Question

Define the terms: (i) Genotype (ii) Phenotype

Answer 1

(i)

Genotype: Genotype is the combination of alleles (genes) that bring the phenotype. A pair of letters denote a genotype. These pairs can contain two capital letters, two small letters, or one capital and one small letter.

Example:

• For the single character, that is height, the genotype will include two alleles.
• T and t are used to represent individual alleles for the characteristic of height.
• The three possible genotypes when two alleles are present will be TT, Tt, and tt.
• TT, TT, and tt represent the genotype.

(iii)

Phenotype: Phenotype is the external or physical characteristics that appear in an organism. This is under the control of both genes and the environment.

Example:

• The phenotype is usually determined by the genotype.
• In Mendel’s monohybrid cross, TT means that the plant is tall. Since T is responsible for tall height and t for a dwarf. Tall and dwarf are phenotypes.