Plasma Membrane Transport Mechanisms — NEET Biology
✅ Asked in NEET 2026One of the most important functions of the plasma membrane is the transport of the molecules across it. The membrane is selectively permeable to some molecules present on either side of it. Many molecules can move bi-directionally across the membrane. Some of the movement is passive and is called passive transport. Neutral solutes may move across the membrane by the process of simple diffusion along the concentration gradient, i.e., from higher concentration to the lower. Water may also move across the membrane from higher to lower concentration. Movement of water across the membrane to equalise the concentration of solutes is through the nonpolar lipid bilayer, they require a carrier protein of the membrane to facilitate their transport across the membrane. A few ions or molecules are transported across the membrane against their concentration gradient, i.e., from lower to the higher concentration. Such a transport is an energy dependent process, in which ATP is utilised and is called active transport, e.g., Na+/K+ Pump.
NEET tests your understanding of how molecules cross the plasma membrane through passive transport (simple diffusion, osmosis) and active transport (Na+/K+ pump). Students commonly confuse these two processes—passive transport doesn't require energy and moves along the concentration gradient, while active transport requires ATP and moves against the gradient. The key trap: mixing up which transport type moves from high to low concentration versus low to high. Remember the rule: passive = no energy, follows concentration gradient; active = uses ATP, opposes concentration gradient. Carrier proteins may be involved in both, but only active transport consumes energy.
Select correct statements about cell membrane in eukaryotic cell: A. Membrane of human RBCs has ~52% protein. B. Major phospholipids form a bilayer. C. Plasma membrane extensions form mesosomes. D. Hydrophobic tails point inward, away from aqueous medium. E. Glycocalyx on outer surface of plasma membrane.
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.