Define F1 and F2 generations.

F1 or first filial generation is the generation of hybrids derived from a cross between two genetically different homozygous individuals.
F2 or second filial generation is the generation produced as a result of interbreeding between individuals of F1 generation.

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Define the terms: Variations, Acquired Variations.

Variations: There are differences found in structure, function, behaviour and genetic make up of different individuals of the same parentage, variety, race and species.
Acquired variations: They are somatic variations which develop in the life time of an individual. Acquired variations are usually non-inheritable and are not passed on to the next generation.

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What do you mean by the following terms: Codominant, Genotype, Phenotype?

Codominant: They are two factors or alleles both of which are able to express their effect when present together and are completely dominant even in heterozygous condition., e.g., IAIB.

Genotype: It is the genetic constitution or gene complement of an individual. Thus genotype for pure tall is TT, hybrid tall Tt and dwarf tt.

Phenotype: It is the external manifestation of a genotype and characteristics which are morphologically visible . Phenotype is not only dependent upon genotype but also upon the environment, nutrition, age and stage of development. Phenotype is usually similar to genotype in the homozygous state, e.g., pure tall (TT), dwarf (tt). The two are dissimilar in heterozygous state.

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What do you mean by the following terms: Dominant, Recessive?


Dominant: The factor of a character which is able to express itself in a heterozygote as well as a homozygote is called dominant. For example, in hybrid or heterozygous tall Pea plant both the factors for tallness (T) and dwarfhess (t) are present. However, only the factor for tallness is able to express itself in the individual because it is dominant.
Recessive: It is a factor in allelic pair which is unable to express itself in a heterozygote or hybrid, because of the presence of contrasting dominant factor. it is expressed only in the homozygous condition. For example, in the hybrid or heterozygous tall Pea plant both the factors for tallness and dwarfness are present (Tt). However, the factor for dwarfness is unable to express itself in the presence of factor for tallness because it is recessive.

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What do you mean by the following terms: Homozygote, Heterozygote?

Homozygote (= Homozygous) It is an organism which possesses similar or identical factors of a character or trait (e.g., TT for tallness or tt for dwarfness). Homozygous individual is also called pure for that character since it breeds true or produces on offspring similar to it in case of self-fertilization or self-breeding.
Heterozygote (= Heterozygous) It is an organism which has two contrasting factors or alleles of a character. Heterozygote or heterozygous individual is also called hybrid, e.g., hybrid tall Pea plant (Tt). It seldom breeds true.

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