Questions: I want you to look at your notes on mitosis or Figures 7.8 and 7.11 in your textbook (pages 157 and 161, respectively) compare the chromosomal arrangement in the mitotic metaphase and metaphase I of meiosis I . What is the main difference? The homologous chromosomes are arranged horizontally, next to each other, in mitosis and vertically along the middle in meiosis I The homologous chromosomes in mitosis are all identical. There are no homologous chromosomes in mitosis. the homologous chromosomes are arranged vertically along the middle in mitosis and horizontally, next to each other, in meiosis I.

The answer is the last one: the homologous chromosomes are arranged vertically along the middle in mitosis and horizontally, next to each other, in meiosis I.

Explanation for each option:

1. The homologous chromosomes are arranged horizontally, next to each other, in mitosis and vertically along the middle in meiosis I.

   • This statement is incorrect. In mitosis, chromosomes align vertically along the metaphase plate. In meiosis I, homologous chromosomes pair up and align horizontally next to each other along the metaphase plate.

2. The homologous chromosomes in mitosis are all identical.

   • This statement is incorrect. In mitosis, sister chromatids are identical, but homologous chromosomes are not necessarily identical as they come from different parents.

3. There are no homologous chromosomes in mitosis.

   • This statement is incorrect. Homologous chromosomes exist in the cell, but they do not pair up as they do in meiosis. Instead, sister chromatids are separated during mitosis.

4. The homologous chromosomes are arranged vertically along the middle in mitosis and horizontally, next to each other, in meiosis I.

   • This statement is correct. In mitosis, chromosomes align vertically along the metaphase plate, while in meiosis I, homologous chromosomes pair up and align horizontally next to each other.

In summary, the main difference in chromosomal arrangement between mitotic metaphase and metaphase I of meiosis I is that in mitosis, chromosomes align vertically along the metaphase plate, whereas in meiosis I, homologous chromosomes align horizontally next to each other.