F.3 bio,,about M..

a(ii)Menstrual period is defined as the sloughing off of the
endometrium. This implying the decrease in the thickness
of endometrium due to the lack of progesterone and oestrogen.
Hence, from the graph, just 0 to 5 day and also the starting
day on 28th.(due to decrease in the thickness of endometrium )

b(i)The endometrium increases its thickness gradually from minium
on day 5 to maximum on day 15

c(i)Ovulation occurs on day 14 due to the completion of the increase
in the thickness of endometrium .
c(ii)Ovulation occurs again ONLY WHEN the thickness of endometrium
decrease to minimum. (原理: The increase in the thickness of the
endometrium is due to the high level of progesterone and oestrogen
which (both of them) will inhibit a hormone called follicle
stimulating hormone ,FSH, from being secreted by anterior pituitary
gland. Without, FSH, the granuolsa cell cannot form egg shell that
means no ovulation.其實你無須要知的,只給你作參考而已)

(d)The reasons is:
1 day after ovulation, the sperm can meet the egg cell in highest chance,
leading to pregnancy.
For 3 day before ovulation, there is still a chance for a egg cell to be
produced before 14th day. In order to lowering this risk, mating should
be avoided. (The ovulation day on 14th is just an assumption, but some
women maybe not follow this rule. Hence it is necessary to avoid).

Endometrium (子宫內膜) = uterine lining當你寫Endometrium時,
個閱卷員會明你的意思的.

你個圖非常清,是用digital camera影的嗎?