Question

Cytoplasmic inheritance is due to
(a) Plastids
(b) Mitochondria
(c) Cytoplasmic particles
(d) All of the above

Answer 1

Hint: Cytoplasmic inheritance also called extracellular inheritance is the transmission of genes outside the nucleus. The trait is transferred from the parent to the offspring through non-chromosomal means.

Complete solution:
Plastids are minute cytoplasmic organelles in plant cells. The most important plastid is the chloroplast. Plastids can self-duplicate and have some amount of DNA which plays an important role in cytoplasmic inheritance.
Mitochondria tend to be inherited from just one parent or the other or unequally inherited from both the parents. In humans, the mother contributes mitochondria to the zygote. Sperms have zygotes but they are not inherited by the zygote.
Cytoplasmic inheritance is found in most eukaryotes and is commonly known to occur in cytoplasmic organelles.

Additional information:
Leaf variegation in Mirabilis jalapa is an example of cytoplasmic (plastid) inheritance.
In 1909, Carl Correns presented conclusive evidence for cytoplasmic inheritance in Mirabilis jalapa.
He studied the inheritance of leaf variegation in the plant.
Variegation is the presence of white or yellow spots of different sizes on the green leaves.
The leaves of M. jalapa may be green, yellow, or variegated. Some of its branches may have only green, only white, or only variegated leaves.
Correns made crosses in all possible combinations among flowers which were produced on these three types of branches.
- Flowers on fully green branches produce seeds that grow into normal plants.
- Flowers on wholly white branches produce seeds that grow into white plants.
- Flower on variegated branches produces offsprings of green, white, and variegated in variable proportions.

So, the correct answer is ‘All of the above’.

Note:
Cytoplasmic inheritance can also be due to plasmids.
Plasmids are a small, extrachromosomal piece of DNA which have the ability to replicate independently.
Cytoplasmic inheritance only includes inheritances through other cell organelles except for the nucleus.