Which of the following statements is true? a. More gametes will be affected if nondisjunction occurs during anaphase I than if nondisjunction occurs during anaphase II. b. Nondisjunction during anaphase I or anaphase II will have the same effect. c. More gametes will be affected if nondisjunction occurs during anaphase II than if nondisjunction occurs during anaphase I. d. Nondisjunction during anaphase I or anaphase II will have no effect on the gametes formed.

The correct answer is **a. More gametes will be affected if nondisjunction occurs during anaphase I than if nondisjunction occurs during anaphase II.**<br /><br />Here's why:<br /><br />* **Nondisjunction** is the failure of homologous chromosomes (anaphase I) or sister chromatids (anaphase II) to separate properly during meiosis. This results in some gametes having an extra chromosome and others missing a chromosome.<br /><br />* **Anaphase I:** Homologous chromosomes separate. If nondisjunction occurs here, *all* resulting gametes will be abnormal. Two gametes will have an extra chromosome, and two will be missing a chromosome.<br /><br />* **Anaphase II:** Sister chromatids separate. If nondisjunction occurs here, *half* of the resulting gametes will be abnormal. One gamete will have an extra chromosome, one will be missing a chromosome, and two will be normal.<br /><br /><br />Therefore, nondisjunction in anaphase I affects all four gametes, while nondisjunction in anaphase II affects only two of the four gametes.<br />