Which event results in a change in the number of chromosomes in a cell?1 pointcrossing overdeletioninsertionnondisjunction

The event that results in a change in the number of chromosomes in a cell is nondisjunction.

Here's a step-by-step explanation:

1. Normal cell division involves the replication of chromosomes and their equal distribution to two daughter cells. This process ensures that each cell gets the correct number of chromosomes.

2. Nondisjunction is an error in this normal cell division process. It occurs when the chromosomes do not separate properly during cell division.

3. This can happen during meiosis (the process that produces sperm and egg cells) or mitosis (the process that produces most of the body's cells).

4. If nondisjunction happens, it results in cells with an abnormal number of chromosomes. For example, this can lead to conditions like Down syndrome, which is caused by an extra copy of chromosome 21.

5. On the other hand, crossing over, deletion, and insertion are types of genetic recombination and mutation. They can change the structure and arrangement of genes on a chromosome, but they do not change the total number of chromosomes in a cell.