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2023Q4(iv)Genetics – Some Basic Fundamentals
DefinitionModerate2 marks

State Mendel’s Law of Segregation.

Topic: Mendel’s Law of Segregation

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Answer

Exam answer

MENDEL’S LAW OF SEGREGATION states that the two alleles of a pair SEPARATE (segregate) from each other during the formation of gametes, so that each gamete receives only ONE allele of the pair. The alleles remain unaltered and are restored in pairs at fertilisation.

Explanation

The essential words are that the alleles SEPARATE during GAMETE FORMATION and that each gamete receives only ONE.

It is also called the LAW OF PURITY OF GAMETES, and that name is worth giving: a gamete is "pure" because it carries one allele only, never a blend of the two.

THE EVIDENCE for it is the reappearance of the recessive character in the F2 generation. If the alleles had blended in the F1 hybrid, the recessive character would have been lost for ever. That it returns unchanged proves the alleles separated intact.

Mendel’s three laws as a set: DOMINANCE (only the dominant shows in a hybrid), SEGREGATION (alleles separate into gametes), INDEPENDENT ASSORTMENT (different pairs are inherited independently).

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