Complete the sentence by putting a cross (X) in the box next to your answer - Edexcel - GCSE Biology - Question 5 - 2013 - Paper 1

This Punnett square shows the combinations of sex chromosomes from the male and female parents.

The chance of having a female child (XX) is 50%. Therefore, the percentage chance is 50%.

The menstrual cycle can be described in several stages:

1. Menstruation: This occurs between day 1 and day 5/6, where the lining of the uterus is shed.

2. Rebuilding the lining: After menstruation, the lining of the uterus is built back up, preparing for a potential pregnancy.

3. Ovulation: At around day 14, ovulation occurs, where an egg is released from the ovary.

4. Preparation for pregnancy: The lining of the uterus is maintained and thickened to prepare for a fertilised ovum.

5. If not fertilised: If the ovum is not fertilised, the cycle starts again.

If a woman becomes pregnant, the uterus lining is maintained and continues to thicken to support the developing embryo. Hormones such as progesterone help to sustain the lining, preventing it from being shed until after the delivery of the baby.