Who coined the phrase 'Survival of the Fittest'?

Any change in gene frequency in a population is called ......

In a population of plants,some were extremely tall,and the remaining were extremely dwarf. No plants of the population showed intermediate height. The type of operation of natural selection in the above case is

Explain the example of insect resistance to pesticides as an instance of natural selection.

Which of the following phenomena supports Darwin's concept of natural selection in biological evolution?

In natural selection, more individuals acquire value other than the mean character value, which indicates . . . . . . .