Hybrid vigour is due to

Variation stands for differences in traits of progenies from

The phenotype of an organism is the result of?

In humans, albinism is controlled by a recessive gene '$a$'. If both parents are known to be carriers $(Aa)$ for albinism, what is the probability of having $1$ normal and $3$ albino children in a family of $4$ (in $/256$)?

Which of the following is genetically dominant in man?

Define/Explain the following terms:
$1.$ Genotype
$2.$ Variation