'Population tends to increase geometrically,while food supply increases arithmetically'. This concept was put forward by

Given below are two statements.
Statement-$I$: Elimination of particular alleles from a population due to natural disasters is called genetic drift.
Statement-$II$: Sudden temporary heritable change in the gene is called point mutation.
In the light of above statements,choose the most appropriate answer from the options given below:

Saltation refers to . . . . . . .

The frequency of a character in a population is found to be increasing when:

Variations caused by mutation,as proposed by Hugo de Vries,are

As a result of the excessive use of herbicides and pesticides,which types of varieties were selected in a short period?