When Mendel crossed a tall plant with a dwarf plant,what was the ratio of dwarf plants in the $F_{2}$ generation (in $, \%$)?

List three main factors responsible for the speciation and briefly describe each one of them.

The maleness of a child is determined by

What is $F_{2}$ generation?

According to the evolutionary theory,the formation of a new species is generally due to:

Select the statements that describe characteristics of genes:
$(i)$ genes are specific sequence of bases in a $DNA$ molecule
$(ii)$ a gene does not code for proteins
$(iii)$ in individuals of a given species,a specific gene is located on a particular chromosome
$(iv)$ each chromosome has only one gene