Question

Changes and effect on plant life, human and marine life if there is no sun

Answer 1

All plants would die if there was no sun as the plants cannot perform photosynthesis in the absence of sunlight.
Humans those who are vegetarians or non-vegetarians will have a bad time as there will not be any food available at the trophic level.
All fishes in water will die as no oxygen will be created and thus it will not fuse with water and all fishes and plants in water will die.