If you zoom in all the way in what is the smallest object on the head of the pin
1 answer:
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Answer:
Explanation:
The phospholipid bilayer is also known as the cell membrane. It covers cells and regulates the transport of substances. Certain ones can pass and others cannot, depending on certain factors like size and polarity.
Smaller substances tend to diffuse or move across the membrane quite easily. However, larger molecules have a much harder time. Many depend on special proteins embedded in the membrane. These are called transport proteins and they form a channel so large molecules can still move in or out of the cell.
So, salt, water, and fats do not contribute to the movement of larger molecules, but <u>channel or transport proteins do and choice A is correct. </u>