Question

The chromosome constitution 2n-2 of an organism represents
A) Monosomic
B) Nullisomic
C) Haploid
D) Trisomic

Answer 1

Hint: The DNA molecule is packaged into thread-like structures in the nucleus of each cell, called chromosomes. Each chromosome is composed of many times tightly coiled DNA around proteins called histones that support its structure.

Complete Answer:
A chromosome is a molecule of DNA ( deoxyribonucleic acid), with part or all of an organism's genetic material (genome). Most eukaryotic chromosomes comprise packaging proteins that bind and condense the DNA molecule to prevent it from becoming an unmanageable tangle, assisted by chaperone proteins.
Four main chromosomal types exist: metacentric, submetacentric, acrocentric, and telocentric. In most living cells, chromosomes are found within the nucleus and consist of DNA that is tightly wound into thread-like structures. Monosomic is a form of aneuploidy with a pair having only one chromosome.
Partial monosomy occurs when a portion of one chromosome is missing in a pair.Haploid is the term used when one cell has half the usual chromosome count. A normal eukaryotic organism is composed of diploid cells, each parent having one set of chromosomes.
Yet, the number of chromosomes in gametes is halved after meiosis. That is the state is known as haploidy. A trisomy is a type of polysomy in which a particular chromosome has three instances, instead of the normal two. Nullisomic is a condition in which diploid cells miss both copies of the same chromosome and are therefore called as 2n-2 It is caused by the meiosis nondisjunction. Fertilisation may be hampered by lack of genetic information.

So the correct option is B i.e Nullisomic .

Note: An abnormal condition in a person's chromosomes because of something unusual. Down syndrome, for example, is a chromosome disorder caused by the presence of an extra copy of chromosome 21, and Turner syndrome is most commonly caused by the presence of only one single sex chromosome: one X chromosome.