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

The Punnett square will be completed as follows:

From the Punnett square, there are 2 female outcomes (XX) and 2 male outcomes (XY). Therefore, the percentage chance that a child will be female is:

$\frac{2}{4} \times 100 = 50\%$

The menstrual cycle can be described in several stages:

1. Menstruation (Days 1-5): This phase begins when the lining of the uterus is shed, leading to menstrual bleeding.
2. Follicular Phase (Days 1-14): After menstruation, the uterine lining begins to thicken. Follicle-stimulating hormone (FSH) stimulates the growth of ovarian follicles.
3. Ovulation (Day 14): A surge in luteinizing hormone (LH) triggers ovulation, releasing an egg from the ovary.
4. Luteal Phase (Days 14-28): Following ovulation, progesterone is secreted, further thickening the uterine lining to prepare for a fertilized ovum.

If a woman becomes pregnant, the lining of the uterus remains thick and is maintained. This is essential to support the developing embryo. The hormone progesterone continues to be produced to prevent menstruation, ensuring that the uterine lining stays in place to provide the necessary nutrients and environment for the growing fetus.