(a) Write a short note on the importance of the presence of an effective transport system in mammals. (b) state eight functions of blood in mammals. (c) lis...

Answer Details

(a) Importance of an effective transport system in mammals

Mammals are large, active, warm-blooded animals with a high metabolic rate and a small surface-area-to-volume ratio, so diffusion alone cannot supply their deep-lying cells fast enough. An effective transport system (the blood circulatory system) is therefore essential to carry oxygen and digested food to all the cells, to remove carbon dioxide and other waste products to the excretory organs, to distribute heat and hormones round the body, and to defend the body against disease. Without it the cells would be starved of nutrients and poisoned by accumulated wastes.

(b) Eight functions of blood in mammals

1. Transport of oxygen from the lungs to the tissues.
2. Transport of carbon dioxide from the tissues to the lungs.
3. Transport of digested food (glucose, amino acids) to the cells.
4. Transport of nitrogenous waste (urea) to the kidneys for excretion.
5. Transport of hormones from endocrine glands to their target organs.
6. Distribution of heat to regulate body temperature.
7. Defence against disease by white blood cells and antibodies.
8. Clotting of blood to seal wounds and prevent loss of blood.

(c) Four materials transported in the bodies of flowering plants

1. Water (through the xylem).
2. Dissolved mineral salts (through the xylem).
3. Manufactured food, especially sucrose (through the phloem).
4. Amino acids and other organic solutes (through the phloem).