Chapter 4 – Evolution
EXERCISES
1. Fill in the blanks.
(a) The first systematic explanation of the concept of evolution was given by _______.
(Charles Darwin, Willard Libby, Louis Leakey)
Ans: Charles Darwin
(b) _______ are the most evolved animals among vertebrates.
(Aquatic animals, Amphibians, Mammals)
Ans: Mammals
2. Answer each question in one sentence.
(a) What do we call animals which live in water and also on land?
Ans: The animals that live in water and also on land are called amphibians.
(b) Where did the first humans appear?
Ans: The first human appeared on the African continent.
3. Give reasons for the following:
(a) The species of dinosaurs, which were enormous in size, suddenly became extinct.
Ans: The species of dinosaurs, which were enormous in size, suddenly became extinct because:
(i) According to Darwin, species that cannot adapt to environmental changes become extinct in the process of evolution.
(ii) Some sudden natural disaster or environmental change is believed to be responsible for the extinction of enormous dinosaurs.
(b) In the course of time, a new species with characteristics different from the original species is created.
Ans:
(i) In the process of surviving by adapting to environmental changes, certain internal physical changes occur in some animals of a species.
(ii) Over a period of time, these internal changes become inherited characteristics seen in all following generations.
(iii) Thus, in the course of time, a new species with characteristics different from the original species is created.
4. Fill in the blanks in the concept chart given below.
Ans:
