The term for having an abnormal number of chromosomes in a cell is known as what?

• A. Polyploidy
• B. Aneuploidy
• C. Diploidy
• D. Haploidy

Answer: (B)

Aneuploidy refers to a condition in which a cell has an abnormal number of chromosomes, meaning that it has either more or fewer chromosomes than the typical diploid number for that organism. This can occur due to errors in cell division, such as nondisjunction, where chromosomes do not properly separate during meiosis or mitosis. This results in gametes with an unbalanced number of chromosomes, leading to offspring with various genetic disorders, such as Down syndrome, which is caused by trisomy of chromosome 21.

In contrast, polyploidy involves the condition of having one or more extra sets of chromosomes, rather than just an abnormal number of individual chromosomes, and is common in certain plants. Diploidy is the standard condition of having two complete sets of chromosomes, one from each parent, while haploidy refers to having only one set of chromosomes, typical of gametes.