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Menstrual cycle Grade 12 Life Sciences Notes with Activities Questions and Answers
Notes
Day 1–7
- Ovaries: New follicles develop and secrete oestrogen
- Uterus: Lining breaks down and is released (menstruation)
Day 8–13
Ovaries: Mature Graafian follicle develops:
- The Graafian follicle moves to edge of the ovary
- It secretes oestrogen
Uterus: Oestrogen stimulates the endometrium to become thicker and develop more blood vessels and glands
Day 14
Ovaries: Graafian follicle bursts to release an egg cell. The process is called ovulation
Day 15–22
- Ovaries: The Graafian follicle becomes a corpus luteum that secretes progesterone
- Uterus: Progesterone stimulates the endometrium to become even thicker and to develop more blood vessels and glands, ready to receive the embryo if an egg cell is fertilised
Day 23–28
Ovaries: If fertilisation does not take place:
• The corpus luteum shrinks and stops secreting progesterone
If fertilisation takes place:
- The corpus luteum remains active in the ovary and continues to secrete progesterone
- No more follicles develop in the ovaries
- No menstruation takes place
PDF Downloadable Notes on Menstrual cycle:
Question and Answers Activities:
Find short and long questions for Grade 12 Life Sciences, which will help you to prepare for the exams, tests, practical tasks, and assignments.
Questions
- Name the hormones A and B.
- Give reasons for your answers in question 1.
- What event occurs on day 14?
- Name the other two hormones involved in this cycle.
- Did fertilisation occur during the cycle shown in Figure 4.6?
- Explain your answer in question 5.
Answers
Answers to activity 3
- A – Oestrogen B – Progesterone
- A: The Graafian follicle secretes oestrogen /Oestrogen reaches
- its maximum level before ovulation.
- B: The corpus luteum produces progesterone /Progesterone reaches its maximum level after ovulation.
- Ovulation
- LH and FSH
- No
- Progesterone levels decrease, towards the end of the cycle.
How to Pass Life Sciences Grade 12 with distinctions
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