Question 11(A)

How many chambers are there in the heart of the following organisms?
How is mixing of oxygenated and deoxygenated blood prevented in their body?
(i) Fishes
(ii) Humans

Answer:

(i) Fishes – The heart of fishes is 2-chambered (one atrium and one ventricle). It pumps only deoxygenated blood to the gills where oxygenation takes place. Hence, mixing of oxygenated and deoxygenated blood does not occur in the heart.

(ii) Humans – The human heart is 4-chambered (two atria and two ventricles). The right side of the heart receives and pumps deoxygenated blood, while the left side receives and pumps oxygenated blood. A complete septum separates the two sides of the heart, thereby preventing any mixing of oxygenated and deoxygenated blood.