Question

Oestrous cycle is reported in
A)Cows and sheep
B)Humans and monkeys
C)Chimpanzees and gorillas
D)None of these

Answer 1

Hint: It is a kind of menstrual cycle in mammals other than primates. The female bodies are prepared for fertilisation during this period.

Complete answer:
Mammals other than primates (human, monkeys and apes) show a different kind of cycle called oestrous cycle . These are seasonal breeders i.e. they reproduce during a particular time of the month. In these animals , when the females are in this reproductive phase that period is called the oestrous phase or we can call it the heat period. This is the time when females are receptive and fertilisation takes place.

It is shown by animals other than those are primates. The primates are the ones whose females have menstrual cycles. The examples of primates are apes, gorillas, monkeys, chimpanzees, baboons atc.
Out of the given options , cows and sheep are not primates. Hence , their females will show an oestrous cycle.

In the case of cows the period is 18 hours. This is a very very short period. If during this period mating happens, the fertilisation will take place otherwise not.

Hence, the correct answer is option (A)

Note: Although it appears to be similar to menstrual cycle but it is not. There are many differences between the two . For example, menstrual cycle takes place every month of the year while this is not the case with oestrous cycle. It takes place only a fixed number of times during the year.