The correct answer is: B. Active transport.
Active transport is the movement of molecules across a cell membrane against the concentration gradient, using energy from ATP. This process is necessary for cells to take in nutrients and expel waste products.
Passive transport is the movement of molecules across a cell membrane down the concentration gradient, without using energy. This process is a result of the random movement of molecules and does not require any input from the cell.
Both active transport and passive transport are important for cell function, but only active transport requires cellular energy.
Here is a more detailed explanation of each option:
- Passive transport is the movement of molecules across a cell membrane down the concentration gradient, without using energy. This process is a result of the random movement of molecules and does not require any input from the cell. Some examples of passive transport include diffusion, osmosis, and facilitated diffusion.
- Active transport is the movement of molecules across a cell membrane against the concentration gradient, using energy from ATP. This process is necessary for cells to take in nutrients and expel waste products. Some examples of active transport include the sodium-potassium pump and the glucose transporter.
- Both A & B is not a correct answer because only active transport requires cellular energy.
- None of the above is not a correct answer because both passive transport and active transport are important for cell function.