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Figure 4 shows how hormone concentrations vary during a normal human menstrual cycle if a woman does not become pregnant - AQA - GCSE Biology Combined Science - Question 6 - 2018 - Paper 2
Question 6
Figure 4 shows how hormone concentrations vary during a normal human menstrual cycle if a woman does not become pregnant. Calculate the rate of increase in LH conce... show full transcript
Worked Solution & Example Answer:Figure 4 shows how hormone concentrations vary during a normal human menstrual cycle if a woman does not become pregnant - AQA - GCSE Biology Combined Science - Question 6 - 2018 - Paper 2
Step 1
Calculate the rate of increase in LH concentration between day 9 and day 12
Answer
To calculate the rate of increase in LH concentration, we first need to determine the LH values on day 9 and day 12 from Figure 4.
- On day 9, the LH concentration is approximately 15 arbitrary units.
- On day 12, the LH concentration is approximately 45 arbitrary units.
Now, we calculate the rate of increase:
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Find the difference in LH concentration:
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Calculate the time interval (from day 9 to day 12) which is 3 days or 72 hours.
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Now calculate the rate of increase per hour:
Rounding to 2 significant figures, the rate is approximately 0.42 arbitrary units per hour.
Step 2
Describe the sequence of hormone interactions in the menstrual cycle
Answer
The menstrual cycle involves a complex interaction between different hormones, primarily FSH, LH, oestrogen, and progesterone. The sequence is as follows:
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FSH (Follicle Stimulating Hormone): Produced by the pituitary gland, it stimulates the growth of follicles in the ovaries, leading to the maturation of an egg.
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Oestrogen: Secreted by the developing follicles, oestrogen contributes to the thickening of the uterine lining. As its levels rise, it also exerts a negative feedback on FSH production to prevent further follicle stimulation.
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LH (Luteinizing Hormone): Triggered by high levels of oestrogen, there's a sudden surge in LH on day 14 of the cycle, which results in ovulation (release of the egg).
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Progesterone: After ovulation, the empty follicle transforms into the corpus luteum, which secretes progesterone. Progesterone maintains the uterine lining and further inhibits FSH and LH production.
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If pregnancy does not occur, progesterone levels fall, leading to the breakdown of the uterine lining and the start of menstruation.
Step 3
Suggest one advantage of using a progesterone patch rather than a progesterone oral contraceptive
Answer
One advantage of using a progesterone patch is that it can provide a more stable release of hormones, leading to fewer side effects compared to oral contraceptives, which may cause fluctuations in hormone levels. Additionally, the patch requires less frequent application compared to taking a pill every day.