What must happen before a chemical reaction can begin?

Consider an organism that is eukaryotic, found in both unicellular and multicellular forms, may resemble a plant but is not photosynthetic, has chitin in its cell walls, and absorbs organic nutrients from decomposing material in the environment. this organism would be classified as which of the following types of organisms? a. fungib. protozoac. bacteriad. archaea

How does an angiosperm prevent self pollination

What were the main components of earth’s earliest atmosphere? oxygen and ammonia hydrogen and helium oxygen and nitrogen hydrogen and nitrogen