Question

When a complete nondisjunction of chromosomes results in an increase in the number of chromosome sets in a given species, the result is a type of polyploidy called?

1) Monoploidy
2) Triploidy
3) Tetraploidy
4) Aneuploidy

Answer 1

The condition resulting from a complete nondisjunction of chromosomes, causing an increase in chromosome sets, is termed polyploidy, specifically triploidy (option 2) when there are three sets of chromosomes.

Step-by-step explanation:

When complete nondisjunction of chromosomes leads to an increase in the number of chromosome sets in a given species, the result is a type of polyploidy. The correct term for this condition depends on the resulting number of chromosome sets. If an abnormal diploid egg were to be fertilized by a normal haploid sperm, creating a zygote with three sets of chromosomes, this would be called triploidy, option 2 on your list. The other options each represent different conditions: Monoploidy (1) refers to the presence of only one set of chromosomes; Tetraploidy (3) is the presence of four sets of chromosomes; and Aneuploidy (4), as depicted in Figure 18.16, is an abnormal number of chromosomes that is not an exact multiple of the haploid number, such as trisomies and monosomies.

In plants, polyploidy is common and can lead to larger and more robust organisms. In contrast, polyploidy in animals is rare and often leads to sterility because an odd number of chromosome sets can disrupt normal meiotic division.