Cells — AQA A-Level Biology
In summary: Cells is a key topic in AQA A-Level Biology. Key exam tip: Use the formula magnification = size of image / size of real object correctly, ensuring units are consistent
Exam Tips for Cells
- Use the formula magnification = size of image / size of real object correctly, ensuring units are consistent
- When describing transport across membranes, always specify whether proteins (carrier/channel) are involved
- For immune system questions, clearly distinguish between the primary and secondary immune response
- Be prepared to interpret data from graphs related to membrane permeability or enzyme-controlled reactions
- Ensure diagrams of cells or organelles are clearly labelled and annotated if requested
Common Mistakes
- Confusing magnification with resolution
- Failing to mention the role of ATP in active transport
- Incorrectly describing the stages of mitosis or the role of spindle fibres
- Confusing the roles of T cells and B cells in the immune response
- Misunderstanding the difference between active and passive immunity
- Inaccurate descriptions of the fluid-mosaic model components
Marking Points
- Structure and function of eukaryotic organelles (nucleus, mitochondria, chloroplasts, Golgi, lysosomes, ribosomes, ER, cell wall, vacuole)
- Structural differences between prokaryotic and eukaryotic cells (e.g., murein cell wall, plasmids, capsule, flagella, smaller ribosomes, circular DNA)
- Principles of optical, transmission electron, and scanning electron microscopes (magnification vs resolution)
- Cell fractionation and ultracentrifugation techniques
- Stages of the cell cycle and mitosis (interphase, prophase, metaphase, anaphase, telophase, cytokinesis)
- Binary fission in prokaryotes
- Fluid-mosaic model of membrane structure (phospholipids, proteins, glycoproteins, glycolipids, cholesterol)
- Mechanisms of transport: simple diffusion, facilitated diffusion, osmosis, active transport, and co-transport
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