EDXL GCSE Biology Paper 1 Summary

Overview

• Suitable for higher end foundation tier double combined or triple separate.
• Covers topics 1 to 5:
  1. Key concepts
  2. Cells and control
  3. Genetics
  4. Natural selection and genetic modification
  5. Health, disease, and medicines
• Key distinctions for triple only topics are noted.

Key Concepts

• Cells:
  • All life consists of cells visible with a light microscope (nucleus visible).
  • Electron microscopes show finer details of organelles with better resolution.
  • Cell Types:
    • Eukaryotic Cells: Have nucleus (DNA), e.g., plant and animal cells.
    • Prokaryotic Cells: No nucleus.
    • Both contain similar organelles.
• Cell Organelles:
  • Cell membrane: Semi-permeable.
  • Cell wall in plants/bacteria: Provides structure.
  • Cytoplasm: Site for chemical reactions.
  • Mitochondria: Site of respiration.
  • Ribosomes: Protein synthesis.
  • Chloroplasts in plant cells: Photosynthesis.
  • Permanent vacuole in plants: Contains sap.

Enzymes

• Biological catalysts breaking down larger molecules.
• Specific to substrates; work on a lock and key principle.
• Factors affecting enzyme activity:
  • Temperature: Increases rate until denaturation at high temps.
  • pH: Optimum pH varies; extremes denature enzymes.
• Practical: Mixing amylase with starch, observing the reaction with iodine.

Nutrient Tests

• Iodine: Orange to black with starch.
• Benedict’s Solution: Blue to orange with sugars.
• Biuret’s Reagent: Blue to purple with proteins.
• Ethanol: Cloudy with lipids.

Movement of Substances

• Diffusion: Passive movement from high to low concentration.
• Osmosis: Diffusion of water through a semi-permeable membrane.
  • Practical: Measuring osmosis in potato cylinders with sugar solutions.
• Active Transport: Uses energy to move substances against gradient.

DNA and Cells

• DNA in Eukaryotic Cells: Contained in the nucleus - 23 pairs of chromosomes in humans.
• Mitosis: Duplication of cells for growth and repair.
• Specialization: Cells develop specific functions; stem cells are unspecialized.

Nervous System

• Structure: CNS (brain/spinal cord) and PNS (nerves).
• Reflex Arc: Fast response, bypassing the brain.
• Reaction Time Investigation: Using a ruler drop test.
• Brain Parts:
  • Cerebral Cortex: Higher functions.
  • Cerebellum: Motor skills, balance.
  • Medulla Oblongata: Controls involuntary actions.

Eye Function

• Accommodation: Ability to focus on objects at varying distances.
• Common Vision Issues: Myopia and hyperopia.
• Vision Correction: Glasses, contact lenses, laser surgery.

Reproduction

• Sexual Reproduction: Involves gametes, meiosis.
• Asexual Reproduction: Cloning, no fusion of gametes.
• Genetic Variation: Results from sexual reproduction.

Genetics

• Genome: Complete set of genetic material.
• DNA Structure: Double helix formed by nucleotides (A, T, C, G).
• Mutations: Changes in DNA can affect function.
• Inheritance Patterns: Dominant vs recessive alleles, Punnett squares.

Evolution

• Natural Selection: Variations increase survival chances.
• Selective Breeding: Enhancing traits through breeding.
• Genetic Modification: Direct alteration of genes for desired traits.

Health and Disease

• Non-Communicable Diseases: E.g., cardiovascular diseases, cancer.
• Communicable Diseases: Caused by pathogens (viruses, bacteria, fungi, protists).
• Immune System: Antibodies, antigens, and vaccination.

Practical Applications

• Antibiotic Resistance: Problematic in treatment overuse.
• Drug Development: Trials for efficacy and side effects.
• Monoclonal Antibodies: Used in treatment and diagnosis.

These notes provide a comprehensive overview of the key topics and concepts in the EDXL GCSE Biology Paper 1, covering both combined science and some specifics for triple science.