Question 1: Define the menstrual cycle and explain its significance in human reproduction.

Answer: The menstrual cycle is a series of physiological changes in the female reproductive system that prepares the body for potential pregnancy, involving hormonal regulation, ovulation, and shedding of the uterine lining.

Question 2: Name the hormones primarily involved in regulating the menstrual cycle and specify their roles.

Answer: The main hormones are oestrogen, which promotes the growth of the uterine lining and regulates other hormones; progesterone, which maintains the uterine lining; and luteinising hormone (LH) and follicle-stimulating hormone (FSH), which control ovulation and hormone production.

Question 3: Describe the sequence of hormonal changes that occur during the first half of the menstrual cycle.

Answer: During the first half, FSH stimulates follicle development, leading to increased oestrogen production. Rising oestrogen causes the uterine lining to thicken and triggers a surge in LH, which leads to ovulation.

Question 1: If the average length of the menstrual cycle is 28 days, calculate the approximate day when ovulation occurs.

Answer: Ovulation typically occurs around day 14 of a 28-day cycle.

Question 2: A woman’s menstrual cycle lasts 32 days. Calculate the expected day of ovulation. Show your working.

Answer: Ovulation is expected around day 16 (32 ÷ 2).

Question 1: Describe a simple experiment to investigate the effect of oestrogen on the growth of the uterine lining in a laboratory setting.

Answer: An experiment could involve tissue culture of uterine lining cells exposed to varying concentrations of oestrogen. The growth of cells would be measured after a set period, with controls lacking oestrogen. Variables include oestrogen concentration (independent), cell growth (dependent), and temperature (control). Safety precautions include using sterile techniques and proper disposal of biological materials.

Question 2: Identify two variables in a study comparing hormone levels in women with regular versus irregular menstrual cycles.

Answer: Variables could include hormone levels (independent variable) and cycle regularity (dependent variable).

Question 1: In a study, women with regular menstrual cycles showed a peak in LH levels on day 14, whereas women with irregular cycles showed no clear peak. Explain what this indicates about ovulation in both groups.

Answer: The peak in LH indicates ovulation. The absence of a clear LH peak in irregular cycles suggests that ovulation is less predictable or absent, indicating hormonal imbalance or anovulatory cycles.

Question 2: A patient reports irregular menstrual cycles and low levels of progesterone. Based on this information, suggest possible causes related to hormonal regulation.

Answer: Possible causes include hormonal imbalances such as low luteinising hormone (LH) or follicle-stimulating hormone (FSH) production, poor function of the ovaries, polycystic ovary syndrome (PCOS), or issues with the hypothalamus or pituitary gland affecting hormone secretion. These imbalances can lead to irregular ovulation and low progesterone levels.

Question 1: Explain how hormonal contraceptives work to prevent pregnancy by affecting the menstrual cycle.

Answer: Hormonal contraceptives contain synthetic oestrogen and progesterone, which inhibit ovulation by preventing the LH surge, thicken cervical mucus to block sperm, and thin the uterine lining, making implantation less likely.

Question 2: Discuss the importance of understanding the menstrual cycle for improving treatments for reproductive health issues.

Answer: Understanding the menstrual cycle allows healthcare professionals to diagnose hormonal imbalances, plan treatments for conditions like infertility, PCOS, or endometriosis, and develop contraceptive methods. It also helps in managing menstrual disorders and improving overall reproductive health through targeted therapies and lifestyle recommendations.