Question

Which of the following is not a mammalian character?
A. Hairy skin
B. Muscular diaphragm
C. 3-chambered heart
D. Large brain.

Answer 1

Hint: Mammals belong to the phylum Chordata, subphylum Vertebrata superclass Tetrapoda, and class Mammalia. Mammals can be both terrestrial and aquatic. The terrestrial mammals are quadruped which means they use either the legs or the four limbs for locomotion. Many modifications (hind flippers of seals) are found in aquatic and semi-aquatic mammals.

Complete answer:
The basic characteristics of mammals are given below:
> Mammals comprise either hair or fur which cover the body's surface.
> Mammals are warm blooded animals. Warm-blooded animals possess a specific internal body temperature that is maintained at any environmental condition.
> Mammals possess mammary glands. The number of mammary glands varies according to the species like humans bear 2 mammary glands, dogs comprise 10 mammary glands, etc. The mammary gland is found in both males and females but it is active in females only. Mammary glands are exocrine glands which are responsible for producing milk to the newborn by the mother.
> Mammals comprise a large complex brain that involves controlling all the biological activities of an individual.
> Mammals possess a muscular structure that is responsible for separating the abdomen and thoracic cavity. This muscular structure is called the diaphragm muscle.
> Mammals comprise a heart with four chambers. They have left atria, left ventricle, right atria, and right ventricle.

So, the correct answer is option C. 3-chambered heart. As mammals do not comprise a 3 chambered heart, it is not the mammalian character.

Note: The heart which comprises 3 chambers is known as a 3-chambered heart. A 3-chambered heart involves left atria, right atria, and single ventricle. This type of heart is found in amphibians and reptiles. In the case of a 3-chambered heart deoxygenated blood from the body enters into the right atria. From the right atria, it is transported to the lung via ventricle. From the lung oxygenated blood enters into the left atria and then transferred to the body through the ventricle.