Formative Practice 10.4 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
At the end of the blood clotting mechanism, fibrin will be formed to trap erythrocytes. Explain the meaning of fibrin and its function.

Answer:
Fibrin is the strand of protein fibre that prevents blood loss when a person is wounded, and entry of microorganisms such as bacteria and foreign substances into the blood.

Question 2:
Describe two health issues related to blood clotting.

Answer:
Haemophilia and thrombosis

Question 3:
Explain the mechanism of blood clotting.

Answer:
• Clumped platelets, damaged cells and clotting factor form thrombokinase

• Thrombokinase (in the presence of Ca²⁺ and vitamin K) converts prothrombin into thrombin

• Thrombin converts fibrinogen to fibrin

• Fibrin forms a mesh of fibres across the wound and prevents loss of blood.

Question 4:
Explain why the formation of blood clots in the blood vessel can cause a heart attack.

Answer:
If blood clot is formed in the coronary artery, the cardiac muscles may die or suffer permanent damage due to the lack of oxygen supply. This may lead to a heart attack.