A pregnant mouse is exposed to high levels of a chemical. Many of the mice in her litter are deformed, but when they are interbred with each other, all their offspring are normal. Which two of the following statements could explain these results? a) In the deformed mice, somatic cells but not germ cells were mutated. b) The original mouse's germ cells were mutated. c) In the deformed mice, germ cells but not somatic cells were mutated. d) The toxic chemical affects development but is not mutagenic.

The correct answers are - a) In the deformed mice, somatic cells but not germ cells were mutated and d) The toxic chemical affects development but is not mutagenic.

Explanation:

Mutation in the somatic cells do not pass in the offsprings and the only mutation in the germ cells can pass to the offspring because offspring are produced by the fertilization between different germ cells. Somatic cell mutation can only cause deformation in individuals but their offspring will be like normal offsprings.

The other cause may be that the toxic chemical used don't cause any mutation but just affect the development of mice so in this case genetic material will remain in normal state in deformed mouse and they will able to produce normal offsprings. So the right answer is a and d.