Question

Which group has gestation period in decreasing order?
(A) Cow, Horse, Goat, Monkey, Swine/Pig
(B) Horse, Cow, Goat, Monkey and Swine
(C) Monkey, Cow, Horse, Goat and Swine
(D) Monkey, Horse, Goat, Cow and Swine

Answer 1

Hint: The period of development of the embryo or foetus inside the mother’s womb is called the gestation period. Gestation period is found only in mammals, as they are viviparous (gives birth to young ones) in nature. But few non-mammals also possess gestation period. This period of embryonic development varies according to the species.

Complete Answer:
- Gestation period in mammals starts from fertilization and ends with parturition. Fertilization refers to the fusion of sperm with an ovum in order to form zygote. Zygote undergoes further division to form embryos, which develops to form foetus in the pregnant female. Parturition refers to the delivery of the foetus. It is also known as childbirth.
 - The duration of gestation varies from species to species. This is in correlation with the size of the mammal. The smaller the mammal, the shorter the duration of gestation. Whereas, the larger mammals take years together to develop a foetus inside the uterus.
- The young ones that are born after a short gestation, are usually immature in nature, compared to those young ones which are born after a longer period of gestation. There are many minor factors which determine the duration of gestation in mammals such as climatic conditions, availability of food, etc.

The average gestation period (in days) for few mammals are as follows,
Cow: 279 – 292 days
Dog: 58 – 65 days
Human: 266 days
Monkey: 155 days
Swine/Pig: 112 – 115 days
Horse: 330 – 342 days
Goat: 145 – 165 days
According to the above information, the animals having gestation period in decreasing order, is as follows, Horse > Cow > Goat > Monkey > Swine.

Therefore, Option (B) is correct.

Note: An easy way to answer this question is to know the fact that smaller animals have shorter duration of gestation and larger animals have longer duration of gestation. Moreover, certain animals prolong the duration of gestation intentionally, according to the climatic conditions and the availability of food.