Answer:
Cellular Energy
Explanation:
Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration. Cellular energy is required to acheive this movement.
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Adaption, evolution, variation are all causes of natural selection.
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brainliest..?
The muscle system for a boy and a girl are the same. They can perform and respond in the same manner. The difference only occurs in the development of muscle mass, where men can develop more muscle mass than female. This difference is brought by the type of activities that the two sexes engage in. Muscle group development can be altered by a person’s current exercise program and way of life.