Back to Separate Sciences (Biology, Chemistry, Physics)Practice this
Paper 1
Cell Biology
Both
Memorise organelles and match each to its job.
Key Facts
- Last-minute priority: organelle functions and transport definitions.
- Higher SA:V ratio means faster diffusion.
- Prokaryotic cells (bacteria) are smaller and lack a nucleus.
- Specialised cells have adaptations that match their function.
Topics Covered
Cell Structure and Microscopy
What you need to know
- •Know organelles and their functions: nucleus, mitochondria, ribosomes, chloroplasts.
- •Magnification = image size / real size.
Exam Tips
- Always link organelle structure to its function in 2-4 mark questions.
Cell Division
What you need to know
- •Mitosis produces two identical cells for growth and repair.
- •Bacteria reproduce by binary fission.
Exam Tips
- Use the words "genetically identical" for mitosis.
Transport Across Membranes
What you need to know
- •Diffusion moves particles from high to low concentration.
- •Osmosis is diffusion of water through a partially permeable membrane.
Exam Tips
- Use key words: gradient, partially permeable, net movement.
Microscopy and Calculations
What you need to know
- •Convert units: 1 mm = 1000 micrometers.
- •Magnification = image size / real size.
Exam Tips
- Convert to the same units before calculating.
Key Terms
Diffusion
Net movement of particles from high to low concentration.
Osmosis
Movement of water through a partially permeable membrane.
Mitosis
Cell division producing two identical daughter cells.
Prokaryote
Cell without a nucleus, like bacteria.
Eukaryote
Cell with a nucleus, like plant and animal cells.
Binary fission
Asexual reproduction in bacteria by splitting.
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Common Exam Questions
Explain why root hair cells are adapted for absorption.
3 marksmediumPaper 1
Model Answer
They have a large surface area from the root hair, thin cell walls, and many mitochondria for active transport.
What examiners want to see
- ✓Mention surface area.
- ✓Link thin walls to short diffusion distance.
- ✓Mention mitochondria for energy.
A cell image is 36 mm long. The real cell is 18 micrometers. Calculate magnification.
3 marksmediumPaper 1
Model Answer
36 mm = 36000 micrometers. Magnification = 36000 / 18 = 2000.
What examiners want to see
- ✓Convert units correctly.
- ✓Use magnification formula.
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