
• Importance: Pushes food/digesta along the digestive tract in one direction. [1]

3. Protein digestion in stomach

• Enzyme: Protease (or Pepsin). [1]
• Product: Polypeptides. [1]

4. Villus adaptations

• Large surface area: Numerous villi and microvilli increase area for absorption. [1]
• Short diffusion distance: One-cell thick epithelium. [1]
• Steep concentration gradient: Rich network of blood capillaries to carry away absorbed nutrients. [1]

5. Artery vs Vein

• Arteries: Thick, elastic walls to withstand high blood pressure. [1]
• Veins: Thinner walls and contain valves to prevent backflow of blood. [1]

6. Blood Group A transfusion

• No. [1]
• Blood group B contains B antigens which would be recognized as foreign by the anti-B antibodies in the recipient's (Group A) plasma, causing agglutination. [1]

7. Heart blood flow

• Vena cava $\rightarrow$ Right Atrium $\rightarrow$ Right Ventricle $\rightarrow$ Pulmonary Artery $\rightarrow$ Lungs $\rightarrow$ Pulmonary Vein $\rightarrow$ Left Atrium $\rightarrow$ Left Ventricle $\rightarrow$ Aorta. [4 marks for correct sequence/major milestones]

8. Aerobic Respiration

• Definition: The process of breaking down glucose in the presence of oxygen to release energy. [1]
• Equation: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{Energy (ATP)}$. [2]

9. Alveoli adaptations

• Large surface area: Millions of tiny sacs. [1]
• Thin walls: One-cell thick epithelium for rapid diffusion. [1]
• Moist lining: Allows gases to dissolve before diffusing. [1]

10. Anaerobic Respiration/Oxygen Debt

• During sprinting, oxygen supply is insufficient for aerobic respiration. [1]
• Muscles switch to anaerobic respiration, producing lactic acid. [1]
• Panting occurs to provide extra oxygen to oxidize lactic acid back into pyruvate/CO2/water (repaying oxygen debt). [1]

11. Tobacco smoke

• Nicotine: Addictive substance / increases heart rate. [1]
• Tar: Carcinogen / causes lung cancer / clogs alveoli. [1]
• (Alternative: Carbon monoxide $\rightarrow$ binds to haemoglobin $\rightarrow$ reduces oxygen transport).

12. Excretion

• Definition: Removal of metabolic waste products from the body. [1]
• Importance: Urea is toxic; accumulation in the blood would lead to organ failure or death. [1]

13. Ultrafiltration

• High blood pressure in the glomerulus forces small molecules (water, glucose, salts, urea) [1] through the basement membrane/podocytes [1] into the Bowman's capsule. [1]

14. Selective Reabsorption

• Role: Reclaiming useful substances from the filtrate back into the blood to prevent loss of nutrients. [1]
• Substances: Glucose, amino acids, or water. (Any two). [2]

15. Homeostasis & Negative Feedback

• Homeostasis: Maintenance of a constant internal environment. [1]
• Negative Feedback: A mechanism where a change in a variable triggers a response that counteracts the initial change. [1]
• Result: Returns the system to its set point/normal level. [1]

16. Response to Cold

• Vasoconstriction: Blood vessels near skin surface narrow to reduce heat loss. [1]
• Shivering: Rapid muscle contractions generate metabolic heat. [1]
• Piloerection: Hairs stand up to trap a layer of insulating air. [1]

17. Blood Glucose Regulation

• Pancreas detects high glucose and secretes insulin. [1]
• Insulin travels via blood to the liver and muscle cells. [1]
• Liver converts excess glucose into glycogen for storage. [1]
• Blood glucose levels drop back to normal. [1]

18. Infectious vs Non-infectious

• Infectious: Caused by pathogens (e.g., Influenza, COVID-19). [1]
• Non-infectious: Not caused by pathogens/not transmissible (e.g., Diabetes, Cancer). [1]

19. Antibiotics vs Viruses

• Pneumonia (bacterial) is treated by antibiotics which disrupt bacterial cell walls/metabolism. [1]
• Influenza is viral; viruses lack cell walls and metabolic machinery. [1]
• Antibiotics have no target to act upon in a virus. [1]

20. Vaccine Mechanism

• A weakened or inactive form of the pathogen is injected. [1]
• This stimulates the immune system/B-lymphocytes to produce specific antibodies. [1]
• Memory cells are produced and remain in the blood. [1]
• Upon future infection, these cells produce antibodies rapidly to neutralize the pathogen. [1]