Heredity:

Terminology Of Genetics:

Gene:
The basic unit of hereditary material which is responsible for development of a trait.

Alleles:
Alternatives forms of genes are called alleles, e.g. tall versus dwarf.

Dominant:
The dominant alleles are those traits which show complete expression even in heterozygous state. Dominant alleles dominate the recessive alleles in heterozygous state.

Recessive:
Recessive alleles or traits are those which fail to express themselves in heterozygous state. For example r and y are recessive alleles for wrinkle and green seeds.

Homozygous:
Homozygous is a condition in which an individual possess similar alleles for a particular trait. For example TT for tallness and tt for dwarfness.

Heterozygous:
Heterozygous is a condition in which an individual possess dissimilar alleles for a particular trait. For example Tt for tallness.

Genotype:
Genetic make of an organism is called genotype.

Phenotype:
External appearance or expression of genotype is called phenotype. For example, roundness, wrinkleness of seeds and tall or dwarf plants represent different phenotype.