In which of the following processes, active transport is NOT used ?

Active transport involves the movement of molecules against a concentration gradient, requiring cellular energy (ATP). In contrast, facilitated diffusion is a passive process where molecules move down their concentration gradient through specific protein channels.

• Option C: The passage of ions like Na⁺ and Cl^- through hydrophilic protein channels is an example of facilitated diffusion. Because the ions move through a channel along their electrochemical gradient, it is a passive process and does not use active transport.
• Option A & D: The reabsorption of glucose and amino acids in the kidneys and their absorption in the small intestine typically utilize secondary active transport (e.g., SGLT transporters).
• Option B: Phloem loading of sugars (sucrose) from source cells into the phloem is an active process requiring ATP to move sugar against its concentration gradient.