Answer: Membrane transport proteins are specific and selective for the molecules they move, and they often use energy to catalyze passage. Also, these proteins transport some nutrients against the concentration gradient, which requires additional energy.
Explanation:
<span>The electron transport chain is, in essence , aseries of redox reactions that conclude cellular respiration. during these redox reactions, NAD+ is reduced,which then oxidizes an electron acceptor in the electron transport chain.</span>
The best answer here would be A.
<span>An element is a pure substance that cannot be broken down into anything simpler by physical or chemical means.</span>
