Lesson focus: Cell structures support functions, but “plant cell” and “animal cell” are useful typical models rather than universal shapes.
Compare typical animal, photosynthetic leaf and root-hair cells.
Build on earlier learning
Observing cellsRevisit how cell structures are observed and represented in microscope images.
You will be successful when you can…
- Identify common animal- and plant-cell structures.
- State accurate functions for organelles.
- Explain why chloroplast presence depends on context.
- Use structure–function evidence to compare cells.
Words that carry the science
- cell membrane
- Selective boundary controlling movement into and out of a cell.
- cytoplasm
- Cell material where many chemical reactions occur.
- nucleus
- Compartment containing most genetic material in a eukaryotic cell.
- mitochondrion
- Organelle where aerobic respiration releases energy.
- chloroplast
- Organelle containing chlorophyll where photosynthesis occurs.
Compare cell structures without turning models into rules
01Shared eukaryotic plan
Typical plant and animal cells have a cell membraneThe thin outer layer of a cell that controls what goes in and out., cytoplasmThe jelly-like substance inside a cell where many chemical reactions happen., nucleusThe control centre of a cell, which holds the genetic information., mitochondrionA tiny part of a cell where aerobic respiration happens, releasing energy from glucose. and ribosomes. Ribosomes make proteins; mitochondria are sites of aerobic respiration.
The nucleus contains most genetic material and helps control cell activities. Same in both: plant and animal cells both have a nucleus, cytoplasm, cell membraneThe thin outer layer of a cell that controls what goes in and out., mitochondria and ribosomes.
02Plant structures depend on function
Plant cells have a cellulose cell wallA strong layer made of cellulose outside the cell membrane of a plant cell, which supports the cell and keeps its shape. outside the membrane and commonly a large permanent vacuole containing cell sap. Photosynthetic leaf cells contain chloroplastA green part of a plant cell that contains chlorophyll, which absorbs light energy for photosynthesis.. Only in plant cells: a cell wall (makes the cell strong and keeps its shape), a large vacuole (full of cell sap) and, in leaf cells, chloroplasts (where photosynthesis happens, using light to make food).
Most root-hair cells underground do not photosynthesise and therefore lack chloroplasts, while their long extension increases absorptive surface area.
03Typical is not universal
Specialised cells can lose or alter structures. Mature human red blood cells lack a nucleus and mitochondria; cell models should support reasoning, not become rigid templates.
Explain a root–leaf difference
Why does a palisade leaf cell contain many chloroplasts while a root-hair cell usually does not?
- Identify the leaf-cell job: absorbing light and photosynthesising.
- Chloroplasts contain chlorophyll and are the site of photosynthesis.
- Identify the root-hair job: absorbing water and mineral ions underground.
- Conclude that organelles reflect location and function.
How to make the reasoning visible: Use feature → effect → function rather than simply listing differences.
Structure and function matrix
Classify each structure, then add the context where it matters.
| Structure | Typical location | Function | Important qualification |
|---|---|---|---|
| Cell membrane | Plant and animal | Controls exchange | Present inside a plant cell wall |
| Cellulose wall | Plant | Support and resistance to bursting | Freely permeable, not the selective boundary |
| Chloroplast | Photosynthetic plant cells | Photosynthesis | Absent from many root cells |
| Mitochondria | Many eukaryotic cells | Aerobic respiration | Abundance varies with energy demand |
Why is “chloroplasts are found in all plant cells” inaccurate?
Why does a plant cell need a membrane as well as a wall?
Name the three structures found in plant cells but not animal cells.
Check your understanding
Answer from memory, then check against the suggested answer.
Where are proteins made?
What is the role of mitochondria?
Which structure supports a plant cell?
What does the nucleus contain?
Where does photosynthesis happen?
A cell secretes large amounts of protein. Predict one structure it may contain in high numbers.
Why might a muscle cell contain many mitochondria?
A root cell from a carrot has no chloroplasts. Is it still a plant cell? Explain.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
Answer the parts to compare a plant leaf cell with an animal cell.
Name two parts that both cells have.
(1)Name a part that only the plant cell has, which keeps it strong.
(1)Name the part that only leaf cells have, where photosynthesis happens.
(1)What does the cell wall do?
(1)Total for this question: 4 marks
Command word: For compareA command word: say how two or more things are similar and how they are different., give ways they are the same and ways they are different.