What is Osmosis _ It’s Meaning and Definition Diffusion of a solvent (usually water molecules).
What is Osmosis _ It’s Meaning and Definition Diffusion of a solvent (usually water molecules).
Here’s a clear and easy-to-understand explanation of Osmosis — its meaning, definition, and concept — perfect for school students, competitive exams (NEET/NCERT), or general science understanding.
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What is Osmosis?
Osmosis is a special type of diffusion that involves only solvent molecules (usually water) moving through a semipermeable membrane.
Definition (English):
Osmosis is the movement of a solvent (usually water) from a region of low solute concentration to a region of high solute concentration through a semipermeable membrane, until equilibrium is reached.
Definition (Hindi – हिंदी में):
ओस्मोसिस (परासरण) एक ऐसी प्रक्रिया है जिसमें जल अणु (या कोई अन्य विलायक) एक अर्ध-पारगम्य झिल्ली के माध्यम से कम सान्द्रता वाले विलयन से अधिक सान्द्रता वाले विलयन की ओर गति करते हैं।
Key Concepts in Osmosis
| Concept | Explanation |
|---|---|
| Solvent | Usually water (the liquid doing the dissolving) |
| Solute | The substance dissolved (like salt or sugar) |
| Semipermeable Membrane | A barrier that allows only certain molecules (like water) to pass |
| Direction of Flow | Water moves from dilute (less solute) to concentrated (more solute) side |
Example in Daily Life:
- Plant Roots Absorbing Water: Water enters root hair cells from the soil by osmosis.
- Raisins in Water: They swell because water enters through osmosis.
- Salt on Plants: Plants shrink/die because water moves out of the cells due to osmosis.
Difference: Osmosis vs Diffusion
| Osmosis | Diffusion |
|---|---|
| Only solvent molecules move | Both solute and solvent can move |
| Requires semipermeable membrane | Does not need a membrane |
| One-way flow until balance | Can be two-way flow |
Simple Diagram Idea:
[Low Solute] Water → [Semipermeable Membrane] → [High Solute]
↓ ↓
More water Less water
Osmosis in NEET/Board Exams:
- Found in Class 9 & 11 Biology (Transport in Plants)
- Key topic for NEET Biology – Plant Physiology & Cell Membrane
Summary:
- Osmosis = Water movement through a semipermeable membrane
- From low solute to high solute concentration
- Driven by difference in water potential
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