Question

In diplospory, embryo develops from the diploid
A. Nucellus
B. Reproductive cell
C. Microspore mother cell
D. Megaspore mother cell

Answer 1

Diplospory is the process by which the female plant clones itself to give rise to off-springs. The process generally takes place by mitosis.

Complete answer: Diplospory is analogous to asexual reproduction. It is the process in which the female parent clones itself to give rise to off-springs. The megaspore mother cell, which is a diploid cell, produces its clones by the process of mitosis. Mitosis takes place thrice to give rise to 8 off-springs.
Microspore mother cell is a diploid cell that undergoes meiosis to form microspores. These microspores develop into pollen grains which carry the male reproductive part of the plant. Microspore mother cell develops in the anther. On maturity of the pollen grains, the anther bursts to scatter the grains. Once these reach the stigma of the female flowers, fertilization occurs.
Nucellus forms an integral part of the ovule. It contains the embryo sac. The nucellus is covered with two layers of integuments except for a tiny area that forms the micropyle.

Therefore, the correct answer is option (D).

Additional information: Diplospory is a type of a process called apomixis in plants. Apomixis is the process of seed development without fertilization. It is a common process in plants like maize and wheat. Apomixis can be of three types: Diplospory, Apospory or Adventitious embryony. In apomixis, all the progeny has the same genetic material as the parent plant. The process can bring about rapid multiplication of species. However, a drawback of the process is lack of genetic diversity in the off-springs due to lack of variation.

Note: Diplospory is the method by which the megaspore mother cells divide by mitosis thrice to give rise to 8 progeny plants. In this process no sexual reproduction or mixing of genes are involved. This process is similar to asexual reproduction. The genes of the parent plant and the progeny are identical.