AQA GCSE Biology Paper 1 Summary

Key Topics

• Cells
• Organization
• Infection and Response
• Bioenergetics

Cells

• Introduction: All life forms consist of cells.
• Microscopy:
  • Light microscopes allow viewing of cells and nuclei but not finer details.
  • Electron microscopes provide higher resolution and resolving power to see organelles.
  • Magnification formula: Image size / Object size.
• Cell Types:
  • Eukaryotic: Contain nucleus (e.g., plant and animal cells).
  • Prokaryotic: Lack a nucleus.
• Cell Structures:
  • Cell Membrane: Semi-permeable, controls substance entry and exit.
  • Cell Wall: Provides structure in plants and bacteria.
  • Cytoplasm: Site of chemical reactions.
  • Mitochondria: Site of respiration.
  • Ribosomes: Protein synthesis.
  • Chloroplasts in plants: Site of photosynthesis.
  • Vacuole: Stores sap in plant cells.
• Cell Division:
  • Binary Fission (Bacteria): Method of reproduction.
  • Mitosis: Process of cell duplication for growth and repair.
• Specialized Cells: Cells adapt for specific functions (e.g., nerve cells, muscle cells).
• Stem Cells: Undifferentiated cells that can develop into various cell types.
  • Ethical Considerations: Cloning and stem cell research.
• Transport Mechanisms:
  • Diffusion: Passive movement of particles from high to low concentration.
  • Osmosis: Diffusion of water across a membrane.
  • Active Transport: Movement of substances against concentration gradient using energy.

Organization

• Hierarchy: Cells → Tissues → Organs → Organ Systems.
• Digestive System: Breakdown of food using organs and enzymes.
• Enzymes:
  • Biological catalysts that speed up reactions.
  • Specific to substrates (e.g., amylase for starch).
  • Affected by temperature and pH.

Infection and Response

• Pathogens: Viruses, bacteria, fungi, and protists causing disease.
• Immune Response:
  • Skin and mucous as barriers.
  • White blood cells producing antibodies and antitoxins.
• Vaccinations: Introduce dead/inert pathogens to stimulate immunity.
• Antibiotics: Treat bacterial infections, ineffective against viruses.
• Drug Trials:
  • Blind and double-blind trials for testing effectiveness and side effects.
  • Use of placebos for control groups.

Bioenergetics

• Photosynthesis:
  • Occurs in chloroplasts, produces glucose and oxygen.
  • Affected by light intensity, carbon dioxide levels, and temperature.
• Respiration:
  • Aerobic: Uses oxygen to release energy from glucose.
  • Anaerobic: Occurs without oxygen, produces lactic acid or ethanol.
• Metabolism: Sum of all biochemical reactions in an organism.

Practical Applications

• Osmosis Experiment: Using potato cylinders in sugar solutions to observe mass changes.
• Enzyme Activity: Testing amylase with starch at different temperatures/pH.
• Photosynthesis Rate: Measuring oxygen production in pondweed under varying light conditions.

Additional Notes for Triple Science

• Bacteria Culture: Technique of growing bacteria using aseptic methods.
• Transpiration and Translocation: Water and nutrient movement in plants.
• Monoclonal Antibodies: Specific antibodies produced for disease treatment and diagnosis.

These notes capture the essentials for AQA GCSE Biology Paper 1, spanning key biological concepts and practical experiments. Remember to focus on understanding processes and their applications.