Explain how the following blood cells are adapted to their functions

i) Red Blood Cell

Presence of haemoglobin molecules; with a high affinity to combine with oxygen as/to form oxyhaemoglobin; bi-concave shape; to increase the surface area for packaging of haemoglobin; absence of nucleus; to accommodate maximum/more haemoglobin molecules; thin membrane; for faster diffusion of gases; Max. 6 mks


ii) White blood cell

Irregular in shape/amoeboid; which changes to enable the cell to squeeze through the capillaries; lymphocytes produce antibodies; which help to prevent diseases; phagocytes are amoeboid-shaped; to change shape and engulf bacteria cells; Max. 6 mks


b) Explain the different ways in which Carbon (IV) Oxide is transported by blood

Carbon (IV) oxide diffuses out of the tissues into the red blood cells where it reacts with water; in the presence of carbonic anhydrase enzyme; to produce carbonic acid; The acid dissociates into hydrogen and hydrogen carbonate ions; the hydrogen carbonate ions then diffuse out of the red blood cells into the plasma; where it further dissociates to produce carbon (IV) oxide on reaching the alveolar cavities of the lungs and diffuses into the alveoli; some carbon (IV) oxide combines with the amine group in the haemoglobin molecule forming carbaminohaemoglobin; which dissociates in the lungs producing carbon (IV) oxide; some carbon (IV) oxide dissolves in the blood plasma forming carbonic acid, which dissociates to carbon (IV) oxide on reaching the lungs;