Why does active transport require energy to move molecules of a substance across a cell membrane?
OA
The cell membrane is very thick.
Lack of the substance makes the cell weak.
ООО
The substance moves from high to low concentration, with the concentration gradient.
OD
The substance moves from low to high concentration, against the concentration gradient.

The reason why active transport require energy to move molecules of a substance across a cell membrane is because: D. The substance moves from low to high concentration, against the concentration gradient.

Active transport refers to the movement of ions or molecules of a substance from a region of lower concentration to a region of higher concentration, across a cell membrane and against a concentration gradient. Thus, active transport require cellular energy to move molecules from a region of lower concentration to a region of higher concentration across a cell membrane and against the concentration gradient.

In conclusion, active transport generally require cellular energy to move molecules of a substance across a cell membrane because they are moved from low to high concentration region, against the concentration gradient.

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the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.