Year 10 – Chapter 1.2

Question 1

Recall the key terms described by:

• One of the strands of a chromosome following replication
• the process of making copies of DNA

Answer 1

• Chromatid

* DNA Replication

Question 2

Name the type of cell division that is responsible for growth and repair in the body.

Answer 2

Mitosis.

Question 3

State the type of cell division that produces gametes.

Answer 3

Meiosis.

Question 4

Explain why it is essential for chromosomes to replicate before cell division occurs.

Answer 4

Each cell needs to maintain the same number of chromosomes, therefore, the chromosomes must replicate before the cell undergoes mitosis or meiosis.

Question 5

A gamete (sex cell) is haploid. Explain what this means.

Answer 5

Haploid means that the cell has half the usual number of chromosomes (46). A haploid cell has 23 chromosomes.

Question 6

• State the types of cell division involved in creating a puppy.
• Explain the role of each type of cell division.

Answer 6

• Mitosis and Meiosis.
• Meiosis occurs when the the two sex cells meet and form a zygote. Once the zygote is formed, mitosis occurs during the rest of its development.

Question 7

Describe the role of the network of fibres in cell division.

Answer 7

These fibres help to split the centromere during anaphase.

Question 8

Explain why it is important to reduce the number of chromosomes when gametes are formed.

Answer 8

The gametes are sex cells, and therefore must meet its sexual counterpart and form a zygote. This zygote will be a diploid cell, due to having half of its chromosomes coming from its mother and another half from its father.

Question 9

Explain what happens in the cell nucleus between cell divisions.

Answer 9

After the chromosomes are pulled to either side of the cell during anaphase, the cell enters telophase, in which there are two nuclei in one cell. This happens due to the the chromosomes being pulled so far from the equator of the nucleus, the nucleus splits into two.

Question 10

A horse has 64 chromosomes in its body cells. How many chromosomes will be in each of its gametes?

Answer 10

32 chromosomes.

Question 11

Calculate how many chromosomes will be in the cells of a tomato plant where there are 12 chromosomes in a gamete.

Answer 11

24

Question 12

Contrast haploid cells with diploid cells.

Answer 12

Diploid cells have the maximum number of chromosomes, haploid cells have half that number.

Question 13

Compare chromosomes and chromatids.

Answer 13

Chromosomes are two strands of chromosomes. Chromatids is one strand.