Diversity and Selection

Question 1

Meiosis

Answer 1

A specialised cell division to form gametes

Question 2

Zygote

Answer 2

Fusion of 2 gametes

Question 3

Diploid

Answer 3

A full set of chromosomes in pairs

Question 4

Haploid

Answer 4

Half a set of chromosomes; one of each pair

Question 5

Homologous

Answer 5

A pair of chromosomes which have the same genes at the same locus

Question 6

Alleles

Answer 6

Different form of a gene

Question 7

Locus

Answer 7

Position on a chromosome where a gene is found

Question 8

Why is meiosis needed?

Answer 8

• maintain the diploid number of chromosomes
• genetic variation

Question 9

What happens during interphase before Meiosis?

Answer 9

DNA replication; 46 strands of DNA become 92Meisosi

Question 10

Explain DNA replication

Answer 10

• Semi-conservative replication
• DNA helicase binds to DNA, breaks H-bonds between strands + unwinds double helix
• Free-floating nucleotides bind to complementary bases (H-BONDS)
• Each strand used as template for new complementary strands
• DNA polymerase makes phosphodiester bonds between nucleotides
• 2 new strands synthesised

Question 11

What happens during Meiosis I?

Answer 11

• Start with a diploid cell: 2 pairs of homologous chromosomes
• Interphase
  Prophase:
  
  • Homologous pairs form