Question

nondisjunction is a mistake that happens when chromosomes fail to separate correctly during meiosis, the process that produces egg and sperm cells. when this occurs, some gametes receive too many chromosomes, while others receive too few. for example, in an organism with a haploid number of n = 8, each normal gamete should have 8 chromosomes. if nondisjunction happens during meiosis i, the homologous chromosome pairs don’t split apart, and all four resulting gametes are affected—two will have 9 chromosomes (n + 1) and two will have 7 chromosomes (n - 1). however, if nondisjunction occurs during meiosis ii, only half of the gametes are affected—one will have 9, one will have 7, and two will remain normal with 8. students can use this information to calculate what percentage of gametes are missing a chromosome or have an extra one when n = 8. one - word answer 1. what is the process called when chromosomes fail to separate properly during meiosis? true or false 2. nondisjunction can result in gametes with either too many or too few chromosomes. multiple choice (mcq) 3. in an organism with a haploid number of n = 8, if nondisjunction occurs during meiosis i, what percentage of gametes will have only 7 chromosomes? a. 0% b. 25% c. 50% d. 75% 4. during which stage of meiosis do sister chromatids fail to separate, leading to nondisjunction? a. meiosis i b. meiosis ii c. prophase d. cytokinesis 5. which of the following best describes the outcome of nondisjunction? a. all gametes are normal b. all gametes have the same number of chromosomes c. some gametes have extra or missing chromosomes d. it does not affect the number of chromosomes (answer key: 1. nondisjunction, 2. true, 3. c, 4. b, 5. c)

Explanation:

1. The text defines nondisjunction as the process where chromosomes fail to separate correctly during meiosis, answering the first - word question.
2. It is stated that when nondisjunction occurs, some gametes receive too many or too few chromosomes, making the true - or - false statement true.
3. When nondisjunction occurs during Meiosis I in an organism with \(n = 8\), four gametes are produced, two with \(n+1 = 9\) and two with \(n - 1=7\) chromosomes. So the percentage of gametes with 7 chromosomes is \(\frac{2}{4}\times100\%=50\%\).
4. Sister chromatids fail to separate during Meiosis II, leading to nondisjunction.
5. The outcome of nondisjunction is that some gametes have extra or missing chromosomes.

Answer:

1. Nondisjunction
2. True
3. C. 50%
4. B. Meiosis II
5. C. Some gametes have extra or missing chromosomes