AQA GCSE Biology Paper 1 Overview

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 (e.g., bacteria)
  • Both types have similar organelles.
• Microscopy
  • Light microscope: basic cell structures visible.
  • Electron microscope: detailed organelle structures visible.
  • Magnification formula: Image size / Object size.
• Cell Structures
  • Cell membrane: semi-permeable.
  • Cell wall: present in plant cells and bacteria, made of cellulose.
  • Cytoplasm: where most chemical reactions take place.
  • Mitochondria: respiration center.
  • Ribosomes: protein synthesis.
  • Chloroplasts: photosynthesis in plant cells.
  • Vacuole: stores sap in plant cells.
• Cell Division
  • Mitosis: process of cell duplication for growth and repair.
  • Stem cells: unspecialized cells that can differentiate.

Organization

• Hierarchical Structure
  • Cells → Tissues → Organs → Organ Systems.
• Digestive System
  • Functions: Breaks down food into nutrients.
  • Components: Stomach, liver, intestines, bile, and enzymes.
• Circulatory System
  • Heart: double circulatory system, composed of chambers.
  • Blood Vessels: arteries, veins, capillaries.
  • Blood Components: red blood cells, white blood cells, plasma, platelets.

Infection and Response

• Pathogens
  • Types: viruses, bacteria, fungi, and protists.
  • Infection process varies by pathogen type.
• Immune Response
  • Barriers: skin, mucus, stomach acid.
  • White blood cells: fight infections via antibodies and antitoxins.
  • Vaccination: introduction of inactive pathogens to stimulate immunity.
• Antibiotics and Resistance
  • Only effective against bacteria.
  • Overuse leads to resistance.

Bioenergetics

• Photosynthesis
  • Occurs in chloroplasts.
  • Equation: Carbon dioxide + Water → Glucose + Oxygen (light energy required).
  • Limiting factors: light intensity, CO2 concentration, temperature.
• Respiration
  • Aerobic: with oxygen, more energy.
  • Anaerobic: without oxygen, less energy (produces lactic acid in muscles).
  • Fermentation: in yeast, produces ethanol and CO2.
• Metabolism
  • Sum of all chemical reactions in an organism.

Practical Experiments

• Osmosis
  • Investigation using potato cylinders in sugar solutions.
• Enzyme Activity
  • Effect of temperature and pH on amylase activity.

Key Concepts

• Diffusion and Osmosis
  • Passive movement down a concentration gradient.
• Active Transport
  • Movement against concentration gradient, requires energy.

Ethical Considerations

• Stem Cell Research
  • Potential benefits vs. ethical concerns.

The lecture aimed to provide a comprehensive review of the topics necessary for AQA GCSE Biology Paper 1. It included detailed explanations of cellular processes, organism organization, infection mechanisms, bioenergetics, and practical experiments, ensuring a thorough understanding of the material.