Chapter 31, Problem 5STP

Summary Introduction

Introduction:

The characteristic that makes a mammal are the existence of hair and fur, warm-blooded, mammary gland and a complex brain. It has a bigger and more complex brain than any other group of animals. Mammals are the only kind of animals that give milk to their young ones.

Answer to Problem 5STP

Correct answer:

The correct answer is Option (A) Adults give birth to live young.

Explanation of Solution

Explanation/justification for the correct answer:

Option (A) Adults give birth to live young. Generally, Mammals can be classified into three broad groups: Monotremes, marsupials and Placentals.

The placental is a mammal that completes embryo development within the mother, nourished by an organ called the placenta. Marsupial and placental mammal adults give birth to young live mammals.

Explanation for incorrect answer:

Option (b) Adults lay eggs. Mammals who lay eggs are known as Monotremes. Thus, this is an incorrect answer.

Option (c) Offspring live in mothers’ pouch after birth. The baby marsupials remain protected in their mother’s pouch like kangaroos Some marsupials have a permanent pack, while in others the pouch forms during birth, as in the shrew opossum, where the young are covered either by skin folds or in the mother's hair. Thus, this is an incorrect answer.

Option (d) Offspring receive milk from their mother. Babies of humans, cows, and horses receive milk from their mothers. A marsupial is an animal that grows its new-born offspring within an outer pouch on the front or underside of their bodies. A marsupial and placental mammal community giving birth to young live mammals is a common characteristic between them. Thus, this is an incorrect answer.

Conclusion

Hence, the correct answer is Option (A) Adults give birth to live young.