AQA GCSE Biology Paper 1 Overview

Key Topics Covered

• Cells
• Organization
• Infection and Response
• Bioenergetics

Cells

• Types of Cells:
  • Eukaryotic Cells: Have a nucleus (e.g., plant and animal cells)
  • Prokaryotic Cells: Do not have a nucleus
• Microscopy:
  • Light vs. Electron Microscopes
  • Magnification calculation: Image size / Object size
• Cell Structures:
  • Cell membrane: Semi-permeable
  • Cell wall: Provides structure (plants and bacteria)
  • Cytoplasm: Site of chemical reactions
  • Mitochondria: Site of respiration
  • Ribosomes: Protein synthesis
  • Chloroplasts: Photosynthesis in plant cells
  • Permanent vacuole: Stores sap in plants

Specialized Processes

• Bacteria Multiplication: Binary fission
  • Practical: Aseptic technique in culturing bacteria
• Chromosomes in Cells:
  • Diploid: 23 pairs in humans
  • Haploid: 23 single chromosomes in gametes
• Cell Division: Mitosis
  • Duplication of genetic material, nucleus divides, two identical cells formed

Cell Specialization and Cloning

• Stem Cells:
  • Found in embryos, bone marrow
  • Potential for treating diabetes, paralysis
  • Ethical considerations
• Cloning Plants: Prevent extinction, desirable characteristics

Transport Processes

• Diffusion: Movement from high to low concentration, passive
• Osmosis: Diffusion of water
  • Practical: Potato in sugar solution, measure mass change
• Active Transport: Movement against concentration gradient, requires energy

Organization

• Tissues, Organs, and Systems
  • Tissues: Groups of similar cells
  • Organs: Functioning units like heart
  • Organ systems: e.g., Circulatory system

Digestive System

• Process: Breakdown of food into nutrients
  • Role of stomach acid, bile, enzymes
• Enzymes:
  • Biological catalysts
  • Enzyme specificity: Lock-and-key model
  • Conditions affecting enzyme activity: Temperature, pH
• Food Tests: Identifying nutrients
  • Iodine for starch, Benedict's for sugars, etc.

Respiratory System

• Gas Exchange:
  • Oxygen into blood via alveoli
  • Carbon dioxide exhaled

Circulatory System

• Heart Function: Double circulatory system
  • Right side: Deoxygenated blood to lungs
  • Left side: Oxygenated blood to body
• Blood Components:
  • Red and white blood cells, platelets
• Heart Health: CHD, use of stents, statins

Infection and Response

• Pathogens: Viruses, bacteria, fungi, protists
  • Disease examples: Measles, HIV, Salmonella
• Body's Defense:
  • Skin, mucus, white blood cells
• Vaccination: Introduces inert pathogen to stimulate immunity
• Antibiotics: Effective against bacteria, not viruses

Bioenergetics

• Photosynthesis: Light-dependent reaction in chloroplasts
  • Factors affecting rate: Light, CO2, temperature
  • Practical: Measuring oxygen production
• Respiration:
  • Aerobic vs. Anaerobic
  • Effects of exercise on respiration
  • Fermentation in yeast

Metabolism

• Definition: Sum of all cellular reactions
  • Includes respiration, synthesis of macromolecules

Leave a comment if you have questions or need further clarification.