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Figure 5 shows the level of progesterone for a female during five different stages of the menstrual cycle - Edexcel - GCSE Biology Combined Science - Question 5 - 2016 - Paper 1
Question 5
Figure 5 shows the level of progesterone for a female during five different stages of the menstrual cycle. | days in the menstrual cycle | progesterone level (nmol/... show full transcript
Worked Solution & Example Answer:Figure 5 shows the level of progesterone for a female during five different stages of the menstrual cycle - Edexcel - GCSE Biology Combined Science - Question 5 - 2016 - Paper 1
Step 1
Describe the changes in progesterone levels during the 28-day cycle.
Answer
During the first nine days of the menstrual cycle, progesterone levels are relatively low, starting at 1.85 nmol/l. This level decreases slightly to 1.48 nmol/l between days 10 to 14. After day 14, there is a significant increase in progesterone levels, peaking at 35.27 nmol/l between days 18 to 23. Following this peak, the levels drop to 17.11 nmol/l during the last days of the cycle (days 24 to 28). Overall, the progesterone levels exhibit a rapid rise after ovulation and a subsequent decrease as the cycle concludes.
Step 2
Explain why progesterone levels changed following day 14.
Answer
Following day 14, the increase in progesterone levels is primarily due to the formation of the corpus luteum after ovulation. The corpus luteum produces progesterone to prepare the uterine lining for potential implantation of a fertilized egg. If fertilization does not occur, the corpus luteum degenerates, resulting in decreased progesterone levels as seen towards the end of the cycle.