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CIE IGCSE Biology Overview

Apr 24, 2025

CIE IGCSE Biology Lecture Notes

Introduction

  • All-in-one CIE IGCSE Biology video designed to help students.
  • Perfect answer revision guides and courses available on the presenter’s website.
  • Overview of features of living organisms, classification, and dichotomous keys.

Characteristics of Living Organisms (MRS GREN)

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition

Classification

  • Need for classification systems due to the vast number of species.
  • Binomial naming system: genus and species (e.g., Mycobacterium tuberculosis).
  • Species: groups that can produce fertile offspring.
  • Traditional vs. Modern Classification: Morphology/Anatomy vs. DNA sequences.

Dichotomous Keys

  • Used to identify organisms based on characteristics.
  • Example of insect identification using a key.

The Five Kingdoms

  • Plants
  • Animals
  • Protists
  • Bacteria
  • Fungi

Vertebrates & Invertebrates

  • Vertebrates: animals with a backbone (mammals, birds, reptiles, fish, amphibians).
  • Invertebrates: animals without a backbone (arthropods).
    • Arthropods: myriapods, insects, arachnids, crustaceans.

Plant Classification

  • Flowering plants (angiosperms)
  • Ferns
  • Viruses: protein coat surrounding genetic material.

Cell Structure

  • Bacterial cells: cell wall, plasmids, no distinct nucleus.
  • Viruses: smaller than bacteria, non-living, always pathogenic.
  • Protists: diverse group, some plant-like (e.g., algae) and some animal-like (e.g., amoeba).
  • Fungi: similar to plant cells but with chitin cell wall, saprotrophic nutrition.
  • Plant and Animal Cells: organelles shared and differences.

Specialized Cells

  • Red blood cells: transport oxygen.
  • Muscle cells: contraction and relaxation.
  • Ciliated cells: move mucus.
  • Nerve cells: conduct electrical impulses.
  • Sperm and Egg cells: reproduction.

Transport in Plants

  • Xylem: transports water and minerals.
  • Phloem: transports sugars.

Photosynthesis

  • Equation: COâ‚‚ + Hâ‚‚O → Glucose + Oâ‚‚
  • Factors affecting photosynthesis: light, carbon dioxide, temperature.

Human Nutrition

  • Balanced diet includes carbohydrates, proteins, fats, vitamins, minerals, water, and fiber.
  • Deficiency diseases: kwashiorkor (protein), scurvy (vitamin C), rickets (vitamin D/calcium).

Digestive System

  • Digestion: breakdown of large molecules into small ones.
  • Enzymes: amylase, protease, lipase.
  • Teeth: types and functions.
  • Stomach: HCl and protease enzyme for digestion.
  • Small intestine: absorption and role of bile.

Human Circulatory System

  • Heart structure and function.
  • Blood vessels: arteries, veins, capillaries.
  • Coronary heart disease: causes and prevention.

Blood Components

  • Red blood cells: carry oxygen.
  • White blood cells: immune response.
  • Plasma: carries dissolved substances.
  • Platelets: blood clotting.

Respiratory System

  • Inhalation and exhalation processes.
  • Gas exchange in alveoli.

Excretion

  • Kidneys: filtration and reabsorption.
  • Role in osmoregulation.

Nervous System

  • Reflex actions: rapid and involuntary.
  • Eye structure: light refraction and focusing.
  • Endocrine system: hormone functions.

Genetics

  • DNA structure: double helix, bases (A, T, C, G).
  • Protein synthesis: role of mRNA and tRNA.
  • Mitosis vs. Meiosis: types of cell division.
  • Inheritance: Punnett squares and genetic crosses.

Evolution

  • Natural selection: variation, adaptation, and survival.
  • Mutation: source of genetic variation.

Ecology

  • Food chains and webs: energy transfer.
  • Carbon and nitrogen cycles: nutrient cycling.
  • Human impact: pollution, deforestation, conservation.

These notes provide a comprehensive overview of the CIE IGCSE Biology curriculum, focusing on the key topics and concepts discussed in the lecture.

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