Question

The graph given below shows how the lining of the uterus in a female who has achieved puberty varies with time.
Examine the graph and answer the following questions.



1. What is happening between A and B?
2. Mark the corresponding points in the second menstrual cycle when the same happens.
3. Fertilization occurs on day 16 of the second menstrual cycle. How do you expect the graph to behave after point C? Will the pattern of the first and second months be followed?

Answer 1

1. The period between A and B represents the menstrual flow. During this phase the uterus lining is shed along with blood and moves out of the body in the form of bleeding.

2. The points I and II correspond to the period when bleeding/menstrual flow will occur.



3. Since fertilisation occurs on day 16, the graph after point C will be straight lined. It is because, once fertilisation occurs, the uterus lining is retained and no bleeding/menstrual flow occurs during that period.