Final answer:
The transport mechanism among the options provided that requires no energy is osmosis through aquaporins (Option C), which is a type of passive transport and uses the concentration gradient to move water across the cell membrane without cellular energy.
Step-by-step explanation:
The student asked which transport mechanism requires no energy. The transport mechanisms listed were endocytosis, secondary active transport, osmosis through aquaporins, active transport, and exocytosis. Among these, the mechanism that does not require energy is osmosis through aquaporins (Option C).
Osmosis is a type of passive transport, which relies on the concentration gradient for the movement of water across the cell membrane, where it moves from an area of higher concentration to an area of lower concentration without the use of cellular energy (ATP).
Endocytosis, which includes pinocytosis and phagocytosis, as well as exocytosis, are forms of active transport that require energy usually in the form of ATP to move substances against their concentration gradient. Similarly, active transport requires ATP when substances move across a cell membrane from a lower to a higher concentration with the help of transport proteins. In contrast, secondary active transport does rely on energy, but it is indirectly obtained from the electrochemical gradients established by primary active transport rather than direct ATP hydrolysis.