Ivan Pavlov discovered the principle of , in which a neutral stimulus acquires the ability to produce a response originally produced by another stimulus.

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

Which of the following shows the results that you would get if you tested beef using the four tests in the gizmo

Which of the following can occur to two segments of a population if they are geographically isolated 1.) they can only share some types of genes 2.)both groups most likely become extinct 3.)they find a way to come back together 4.)eventually they become separate species