Question

When the female albino plant of maize is crossed with the male green plant all progeny is albino because of
A. Plastid inheritance
B. Albino being a dominant trait
C. Mutations in plastids
D. None of the above

Answer 1

Hint: The self-replicating genes are also present in the cytoplasm like in the mitochondrial DNA and the chloroplast DNA. The plastidial genes are responsible for the inheritance of characters from one generation to another known as the cytoplasmic inheritance.

Complete step by step answer: Cytoplasmic inheritance is the inheritance in which the characters are inherited through cytoplasmic genes and not by the nuclear genes. One important aspect of cytoplasmic inheritance is maternal inheritance. The number of genes shared by the two gametes of the opposite sexes is always the same. But the amount of cytoplasm shared by the egg is much more than that of sperm. In extranuclear inheritance, the contribution of the female egg is more. Due to this, the maternal characteristics are inherited. This is known as maternal inheritance. A common example of maternal inheritance is the female albino plant of maize. When the female albino plant of maize is crossed with the male green plant all progeny is albino because of maternal inheritance. Since the maternal cytoplasm contributes more and the maternal characteristic is albino, so all the progeny produced is albino. Also, the albino genes are present on the plastids so it is also known as the plastid inheritance. Thus, when a female albino plant of maize is crossed with a male green plant all progeny is albino because of plastid inheritance.
Hence, the correct answer is option (A).

Note: There are self-replicating genes or DNA present in the cytoplasm also. These genes are present in the mitochondrial DNA and the chloroplast DNA. These genes are known as the plasmagenes since they are present in the plasma or the cytoplasm. All the plasmagenes together constitute a plasmon like a genome. The inheritance of the traits and characters through the plasmagenes is known as the extranuclear inheritance or extrachromosomal inheritance of cytoplasmic inheritance.