GCSE Biology: Paper 1 Lecture Notes

Introduction

• Video provides help for GCSE Biology and Combined Science exams.
• Additional resources like revision workbooks and maps available.
• Encouragement and good luck for exams.

Cell Biology

Microscopy

• Light Microscope
  • Developed in the 17th century.
  • Uses light to form images, can view live specimens.
  • Advantages: cheap, easy to use, magnifies up to 2000x.
  • Resolution: about 200 nanometers.
• Electron Microscope
  • Developed in the 1930s, uses electrons to form images.
  • Specimens must be dead, very expensive.
  • Magnification: up to 2 million times, resolution: 0.2 nanometers.
  • Allows detailed understanding of subcellular structures.

Animal and Plant Cells

• Animal Cells
  • Organelles: nucleus, cell membrane, cytoplasm, mitochondria, ribosomes.
  • Functions: control activities, passage of substances, chemical reactions, energy release, protein synthesis.
• Plant Cells
  • Includes animal cell organelles plus chloroplasts, permanent vacuole, cell wall.
  • Functions: photosynthesis, rigidity, support.

Eukaryotic and Prokaryotic Cells

• Eukaryotic Cells
  • Includes animal, plant, fungi, and protists.
  • Features: cell membrane, cytoplasm, nucleus.
• Prokaryotic Cells
  • Includes bacteria.
  • Features: cell wall, no nucleus, plasmids, some have slime layer and flagella.

Specialized Cells

• Specialized Animal Cells
  • Examples: sperm cell (movement, fertilization), muscle cell (contraction, energy storage), nerve cell (impulse transmission).
• Specialized Plant Cells
  • Examples: root hair cell (water absorption), xylem (water transport), phloem (food transport).

Diffusion, Osmosis, and Active Transport

• Diffusion
  • Movement from high to low concentration, passive process.
• Osmosis
  • Special case of diffusion, water movement through semi-permeable membrane.
• Active Transport
  • Movement against concentration gradient, requires energy.

Mitosis and the Cell Cycle

• Mitosis
  • Purpose: growth, development, repair.
  • Stages: growth and DNA replication, mitosis, division of cytoplasm.

Stem Cells

• Types
  • Embryonic (can become any cell type), Adult (limited differentiation).
• Uses
  • Treatment of conditions, cloning plants and animals.

Culturing Microorganisms

• Binary Fission
  • Bacterial reproduction process.
• Aseptic Techniques
  • Sterilization, use of inoculating loops, storage methods to prevent contamination.

Organization

Principles of Organization

• Hierarchy: Cells -> Tissues -> Organs -> Organ Systems -> Organism.

Human Digestive System

• Process
  • Mechanical digestion in mouth, chemical digestion in stomach, absorption in intestines.

Enzymes

• Function
  • Biological catalysts, specific to substrates (lock-and-key model).

Factors Affecting Enzymes

• Temperature and pH
  • Optimal conditions for activity, denaturation at extremes.

Blood and Circulatory System

• Components
  • Plasma, red and white blood cells, platelets.
• Blood Vessels
  • Arteries, veins, capillaries.
• Heart
  • Structure, function, double circulatory system.

Coronary Heart Disease

• Causes and Treatments
  • Fatty deposits in arteries, treatments include stents and statins.

Health and Disease

Health Issues

• Types of Diseases
  • Communicable vs. Non-communicable.

Non-communicable Diseases

• Causes and Risks Factors
  • Lifestyle choices, environmental factors.

Cancer

• Types
  • Benign vs. Malignant tumors.
• Treatments
  • Radiotherapy, Chemotherapy.

Plant Biology

Plant Tissues and Organs

• Leaf Structure
  • Epidermal tissues, mesophyll tissues, transport systems (xylem and phloem).

Transpiration

• Process and Factors
  • Water movement through plants, affected by light, temperature, humidity, and wind.

Infection and Response

Communicable Diseases

• Pathogens
  • Bacteria, viruses, fungi, protists.
• Prevention Methods
  • Hygiene, isolation, vectors, vaccination.

Viral Diseases

• Examples
  • Measles, HIV, TMV.

Bacterial Diseases

• Examples
  • Salmonella, Gonorrhea.

Human Defense Systems

• First Line of Defense
  • Skin, mucus, stomach acid.

Vaccination

• Process
  • Introduction of inactive pathogen to stimulate immune response.

Antibiotics and Medicines

• Functions and Limitations
  • Antibiotics kill bacteria, do not affect viruses.

Development of Drugs

• Testing and Trials
  • Preclinical and clinical testing, double-blind trials.

Monoclonal Antibodies

• Production and Uses
  • Target specific antigens, used in pregnancy tests, disease detection.

Plant Diseases

• Detection and Treatment
  • Identification through symptoms, treatment with chemicals or biological methods.

Bioenergetics

Photosynthesis

• Process
  • Conversion of light energy into chemical energy.

Rate of Photosynthesis

• Limiting Factors
  • Light, carbon dioxide, temperature, chlorophyll.

Uses of Glucose

• In Plants
  • Stored as starch, used in respiration.

Respiration

• Aerobic vs. Anaerobic
  • Energy release, conditions, and products.

Response to Exercise

• Body Changes
  • Increased heart rate, breathing rate, and volume.

Metabolism

• Overview
  • Total of all biochemical reactions in an organism.