Question

In which mode of inheritance do you expec more maternal influence among the offspring ?

• A. Autosomal
• B. Cytoplasmic
• C. Y-linked
• D. X-linked

Answer 1

Answer: (B)

Cytoplasmic

Answer 2

The more maternal influence can be expected in the cytoplasmic inheritances (ie, the inheritance of genes contained in the cytoplasm of a cell, rather than the nucleus). The reason is that the female reproductive cell or the egg has large amount of cytoplasm containing many organelles which contain their own genes and can reproduce independently (eg, mitochondria and chloroplast) and which are consequently incorporated into the cytoplasm of all the cells of the embryo. The male reproductive cell (sperm or pollen) consists almost solely of a nucleus. Cytoplasmic organelles are thus, not inherited from the male parent. This is why, the cytoplasmic inheritance is also called maternal inheritance.
Genes located on $Y$-chromosome are called $Y$-genes and their in inheritance is called $Y$-linked inheritance. This carries the paternal influences.
A gene located in the $X$-chromosome is said to be $X$-linked and its inheritance is called $X$-linked inheritance. In this, a male transmits his $X$-chromosome only to his daughters while a female transmits one of her $X$-chromosome to the offspring of both sexes.