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>
The water cycle is the correct answer, the water evaporates, then condenses into clouds, and turns into rain and precipitation occurs.
Answer is D.
Waste products from metabolism are carried by the circulation to the kidneys, which filter them out if the blood to be excreted in urine.
2, they line up to form a polypeptide chain this forms part of a protein molecule.