There is an inbuilt tendency to variation during reproduction,both because of errors in $DNA$ copying,and as a result of sexual reproduction.

Explain the following scenarios in a group of organisms,providing reasons for each:
$(a)$ Predators are more in the group.
$(b)$ Organisms survive accidentally.
$(c)$ Organisms are not able to survive in changing environmental conditions.

$(a)$ When a pesticide is sprayed on a population of insects,all insects do not get killed but few of them survive. Give reason.
$(b)$ When is a recessive trait capable of expressing itself? Write its expression with respect to the height of a plant (genotype).

When are the genetic traits of parents transmitted to the offspring?

What is the scientific name of the human species?

How can we say that a change in genes can bring about a change in $DNA$?