Any one want to talk? so bored

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

The idea that all living things are made up of cells is considered scientific law. this means the idea is an emerging scientific idea that has a logical explanation. has been tested with similar results at least twice. is supported by scientific consensus and a large amount of evidence. has been rejected only once by the scientific community

List five ways we are indebted to phytoplankton