The electron transport system in the light dependent reaction of photosynthesis is the one that is responsible for the production of electrons that are used as precursor for NADPH production. The NADPH and the other products that are made during the light dependent reaction are used during the dark reaction to produce sugar molecules. So, if the electron transport is disabled, glucose molecule will not be produced during the dark reaction.<span />
Nonsense mutations make stop codons. If the mutation is towards the beginning of a gene, then the protein that gets created will be cut short and not function properly. But if it was towards the end, there is still a chance that the protein will still be able to work.
