Magnification
M magnification, I image size, A actual size.
M = I / A AQA A-Level 2025
🧬 AQA A-Level Biology Formula Sheet
Essential formulas for biological molecules, cells, genetics, and ecology aligned to AQA A-Level Biology (7401/7402) specification.
Cells Genetics Ecology
Master A-Level Biology
This formula sheet covers fundamental biology relationships from the AQA A-Level Biology specification, helping you solve complex problems involving cells, genetics, and ecosystems.
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Cell calculations
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Genetics formulas
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Ecology relationships
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Statistical analysis
Cell Biology & Microscopy
Calculations involving cell size, magnification, and microscopy.
Surface Area to Volume Ratio
Important for understanding cell size limitations.
Smaller cells have higher SA:V ratios, allowing more efficient exchange.
SA:V = Surface Area / Volume Topic Focus
Microscopy Calculations
- Always use the same units for image size and actual size (usually micrometers, μm).
- Magnification has no units—it's a ratio.
- Convert units if needed: 1 mm = 1000 μm, 1 cm = 10,000 μm.
Genetics & Inheritance
Basic genetic calculations and inheritance patterns.
Genotype Ratio
Ratio of different genotypes in offspring.
Use Punnett squares to predict genotype and phenotype ratios.
Phenotype Ratio
Ratio of different phenotypes in offspring.
Phenotype = observable characteristics (e.g., tall/short, red/white flowers).
Topic Focus
Genetic Crosses
- Use Punnett squares to predict offspring genotypes and phenotypes.
- Genotype = genetic makeup (e.g., TT, Tt, tt). Phenotype = physical appearance.
- Dominant traits mask recessive traits in heterozygous individuals.
Ecology & Populations
Population growth, density, and ecosystem calculations.
Population Density
Number of individuals per unit area.
Population Density = (Number of Individuals) / (Area) Percentage Cover
Percentage of area covered by a species.
% Cover = (Area Covered by Species / Total Area) × 100% Topic Focus
Population Studies
- Population density helps compare populations in different areas.
- Percentage cover is useful for studying plant communities in quadrats.
How to Use This Formula Sheet
Boost your Cambridge exam confidence with these proven study strategies from our tutoring experts.
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Use Correct Units
Always check units match in calculations. Convert between mm, cm, m, and μm as needed.
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Draw Diagrams
Sketch Punnett squares, cell structures, or ecosystems to visualize relationships before calculating.
Excel in AQA A-Level Biology
Master advanced biology concepts with expert A-Level tutors who help you understand living systems and solve biological problems confidently.
Formulas align with AQA A-Level Biology specification (7401/7402) for UK students.
Always show your working, include units, and check that answers make biological sense.