1. A – The reproductive system
The structure and function of reproductive organs and gametes and their role in fertilisation
Hormonal control of reproduction
The biology of controlling fertility
Ante- and postnatal screening

2. KA 3: The Biology of Controlling Fertility
(a) Basis of controlling fertility
(d) Contraception
(b) Fertile Periods
(c) Treatments for infertility

3. The Biology of Controlling Fertility (a) + (b)
Explain why infertility treatments and contraceptives are based on the ‘biology of fertility’
State which sex is continuously fertile
Explain why this sex is continuously fertile
State which sex is cyclically fertile
Explain why this sex is cyclically fertile
Describe two simple changes which occur in a female immediately following ovulation and could be used to identify her fertile period.
Identify the hormone responsible for these changes.

4. What is “Biology of Fertility”?
Biology of fertilisation refers to the information you learnt in key areas 1 and 2:
Structure and function of reproductive organs
Site of gamete production
Requirements for gametes
Hormone production and their effects
This information helps people to understand how, when and what is needed for fertilisation to occur.
This is important to know for when a couple ARE trying or ARE NOT trying to conceive a baby
Therefore, this knowledge of ‘the biology of fertilisation’ is effective in:
Designing infertility treatments
Devising methods of contraception

5. (a) The basis of controlling fertility
Infertility treatments and contraceptives are based on the biology of fertility.
Both rely on knowledge of when and where the gametes will be released (i.e. fertile periods) and the pattern of hormones which control the female menstrual cycle.

6. Fertile Periods: Males vs. Females
THINK / PAIR / SHARE
Who do you think is continuously fertile?
Explain why.
Who do you think has a specific period of fertility?

7. (b) Fertile Periods: Males vs. Females
Men are continuously fertile
This is because:
This is in great contrast with the cyclical fertility in females…
Negative feedback effect of testosterone
Constant levels of pituitary hormones in bloodstream maintained
Steady quantity of testosterone being secreted and sperm being produced

8. Fertile Periods: Males vs. Females
Women have a period of fertility being restricted to 3-4 days immediately after ovulation.

9. Calculating fertile periods
The calculation of fertility can help a couple (who wish to have a child) know when sexual intercourse is most likely to achieve fertilisation.

10. Calculating fertile periods
Temperature:

11. Calculating fertile periods
Temperature:
Approx. 1 day after the surge of LH and ovulation, a woman’s temperature rises by °C, due to the action of progesterone and remains elevated during the luteal phase

12. Calculating fertile periods
Mucus:

13. Calculating fertile periods
Mucus:
During the fertile period, the mucus secreted into the vagina is thin and watery to allow sperm easy access to the female reproductive system.
However, after ovulation, the mucus gradually increases in viscosity, due to progesterone levels.
This shows the system has returned to the infertile phase.