Which one of the following occurs in meiosis but not in mitosis?Multiple choice question.Sister chromatids separationSpindle fibers attaching to centromeresCrossing-overDiploid cellsDisintegration of the nuclear envelope

The correct answer is "Crossing-over". This process occurs during meiosis but not in mitosis.

Here's a step-by-step explanation:

1. Both meiosis and mitosis involve the separation of sister chromatids, the attachment of spindle fibers to centromeres, and the disintegration of the nuclear envelope. Therefore, these options are not unique to meiosis.

2. Diploid cells are not unique to meiosis either. Both meiosis and mitosis can start with diploid cells.

3. Crossing-over, however, is a process that occurs only in meiosis. During the prophase I stage of meiosis, homologous chromosomes pair up and exchange segments of DNA in a process known as crossing-over. This leads to genetic recombination, increasing genetic diversity in the offspring. This does not occur in mitosis, where the goal is to produce two identical daughter cells.

The correct answer is "Crossing-over". This process occurs during meiosis but not in mitosis.

Here's a step-by-step explanation:

1. Both meiosis and mitosis involve the separation of sister chromatids, so this option is not correct.

2. Spindle fibers attaching to centromeres is a common process in both meiosis and mitosis, so this option is also not correct.

3. Crossing-over is a process where homologous chromosomes exchange genetic material. This occurs during the prophase I stage of meiosis but does not occur in mitosis, making this the correct answer.

4. Both meiosis and mitosis can start with diploid cells, so this option is not correct.

5. The disintegration of the nuclear envelope occurs in both meiosis and mitosis, so this option is not correct.