Question

Reduced size of one of the daughter cell in diatom formed during division is restored by ________ which has _______ ploidy
A. Statospore, N
B. Rejuvenescent cell, N
C. Statospore, 2N
D. Auxospore, 2N

Answer 1

Hint: The diatoms belong to algae. They are found in oceans, waterways, and soils. Usually, they reproduce by asexual reproduction, specifically binary fission. Two daughter cells, one having a large size and the other having a small size are produced. The large daughter cells form from the same parent cell but the smaller cell reproduces sexually to restore normal size.

Complete answer:
Cell division is the basic requirement in diatoms to reproduce. Diatoms reproduce asexually by binary fission. Binary fission is a method of asexual reproduction in which the parent body divides into two individual daughter cells. The diatoms show a special type of division. The parent cell divides into two daughter cells having different sizes.

One daughter cell is large and thus changes directly into an adult diatom. But the other daughter cell is small. Also, repeated division results in a decrease in chromosome count. This cell needs to restore the normal cell size and chromosome count to become an adult diatom. Thus, it undergoes further reproduction which is a sexual type of reproduction. One small daughter cell fuses with another small daughter cell. This is called the auxospore. The auxospore develops to form a zygote with normal cell size and a 2N set of chromosomes. Thus, the zygote is diploid.

Therefore, the correct answer is option D, Auxospore, 2N.

Note: The diatoms produce about $20-50%$ of oxygen each year. They make a significant portion of the Earth’s biomass. They contribute largely to half of the organic matter in the oceans. The shells of diatoms reach deep on the ocean floor when the diatoms die. This acts as a fertilizer.