CIE IGCSE Biology - All-in-One Lecture Notes

Introduction

• Video created to help with CIE IGCSE Biology.
• Perfect answer guides and revision courses available on the website.

Characteristics of Living Organisms

• Mrs Nerg (Mrs Gren)
  • Movement
  • Respiration
  • Sensitivity
  • Nutrition
  • Excretion
  • Reproduction
  • Growth
• Non-living organisms like viruses do not exhibit these traits.

Classification

• Need for Classification: To organize billions of species.
• Binomial Naming System:
  • Two names: Genus and Species (e.g., Mycobacterium tuberculosis).
• Definition of Species:
  • Group of organisms that can produce fertile offspring.
  • Example: Dogs are the same species; mules are not (sterile).
• Traditional vs. Modern Classification:
  • Traditional based on morphology and anatomy.
  • Modern uses DNA sequences.

Dichotomous Keys

• Used for identifying organisms based on physical characteristics.
• Example: Identifying insects based on body shape, antenna visibility, and patterns.

Five Kingdoms of Life

• Plants, Animals, Protists, Bacteria, Fungi.
• Vertebrates: Animals with a backbone.
  • Groups: Mammals, Birds, Reptiles, Fish, Amphibians.
• Invertebrates & Arthropods:
  • Arthropods: Exoskeleton, e.g., crabs.
• Types of Arthropods:
  • Myriapods, Insects, Arachnids, Crustaceans.

Plant Classification

• Flowering Plants (Angiosperms):
  • Produce flowers, fruits, and seeds.
  • Examples: Monocotyledons and Dicotyledons.
• Ferns:
  • Reproduce via spores, not seeds.
• Viruses:
  • Protein coat around genetic material (DNA/RNA).

Cell Structure and Function

• Bacterial Cells:
  • Cell wall, sometimes slime capsule, flagella.
  • Nucleoid (circular DNA).
  • Pathogenic and non-pathogenic types.
• Viruses:
  • Non-living, always pathogenic.
  • Examples: Flu, cold, HIV.
• Protoctists:
  • Mixed characteristics of plants and animals.
  • Example: Plasmodium causes malaria.
• Fungi:
  • Similar to plant cells but with chitin cell wall.
  • Example: Yeast used in baking and brewing.

Plant and Animal Cells

• Common Organelles: Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.
• Plant-specific Organelles: Cell wall, vacuole, chloroplasts.
• Roles of Organelles:
  • Nucleus controls cell activities.
  • Cytoplasm for chemical reactions.
  • Cell membrane for controlling entry/exit.
  • Ribosomes for protein synthesis.

Specialized Cells

• Red Blood Cells: Transport oxygen via hemoglobin; biconcave disc shape.
• Muscle Cells: Contract and relax for movement.
• Ciliated Cells: Move mucus in respiratory tract.
• Nerve Cells: Conduct electrical impulses.
• Sperm Cells: Tail for swimming, mitochondria for energy.
• Egg Cells: Large, nutrient-rich.
• Plant Cells: Root hair cells absorb water/minerals; xylem and phloem for transport.

Biological Molecules

• Organic Compounds: Carbohydrates, proteins, lipids.
• Carbohydrates: Monosaccharides and polysaccharides.
• Proteins: Chains of amino acids.
• DNA: Double helix, base pairing (A-T, C-G).
• Enzymes: Biological catalysts, affected by temperature and pH.

Photosynthesis

• Process: CO2 + Water -> Glucose + Oxygen.
• Limiting Factors: Light intensity, CO2 concentration, temperature.
• Leaf Structure: Adaptations for photosynthesis (e.g., large surface area, stomata).

Human Nutrition

• Balanced Diet: Contains carbohydrates, proteins, fats, minerals, vitamins, water, fiber.
• Deficiency Diseases: Kwashiorkor, scurvy, rickets, anemia.
• Digestive System: Mechanical and chemical digestion.

Digestive Enzymes

• Amylase: Starch to glucose.
• Protease: Proteins to amino acids.
• Lipase: Lipids to fatty acids and glycerol.

Transport in Plants

• Xylem: Water/mineral transport.
• Phloem: Sugar transport.
• Transpiration: Water vapor loss from leaves.

Transport in Animals

• Circulatory System: Heart pumps blood.
• Blood Vessels: Arteries, veins, capillaries.
• Blood Composition: Red blood cells, white blood cells, plasma, platelets.

Human Respiration

• Aerobic: Oxygen used, CO2 and water produced.
• Anaerobic: No oxygen, lactate produced.

Excretion

• Kidneys: Filter blood, produce urine.
• Osmoregulation: Water balance in body.

Nervous System

• Reflex Actions: Involuntary, quick responses.
• Eye Structure: Cornea, pupil, lens, retina.

Hormones

• Adrenaline: Fight or flight response.
• Insulin: Lowers blood sugar.

Reproduction

• Sexual vs. Asexual:
  • Sexual involves two parents, genetic variation.
  • Asexual involves one parent, clones produced.
• Plant Reproduction: Pollination, fertilization, seed formation.
• Human Reproductive Systems: Male and female anatomy and functions.

Genetics

• Genotype vs. Phenotype: Genetic makeup vs. physical traits.
• Dominant and Recessive Alleles: Affect trait expression.
• Monohybrid Crosses: Predicting offspring traits.

Ecology

• Ecosystems: Interactions between organisms and their environment.
• Food Chains/Webs: Energy flow through ecosystems.
• Carbon and Nitrogen Cycles: Matter recycling in nature.

Human Impact on the Environment

• Eutrophication: Nutrient run-off leading to water pollution.
• Deforestation: Habitat loss, increased CO2 levels.
• Pollution: Plastic waste, greenhouse gases.

Conservation

• Sustainable Resources: Non-depleting supply management.
• Endangered Species Protection: Monitoring, protection, education.

Biotechnology

• Genetic Engineering: Altering DNA for desired traits.
• Fermenters: Used for producing substances like insulin.

These notes provide a comprehensive summary of key biological concepts and processes as outlined in a CIE IGCSE Biology lecture.