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Which of the following scenarios requires an input of energy to occur?

A. The movement of a solution from a region of higher concentration on one side of a membrane to a region of lower concentration on the other side.
B. The movement of a solution from a region of lower concentration on one side of a membrane to a region of higher concentration on the other side.
C. Both A and B require an input of energy.
D. Neither A nor B requires an input of energy.

1 Answer

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Final answer:

The movement from a lower to a higher concentration (Option B) requires energy and is known as active transport, while the opposite movement (Option A) occurs naturally and is known as passive transport.

Step-by-step explanation:

The correct answer to this question is B: The movement of a solution from a region of lower concentration on one side of a membrane to a region of higher concentration on the other side. This scenario describes active transport, which requires an input of energy. Osmosis and passive transport, described in scenario A, move substances from higher to lower concentrations without the need for energy.

Active Transport

In active transport, substances move against their concentration gradient, which necessitates energy input, often in the form of ATP (adenosine triphosphate). This is like carrying something heavy uphill, going against the flow, which requires extra effort.

Passive Transport

Passive transport, on the other hand, does not require energy as substances move with the concentration gradient, akin to a ball rolling down a hill.

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