Question

What is the central role of the nucleus?
A. Diffusion
B. Osmosis
C. Excretion of toxic materials
D. Reproduction

Answer 1

Nucleus is the most important organelle of the cell. It contains genetic material in it that is DNA. it is enclosed with the nuclear envelope. Nuclear envelope has protein channels for the exchange of materials. Karyokinesis is the important role of the nucleus. It occurs during cell division.

Complete answer:
Cells are the building blocks of the body. It contains many cell organelles such as nucleus, mitochondria, ribosome, endoplasmic reticulum, etc. Animal cells contain nucleus in the center while the plant cell has a nucleus near the cell wall. Prokaryotes have undefined nucleus while eukaryotes have well defined nucleus. All the components of the nucleus confined in a nuclear envelope. Nuclear envelope is the double membrane that encloses the entire organelle and isolates the nuclear components from the cytoplasm and the nuclear matrix.
It has a nucleoplasm separated from cytoplasm. It contains the whole genome of the cell. Nuclear membrane is the discontinuous membrane, it contains nuclear pores in it. These nuclear pores act as a protein channel. The exchange of materials between cytoplasm and nucleoplasm occur through these channels.
Nucleus is a very important organelle but its main function is to regulate cell division. Cell division includes cytokinesis and karyokinesis. Karyokinesis is the division of the nucleus. From this we can say that the nucleus's central function is reproduction.

Hence, the correct answer is option (D).

Note: Most eukaryotes have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei while the osteocytes have many nuclei. The size of the nucleus can vary with the size of the cell. It contains chromosomes which are transferred from one generation to another. It carries the genes which are responsible for specific characters of the individual.