Answer:
Even though it can be undone, a new product is formed in photosynthesis. So it's a chemical process
Because clouds are to high and not able to be held
Pigs I believe because we take organs from them to perform transplants
Probably for easier movement of the chromatin or chroma.....I forgot the full name. but this is because the DNA inside will be separating until it forms two whole cells. if it didn't disintegrate it would probably either take more energy (and possibly split open the nucleus anyways), or not happen.
The process which ribosomes in a cell's cytoplasm create proteins, following transcription of DNA to RNA in the cell's nucleus.