Cells- Topic 5- meiosis

Question 1

what is interphase in meiosis?

Answer 1

1. DNA is in chromatin form.
2. DNA replication occurs.

Question 2

What is prophase 1 in meiosis?

Answer 2

1. Chromatin condenses into chromosomes.
2. Homologous chromosomes further condense.
3. Crossing over of non-sister chromatids occurs.
4. Chromosomes randomly attach to cytoskeleton.

Question 3

what is metaphase 1 in meiosis?

Answer 3

1. homologous chromosomes line up along the metaphase plate.
2. independent assortment occurs (random orientation of homologous chromosome pairs)

Question 4

what is anaphase 1 in meiosis?

Answer 4

1. Homologous chromosomes separate.
2. Cytoskeleton pulls homologous chromosomes to opposite poles.

Question 5

what is telophase 1 in meiosis?

Answer 5

1. Chromosomes decondense into chromatin
2. Cytokinesis begins.
3. Two cells formed.

Question 6

what is prophase 2 in meiosis?

Answer 6

1. Chromatin condenses into chromosomes.
2. Chromosomes randomly attach to cytoskeleton.

Question 7

what is metaphase 2 in meiosis?

Answer 7

1. Chromosomes align along the cell equator.

Question 8

What is anaphase 2?

Answer 8

1. Cytoskeleton pulls chromatids apart to opposite poles.

Question 9

what is telophase 2 in meiosis?

Answer 9

1. Chromosomes decondense into chromatin and nuclear membrane reforms.
2. Cytokinesis begins.
3. Four cells formed.

Question 10

how many chromosomes does each cell have after meiosis?

Answer 10

After meiosis, each cell ends up with half the original number of chromosomes.

Question 11

why is crossing over important in meiosis?

Answer 11

During Prophase 1 homologous chromosomes are paired, chromatids are intertwined, non-sister chromatids of homologous chromosomes break and re-join forming new combinations of genes.

Question 12

why is independent assortment important in meiosis?

Answer 12

Random alignment of homologous chromosomes across the equator of the cell in metaphase 1, resulting in a new combination of maternal and paternal genes.

Question 13

how does fertilisation restore the diploid number of a cell?

Answer 13

fertilisation is the fusion of two gametes (sperm and egg) which creates a zygote, restoring the diploid number. fertilisation is random and contributes to genetic variation.

Question 14

compare the products of mitotic and meiotic cell division

Answer 14

mitotic is asexual, produces 2 genetically identical cells, and usually remains diploid. Meiotic is sexual, produces 4 genetically different cells, and goes from diploid to haploid.

Question 15

Compare the sources and degree of genetic variation of the products of asexual and sexual reproduction.

Answer 15

In Mitotic division:
1. Cells produced have little genetic variation.
2. Mutations can occur in DNA replication.

In Meiotic
1. Cells produced have genetic variation.
2. Crossing over in Prophase 1.
3. Independent assortment in Metaphase 1.
4. Random union of gametes during fertilisation.