Explain the following terms:

(a) Heterozygous

(b) Homozygous

(c) Pedigree chart.

(a) Heterozygous: It is the condition when the two genes controlling one character are different, one dominant and one recessive. Such genes are dissimilar and constitute a pair of alleles.

For example, Tt represents the heterozygous condition, having an allele of tallness and an allele of dwarfness.

(b) Homozygous: It is the condition when both the genes controlling that character are identical.

For example, TT represents homozygous dominant condition while tt shows homozygous recessive condition.

(c) Pedigree chart: The Pedigree chart is a diagram that represents the family history for a few generations with regard to a particular trait. In the pedigree, chart males are shown by squares and females by circles.