EDXL GCSE Biology Paper One Lecture Notes

Introduction

• Covers topics 1 to 5: Key concepts, cells and control, genetics, natural selection and genetic modification, health, disease, and medicines.
• Suitable for higher end foundation tier, double combined, or triple separate.
• Distinction made for triple content versus higher/foundation tier.

Cells

Types of Cells

• Eukaryotic cells: Have a nucleus, e.g., plant and animal cells.
• Prokaryotic cells: No nucleus, e.g., bacteria.
• Both cell types contain similar organelles.

Cell Components

• Cell Membrane: Semi-permeable, controls substance passage.
• Cell Wall: Found in plant cells and most bacteria for rigid structure.
• Cytoplasm: Site for chemical reactions.
• Organelles:
  • Mitochondria: Respiration and energy release.
  • Ribosomes: Protein synthesis.
  • Chloroplasts (in plants): Photosynthesis.
  • Vacuole (in plants): Storage of sap.

Enzymes

• Biological catalysts.
• Specific in action (lock and key model).
• Types: Amylase (starch to glucose), protease (proteins to amino acids), lipase (lipids to glycerol and fatty acids).
• Activity influenced by temperature and pH.

Diffusion and Osmosis

• Diffusion: Passive movement from high to low concentration.
• Osmosis: Diffusion of water across a semi-permeable membrane.
• Factors increasing rate: Concentration gradient, temperature, surface area.

Genetics

DNA and Genes

• DNA: Two-stranded polymer in a double helix.
• Genes: DNA sections coding for proteins.
• Genome: Total genetic material.

Cell Division

• Mitosis: Cell duplication for growth/repair.
• Meiosis: Formation of gametes (sex cells).

Inheritance

• Alleles: Different forms of a gene.
• Dominant allele expressed over recessive.
• Use of Punnett squares for predicting inheritance.

Evolution

• Natural Selection: Variations advantageous for survival.
• Epigenetics: Environmental influence on gene expression.

Health and Disease

Disease Types

• Non-communicable: e.g., CVD, diabetes, cancer.
• Communicable: Caused by pathogens (viruses, bacteria, fungi, protists).

Immune System

• Pathogen defense: Skin, mucus, white blood cells.
• Vaccines: Introduce inactive pathogen to stimulate immunity.

Medicines

• Development from natural sources.
• Antibiotics: Bacteria-specific treatment.
• Drug Trials: Lab, animal, then human testing.

Advanced Topics

Triple Content

• Monoclonal Antibodies: Cloned cells for specific treatment.
• Genetic Engineering: Modifying organisms for desired traits.

Conclusion

• Encouragement to review and ask questions.