1.1. The genetic disorder Down's syndrome is a condition caused by a change in the chromosomes.

Figure 3 shows the chromosomes from one cell of a person with Down's syndrome.

Figure 3

How does Figure 3 show that this person is female?

1.2. Describe how the chromosomes shown in Figure 3 are different from the chromosomes of a person who does not have Down's syndrome. 

1.3. As a woman gets older the chance of her having a baby with Down's syndrome increases.

Figure 4 shows this.

Figure 4

The chance of a 25-year-old woman having a baby with Down's syndrome is 1 per 1000 births.

What is the chance of a 40-year-old woman having a baby with Down's syndrome?

1.4. Some older mothers may choose to undergo embryo screening.

(i) What is embryo screening?

[1]

(ii) Why do some people disagree with the practice of embryo screening for pregnant women?

[2]