AQA GCSE Biology Paper 1 Revision Notes

Introduction

• Covers higher and foundation tier, double combined trilogy and triple (separate biology).
• Focus areas: cells, organization, infection and response, bioenergetics.

Cells

• Types of Cells:
  • Eukaryotic: Have a nucleus, e.g., plant and animal cells.
  • Prokaryotic: No nucleus.
• Microscopy:
  • Light microscope: Can see cells and nucleus.
  • Electron microscope: Can see finer cell structures.
• Cell Structure:
  • Cell membrane: Semi-permeable.
  • Cell wall (plants/bacteria): Provides structure.
  • Cytoplasm: Site of chemical reactions.
  • Mitochondria: Site of respiration.
  • Ribosomes: Protein synthesis.
  • Chloroplasts (plants): Site of photosynthesis.
  • Permanent vacuole (plants): Stores sap.

Calculations in Microscopy

• Actual size of cells:
  • Formula: Magnification = Image size / Object size.
  • Rearrange to find actual size.

Bacteria (Triple Science)

• Multiply by binary fission.
• Culturing bacteria in the lab using aseptic technique.
• Practical: Measure culture growth or effect of antibiotics using area calculations.

DNA and Mitosis

• DNA in Eukaryotic Cells: Stored in chromosomes.
• Human Cells: 23 pairs of chromosomes (diploid), gametes have 23 single chromosomes (haploid).
• Mitosis Process:
  • Genetic material duplicates.
  • Nucleus divides, chromosomes separate, new nuclei form.
  • Two identical cells result.

Specialized Cells and Stem Cells

• Different cell types for specific functions.
• Stem Cells:
  • Embryonic stem cells can differentiate into any cell type.
  • Adult stem cells (e.g., bone marrow) mainly produce blood cells.
  • Application in treating diseases and cloning plants.

Diffusion and Osmosis

• Diffusion: Movement from high to low concentration.
• Osmosis: Diffusion of water across a semi-permeable membrane.
• Factors affecting rate: Concentration gradient, temperature, surface area.
• Practical: Measure osmosis using potato cylinders in sugar solutions.

Active Transport

• Movement of substances against a concentration gradient using energy.
• Example: Mineral ions into plant root hair cells.

Organization

• Hierarchical Structure:
  • Cells → Tissues → Organs → Organ Systems.
• Digestive System:
  • Breaks down food using stomach acid, bile, and enzymes.
  • Enzymes: Amylase, proteases, and lipases.
  • Lock and key model for enzyme specificity.
  • Factors affecting enzyme activity: Temperature, pH.

Respiratory System

• Breathing vs. Respiration:
  • Breathing supplies oxygen for cellular respiration.
• Gas Exchange: Occurs in alveoli.

Circulatory System

• Heart Structure and Function:
  • Double circulatory system overview.
  • Oxygenated and deoxygenated blood pathways.
• Blood Vessels: Arteries, veins, and capillaries.
• Coronary Heart Disease: Issues and treatments (like stents).
• Blood Components: Red and white blood cells, platelets.

Infection and Response

• Non-Communicable vs. Communicable Diseases:
  • Examples and causes.
  • Pathogens: Viruses, bacteria, fungi, protists.
• Body Defenses: Skin, mucus, white blood cells, etc.
• Vaccines and Immunity: How vaccines work.
• Antibiotics: Function and resistance issues.
• Drug Development: Testing and trials.

Monoclonal Antibodies (Triple Science)

• Production and applications.

Bioenergetics

• Photosynthesis:
  • Process and rate factors.
  • Practical: Measure rate with pondweed.
• Respiration:
  • Aerobic and anaerobic processes.
  • Differences in plant and yeast cells.

Metabolism

• Sum of all chemical reactions in an organism.
• Examples include respiration and synthesis of various molecules.

These notes provide a concise overview of the key points from the AQA GCSE Biology Paper 1 lecture, covering cells, organization, infection, response, and bioenergetics.