I believe the answer is A!
Answer:
The presence of cholesterol in the plasma membranes of some animal cells <u>enables the membranes to stay fluid when cell temperature drops</u>.
Explanation:
Cholesterol is an essential lipid in the basic structure of cell membranes. The membranes must have a fluid structure so that the proteins integrated in them can move ''horizontally'' to interact with their ligands and with other proteins. With excess saturated fat the membranes become rigid, but only with the necessary unsaturated fat the membranes are extremely fluid, and very sensitive to changes in temperature. Cholesterol stabilizes the structure of the membranes; preventing the collapse and crystallization between lipid chains that would lead to loss of fluidity and excessive rigidity in the membrane. By decreasing the temperature; as temperatures drop, fluidity decreases, an effect that partially counteracts the presence of cholesterol.
The last answer is correct luv
5. Because of rain and oxygen, if a set of tools is left outdoors in the rain for a long time, it will rust.
6. Yes, I believe it is possible for any of the earth materials scenes to be affected by both mechanical and Chemical weathering, but I am more positive about #5.
The main parts of a controlled experiment are the dependent variable and the independent variable...
