How many pairs of chromosomes are present in the human cell?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-3rd)

Explanation

Human somatic (non-sex) cells are diploid, containing a total of 46 chromosomes.
These chromosomes are organized into 23 pairs, with one chromosome in each pair inherited from each parent.
The 23 pairs are composed of 22 pairs of autosomes (body chromosomes) and one pair of sex chromosomes (XX or XY).

Option A: This represents the number of pairs of autosomes (non-sex chromosomes), but it excludes the single pair of sex chromosomes.
Option C: This is the total number of individual chromosomes in a diploid human cell, not the number of pairs.
Option D: This is the total number of individual autosomes (22 pairs = 44 chromosomes), not the total number of chromosome pairs.

Visual 1: Diagram - A human karyotype showing the 23 pairs of chromosomes, clearly distinguishing the 22 autosomes and the XY sex chromosomes. This helps visualize the concept of paired chromosomes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Human Chromosome Number as background academic context rather than a clinical decision trigger.
Understanding the correct number of chromosomes is fundamental for genetics and identifying chromosomal abnormalities (aneuploidy), which can lead to various genetic disorders.
For example, Down syndrome (Trisomy 21) is caused by having an extra copy of chromosome 21, resulting in 47 total chromosomes instead of the normal 46.
Karyotyping, the process of pairing and ordering all the chromosomes of an organism, is a key diagnostic tool in clinical genetics to detect such abnormalities.

How to Approach the Question

This is a factual recall question from biology.
Identify the keywords in the question: 'how many', 'pairs', and 'chromosomes'.
The word 'pairs' is the most critical part of the question. It is not asking for the total number of individual chromosomes.
Recall the basic fact that human somatic cells have 46 total chromosomes.
Since chromosomes exist in pairs, divide the total number by two: 46 chromosomes / 2 = 23 pairs.
Evaluate the options to see which one matches your calculated answer and eliminate the distractors based on what they represent (e.g., 46 is the total count, 22 is the autosomal pair count).

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-3rd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.