Cholesterol molecules in the plasma membrane a. form bilayers b. can form spherical vesicles c. have two fatty acid tails d. keep the membrane fluid e. have a polar phosphate head

The correct answer is option d. "Keep the membrane fluid".

Explanation:

Cholesterol is a major constituent of animal cell membranes, being present within its structure in about the same molar amounts as the phospholipids. Cholesterol plays an important role in keeping the plasma membrane fluid. At low temperatures, cholesterol interferes with interactions between fatty acid chains, keeping the membrane fluid and preventing the membrane to freeze. However, at high temperatures cholesterol has the opposite effect and reduces the membrane permeability to small molecules.

a motor homunculus represents a map of brain areas dedicated to motor processing for different anatomical divisions of the body.

homunculus represents the importance of various parts of your body as seen by your brain. as a result, they take up a lot of brain space. although the cortical homunculus is a curiosity, penfield's work in mapping the brain's relationship to the body was invaluable.

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.