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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 1–9 1.85 10–14 ... 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 28-day menstrual cycle, progesterone levels fluctuate notably:
- From days 1 to 9, levels remain low at 1.85 nmol/l.
- From days 10 to 14, there is a slight decrease to 1.48 nmol/l.
- A significant increase is observed from days 15 to 17, where levels rise to 14.28 nmol/l, indicating the start of the luteal phase.
- The peak progesterone level occurs between days 18 to 23, reaching 35.27 nmol/l, supporting potential pregnancy.
- Lastly, from days 24 to 28, levels decrease to 17.11 nmol/l, as the cycle approaches menstruation.
Step 2
Explain why progesterone levels changed following day 14.
Answer
Following day 14, progesterone levels increased due to the secretion from the corpus luteum, which forms from the ruptured follicle post-ovulation. The corpus luteum produces progesterone, which prepares the uterine lining for potential implantation of a fertilized egg. If fertilization does not occur, the corpus luteum degrades, leading to a decline in progesterone levels.