the radiations that are used to treat cancers are of the gamma type. primarily emitted from cobalt-60 (a radioactive isotope). and it is more controlled than other radiation exposures. i.e. solar radiation which is not controlled.
hope that this helps.
In photosynthesis experiment, the effect of the light will be observe during the starch production- thus you need to have a plant without a starch to observe if the starch is produced during photosynthesis. Letting the leaves of the plant deprived from light for 48 hours will be forced to use its reserved starch making the storage of the starch decrease.
The answer is nucleus (structure A)
because nucleus DNA would be destroyed