Question

Nondisjunction is the failure of chromosones to seperate correctly during cell division. Nondisjucntion during meiosis violates Mendels Law of Segregation, producing gametes with an incorrect number of chromosones.

The two types of nondisjunction during meiosis in females are shown in the image. The genetic contents of the zygotes that would result from the fertilization of each egg by a sperm are also shown.
For an organism with a haploid number of n=8, what percentage of the gametes resulting from a nondisjunction event of one chromosone pair during meiosis 1 will have only seven chromosones?
A: 25%
B: 50%
C: 75%
D: 0%

Answer 1

When nondisjunction occurs during meiosis I, two out of the four resulting gametes will have one less chromosome, resulting in 50% of gametes having only seven chromosomes for an organism with a haploid number of 8. The correct answer to the question is B: 50%.

Step-by-step explanation:

Nondisjunction during meiosis can lead to gametes with an incorrect number of chromosomes. Specifically, if nondisjunction occurs during meiosis I, the homologous chromosomes fail to separate properly. This results in two gametes with an extra chromosome (n+1) and two gametes with one less chromosome (n-1). For an organism with a haploid number (n) of 8, if nondisjunction of one chromosome pair occurs during meiosis I, then two out of the four resulting gametes will have seven chromosomes.

Therefore, the percentage of gametes that will have only seven chromosomes is 50%, as two out of four represent half of the gametes produced. The correct answer to the question would be B: 50%.