The two versions of a trait (character) which are brought in by the male and female gametes are situated on

$(a)$ Write the full form of $DNA$.
$(b)$ Why are variations essential for the species?

In human males and females, how many pairs of chromosomes are identical?

In human beings,the statistical probability of getting either a male or female child is $50 : 50$. Give a suitable explanation.

$A$ guinea pig having black color,when crossed with a guinea pig having the same color,produced $80$ offspring,out of which $60$ were black and $20$ were white. Now,find out:
$(i)$ What is the possible genotype of the guinea pig?
$(ii)$ Which trait is dominant and which trait is recessive?
$(iii)$ What is this cross called,and what is its phenotypic ratio?

Two pea plants,one with round green seeds $(RRyy)$ and another with wrinkled yellow $(rrYY)$ seeds,produce $F_1$ progeny that have round,yellow $(RrYy)$ seeds. When $F_1$ plants are selfed,the $F_2$ progeny will have new combinations of characters. Choose the new combinations from the following:
$(i)$ Round,yellow
$(ii)$ Round,green
$(iii)$ Wrinkled,yellow
$(iv)$ Wrinkled,green