Osmosis refers to the diffusion of water across a differentially permeable or semipermeable membrane. A semipermeable membrane selectively allows the movement of a solvent while restricting the movement of solutes.Complete answer:
The physiological demonstration of osmosis involves a semipermeable membrane tied to the mouth of thistle funnel, which is filled with sucrose solution. This semi-permeable membrane can be natural or artificial. The egg cell membrane is a natural semipermeable membrane while parchment paper is an artificial semipermeable membrane.Additional Information:
This physiological demonstration of osmosis involves filling of a thistle funnel with sucrose solution and kept inverted in a beaker containing water. A semipermeable membrane acts as a barrier between the sucrose solution and pure water.
As osmosis involves the passive movement of water from a region of its high concentration to a region of its lower concentration, water will move into the funnel as pure water has the highest concentration of water and addition of any solute only decreases its concentration. This continuous movement of water from beaker into the funnel will result in a rise in the level of sucrose solution. This will continue until the equilibrium is reached.
Bell jar experiment proves that for any sound to propagate, it requires a material as its medium.So, the correct answer is ‘both a and b.’Note:
Membranes can be impermeable, permeable, semi permeable or selectively permeable.
― Impermeable membranes don’t permit the entry of any solvent or solute. E.g. Lignified cell wall.
― Permeable membranes like a cellulosic cell wall allow all solute and solvents to pass through them.
― Selectively permeable membranes like plasma membrane and tonoplast allow only certain substances to pass through while preventing others.