AQA GCSE Biology Paper One Overview

Lauren, an expert examiner, provides a walkthrough of AQA GCSE Biology Paper One, covering key topics and expected answers in exams.

Resources

• Time stamps and descriptions for specific sections
• Links to predicted papers and walkthroughs
• Free questions and flashcards on the website

Cell Structure

Animal Cell Structure

• Parts: Cell membrane, cytoplasm, ribosomes, nucleus, mitochondria
• Functions:
  • Cell membrane: Controls entry/exit of substances
  • Cytoplasm: Site of chemical reactions
  • Ribosomes: Protein synthesis
  • Nucleus: Controls cell activities
  • Mitochondria: Site of aerobic respiration

Plant Cell Structure

• Parts: Cell wall, cell membrane, chloroplasts, vacuole, nucleus, ribosomes, mitochondria
• Functions:
  • Chloroplasts: Absorb light energy for photosynthesis
  • Vacuole: Supports cell structure
  • Cell wall: Made of cellulose, provides structure

Comparing Animal and Plant Cells

• Differences: Plant cells have cell wall, vacuole, chloroplasts
• Both are eukaryotic: Have nuclei and DNA

Prokaryotic Cells

• Examples: Bacterial cells
• Characteristics: No nucleus, DNA floating in cytoplasm, sometimes have flagella
• Parts: Cell membrane, cytoplasm, flagellum, plasmids, ribosomes, DNA, cell wall

Specialized Cells and Differentiation

Specialized Cells Examples

• Plant: Root hair cells, xylem, phloem
• Animal: Sperm cells, nerve cells, muscle cells

Cell Differentiation

• Process where cells become specialized
• Stem Cells: Undifferentiated cells, can become various cell types
  • Types:
    • Embryonic: Can become almost any cell type
    • Adult: Found in bone marrow, limited differentiation
    • Plant: Found in meristems, can differentiate throughout life

Microscopes

Types

• Optical/Light Microscope: Magnifies images using light
• Electron Microscope: Higher magnification and resolution than light microscope

Practical Use

• Preparing slides and viewing samples
• Calculating magnification

Culturing Microorganisms

Bacterial Growth

• Divide rapidly by binary fission
• Grown in liquid broth or nutrient agar

Aseptic Techniques

• Flame instruments, sterilize surfaces
• Incubate plates at 25°C, loosely tape lids

Chromosomes and Cell Division

Chromosomes

• DNA coiled into chromosomes, usually in pairs
• Humans: 23 pairs

Mitosis and Cell Cycle

• Stages: Interphase (preparation), Mitosis (division)
• Function: Growth, replacement of cells

Stem Cells

Uses

• Therapeutic cloning to produce embryonic stem cells
• Potential for treating diseases like diabetes, paralysis

Ethical Concerns

• Embryos can't consent, potential for life

Diffusion, Osmosis, and Active Transport

Diffusion

• Movement from high to low concentration, passive process
• Factors: Concentration gradient, distance, temperature, surface area

Osmosis

• Movement of water across semi-permeable membrane
• Conditions: Dilute, isotonic, concentrated solutions

Active Transport

• Movement against concentration gradient, requires energy
• Examples: Nutrient absorption in root hair cells, glucose absorption in intestines

Organization in Living Organisms

Levels

• Cells -> Tissues -> Organs -> Organ Systems -> Organism

Digestive System

• Enzymes and digestion of carbohydrates, proteins, lipids

Enzymes

• Lock and key mechanism
• Factors affecting enzyme action: Temperature, pH

Blood and Circulation

Blood Vessels

• Types: Arteries, veins, capillaries
• Functions: Transport blood, exchange substances

Blood Components

• Plasma: Liquid with dissolved substances
• Cells: Red blood cells, white blood cells, platelets

Heart Structure

• Chambers: Atria, ventricles
• Double circulatory system

Lungs and Gas Exchange

• Alveoli: Gas exchange, adaptation for diffusion

Non-Communicable Diseases and Cancer

Risk Factors

• Poor diet, lack of exercise, smoking

Treatments

• Statins, stents, heart transplants

Cancer

• Uncontrollable cell division, tumors
• Risk factors: Smoking, UV radiation, obesity

Plant Biology and Photosynthesis

Leaf Structure

• Tissues: Xylem, phloem, palisade mesophyll, spongy mesophyll

Transpiration and Translocation

• Water movement, nutrient transport

Photosynthesis

• Chemical reaction to produce glucose
• Factors affecting rate: Light, CO2, temperature

Practical Investigation

• Measuring rate of photosynthesis, controlling variables

Communicable Diseases

Pathogens and Spread

• Types: Virus, bacteria, fungi, protists

Human Defense Systems

• Physical and chemical barriers
• Immune response: Antibodies, vaccines

Drug Development and Use

Drug Trials

• Phases: Preclinical, clinical
• Testing for: Toxicity, efficacy, dosage

Antibiotics and Resistance

• Misuse leading to resistance
• Importance of completing antibiotic courses

Monoclonal Antibodies

Production and Use

• Specific to antigens, used in diagnostics and treatments

Evaluation

• Pros: Targeted treatment
• Cons: Side effects, ethical concerns

Summary

This lecture covers foundational concepts and key topics in GCSE Biology, emphasizing the structure and function of cells, the processes of life, and the importance of scientific methods and ethics in biological research.