AQA GCSE Biology Paper 1 Overview

Topics Covered:

• Cells
• Organization
• Infection and Response
• Bioenergetics

Note: Information is applicable for higher and foundation tier, double combined trilogy, and triple/separate biology.

Cells

• Microscopes
  • Light microscopes: See cells and nucleus.
  • Electron microscopes: See organelles, better resolution.
• Magnification
  • Formula: Magnification = Image size / Object size.
• Cell Types
  • Eukaryotic: Nucleus present (e.g., plant and animal cells).
  • Prokaryotic: No nucleus.
• Cell Structures
  • Cell membrane: Semi-permeable.
  • Cell wall (plants and bacteria): Made of cellulose, provides structure.
  • Cytoplasm: Site of chemical reactions.
  • Mitochondria: Respiration takes place here.
  • Ribosomes: Protein synthesis.
  • Chloroplasts (plants): Photosynthesis.
  • Vacuole (plants): Stores sap.
• Triple Only
  • Bacteria multiply by binary fission.
  • Practical: Aseptic technique to culture bacteria.

Mitosis and Genetics

• DNA and Chromosomes
  • Eukaryotic cells have DNA in chromosomes.
  • Humans have 23 pairs of chromosomes (diploid).
  • Gametes have 23 single chromosomes (haploid).
• Mitosis Process
  • DNA duplicates, nucleus divides, results in two identical cells.
• Specialized Cells and Stem Cells
  • Cells specialize based on function (e.g., nerve, muscle).
  • Stem cells: Unspecialized, found in embryos and bone marrow.
  • Uses in treating diseases like diabetes and paralysis.

Diffusion, Osmosis, and Active Transport

• Diffusion
  • Movement from high to low concentration.
• Osmosis
  • Diffusion of water across a membrane.
• Practical: Osmosis in Potatoes
  • Measure mass change in different sugar solutions.
• Active Transport
  • Movement against a concentration gradient using energy.

Organizational Hierarchy

• Cells form tissues, tissues form organs, organs form systems.
• Digestive System
  • Breaks food into nutrients, involves enzymes and bile.

Enzymes

• Function
  • Biological catalysts, specific to substrates.
  • Break down carbohydrates, proteins, lipids.
• Factors Affecting Enzyme Activity
  • Temperature, pH.
• Practical: Enzyme Activity
  • Measure starch breakdown with iodine.

Respiratory System

• Flow of Air
  • Trachea > Bronchi > Bronchioles > Alveoli.
• Gas Exchange
  • Oxygen into blood, CO2 exhaled.

Circulatory System

• Heart Structure and Function
  • Double circulatory system.
  • Blood flow pathway: Vena cava > Right atrium > Right ventricle > Lungs > Left atrium > Left ventricle > Body.
• Blood Vessels
  • Arteries: Carry blood away, higher pressure.
  • Veins: Carry blood to heart, lower pressure, valves prevent backflow.
• Heart-Related Diseases
  • Coronary heart disease (CHD), treatments include stents and statins.
• Components of Blood
  • Red blood cells, white blood cells, platelets, plasma.

Non-Communicable and Communicable Diseases

• Non-Communicable Diseases
  • Examples: Cardiovascular disease, diabetes, cancer.
• Communicable Diseases
  • Caused by pathogens like viruses, bacteria, fungi.
  • Examples: Measles, HIV/AIDS, gonorrhea, malaria.

Plant Biology

• Photosynthesis
  • Occurs in chloroplasts, equation provided.
  • Affected by light, temperature, CO2.
• Transpiration and Translocation
  • Movement of water and nutrients in plants.
• Leaf Structure
  • Layers: Waxy cuticle, epidermis, palisade mesophyll, spongy mesophyll, vascular bundle.

Infection and Response

• Immune System
  • Skin, mucus, white blood cells defend against pathogens.
  • Vaccination introduces inactive pathogens to build immunity.
• Antibiotics
  • Kill bacteria, not viruses.
  • Overuse leads to resistance.

Bioenergetics

• Respiration
  • Aerobic: With oxygen.
  • Anaerobic: Without oxygen, produces lactic acid.
• Metabolism
  • Sum of all chemical reactions in a cell/organism.

These notes cover the essential topics and practicals for the AQA GCSE Biology Paper 1. Review these notes regularly to reinforce your understanding and retention of the material.