Question

Heart is two chambered in-
a. Fishes
b. Amphibians
c. Reptiles
d. Birds
e. Mammals

Answer 1

There is no need for additional chambers in the heart beyond the first two. Animals with 2-chambered hearts have simpler circulatory systems than animals with lungs and subsequently, 3- and 4-chambered hearts. This is because blood needs to immediately circulate throughout the body.

Complete answer:

Animals with 2-chambered hearts are the ones that use gills to refill oxygen in the blood supply. The circulatory and respiratory systems are very closely linked. Blood circulating through the body must go through the respiratory system for gas exchange, which is just carbon dioxide exchanged for oxygen. Fish have lower metabolic capacity than these animals. However, the metabolic needs of fish are not as demanding as those of warm-blooded animals.

Option A, Fishes possess a two-chambered heart in which there are one auricle and one ventricle. It is simplest among all of the options.

Option B, Amphibians have a three-chambered heart in which they have two auricles and one ventricle.

Option C, Reptiles have an incompletely four-chambered heart in which they possess two auricles and partly divided ventricles.

Option D, Birds possess a four-chambered heart in which there are two auricles and two ventricles.

Option E, Mammals have a four-chambered heart consisting of two auricles and two ventricles. They have the most complex circulatory system.

Hence, the correct answer is option (A).

Note: Fishes possess a two-chambered heart consisting of one auricle and one ventricle. The auricle is responsible for sucking in blood from the body and the ventricle pumps out the blood that has entered the heart with the help of gills and gives fresh oxygen to the blood. Due to a two-chambered heart, less amount of oxygen reaches the body tissues as compared to three and four-chambered hearts.