Definition of Osmosis:
Osmosis is the movement of water molecules through a semipermeable membrane from an area of higher water concentration to an area of lower water concentration, until the concentration is equal on both sides.
What happens in osmosis?
• Water moves from a place where there is more water to a place where there is less water.
• This happens through a semipermeable membrane—a thin wall that only lets water through, not other things like salt or sugar.
• The water moves to try to make both sides even.
• This movement happens on its own—the cell doesn’t need to use energy.
• It keeps the amount of water balanced inside and outside the cell.
In short:
In osmosis, water moves through a thin membrane to where there is less water, to keep things balanced.
Why does water have to be equal in cells?
Water moves in osmosis to make things equal because cells and living things need balance to stay healthy.
Here’s why:
If there is too much water inside a cell, it can swell and burst.
If there is too little water inside, the cell can shrink and dry out.
So, osmosis helps move water in or out of the cell to keep the right amount.
Cells work best when the amount of water and dissolved things (like salts or sugars) is just right—not too much, not too little. Osmosis helps the cell stay in that safe balance.
How did it get it’s name?
The word “osmosis” comes from Greek.
It comes from the Greek word “ōsmos” (ὠσμός), which means “a push” or “impulse”.
It was made from “ōthein”, which means “to push”.
So the word osmosis was chosen because it describes how water gets pushed or moves through a thin barrier (membrane) from one side to another.
The term was first used in the 18th century by scientists studying how liquids move through animal bladders and plant tissues. Over time, it became a key word in biology and chemistry.
How membrane stops sugar and salt from entering the cell but allows water molecules to enter?
Osmosis doesn’t exactly “stop” sugar and salt—it’s the membrane that does that.
Here’s how it works in simple words:
Osmosis happens through a semipermeable membrane.
A semipermeable membrane is like a filter with tiny holes.
These holes are small enough for water molecules to pass through.
But sugar and salt molecules are bigger, so they cannot fit through the holes.
So:
Water can move through the membrane (osmosis).
Salt and sugar cannot move through the membrane—only water.
Favourite part/ note/ summary- In short osmosis is the process where water is transferred inside and outside the cell. Which helps to balance both sides (inside and outside) of the membrane. If the water is too less in the cell, the cell can shrink and dry, if the water content is too much it can burst due to the over fill of water.
