Question

Which one of the following stages is necessary in the life cycle of an animal in which complete metamorphosis occurs?
A. Adult
B. Egg
C. Larva
D. All of the above

Answer 1

Hint: The physical changes in an organism after birth till it becomes an adult is called metamorphosis. It is regulated by the hormone. It takes place in organisms like frog, butterfly, fish etc.

Complete Answer:
Metamorphosis is the process of growth and differentiation after birth till it becomes an adult. It is marked by change in physiology, biochemistry and behaviour. There are two types of metamorphosis.
1. Complete metamorphosis -The complete metamorphosis occurs in the insects. It undergoes four distinct changes from egg- larva- pupa- adult. The larva does not resemble the adult. The larva is very active and eats vigorously whereas the pupa is the inactive stage. It is also called holometabolism.
2. Incomplete metamorphosis- In this the changes involved are egg – nymph- adult. Nymph is the smaller version of adult. Example is grasshopper, bugs.

The correct answer is (D).

Note: The advantage of complete metamorphosis is it helps the larva and adult place themselves in different niches in the ecosystem. This curbs the competition between the young one and adult. In some organisms the pupa stage is enclosed in a cocoon. This gives them extra protection in the extreme environment. The disadvantages of metamorphosis are the adult has shorter life span, and the adult only has mobility.