4.6.1.2 Meiosis

Question 1

Explain how meiosis halves the number of chromosomes in gametes.

Answer 1

• They’re called “haploid” cells as they only contain half the genetic material of a normal cell (23 chromosomes)

Question 2

Explain how fertilisation restores the full number of chromosomes.

Answer 2

• They are called “diploid” cells as when two gametes fuse they form a normal cell (46 chromosomes)

Question 3

What do cells in reproductive organs do?

Answer 3

• Divide by meiosis from gametes

Question 4

What happens when a cell divides to form gametes?

Answer 4

• Copies of the genetic information are made
• The cell divides twice to form four gametes each with a single set of chromosomes
• All gametes are genetically different from each other

Question 5

Why do gametes join at fertilisation?

Answer 5

• To restore the normal number of chromosomes

Question 6

How does the new cell divide?

Answer 6

• The new cell divides by mitosis

Question 7

What happens as the embryo develops?

Answer 7

• As the embryo develops cells differentiate

Question 8

What happens to the number of cells?

Answer 8

• The number of cells increases