The correct answer is; the open mouth of a baby robin is seen as a sign stimulus for the female robin (parent), and that the open mouth is the impending cause for her behavior.
Answer:
There are two major ways that molecules can be moved across a membrane, and the distinction has to do with whether or not cell energy is used. Passive mechanisms like diffusion use no energy, while active transport requires energy to get done.
Explanation:
1. there is not diagram to examine 2 no answer choice so how are we supposed to answer this?
