<span>The food chain describes who eats whom in the wild. Every living thing—from one-celled algae to giant blue whales—needs food to survive. Each food chain is a possible pathway that energy and nutrients can follow through the ecosystem.</span>
The substance is your saliva
When you look at the orange you see those little dots on it? Those are the seeds they are spread when they are still on the the tree and they blow away onto the ground.
C, (infeaspecific competition)
