Polyploidy refers to:

Appeared in: HP CHO -9 October 2022

Explanation

Polyploidy is defined as the state where a cell or organism has more than two paired (homologous) sets of chromosomes.
This means having one or more complete extra sets, such as triploidy (3n) or tetraploidy (4n).
Humans are normally diploid (2n), with two sets of 23 chromosomes, totaling 46.
An individual with complete extra sets of chromosomes fits the exact definition of polyploidy.

Option A: This describes gene duplication, where a segment of a chromosome is repeated. It involves extra copies of a gene or genes, not an entire extra set of all chromosomes.
Option C: This describes a normal chromosome after DNA replication (in the G2 or M phase of the cell cycle). The chromosome consists of two identical sister chromatids. This is a temporary state in all dividing cells, not a permanent chromosomal abnormality.
Option D: This describes a polysome or polyribosome. It is a structure involved in protein synthesis where multiple ribosomes translate a single mRNA molecule simultaneously. It is related to gene expression, not chromosome number.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition of Polyploidy as background academic context rather than a clinical decision trigger.
In human genetics, polyploidy (especially triploidy) is a major cause of spontaneous abortion, accounting for a significant percentage of first-trimester pregnancy losses.
Unlike aneuploidy (e.g., Down syndrome), where an individual has an extra single chromosome, polyploidy involves entire sets and is almost always lethal in humans, preventing development to term.
What if only a single extra chromosome is present, not a whole set? This condition is called aneuploidy. Unlike the near-universal lethality of polyploidy in humans, some aneuploid conditions, such as Trisomy 21 (Down syndrome), are viable.

How to Approach the Question

First, analyze the term 'polyploidy'. Break it down: 'poly-' means 'many', and '-ploidy' refers to sets of chromosomes.
This etymology directly points to the concept of having 'many sets' of chromosomes.
Evaluate each option against this core definition.
Option A discusses genes, not chromosome sets. Eliminate it.
Option B discusses 'complete extra sets of chromosomes', which perfectly matches the definition of polyploidy.
Option C describes a temporary state of a single chromosome during cell division, not a condition of the entire organism's chromosome count. Eliminate it.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 807-809

E6 Pathology-Vandana Puri & Kavita Gaur Textbook of Pathology and Genetics p. 483-485

Practise the full HP CHO -9 October 2022

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