Plant Cells: Three Additional Organelles
Part of Cell Organelles · GCSE GCSE Biology revision
This deep dive covers Plant Cells: Three Additional Organelles within Cell Organelles for GCSE Biology. Revise Cell Organelles in Cell Biology for GCSE Biology with 12 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 4 of 13 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 13
Practice
12 questions
Recall
15 flashcards
🌱 Plant Cells: Three Additional Organelles
Plant cells contain all the organelles found in animal cells, plus three unique structures:
🌿 Chloroplasts
- Site of photosynthesis
- Contain chlorophyll — green pigment absorbing light energy
- Convert light energy, carbon dioxide, and water into glucose and oxygen
- Double membrane; inner membrane forms thylakoids (stacked into grana)
- Have their own DNA and ribosomes — evidence of ancient bacterial origin
- Only in cells that photosynthesise (leaves, green stems)
🧱 Cell Wall
- Rigid layer outside the cell membrane — made of cellulose
- Provides structural support and maintains cell shape
- Prevents cells from bursting when they absorb water (supports turgor pressure)
- Fully permeable to water and dissolved substances
- NOT the same as cell membrane — completely different structure and function
💧 Permanent Vacuole
- Large, central, fluid-filled space
- Bounded by the tonoplast membrane
- Contains cell sap: water + dissolved salts, sugars, pigments
- Maintains turgor pressure — pushes against cell wall to keep plant rigid
- When vacuole loses water, plant cells become flaccid → plant wilts
Quick Check: Plant cells placed in pure water do not burst, but animal cells do. Explain why, referring to specific structures.
Plant cells have a rigid cellulose cell wall outside the cell membrane. When water enters by osmosis, the cell wall prevents the cell from expanding too far — the cell becomes turgid but does not burst. Animal cells have only a cell membrane (no cell wall), so they swell and can burst (lyse) when too much water enters.