Active transport via efflux pumps requires specific genetic machinery

Steps:

• Recognize the mechanism: antibiotic resistance via active transport out of the cell, which moves substances against concentration gradients.
• Recall active transport definition: uses energy to power membrane proteins called pumps, not passive channels.
• Identify bacterial requirements: cells need genes to produce these pump proteins for efflux.
• Eliminate unrelated options: bacteria lack organelles like mitochondria and rely on chemical energy sources already present.

Why D is correct:

• D (gene coding for a pump protein) enables synthesis of efflux pumps, essential for active transport per the definition of carrier-mediated transport against gradients.

Why the others are wrong:

• A: Channel proteins facilitate passive diffusion, not energy-dependent active transport.
• B: Chemical energy (e.g., ATP) is necessary but insufficient alone; specific pump proteins are required for the mechanism.
• C: Bacteria are prokaryotes without mitochondria, which generate energy in eukaryotes.

Final answer: D