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CognitoAnimal and plant cells
CognitoEukaryotic and prokaryotic cells
Key facts & methods
Animal cell structures
- Cell membrane: controls what enters/leaves the cell. Partially permeable.
- Cytoplasm: jelly-like fluid where chemical reactions occur.
- Nucleus: contains DNA (genetic material). Controls cell activity.
- Mitochondria: site of aerobic respiration. Produce ATP (energy).
- Ribosomes: site of protein synthesis.
Plant cell — additional structures
- Cell wall: rigid, made of cellulose. Provides structural support.
- Chloroplasts: contain chlorophyll. Site of photosynthesis.
- Permanent vacuole: filled with cell sap. Maintains turgor pressure.
- Plant cells also have: cell membrane, cytoplasm, nucleus, mitochondria, ribosomes.
- Key exam point: chloroplasts and cell wall are ONLY in plant cells (not all plant cells have chloroplasts).
Eukaryotic vs prokaryotic cells
- Eukaryotic (animal, plant, fungal): has a membrane-bound nucleus and membrane-bound organelles.
- Prokaryotic (bacteria): no true nucleus — DNA is in the cytoplasm as a loop. No membrane-bound organelles.
- Prokaryotic cells are much smaller (~1–10 μm vs ~10–100 μm for eukaryotic).
- Bacteria also have: cell wall (but made of murein, not cellulose), plasmids (small circular DNA), flagella (some).
Microscopy
- Light microscope: magnification up to ~×2000. Can see cells and larger organelles.
- Electron microscope: magnification up to ×2,000,000. Can see ribosomes, internal membrane structures.
- Magnification = image size ÷ actual size.
- Scale bars on micrographs: use to calculate actual size.
Exam questions — 5 questions · 11 marks · AQA 8461 style
⚡ Show all reasoning — the AI marks against the AQA mark scheme. Partial credit for correct biology even if wording differs.
1 markPlant-only structureAQA 8461 style
Which structure is found in plant cells but NOT in animal cells?
A Mitochondria
B Ribosomes
C Cell membrane
D Cell wall made of cellulose
1 markProkaryotic cellAQA 8461 style
Which feature is present in prokaryotic cells but NOT in eukaryotic cells?
A Cell membrane
B Ribosomes
C DNA as a circular loop in the cytoplasm (no membrane-bound nucleus)
D Mitochondria
4 marksCompare cell typesAQA 8461 P1 style
Describe THREE differences between a plant cell and an animal cell. (3 marks)
Hint: One mark per valid difference. State what plant cells HAVE that animal cells lack.
+40 XP
4 marksMitochondria functionAQA 8461 style
Cells that are very active, such as muscle cells and sperm cells, contain many mitochondria. Explain why. (3 marks)
Hint: State what mitochondria do → link to energy need → explain why active cells need more energy.
+40 XP
1 markMagnification calculationAQA 8461 style
A cell appears 5 mm long under the microscope. The actual length is 0.05 mm. What is the magnification?
A ×10
B ×100
C ×1000
D ×0.01
Module complete! 🎉
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