Is it correct to say: Calling mitochondria and chloroplasts identical?

Both have own DNA/ribosomes but they do OPPOSITE jobs — mitochondria RELEASE energy (respiration); chloroplast STORES it via photosynthesis.

Is it correct to say: Confusing diffusion and osmosis?

Diffusion: any molecule (solute or solvent) moves down gradient. Osmosis: only SOLVENT (water) moves across a semi-permeable membrane.

Is it correct to say: Writing that all cells have a cell wall?

Cell wall is present in PLANTS, fungi, bacteria — NOT in animal cells.

Is it correct to say: Considering ribosome as membrane-bound?

Ribosomes are NOT membrane-bound. They may sit free in cytoplasm or attach to the rough ER surface.

Is it correct to say: Saying plasma membrane is impermeable?

Plasma membrane is SELECTIVELY PERMEABLE — allows some substances through (O₂, small molecules), blocks others.

Is it correct to say: Confusing 'nuclear membrane' with 'plasma membrane'?

Plasma (cell) membrane encloses the whole cell; nuclear membrane encloses only the nucleus.

Cell — The Basic Unit of Life

Cell theory, prokaryotic vs eukaryotic cells, structure and function of organelles — revision notes for Class 10 board preparation

📐 7 formulas✏️ 3 examples🎯 6 practice⚖️ 3-4 marks🏫 CBSE📚 Class 10✓ 2025–26 syllabus

💡

Board Exam Tips

→Labelled diagram of an animal / plant cell — the single most frequent 3-mark question of this topic.
→Prokaryote vs eukaryote table — 3 marks, learn 4-5 differences.
→Function of any one organelle (mitochondrion / chloroplast / ribosome) — 2 marks.
→Plant vs animal cell differences (cell wall, vacuole, chloroplast, centriole) — 3 marks.
→Osmosis vs diffusion — commonly confused, 2 marks safe.

📊 Diagram

Labelled diagram of a typical animal (or plant) eukaryotic cell showing key organelles

📐 Formulas(7)

Cell Theory (Schleiden and Schwann)★ Board fav

All living organisms = one or more cells; Cell = basic unit; New cell = pre-existing cell

Prokaryote vs Eukaryote★ Board fav

Prokaryote (no nucleus) vs. Eukaryote (true nucleus)

Diffusion

Movement \propto concentration gradient (high \to low)

Osmosis★ Board fav

Solvent movement across semi-permeable membrane: dilute \to concentrated

Function of Mitochondrion

Glucose + O_{2} ⟶ A T P (energy currency)

Function of Chloroplast

C O_{2} + H_{2} O sunlight glucose + O_{2}

Function of Ribosome

mRNA ⟶ Protein

✏️ Solved Examples

1Solved Exampleeasy3 steps

State the three postulates of the cell theory.

1. All living organisms are made up of one or more cells.

2Solved Exampleboard5 steps

Give a five-point comparison between plant and animal cells.

Cell wall — plant YES (cellulose), animal NO.

3Solved ExampleHOTS4 steps

A dry raisin is placed in a beaker of pure water; a second raisin is placed in concentrated sugar solution. Predict what happens to each raisin and explain using the concept of osmosis.

Raisin in water: outside water concentration > inside cell sap concentration. Water enters the raisin by ENDOSMOSIS.

⚠️ Traps & Common Mistakes

⚠️Common Mistakes6

1
Calling mitochondria and chloroplasts identical
✓Both have own DNA/ribosomes but they do OPPOSITE jobs — mitochondria RELEASE energy (respiration); chloroplast STORES it via photosynthesis.
2
Confusing diffusion and osmosis
✓Diffusion: any molecule (solute or solvent) moves down gradient. Osmosis: only SOLVENT (water) moves across a semi-permeable membrane.
3
Writing that all cells have a cell wall
✓Cell wall is present in PLANTS, fungi, bacteria — NOT in animal cells.
4
Considering ribosome as membrane-bound
✓Ribosomes are NOT membrane-bound. They may sit free in cytoplasm or attach to the rough ER surface.
5
Saying plasma membrane is impermeable
✓Plasma membrane is SELECTIVELY PERMEABLE — allows some substances through (O₂, small molecules), blocks others.
6
Confusing 'nuclear membrane' with 'plasma membrane'
✓Plasma (cell) membrane encloses the whole cell; nuclear membrane encloses only the nucleus.

🎯 Practice Yourself

🎯Practice Yourself6 questions

Q1
Name the scientist who discovered the cell and coined the term 'cell'.
Q2
Name any three organelles found only in plant cells.
Q3
What is the function of Golgi apparatus?
Q4
Define 'plasmolysis'.
Q5
Give two differences between rough and smooth endoplasmic reticulum.
Q6
Which cell organelles are called 'suicide bags' and why?

📝 Notes

Cell — The Basic Unit of Life

Every living thing is built of cells — the smallest self-sustaining units of life. This chapter revisits key ideas for Class 10 board revision.

Cell theory (Schleiden, Schwann, Virchow)

All organisms are made of one or more cells.
The cell is the basic structural and functional unit of life.
All cells come from pre-existing cells.

Prokaryote vs Eukaryote

| Feature | Prokaryote | Eukaryote | |---|---|---| | Nucleus | No (nucleoid) | Yes (true) | | Membrane organelles | Absent | Present | | Size | ~ 1-10 μm | ~ 10-100 μm | | Examples | Bacteria, blue-green algae | Plants, animals, fungi |

Key organelles — one-liner functions

| Organelle | Job | |---|---| | Plasma membrane | Selective barrier | | Nucleus | Stores DNA, controls cell | | Mitochondrion | Aerobic respiration → ATP | | Chloroplast (plants) | Photosynthesis → glucose | | Ribosome | Protein synthesis | | ER (rough / smooth) | Protein / lipid synthesis | | Golgi apparatus | Packaging & dispatch | | Lysosome | Suicide bag; digestion | | Vacuole | Storage; turgor in plants | | Cell wall (plants) | Rigidity, shape |