Meiosis

Question 1

What does meiosis do

Answer 1

Produces cells which are haploid for sexual reproduction (gametes)

Question 2

Prophase I

Answer 2

• chromosomes form bivalents (pairs of homologous chromosomes)
• arms of chromatids may cross over to form chiasmata. Genetic material can be exchanged between chromosomes and increase genetic variation

Question 3

Describe crossing over

Answer 3

Arms of chromatids cross over each other, forming chiasmata. Genetic material can be exchanged between homologous chromosomes. This increases genetic variation

Question 4

Metaphase I

Answer 4

• homologous chromosomes arrange themselves in pairs along equator.

• random assortment occurs. Homologous chromosomes from both parents arrange themselves randomly along spindle, facing each pole

Question 5

Describe random assortment

Answer 5

Homologous chromosomes from both parents arrange themselves randomly along the spindle facing each pole

Question 6

Anaphase I

Answer 6

Chromosome bivalents separate as each chromosome is pulled by its centromere (doesn’t split) towards opposite poles

Question 7

Telophase I

Answer 7

• nuclear envelope reforms around the chromosomes at the poles.
• as the chromosome pairs have separated, chromosomes are no linger in lairs and the cells are haploid

Question 8

Prophase, metaphase, anaphase and telphase II

Answer 8

Events occur in each new nucleus exactly like in mitosis. Then cytokinesis occurs to create 4 genetically varied cells

Question 9

Compare mitosis and meiosis

Answer 9

• 1 nuclear division in Mitosis, 2 in meiosis.
• 2 daughter cells in Mitosis, 4 in meiosis.
• genetically identical cells in mitosis, genetically different in meiosis.
• no pairing of homologous chromosomes in mitosis, is in meiosis to form bivalents.

Question 10

Can haploid cells divide by meiosis?

Answer 10

No, only mitosis