The Molecular Basis Of Inheritance

The reason for the deviation from Mendel's dihybrid cross in T.H. Morgan's experiment is "Linkage."

In Morgan's experiments with fruit flies (Drosophila melanogaster), he observed that certain traits that were expected to segregate independently according to Mendel's principles actually appeared together more often than expected. This phenomenon occurred because the genes responsible for these traits were located close to each other on the same chromosome, resulting in their linkage.

Linkage refers to the tendency of genes on the same chromosome to be inherited together as a unit, rather than independently assorting during meiosis. This discovery of linkage led to the understanding of genetic recombination and the concept of genetic mapping.

The correct answer is: (A), (C), (D), (E)

A nucleosome is the fundamental unit of DNA packaging in eukaryotes. It is composed of DNA wrapped around histone proteins. Each nucleosome core particle contains eight histone protein molecules, forming an octamer. This octamer consists of two molecules each of the four core histones: H₂A, H₂B, H₃, and H₄.

Thus, the statement that a nucleosome is associated with eight molecules of histones is correct.

Therefore, the correct answer is Eight.