IGCSE Biology Lecture Notes

Introduction

• Focus on CIE IGCSE Biology material.
• Perfect answer guides available for exam preparation.
• Lecture covers common features of living organisms, classification, and more.

Common Features of Living Organisms

• MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.
• Viruses do not exhibit these characteristics.

Classification Systems

• Binomial Naming System: Species and genus (e.g., Mycobacterium tuberculosis).
• Species Definition: Group with ability to produce fertile offspring.
• Morphology and Anatomy: Traditional basis for classification.
• Modern Classification: DNA sequences and protein structures.

Dichotomous Keys

• Used to identify organisms through a series of choices.
• Example with insects: Identify based on physical characteristics like antennae and patterns.

Classification and Vertebrates

• Five Kingdoms: Plants, Animals, Protists, Bacteria, Fungi.
• Vertebrate Characteristics: Mammals (hair, mammary glands), Birds (feathers, scales), Reptiles (dry skin), Fish (gills, fins), Amphibians (moist skin).
• Invertebrates: Arthropods, Myriapods, Insects, Arachnids, Crustaceans.

Plant Classification

• Flowering Plants (Angiosperms): Flowers, fruits, seeds, root systems.
• Ferns: Long fronds, reproduction via spores.

Cell Structures

• Animal and Plant Cells: Organelles like nucleus, cell membrane, mitochondria.
• Prokaryotes vs. Eukaryotes: Prokaryotes lack membrane-bound organelles.

Specialized Cells

• Examples: Red blood cells (transport oxygen), Muscle cells (contract/relax), Ciliated cells (waft mucus), Sperm cells (reproduction), Root hair cells (absorb water/minerals).

Organization in Organisms

• Hierarchy: Cells → Tissues → Organs → Organ Systems → Organisms.

Biological Molecules

• Carbohydrates, Proteins, Lipids: Elements and structure.
• DNA Structure: Double helix, nucleotide bases (Adenine, Thymine, Cytosine, Guanine).

Enzymes

• Function: Biological catalysts that speed up reactions.
• Factors Affecting Activity: Temperature, pH.
• Denaturation: Loss of structure and function at extreme conditions.

Photosynthesis

• Equation: CO2 + H2O → Glucose + O2.
• Chloroplasts: Site of photosynthesis.
• Limiting Factors: Light, CO2, Temperature.

Transport in Plants

• Xylem and Phloem: Water/nutrient transport.
• Transpiration: Water loss through stomata, influenced by environmental factors.

Human Nutrition and Digestion

• Balanced Diet: Carbohydrates, Proteins, Fats, Vitamins, Minerals, Water, Fiber.
• Digestion: Breakdown of large molecules into absorbable units.
• Enzymes in Digestion: Amylase, Protease, Lipase.

Circulatory System

• Heart and Blood Vessels: Structure and function.
• Double Circulatory System: Blood passes through heart twice per cycle.
• Blood Components: Red/white blood cells, plasma, platelets.

Immune System

• Phagocytes and Lymphocytes: Pathogen defense mechanisms.
• Vaccinations: Trigger immune response without causing disease.

Breathing and Gas Exchange

• Lungs and Alveoli: Adaptations for gas exchange.
• Ventilation: Inhalation and exhalation mechanics.

Respiration

• Aerobic vs. Anaerobic: Energy release differences.
• Equations: Glucose + O2 → CO2 + H2O + Energy.

Excretion

• Kidneys: Filtration and reabsorption processes.
• Osmoregulation: Water balance in the body.

Nervous System

• Neurons and Reflex Arcs: Pathways for signals.
• Sense Organs: Eye structure and function.

Hormones

• Endocrine System: Roles of insulin, adrenaline, etc.
• Feedback Mechanisms: Blood sugar regulation.

Reproduction

• Sexual vs. Asexual: Differences in processes and outcomes.
• Human Reproductive Systems: Male and female anatomy.

Genetics

• Inheritance Patterns: Dominant/recessive alleles, Punnett squares.
• Gene Expression: From DNA to protein.

Ecology

• Ecosystem Interactions: Food chains, pyramids of numbers/biomass.
• Human Impact: Deforestation, pollution, conservation efforts.

Biotechnology

• Genetic Engineering: Techniques and applications.
• Microorganisms in Industry: Use in fermentation processes.

These notes capture the key concepts and details covered in the comprehensive IGCSE Biology lecture. Be sure to review specific examples and processes for exams.