Meiosis

Question 1

How does meiosis result in half chromosomes number and show genetic variation?

Answer 1

• homologous chromosomes pair up
• crossing over forms chiasmata
• produces new combo of alleles
• chromosomes separate randomly
• produce different combo of chromosomes
• chromosomes separate at meiosis II

Question 2

What does a chromosome look like in prophase? Why?

Answer 2

• chromosomes formed of two chromatids
• cuz DNA replication has occurred
• sister chromatids held by centromere

Question 3

What happens in the 1st division in meiosis?

Answer 3

• homologous pairs of chromosomes
• one of each into a daughter (haploid) cell

Question 4

What happens in the 2nd division in meiosis?

Answer 4

• sister chromatids desperate
• centromere divides

Question 5

Why does meiosis produce genetic variation?

Answer 5

• random assortment of homologous chromosomes
• crossing over forms chiasmata

Question 6

Describe the process of crossing over which increases genetic diversity

Answer 6

• homologous chromosomes pair up
• crossing over forms chiasmata
• alleles are exchanged
• produce new combo of alleles

Question 7

How can a mutation cause a change in the chromosome number?

Answer 7

• meiosis
• homologous pairs of chromosomes don’t separate

Question 8

Why will a mutation in the chromosome number not occur to all cells? (2)

Answer 8

-all cells derived from single cell by mitosis
-mitosis produces genetically identical daughter cells

Question 9

Give an advantage of asexual reproduction (1)

Answer 9

-only needs one parent so can colonise new env