Question

explain cell permeability by practical of cucumber slices

Answer 1

The salt cause water to be drawn out of the cucumber. Water is drawn to it because it goes from a higher concentration of water to lower concentration. When there is random motion that will always happen and is called diffusion. Osmosis is a type of diffusion that involves a semipermeable membrane or a membrane like exists in the cells of cucumbers that allows water through but not the salt. That is why it is called semipermeable. Only some things gets through the membrane. When there is more salt dissolved in the water on one side of the membrane compared to the other there is less water on that side. They call that hypertonic. Water will move from the higher concentration hypotonic side to the lower concentration of water on the hypertonic side. That is how you should think of it. It will often be express as more salt but you should think of it as more salt dissolved actually means less water. Water will diffuse from higher concentration of water (lower salt) to lower concentration (higher salt). Think of it like this. If you had 50 people in a single room and 20 in the other during a party and they were all moving around randomly. After an hour there will be fewer people in the crowded room if they move around randomly. That is why diffusion goes from higher concentration to lower. Just don't be confused when they say higher concentration of salt. High salt means less water. The water molecules are what moves around and when it involves a semipermeable membrane like in most living cells it is called osmosis"