Question

The accompanying diagram shows the uterine tubes of four women (P, Q, R and S)

In which of two women, fertilisation is impossible at present?
A. P and Q
B. Q and R
C. R and S
D. S and P

Answer 1

Hint:For the process of fertilisation, it is important for the egg and sperm to have a contact This would not be possible if the egg does not reach the uterus. Therefore, for this process to occur, the path should be clear for the ovule to reach the uterus without any obstruction.

Complete Step by Step Answer:
In the figure P, it is shown that there is partial blockage in the fallopian tubes. Thus, there is a probability that the ovule released from the ovary will reach the uterus. Thus, there are chances of fertilisation.

In the figure Q, we see a complete blockage of the fallopian tube from one side while the other fallopian tube provides no obstruction. Therefore, again fertilisation is possible due to the concept explained above.

In the figure R, there is complete blockage of fallopian tubes. This rules out any chance of fertilisation.

In the figure S, both the fallopian tubes are ligated. This too would not allow fertilisation as the carrier path has blocked.

Thus, we conclude that the correct answer is C: R and S

Note: In the figure S, the process that is shown is called Tubectomy. This is a surgical procedure that involves cutting and tying the fallopian tubes to prevent the entry of ovules in the uterus. Vasectomy on the contrary involves the process of ligation of vas deferens. This prevents the entry of sperm into semen. Both procedures are efficient contraceptive methods but have a poor reversibility rate.