The graph shows how the plasma concentration of oestrogen and the thickness of the endometrium vary during a woman's menstrual cycle - Scottish Highers Human Biology - Question 4 - 2017
Question 4
The graph shows how the plasma concentration of oestrogen and the thickness of the endometrium vary during a woman's menstrual cycle.
(a) Ovulation occurs on day 15... show full transcript
Worked Solution & Example Answer:The graph shows how the plasma concentration of oestrogen and the thickness of the endometrium vary during a woman's menstrual cycle - Scottish Highers Human Biology - Question 4 - 2017
Step 1
Describe the role of oestrogen in triggering this event.
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Answer
Oestrogen stimulates the production of luteinizing hormone (LH), which is crucial for triggering ovulation. This hormone surge leads to the release of the egg from the ovary.
Step 2
State the thickness of the endometrium on day 15.
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Answer
The thickness of the endometrium on day 15 is 3 mm.
Step 3
Express, as a simple whole number ratio, the thickness of the endometrium on day 6 compared to day 22.
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The ratio is 1:4.
Step 4
Oestrogen stimulates thickening of the endometrium. Describe evidence from the graph which indicates that another factor also stimulates thickening of the endometrium.
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Answer
From the graph, it can be observed that the thickness of the endometrium continues to increase even after the oestrogen concentration begins to decrease around day 14. This suggests that another factor, potentially LH or progesterone, contributes to maintaining or stimulating thickness.
Step 5
Suggest one way in which the graph for the next menstrual cycle would differ from this one if the woman became pregnant during that cycle.
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If the woman became pregnant, the graph would likely show a sustained high level of oestrogen and a thicker endometrium throughout the cycle, rather than a decrease after ovulation.
Step 6
State how fertility drugs stimulate ovulation.
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Fertility drugs prevent the negative feedback effect of oestrogen, either by mimicking the action of FSH/LH or by stimulating the production of FSH/LH, thereby promoting ovulation.
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