**Question:**Which of the following movements across a cell membrane will likely be least affected if the synthesis of membrane-bound proteins becomes inhibited?**Choices:**- **A:** the movement of calcium (\( \text{Ca}^{2+} \)) along the concentration gradient- **B:** the movement of glucose (\( \text{C}_6\text{H}_{12}\text{O}_6 \)) against the concentration gradient- **C:** the movement of water (\( \text{H}_{2}\text{O} \)) along the concentration gradient- **D:** the movement of oxygen (\( \text{O}_{2} \)) along the concentration gradient

Cell membranes are double-layered structures made up of phospholipids and they are selectively permeable to various small molecules while impermeable to some others. The plasma membrane is one among such membranes and forms a barrier that separates the cytoplasm and the outside environment. Various methods are employed for the transport of various small molecules and they are passive diffusion, facilitated diffusion, the carrier protein, ion channels, and active transport.D. The movement of oxygen along the concentration gradient. The movement of gases across membranes is by simple diffusion that is not aided by either energy or membrane-bound proteins. Hence, option D, The movement of oxygen along the concentration gradient is also a correct answer.A. The movement of calcium along the concentration gradient. Calcium pumps are used by the cells for pumping calcium ions through various membranes. This movement is used by various cells for the conduction of signals among many other functions. The calcium pumps are membrane-bound proteins and inhibition of the synthesis of the same will affect the movement of the ion across the membrane. B. The movement of glucose against the concentration gradient. Glucose is transported along with sodium ions. Sodium-glucose cotransporters aid in the same. Inhibition of the synthesis of cotransporter will affect the movement of glucose across membranes in the small intestine and renal tubules. C. The movement of water along the concentration gradient. The movement of water along the concentration gradient through a semi-permeable membrane is called osmosis. Membrane-bound proteins such as aquaporins aid in the regulation of the flow of water into and out of the cell.The movement of water along the concentration gradient is the correct answer.