Final answer:
Both primary and secondary active transport mechanisms require energy. Primary active transport directly uses ATP, while secondary active transport indirectly relies on the electrochemical gradient established by primary active transport. The correct answer to the question is D) both primary and secondary active transport.
Step-by-step explanation:
Active Transport Mechanisms and Energy RequirementsThe transport mechanisms that require energy are both primary and secondary active transport. Primary active transport relies directly on ATP to move ions or molecules across a cell membrane, typically against their concentration gradient. This creates a difference in charge across the membrane. On the other hand, secondary active transport does not use ATP directly. Instead, it utilizes the electrochemical gradient established by the primary active transport as its energy source.
Hence, even though it's called 'secondary', it indirectly relies on the energy that was initially provided by ATP during primary active transport. Facilitated diffusion, however, does not require energy as it moves substances down their concentration gradient through a carrier protein.
Therefore, the correct answer to the question 'Which of the following transport mechanisms requires energy?' is D) both primary and secondary active transport. Answer options A, B, and C are incorrect as facilitated diffusion does not require energy, and both primary and secondary active transports are energy-dependent.