(a)(i) The boxes on the left show some of the components of blood. The boxes on the right show the functions of the components. Draw lines to link each component with its function or functions. Draw four lines.
(ii) Plasma is also a component of blood. Describe the function of plasma.
(b)
Fig. 1.1 is a photomicrograph of one component of blood.
(i) State the name of the component of blood shown in Fig. 1.1.
(ii) Identify structures A, B, and C shown in Fig. 1.1.
(iii) Describe one function of the cytoplasm.
▶️ Answer/Explanation
(a)(i) The correct matching is as follows:
Explanation: Red blood cells transport oxygen, platelets help in clotting, white blood cells defend against pathogens, and plasma proteins maintain osmotic balance.
(a)(ii) Plasma functions to transport substances such as blood cells, nutrients (e.g., glucose), hormones (e.g., insulin), and waste products (e.g., carbon dioxide, urea).
(b)(i) The component shown is a white blood cell (e.g., lymphocyte or phagocyte).
(b)(ii) Structures identified:
A: Cell membrane
B: Nucleus
C: Mitochondrion
(b)(iii) The cytoplasm functions as the site of metabolic reactions (e.g., glycolysis) and provides a medium for organelles to operate efficiently.
Fig. 3.1 is a photomicrograph of a sample of human blood.
(a) Identify and describe the functions of the cells labelled A and B in Fig. 3.1.
(b) Describe how platelets in the blood prevent disease.
(c) Blood plasma transports many substances including excretory products and hormones.
(i) Circle the names of two excretory products in humans.
amino acids cellulose carbon dioxide glucose
lipase oxygen urea
(ii) State the names of two hormones that are produced by the reproductive organs.
▶️ Answer/Explanation
(a) A is a white blood cell (leukocyte). Its functions include immune defense through antibody production and phagocytosis (engulfing pathogens). B is a red blood cell (erythrocyte), specialized for oxygen transport via hemoglobin.
(b) Platelets prevent disease by forming blood clots at injury sites, creating a physical barrier that prevents pathogen entry. They also release chemicals that initiate the clotting cascade.
(c)(i) The excretory products are carbon dioxide (waste from cellular respiration) and urea (nitrogenous waste from protein metabolism).
(c)(ii) Reproductive hormones include testosterone (produced by testes), oestrogen and progesterone (produced by ovaries).