Question

Mammals are characterized by
a. Hairs on the body
b. Mammary glands
c. Endothermic
d. All of the above

Answer 1

Hint: Mammals are the vertebrate animals that belong to Kingdom Animalia and the class Mammalia. All the vertebrates have nucleated red blood cells except mammals, there mature RBCs lack a nucleus. All mammals are viviparous except monotremes. The distribution of Mammalia is worldwide. Mammals are of three types: Monotremes, marsupials, and placentals.

Complete answer:
- Mammals are characterized by the presence of hairs or fur on the body, presence of mammary glands.
- Hairs or fur on the body of mammals provide protection to the body, regulates body temperature, and also acts as sense organs.
- Mammary glands in females produce milk for feeding youngsters.
- These are also characterized by the presence of three middle ear bones and the neocortex, a region of the brain.
- The presence of these characteristics distinguishes mammals from birds and reptiles.
- Mammals are endothermic.
- Endotherms are warm-blooded animals. These animals maintain a constant temperature of the body independent of the environment.

Hence, the correct answer is option (D).

Additional information:
- The basic body type of mammals is quadruped. They use four legs for the terrestrial locomotion but some use two legs which are adapted for life in trees, in the air, or at sea.
- The size of mammals ranges from 30-40 mm.
- The largest animals to have ever lived are blue whales.
- Mammals can communicate and vocalize in many ways. They produce alarm signals, ultrasound, singing, scent-marking, and echolocation.

Note: Mammals are vertebrate animals that have hair or fur on the body for the protection of the body and regulation of temperature, the presence of mammary glands produces milk in females to feed young ones. Mammals have lungs and all the spines. Mammals are warm-blooded animals. Mammals are intelligent animals due to the presence of the brain. They have well developed four-chambered hearts and specialized teeth.