Explain why an electron microscope would not be used to watch the heart of a water flea pumping

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

label a cell membrane

label b cytoplasm

label c ribosomes

label d dna

the membrane forms the outside of the cell

cytoplasm is the liquid within

ribosomes are the components within that distribute rna

the dna is the genetic make-up

the sun creates it's own light, also gives light and life to bunch of stuff like plants,animals,humans etc.photosyntesis is the process of making food which needs sun,water,nutrients etc.