AQA GCSE Biology Paper 1 Summary

Overview

This lecture covers essential topics for AQA GCSE Biology Paper 1, applied to both higher and foundation tiers, including:

• Cells
• Organization
• Infection and Response
• Bioenergetics

The guide includes information relevant to Double Combined Trilogy and Triple or Separate Biology streams.

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Cells

• Microscopes:

  • Light microscopes show cells and nuclei.
  • Electron microscopes show detailed organelles.
  • Magnification formula: ( \text{Magnification} = \frac{\text{Image size}}{\text{Object size}} ).

• Cell Types:

  • Eukaryotic (with nucleus) - plant and animal cells.
  • Prokaryotic (no nucleus).

• Subcellular Structures:

  • Cell membrane: semi-permeable.
  • Cell wall (plants/bacteria): rigid structure.
  • Cytoplasm: site for chemical reactions.
  • Mitochondria: site of respiration.
  • Ribosomes: protein synthesis.
  • Chloroplasts (plants): photosynthesis.
  • Vacuole (plants): stores sap.

• Triple Biology: Bacteria multiplies by binary fission.

• Practical: Growing bacterial cultures on agar using aseptic techniques.

DNA and Mitosis

• DNA

  • Stored in chromosomes; humans have 23 pairs.
  • Gametes are haploid (23 single chromosomes).

• Mitosis

  • Process of cell duplication for growth and repair.
  • Steps: DNA duplication, nucleus breakdown, chromosomes pulled apart, new nucleus formation.

• Specialized Cells

  • Different cells for different functions (e.g., nerve, muscle, etc.).

• Stem Cells:

  • Unspecialized cells found in embryos and bone marrow.
  • Potential treatment for diseases like diabetes.

• Cloning in Plants: Preservation and crop production.

Transport in Cells

• Diffusion: Movement from high to low concentration.
• Osmosis: Water diffusion across membranes.
• Active Transport: Movement against the gradient using energy.
• Practical: Osmosis in potato cylinders.

Organization

• Hierarchy:

  • Cells → Tissues → Organs → Organ Systems

• Digestive System:

  • Breaks down food into nutrients.
  • Involves stomach, liver, gallbladder, small intestine, etc.
  • Enzymes: biological catalysts (e.g., amylase, proteases, lipases).

• Respiratory System:

  • Gas exchange through trachea, bronchi, bronchioles, and alveoli.

• Circulatory System:

  • Double circulatory system: blood enters heart twice per cycle.
  • Heart anatomy and functions (e.g., arteries, veins, capillaries).
  • Conditions like coronary heart disease.

Disease and Immunity

• Non-Communicable Diseases: e.g., coronary heart disease, diabetes.

• Communicable Diseases: Viral, bacterial, fungal, and protist infections.

  • Examples include measles, HIV, salmonella, malaria, etc.

• Body Defenses: Skin, mucus, stomach acid, and white blood cells.

• Vaccines: Provide immunity by exposing the immune system to a pathogen's antigens.

• Antibiotics: Kill bacteria, not viruses; resistance issues.

• Drug Development: Includes trials from cell to human testing.

Plant Biology

• Photosynthesis:

  • Occurs in chlorophyll and chloroplasts; endothermic reaction.
  • Factors affecting rate: temperature, light intensity, CO2 concentration.

• Plant Transport:

  • Transpiration (water through xylem) and translocation (nutrients through phloem).

Bioenergetics

• Respiration:

  • Aerobic (with oxygen) and anaerobic (without oxygen).
  • Effects of exercise on respiration.

• Metabolism: Sum of all chemical reactions within an organism.

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Note: The lecture emphasizes practical applications and scientific principles, offering a comprehensive review of key topics for the exam.