No. Osmosis is the movement of a solvent through a membrane (semi-permeable) from a less concentrated solution to a more concentrated solution to the point where the two sides reach equilibrium. Isotonic solutions are solutions where the two sides of the membrane are already at equilibrium - so there is no movement of the solvent (like water) - so this is different from osmosis.
The shape of an enzymes active site fits the shape of a certain molecule that is affected by the enzyme. It's like a puzzle piece fitting into another puzzle piece. The molecule in the reaction being catalyzed fits into the enzyme. Hopefully this helps, this is how I was taught
Movement of Na+ and K+ in neurons are active transport during stimulation.
