What do you think selectively permeable means? A. The membrane lets nothing in or out.

B. The membrane lets certain substances move across it freely, while others must move through a “gate”.

C. The membrane lets everything in and out.

B. The membrane lets certain substances move across it freely, while others must move through a “gate”.

Explanation:

Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell. This is important for the cell to maintain its internal order irrespective of the changes to the environment. For example, water, ions, glucose and carbon dioxide may need to be imported or exported from the cell depending on its metabolic activity. Similarly, signaling molecules may need to enter the cell and proteins may need to be released into the extracellular matrix. The presence of a selectively permeable membrane allows the cell to exercise control over the quantum, timing and rate of movement of these molecules.

B. The membrane lets certain substances move across it freely, while others must move through a “gate”.

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.

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