A trait that helps a species become better suited to its
environment

this is a good question! i'll do some research and come back when i have the answer!

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

sex cells are usually half's then they find another half and make a fertilize egg