Hereditary and Variation MCQs for NEET — Botany Questions with Answers

In humans, height shows a lot of variation because it is an example of polygenic inheritance. This means that multiple genes contribute to the trait, resulting in a wide range of phenotypes.

The 7:1:1:7 ratio was observed by Bateson and Punnett in a test cross involving a dihybrid cross. This ratio is indicative of gene linkage with partial recombination, showing that the genes are not assorting independently but are somewhat linked.

no.of gametes=2ⁿ  

^{where n is the number of heterozygotes.}

The occurrence of Free Martin in cattle is due to multiple factors: both twins being connected by a common umbilical cord, the earlier development of male gonads, and the influence of male hormones on the female embryo. These combined factors result in the female embryo developing intersex characteristics and becoming sterile.

Discontinuous variation in a population is primarily caused by mutations. Mutations introduce new genetic variations that can lead to distinct phenotypic changes, which do not follow a continuous range but appear as distinct categories.

A back mutation, or reversion mutation, is a genetic change that reverses the effect of a previous mutation. This type of mutation restores the original sequence of DNA, thus reversing the mutation.