Chapter 9: Heredity and Evolution- Exercise- 1

 

Science

(www.olympiadsuccess.com)

Chapter 9: Heredity and Evolution

Class: X

Exercise number 1

 

Question 1

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B

exists in 60% of the same population, which trait is likely to have arisen earlier?

 

Answer 1

Trait B is likely to have arisen earlier as, Trait B has more percentage than Trait A. We know that in asexual reproduction traits from previous generation are carried over to the next generation with minimal variation.

 

The above figure clearly explains that in asexual reproduction, very few variations are allowed. Therefore, if a trait is present in only 10% of the population, it is more likely that the trait has arisen recently. Hence, it can be concluded that trait B, that exists in 60% of the same population has arisen earlier than trait A.

 

Question 2

How does the creation of variations in a species promote survival?

Answer 2

In case of sudden change in the environmental conditions, survival of some species becomes difficult. For example, if the temperature of water increases suddenly, most of the bacteria living in that water would die. Only few variants resistant to heat would be able to survive. The entire species of bacteria would have been destroyed, in absence of theses variants. Thus, these variants help in the survival of the species. However, all the variations in the species do not have equal chance of survival in the environment.