Since Dolly the sheep, many other mammals have also been cloned by somatic cell nuclear transfer. The genetic material from a body cell is inserted into an egg cell that has had its own nucleus removed. The success rate ranges from 0.1% to 3%, which is why so few cloned animals have been produced.

Which of the following are possible correct reasons why cloning may fail?

1. An egg with a newly transferred nucleus may not begin to divide or develop properly.
2. The sperm cell may not fertilise the egg cell.
3. Implantation of the embryo into the surrogate mother might fail.
4. Implanted stem cells may not differentiate properly.
5. The enucleated egg and the transferred nucleus may not be compatible.

Answer:

17) A

1 – Correct
If the off does not divide then the organism cannot form.

2 – Wrong
There is no use of sperm cells

3 – Correct
If the implantation fails, then the cloning will obviously fail

4 – Wrong
The egg must divide and not differentiate

5 – Correct
If the enucleated egg and the transferred nucleus are not compatible, then the cloning will not take place

Statements 1, 3 and 5 are correct so A is the answer.