Define the following terms:

(i) Allele …………………………………

(ii) Dominant gene ………………………

(iii) Genotype ………………………………..

(iv) Phenotype ……………………………

(v) Heterozygous dominant ……………………

(i) Allele: The alternative forms of the gene located at the same position on the homologous chromosome and affect the same characteristic but in different ways.

(ii) Dominant gene: In a heterozygous condition, the gene which express itself is called dominant gene while the gene that is unable to express itself is called recessive gene.

Note: For example, let T be for tallness of plant and r for shortness of plant. Now the plant having TT will be tall and tt will be short. In case of Tt pairing, the alleles are different thus one has to mask the expression of the other thus giving rise to a tall plant.

(iii) Genotype: It is genetic expression of a character in terms of alleles. Example- TT, tt, Tt.

(iv) Phenotype: It is the external or physical expression of a character. Example- tall or dwarf.

(v) Heterozygous dominant: 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.