Are chemicals internal or external?

As , plants meet their needs for making food from air, soil, water, and the sun's energy in a process called there are plants called grow high in trees without here are words to put in the blanks. 1.) producers 2.) consumers 3.) chloroplasts 4.) epiphytes

When does dna replication(make a copy of itself)?

In what for do plants utilize nitrogen? why do they need nitrogen?