Explain low of Multiple Alleles / Dominance and law of segregation.

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 Law of Dominance

$(i)$   Characters are controlled by discrete units called factors.
$(ii)$  Factors occur in pairs.
$(iii)$   In a dissimilar pair of factors one member of the pair dominates
(dominant) the other (recessive).
          The law of dominance is used to explain the expression of only one of the parental characters in a monohybrid cross in the $F_1$ and the expression of both in the $F_2$. It also explains the proportion of $3:1$ obtained at the $F_2$.

  Law of Segregation

This law is based on the fact that the alleles do not show any blending and that both the characters are recovered as such in the $F_2$ generation though one of these is not seen at the $F_1$ stage.

Though the parents contain two alleles during gamete formation, the factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors. Of course, a homozygous parent produces all gametes that are similar while a heterozygous one produces two kinds of gametes each having one allele with equal proportion.

Similar Questions

Definitions / Explanation : Heterozygous
 

Normal maize has starchy seeds which remain smooth when dry. A mutant form has sugary seeds which go crinckled when dry. When a mutant was crossed with a normal plant, an $F_1$ was produced which had smooth seeds. What would be the relative ratios of the different seed types, if the $F_1$ was allowed to self

  • [AIIMS 1993]

Which one of the following can be explained on the basis of Mendel's Law of Dominance?

$A$. Out of one pair of factors one is dominant and the other is recessive.

$B$. Alleles do not show any expression and both the characters appear as such in $F_2$ generation.

$C$. Factors occur in pairs in normal diploid plants.

$D$. The discrete unit controlling a particular character is called factor.

$E$. The expression of only one of the parental characters is found in a monohybrid cross.

Choose the correct answer from the options given below:

  • [NEET 2024]

Test cross is

Organisms phenotypically similar but genotypically different are said to be