Which of these best explains why energy is needed for active transport? *

Ions are moved against the concentration gradient.

Explanation:

Active transport mechanisms require the use of the cell's energy, usually in the form of adenosine triphosphate (ATP).

plato users:

d.  

there was a variety of food available on island x, but there were only large seeds and nuts on island y.

not always but somethings can be reproduced in a laboratory.