AQA GCSE Biology Paper 1 Revision Notes

Topics Covered

• Cells
• Organization
• Infection and Response
• Bioenergetics

Cells

• Types of Microscopes:
  • Light Microscope: Can see cells and perhaps nucleus, but not finer details.
  • Electron Microscope: Higher resolution, can see subcellular structures.
• Cell Types:
  • Eukaryotic Cells: Contain a nucleus (plant and animal cells).
  • Prokaryotic Cells: No nucleus.
• Cell Structures:
  • Cell Membrane: Semi-permeable.
  • Cell Wall: In plants/bacteria, made of cellulose.
  • Cytoplasm: Site of chemical reactions.
  • Mitochondria: Site of respiration.
  • Ribosomes: Protein synthesis.
  • Chloroplasts (Plant cells): Photosynthesis.
  • Vacuole (Plant cells): Storage of cell sap.
• Mitosis: Cell duplication for growth and repair.
• Meiosis: Formation of gametes (haploid cells).
• Stem Cells: Unspecialized cells used for repair and cloning.
• Diffusion/Osmosis: Movement of substances across membranes.
• Practical on Osmosis: Using potato cylinders in sugar solution.
• Active Transport: Movement of substances against concentration gradient.

Organization

• Tissues and Organs: Groups of cells, organs form systems.
• Digestive System: Breakdown of food using enzymes, bile.
  • Enzymes: Biological catalysts, specific to substrates.
    • Amylase: Starch to glucose.
    • Protease: Proteins to amino acids.
    • Lipase: Lipids to fatty acids and glycerol.
  • Enzyme Activity: Affected by temperature and pH.
• Respiratory System: Gas exchange in alveoli.
• Circulatory System: Heart, blood vessels, and double circulation.
  • Heart Functioning: Valves prevent backflow, artificial pacemakers for rhythm.
  • Vessels: Arteries (away from heart), veins (to heart), capillaries.

Infection and Response

• Pathogens: Cause communicable diseases (viruses, bacteria, fungi, protists).
• Body Defenses: Skin, mucus, white blood cells (lymphocytes, phagocytes).
• Vaccination: Exposes immune system to pathogen antigens, provides immunity.
• Antibiotics: Treat bacterial infections, not viruses.
• Drug Trials: Lab, animal, human (blind and double-blind trials).
• Monoclonal Antibodies: Used for treatment, diagnosis, have side effects.

Bioenergetics

• Photosynthesis: In chloroplasts, endothermic reaction.
  • Equation: CO2 + H2O (+ light) → C6H12O6 + O2.
• Respiration: Provides energy for cellular processes.
  • Aerobic Respiration: With oxygen, more energy produced.
  • Anaerobic Respiration: Without oxygen, produces lactic acid (muscle fatigue).
• Metabolism: Sum of all reactions in the cell, includes respiration and synthesis.

Additional Information

• Practical experiments to solidify understanding of key concepts.
• Importance of understanding the relationship between organisms and their environment (e.g., transpiration, photosynthesis, diffusion).
• Ethical implications of scientific advancements (e.g., stem cell research).

Note: These notes are structured to provide a comprehensive overview for revision and study purposes. Ensure practical understanding through experiments and apply ethical considerations when discussing scientific applications.