SL/HL Topic D3.1 Reproduction (id: deecc9c76)

本题目来源于试卷: SL/HL Topic D3.1 Reproduction，类别为 IB生物学

[问答题]
7. The image shows the coqw c9k(n0*j gwz8v wjft;-0 u)k nt)hhncentration of hormones of the ovarian -la cl/zeno9 )and uterine parts of the menstrual cycle over the 28-day cyc9nl-)/ l zcaoele.

Using the diagram explain one example of positive and one example of negative feedback in the menstrual cycle.

参考答案:

Positive feedback

Positive feedback is when a stimulus causes a response which increases the stimulus

e.g. As oestradiol reaches higher levels positive feedback causes an increase in FSH & LH levels. Increased release of FSH causes further development of the follicle and increased oestradiol.

Negative feedback example:

Negative feedback is when a stimulus causes a response which reduces the stimulus.

e.g. Low levels of oestradiol from a developing follicle exert negative feedback to reduce LH & FSH production by the pituitary. This reduces the stimulus for follicles to develop and release oestradiol.

e.g. Progesterone and some oestradiol released by corpus luteum after ovulation, inhibits the production of FSH and LH by the pituitary, which reduces the development of the corpus leuteum.

e.g. Growth of endometrium followed by maintenance.

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