Photosynthesis is important to living organisms because it is

the foundation of most food chains.
the source of nitrogen gas in the air.
how animals get carbon dioxide to breathe.
the process that occurs in most ecosystems.

How did the research presented in the article affect scientists' understanding of the evolution of eukaryotes

Which statement describes characteristics of planarians? a they live in oceans, are parasites, and reproduce only sexually. b they live in fresh water, are parasites, and reproduce only asexually. c they live in oceans, are free living, and reproduce sexually and asexually. d they live in fresh water, are free living, and reproduce sexually and asexually.

How can an organ, such as the lungs, work for multiple body systems?