Question

In which mode of inheritance do you expect more maternal influence in the offspring?
A. Y-linked
B. X-linked
C. Autosomal
D. Cytoplasmic

Answer 1

Hint: An individual's phenotype is defined by his or her genotype. Alleles passed down through the generations determine a person's genotype (one from maternal side and one from paternal side). These alleles determine whether or not a characteristic is "dominant" or "recessive". The position of alleles in the genome also determines whether a characteristic is "autosomal", "X-linked," or "Y-linked".

Complete answer:
Let us introspect each of the inheritance patterns given in the options and find out the answer.
Option:A - Characters that are controlled by genes on the Y chromosomes are passed down through Y linked inheritance. This has no bearing on maternal characteristics.
Thus, Option:A is not the correct answer.
Option:B - Characters that are governed by genes on the X chromosomes are passed down through X linked inheritance. However, because each cell may only contain two copies of the X chromosome, it cannot account for a greater or lesser effect on maternal characteristics in children.
Thus, Option:B is not the correct answer.
Option:C - Characters controlled by the autosomes are passed down through the generations via autosomal inheritance. Autosomal inheritance has no effect on an offspring's maternal or paternal characteristics.
Thus, Option:C is not the correct answer.
Option:D - The phenomenon of cytoplasmic inheritance is the transmission of maternal characteristics found in the genetic material of the cytoplasm. It is produced mostly by the expression of genes found in extrachromosomal regions.
Mitochondria and chloroplast are the only semi-autonomous organelles that contain their own DNA. Mitochondrial DNA is referred to as mt-DNA, while chloroplast DNA is referred to as ct-DNA. The mitochondrial and chloroplast functional genes express themselves, allowing maternal characteristics to be passed along.
Since most of the cytoplasm of the zygote is from the maternal side it influences more on the offspring.
Thus, Option:D is the correct answer.

Hence, Option D. Cytoplasmic, is the correct answer.

Note:
Multiple, homogenous genomes are found in cytoplasmic organelles, which are generally inherited from only one parent (in this example, and most commonly, the female parent). Because certain organelles, such as mitochondria and chloroplasts in plants, possess their own DNA and may reproduce independently, this phenomenon happens. Such an inheritance is called Cytoplasmic inheritance.