Living things require specific organic molecules in order to survive. the picture above represents some specific examples of foods that are mainly composed of one of these necessary organic molecules. the organic molecules found in these types of food are

a)
lipids.

b)
proteins.

c)
nucleic acids

d)
carbohydrates.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms