Edexcel AS-level Biology
Free Edexcel AS-level Biology revision for Edexcel Biology (8BI0): 17 topics and 368 short lessons, each with R.E.C.I.P.E. recall steps and a quiz. The topics follow the Edexcel specification.
1. Chemistry for Life
2. Biological Molecules
- Organic Compounds
- Carbohydrates
- Monosaccharides
- Disaccharides
- Test for Sugars
- Polysaccharides
- Starch
- Test for Starch
- Glycogen
- Cellulose
- The Nature of Lipids
- Fatty Acids and Glycerol
- Triglycerides
- Phospholipids
- Unit Membrane
- Test for Lipids
- Amino-acids
- Hydrogen Bonding
- Disulfide Bridges
- Ionic Bonds
- Protein Structure
- Globular Proteins
- Fibrous Proteins
- Collagen
- Conjugated Proteins
3. DNA, Genes and Protein Synthesis
4. Enzymes
- Enzymes
- Extra-Cellular and Intracellular Enzymes
- Biological Catalysts
- Lock and Key Hypothesis
- Induced Fit Hypothesis
- Measuring Rate of Reaction
- Effect of Substrate Concentration
- Effect of Temperature
- Effect of pH
- Effect of Enzyme Concentration
- Reversible and Irreversible Inhibition
- Competitive Inhibition
- Non-competitive Inhibition
- End-Product Inhibition
5. Eukaryotic Cells
- Magnification and Resolution
- Light Microscope
- Electron Microscope
- Transmission Electron Microscope
- Scanning Electron Microscope
- Ultrastructure
- Membranes
- Phospholipid Bilayer
- Membrane Proteins
- Fluid Mosaic Model
- Eukaryotic Cells
- Protoplasm
- The Nucleus
- Mitochondria
- Centrioles
- Cytoskeleton
- Vacuoles
- Ribosomes
- Rough ER
- Smooth ER
- Golgi Apparatus
- Lysosomes
- Plant Cells
- Plant Cell Walls
- Plasmodesmata
- Permanent Vacuole
- Chloroplasts
- Organisation of Cells
- Epithelial Cells
- Organ Systems
6. Prokaryotic Cells
- Bacterial Cell
- Pili and Flagella
- Cell Surface Membrane
- Plasmids
- Nucleoid
- 70S Ribosomes
- Gram-Staining
- Antibiotics
- Alternative Classification of Bacteria
- Viruses
- The Structure of Viruses
- DNA Viruses
- RNA Viruses
- RNA Retroviruses
- Viral Reproduction
- Virus Life Cycle
- DNA Virus Latency
- DNA Virus Lytic Pathway
- RNA Virus Replication
- Positive ssRNA Viruses
- Negative ssRNA Viruses
- Retrovirus Replication
- Viruses and Disease
- The Spread of Viral Diseases
- Treating Viral Diseases
- Preventing Viral Diseases
- Vaccination
- Disease Control
- Drug Development
- Pandemics
- Ethics
7. The Cell Cycle
8. Meiosis and Sexual Reproduction
- Sexual Reproduction
- Gametes
- Formation of Gametes
- Meiosis
- Prophase 1
- Metaphase 1
- Anaphase 1
- Telophase 1
- Meiosis 2
- The Importance of Meiosis
- Chromosome Mutation
- Non-disjunction
- Down's Syndrome
- Turner's Syndrome
- Spermatogenesis
- Oogenesis
- The Male Gamete
- The Female Gamete
- Gametogenesis in Plants
- Formation of Pollen
- Formation of Plant Egg Cells
- Pollination
- Internal Fertilisation
- External Fertilisation
- Fertilisation in Humans
- Fertilisation in Plants
- Embryo Development in Mammals
- Differentiation
9. Classification
- Biodiversity
- Classification
- Taxonomy
- Taxonomic Groups
- Binomial System
- Species
- Morphological Concept of Species
- Biological Concept of Species
- Other Species Models
- Limitations of Species Models
- Identifying a Species
- DNA Barcode
- DNA Analysis and Proteomics
- New Evolutionary Models
- Biochemical Relationships
- More Biochemical Relationships
- Gel Electrophoresis
- Domains
- Kingdoms
10. Natural Selection
- The Theory of Evolution
- Neo-Darwinism
- Adaptation
- Anatomical Adaptation
- Physiological Adaptation
- Behavioural Adaptation
- Grayling Butterflies
- Fungal Carnivores
- The Same Species in Different Environments
- Natural Selection
- Natural Selection in Oysters
- Natural Selection in Moths
- Reproductive Success
- Directional Selection
