Which is a form of active transport?
A.
Proteins open up channels in the cell membrane.
B.
Proteins push molecules through the cell membrane.
C.
Proteins create openings on another side of the cell membrane.
D.
Proteins enter and exit the cell freely.
i have no idea which one it is
http://www.biology4kids.com/files/cell2_activetran.html
The answer is B. Some proteins present in the membrane move polar molecules by using the energy in the form of ATP.
To determine which option is a form of active transport, let's understand what active transport is. Active transport is the movement of molecules or ions across a cell membrane against their concentration gradient, which requires the expenditure of energy in the form of ATP (adenosine triphosphate).
Now, let's evaluate each option and identify the one that fits the definition:
A. Proteins open up channels in the cell membrane.
This option describes facilitated diffusion, not active transport, as it involves the movement of molecules down their concentration gradient through protein channels without the expenditure of energy.
B. Proteins push molecules through the cell membrane.
This option describes a process called active transport. Here, proteins actively transport molecules against their concentration gradient, involving energy expenditure.
C. Proteins create openings on another side of the cell membrane.
This option does not describe active transport; it is ambiguous and does not clearly define a known process of molecular transport.
D. Proteins enter and exit the cell freely.
This option describes passive transport since proteins are able to move freely across the cell membrane without energy expenditure. It is not an example of active transport.
Based on our evaluation, the correct answer is option B: Proteins push molecules through the cell membrane.