Give differences: Incomplete dominance and Co-dominance.

In bread wheat,the chromosome number is:

Differentiate between the following:
$(a)$ Dominant and Recessive
$(b)$ Homozygous and Heterozygous
$(c)$ Monohybrid and Dihybrid.

Among the four couples given,who could be the biological parents of a child with $O^+$ blood group?

$A$ : Test cross is the tool for knowing linkage between genes.
$R$ : Monohybrid test cross gives two phenotypes and two genotypes.

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 $/256$)?