AQA GCSE Biology Paper 1 Lecture Notes

Introduction

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Cell Structures

Animal Cell Structure

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

Plant Cell Structure

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

Comparison

• Plant cells have chloroplasts, vacuole, and cell wall which are not in animal cells.
• Both plant and animal cells are eukaryotic (have a nucleus).

Prokaryotic Cells

• Examples: Bacterial cells.
• Components: Cell membrane, cytoplasm, sometimes flagellum, plasmids, ribosomes, cell wall (not cellulose).
• Differences from Eukaryotic: No nucleus, DNA in cytoplasm.

Specialized Cells

• Examples: Root hair cells, xylem, phloem, sperm cells, nerve cells, muscle cells.
• Cells change shape and structure to perform specific functions.

Microscopy

• Types: Light microscopes, electron microscopes.
• Light Microscopes: Used for observing cell structure.
• Electron Microscopes: Higher magnification and resolution, can see smaller structures.

Cell Division and Stem Cells

• Cell Cycle: Interphase (growth and DNA replication) and mitosis (cell division).
• Stem Cells: Undifferentiated cells that can differentiate into various cell types.
• Sources: Embryonic stem cells, adult stem cells, plant stem cells.

Transport in Cells

Diffusion

• Movement from high to low concentration without energy.
• Factors affecting rate: Concentration gradient, distance, temperature, surface area.

Osmosis

• Movement of water from dilute to concentrated solution through a semi-permeable membrane.
• Practical methods: Using plant tissues in solutions of varying concentrations.

Active Transport

• Movement against concentration gradient using energy.
• Examples: Mineral ion uptake in root hair cells, glucose uptake in the intestine.

Organisation of Living Organisms

• Hierarchical structure: Cells → Tissues → Organs → Organ Systems → Organisms.
• Example: Digestive system.

Enzymes and Digestion

• Enzymes: Catalysts breaking down substrates like carbohydrates, proteins, and lipids.
• Factors affecting enzymes: Temperature, pH, substrate concentration.
• Bile: Neutralizes stomach acid, emulsifies fats.

Circulatory System

Blood Vessels

• Arteries: Carry blood away from heart, high pressure.
• Veins: Carry blood to heart, low pressure.
• Capillaries: Exchange of substances.

Blood Composition

• Components: Plasma, red blood cells, white blood cells, platelets.

Heart and Transport

• Structure of the heart and double circulatory system.
• Blood flow through heart and lungs.

Diseases

Coronary Heart Disease

• Caused by plaque buildup in coronary arteries leading to heart attacks.
• Treatments: Statins, stents, heart transplants.

Types of Diseases

• Communicable: Spread by pathogens.
• Non-communicable: Not spreadable, often lifestyle-related.

Cancer

• Caused by uncontrollable cell division.
• Types: Benign and malignant tumors.
• Risk factors: Smoking, UV exposure, obesity.

Plant Biology

Structure and Function

• Leaf structure: Palisade tissue, upper/lower epidermis, xylem, phloem.
• Transpiration: Water movement through plant.
• Translocation: Movement of sugars and nutrients.

Photosynthesis

• Process of converting light energy into glucose and oxygen.
• Factors affecting rate: Light intensity, CO2 concentration, temperature.
• Practical methods: Measuring oxygen bubbles in water plants.

Human Defense Systems

Pathogens

• Types: Viruses, bacteria, fungi, protists.

Immune System

• Non-specific defenses: Skin, mucus, hydrochloric acid.
• Specific defenses: White blood cells, vaccines.

Drugs and Treatments

• Painkillers: Relieve symptoms but don't kill pathogens.
• Antibiotics: Kill bacteria, not effective against viruses.

Antibiotic Resistance

• Caused by overuse and misuse of antibiotics.
• Prevention: Proper prescription and adherence to treatment.

Monoclonal Antibodies

• Produced from single clones and used for diagnosis and treatment.
• Uses: Pregnancy tests, cancer treatment.

Plant Diseases and Defenses

• Deficiency diseases: Caused by lack of nutrients.
• Defense mechanisms: Physical (thorns), chemical (toxins), mechanical (leaf movement).

These notes cover the extensive content needed for AQA GCSE Biology Paper 1, providing a summary of key concepts and details necessary for understanding and revising the material presented in the lecture.