EDXL GCSE Biology Paper One

This lecture covers key concepts for higher end foundation tier, double combined, or triple separate in GCSE Biology. It includes topics 1-5: Key concepts, cells and control, genetics, natural selection and genetic modification, health, disease, and medicines. Emphasis is placed on identifying which concepts are for triple and which for higher and foundation tiers.

Key Concepts of Cells

• Microscopy

  • Light microscope: See cells and nuclei, but not subcellular structures.
  • Electron microscope: Higher resolution, shows organelles.
  • Magnification formula: Image size / Object size. Actual cell size = Measured size / Magnification.

• Cell Types

  • Eukaryotic Cells: Have a nucleus (e.g., plants, animals).
  • Prokaryotic Cells: No nucleus.
  • Organelles common to both: Cell membrane, cytoplasm, mitochondria, ribosomes.
  • Plant Cells: Chloroplasts (photosynthesis), permanent vacuole.

• Enzymes

  • Act as biological catalysts.
  • Specific enzymes for specific molecules (lock and key principle).
  • Factors affecting enzyme activity: Temperature, pH.
  • Practical examples: Mixing amalayise and starch for pH and temperature tests.

• Nutrient Tests

  • Iodine for starch, Benedict's solution for sugars, Biuret's for proteins, ethanol for lipids.

Transport Mechanisms

• Diffusion

  • Passive movement from high to low concentration.
  • Happens across semi-permeable membranes.

• Osmosis

  • Specific to water diffusion.
  • Practical: Potato cylinders in sugar solutions.

• Active Transport

  • Uses energy to move substances against a gradient.
  • Example: Mineral ions in root hair cells.

Genetics and Cell Division

• DNA and Chromosomes

  • Eukaryotic nuclei contain DNA in chromosomes.
  • Diploid cells (23 pairs in humans), haploid cells (23 chromosomes in gametes).

• Cell Division

  • Mitosis: Produces identical cells for growth and repair.
  • Stem Cells: Unspecialized, can differentiate.

• Genetic Engineering

  • Cloning, selective breeding, genetic modification (insulin, GM crops).
  • Ethical considerations.

Nervous System

• Structure

  • CNS: Brain and spinal cord.
  • PNS: Nerves throughout the body.
  • Reflex arc: Fast, bypasses brain.

• Brain Functions

  • Cerebral cortex: Higher functions.
  • Cerebellum: Movement.
  • Medulla: Involuntary actions.

• Eye Functionality

  • Accommodation: Focus on objects at varying distances.
  • Issues: Myopia, hyperopia, corrected with lenses.

Reproduction

• Sexual vs. Asexual Reproduction

  • Sexual: Involves gametes, variation.
  • Asexual: Cloning, no variation.

• Mendelian Inheritance

  • Dominant and recessive alleles.
  • Use of Punnett squares for predicting inheritance patterns.
  • Sex determination (XX, XY).

Evolution and Variation

• Darwin vs. Lamarck

  • Darwin: Natural selection.
  • Lamarck: Epigenetics influences gene expression.

• Antibiotic Resistance

  • Bacterial evolution due to mutations.

Health, Disease, and Medicines

• Non-Communicable Diseases

  • Examples: CVD, diabetes, cancer.
  • Factors: Diet, smoking, alcohol.

• Communicable Diseases

  • Pathogens: Viruses, bacteria, fungi, protists.
  • Body defenses: Skin, mucus, white blood cells.
  • Vaccination: Prepares immune system with a dead or inert pathogen.

• Antibiotics and Drug Development

  • Antibiotics target bacteria, not viruses.
  • Drug trials: Lab, animal, human; placebos for control.

• Monoclonal Antibodies

  • Produced from cloned cells, used in diagnosis and treatment.
  • Side effects can be significant.

These notes summarize the complex and wide-ranging topics covered in the GCSE Biology Paper One lecture, providing a comprehensive overview of key concepts, practical applications, and scientific theories.