Section 3 - Cell Division (Meiosis)

Question 1

In sexual reproduction. are the offspring genetically identical or different from their parents?

Answer 1

Different

Question 2

Each parent produces sex cells (_________) containing just one set of genetic material. This involves a special kind of cell division, called _________.

Answer 2

gametes, meiosis

Question 3

What happens during fertilisation?

Answer 3

The nuclei of the gametes join together to form a zygote

Question 4

As they have only one set of genetic material, gametes are described as being _________.

Answer 4

haploid

Question 5

The zygote has two complete sets of genetic material, and is said to be _________.

Answer 5

diploid

Question 6

How does the zygote form the embryo?

Answer 6

The zygote grows by simple cell division (mitosis) to form the embryo.

Question 7

Where are the only cells in the human body that divide by meiosis?

Answer 7

Testes and ovaries

Question 8

What do the cells in the testes and ovaries divide to produce?

Answer 8

Gametes (sperm and eggs)

Question 9

What is step one of meiosis?

Answer 9

The DNA replicates, so each of the 46 chromosomes become two chromatids joined by a centromere.

Question 10

What is step two of meiosis?

Answer 10

The 46 chromosomes sort themselves into the 23 homologous pairs, then the pairs separate. One of each pair goes to one side of the cell and one goes to the other.

Question 11

What is step three of meiosis?

Answer 11

The cytoplasm now divides. Each of the new cells contains 23 chromosomes (consisting of two chromatids joined by a centromere).

Question 12

What is step four of meiosis?

Answer 12

In both of these new cells the chromatids separate and the cytoplasm divides to form two cells.

Question 13

What is step five of meiosis?

Answer 13

At the end of meiosis, four haploid cells have been produced from every original diploid cell.