Meiosis

Question 1

Homologous chromosomes carry the same genes but they are not genetically identical

Explain why (1)

Answer 1

Carry different alleles

Question 2

Appearance of each chromosome in figure 2 is different from those shown in figure 1

Explain why (1)

Answer 2

Chromatids haven’t been replicated

Question 3

During meiosis, one chromosome from each homologous pair goes to each of the cells produced

Explain why this is important (2)

Answer 3

To get haploid cells

So each cell gets one copy of each chromosome

Question 4

Describe how crossing over occurs during meiosis 1 (2)

Answer 4

Chromosomes in each pair twist around each other

Chromatids break and rejoin to chromatid on sister chromosome

Question 5

In tissues that produce gametes, there is a greater proportion of cells undergoing meiosis in male tissue than in female tissue

Suggest one advantage of this (1)

Answer 5

More gametes produced

Question 6

Suggest why there are fewer gametes with genotypes Gd and gD than GD and gd (1)

Answer 6

Crossing over is infrequent between close genes