- Antibiotics
- Antibiotic Resistance
- Preventing Antibiotic Resistance
- Speciation
- Types of Isolation
- Allopatric Speciation
- Endemic Species
- Desert Pupfish
- Adaptive Radiation
- Sympatric Speciation
- Howea Palm Tree
- Fruit Fly Rhagoletis pomonella
- Cichlid Fish
- Cichlid Speciation
- Cichlids Under Threat
11. Biodiversity
- Biodiversity
- The Importance of Biodiversity
- Species Richness
- Endemic Species
- Species Abundance
- Index of Diversity
- Biodiversity of Different Habitats
- Changing Biodiversity
- Allele Frequency
- Measuring Genetic Biodiversity
- Hawaii
- Ethical Argument for Biodiversity
- Ecosystem Services
- Conserving Ecosystems
- Conservation
- Ex-Situ Conservation of Plants
- Ex-situ Conservation of Animals
- In-Situ Conservation
- In-situ Conservation Strategies
- National Parks
- Conflicts with Conservation
- Sustainability
12. Cell Transport Mechanisms
- The Need for Transport
- Transport Across the Cell Membrane
- Passive and Active Transport
- Diffusion
- Facilitated Diffusion
- Water Potential ψ
- Osmosis
- Modelling Osmosis
- Osmotic Concentrations
- Osmosis in Animal Cells
- Water Potential in Plant Cells
- Osmosis in Plant Cells
- Turgor Pressure (P)
- Osmotic Potential (π)
- Water Potential, Turgor Pressure and Osmotic Potential
- Active Transport
- Evidence for Active Transport
- Endocytosis and Exocytosis
13. Gas Exchange
- Gas Exchange in Small Organisms
- Surface Area to Volume Ratio
- Gas Exchange in Large Organisms
- Factors Affecting the Rate of Diffusion
- Effective Gas Exchange Systems
- The Human Gas Exchange System
- Gas Exchange in the Alveoli
- Adaptations of the Human Gas Exchange System
- Breathing
- Inhalation
- Exhalation
- Protecting the Lungs
- Gas Exchange in Insects
- The Tracheal System
- Very Active Insects
- Gas Exchange in Fish
- Fish Gills
- Ventilating the Gills
- The Countercurrent Exchange System
- Gas Exchange in Plants
- Stomata
- Opening and Closing the Stomata
- Lenticels
14. Circulatory Systems
- The Need for Transport Systems
- Features of a Mass Transport System
- Circulation Systems
- Single Circulation System
- Double Circulation System
- Cardiovascular System
- Components of Blood
- Plasma
- Erythrocytes
- Leucocytes
- Granulocytes
- Agranulocytes
- Platelets
- Haemoglobin and Oxygen Transport
- Oxygen Dissociation Curve for Haemoglobin
- The Bohr Effect
- Fetal Haemoglobin
- Myoglobin
- Transport of Carbon Dioxide
- Blood Clotting
- The Blood Clotting Cascade
- Blood Vessels
- Arteries
- Arterioles
- Capillaries
- Veins and venules
- Tissue Fluid
- Oncotic Pressure
- Hydrostatic Pressure
- Arterial End of Capillaries
- Venous End of Capillaries
- Formation of Lymph
- Lymph Nodes
15. The Heart
16. Cardiovascular Diseases
- Cardiovascular Diseases in the UK
- Atherosclerosis
- Aneurysms
- Raised Blood Pressure
- Heart Disease
- Angina
- Thrombosis
- Heart Attacks
- Strokes
- Epidemiology
- Risk
- Non-modifiable Risk Factors
- Modifiable Risk Factors
- Smoking and Atherosclerosis
- Exercise and Atherosclerosis
- Weight and Atherosclerosis
- Stress and Atherosclerosis
- Diet and Atherosclerosis
- Links Between Factors, Correlation and Causation
- Preventing Atherosclerosis
17. Transport in Plants
- Xylem and Phloem
- Xylem
- Evidence for the Movement of Water Through Xylem
- Phloem
- Root Hair Cells
- Symplast Pathway
- Apoplast Pathway
- Transpiration
- Cohesion-Tension Theory
- Adhesion and Capillarity
- Modelling Transpiration
- Measuring the Rate of Water Uptake
- Factors Affecting Transpiration
- Root Pressure
- Translocation in the Phloem
- Phloem Loading
- The Symplast Pathway
- The Apoplast Pathway
- Phloem Unloading
- Mass Flow Hypothesis
- Pressure Flow Hypothesis