Question

1. which of the following structures must be separated to form a haploid cell? a) sister chromatids. b) homologous chromosomes. c) x and y chromosomes during sperm production. d) both a) and b). e) both b) and c). 5. using your lecture notes, and textbook figures focus figure 3.4 (page 100 & 101) 27.4, and focus figure 27.1, compare and contrast the events of mitosis with those of meiosis i and meiosis ii.

phase	mitosis	meiosis i	meiosis ii
metaphase/metaphase i/metaphase ii
anaphase/anaphase i/anaphase ii
telophase/telophase i/telophase ii

exercise 5 - on early development: the process of meiosis is critical to the production of haploid gametes. haploid gametes can then be combined through a process called “fertilization”, during which a sperm cell contacts and penetrates an early stage of an ovum (egg) called a “secondary oocyte”. once the haploid (n) nuclei of the sperm and the ovum combine, a single new diploid (2n) cell is formed called a zygote. all of the cells that make up your body and all of the cells that make up most of the extraembryonic membranes (including the fetal part of the placenta) will develop from this one single cell through the processes of mitosis and differentiation.

Explanation:

1. In meiosis, homologous chromosomes separate during meiosis I and X and Y chromosomes (in sperm - production) also separate during meiosis I to form haploid cells. Sister chromatids separate during meiosis II and mitosis, but their separation does not directly lead to the formation of haploid cells from diploid cells.
2. Mitosis is a process of cell division for growth, repair, and asexual reproduction, resulting in two genetically identical diploid daughter cells. Meiosis I is a reduction - division where homologous chromosomes pair, cross - over, and separate, resulting in two haploid cells with replicated chromosomes. Meiosis II is similar to mitosis in that sister chromatids separate, resulting in four haploid cells. In prophase of mitosis, chromosomes condense. In prophase I of meiosis, homologous chromosomes pair and cross - over. In prophase II of meiosis, chromosomes condense again. In metaphase of mitosis, chromosomes line up at the equator. In metaphase I of meiosis, homologous chromosome pairs line up. In metaphase II of meiosis, chromosomes line up as in mitosis. In anaphase of mitosis, sister chromatids separate. In anaphase I of meiosis, homologous chromosomes separate. In anaphase II of meiosis, sister chromatids separate. In telophase of mitosis, two nuclei form. In telophase I of meiosis, two nuclei form in the two haploid cells. In telophase II of meiosis, four nuclei form in the four haploid cells.

Answer:

1. E. Both b) and c).

5.

PHASE	MITOSIS	MEIOSIS I	MEIOSIS II
Metaphase/Metaphase I/Metaphase II	Chromosomes line up at equator.	Homologous chromosome pairs line up.	Chromosomes line up as in mitosis.
Anaphase/Anaphase I/Anaphase II	Sister chromatids separate.	Homologous chromosomes separate.	Sister chromatids separate.
Telophase/Telophase I/Telophase II	Two nuclei form.	Two nuclei form in two haploid cells.	Four nuclei form in four haploid cells.