Question

Genes are segments of
A. Chromosomes
B. DNA
C. mRNA
D. Nucleolus

Answer 1

A gene is a piece of DNA that holds information and passes it on from generation to generation. Transcription into RNA and then translation into proteins are the first steps of gene expression in DNA. The DNA is first copied into RNA during gene expression. DNA is known to be discovered by Watson and Crick.

Complete answer:
Human cell contains $46$ double-stranded DNA molecules. Chromosomes are made up of coiled and supercoiled DNA around histone proteins. Around $50$ to $250$ million bases make up each chromosome.
So, option A is incorrect.
A gene is a fundamental unit of heredity in biology, consisting of a series of nucleotides in DNA or RNA that codes for the synthesis of a gene product, such as RNA or protein.
So, option B is correct.
Messenger ribonucleic acid (mRNA) is a single-stranded RNA molecule that refers to a gene's genetic sequence in molecular biology.
So, option C is incorrect.
The nucleolus is a distinct structure found in eukaryotic cells' nuclei. It is primarily involved in the assembly of ribosomes, the modification of transfer RNA, and the detection of cellular stress. RNA and proteins form the nucleolus, which forms around various chromosomal areas.
So, option D is incorrect.

So, Option B is the correct answer.

Note:
Deoxyribonucleic acid (DNA) is a molecule made up of two polynucleotide chains that coil around each other to form a double helix and contain genetic instructions for the creation and operation of all living things. The DNA molecule is a two-stranded spiral that forms a double helix. Each strand is made up of millions of bases, which are chemical building blocks. Adenine, thymine, cytosine, and guanine are the only four groups of bases found in DNA. Permutation and combination in a sequence alter the order of these bases.