Summary

• Description:

  The PDF document comprises Form 2 Biology notes on Gaseous Exchange in Plants and Animals.

  The topics and sub-topics covered in the document include:

  • Introduction to Gaseous Exchange
    • The necessity of gaseous exchange for living organisms to obtain oxygen for respiration and get rid of carbon (IV) oxide. In plants, carbon (IV) oxide is also needed for photosynthesis.
    • Definitions of gaseous exchange, breathing (ventilation), and respiratory surface. Diffusion is highlighted as the main process involved.
  • Gaseous Exchange in Plants
    • The primary site for gaseous exchange in plants is through the stomata.
    • Stomata: The structure of guard cells is described, noting their thicker inner walls which control the opening and closing of the stoma. The mechanism of opening and closing is explained based on turgor changes driven by osmosis. Theories for these changes, including sugar accumulation, pH changes, and potassium ion movement, are also discussed.
    • Gas Exchange in Different Plant Parts: The notes detail the process in terrestrial and aquatic leaves, stems (via lenticels), and roots (including specialized breathing roots called pneumatophores in mangroves).
  • Gaseous Exchange in Animals
    • Respiratory Surfaces: An overview of different respiratory surfaces like the cell membrane, gills, skin, and lungs, along with their key characteristics (large surface area, thin, moist, permeable, and well-vascularized).
    • Mechanisms in Different Animals:
      • Amoeba: Gaseous exchange occurs across the cell membrane by simple diffusion.
      • Insects: Utilizes a tracheal system with openings called spiracles for air intake.
      • Bony Fish: Gaseous exchange takes place across the gills, enhanced by a counter-current flow system for maximum oxygen absorption from water.
      • Amphibians (Frog): Uses multiple surfaces including the skin, the lining of the buccal cavity, and a pair of small lungs.
      • Mammals (Human): Involves a complex breathing system with lungs, which contain millions of alveoli adapted for efficient gas exchange. The mechanism of ventilation (inspiration and expiration) via the diaphragm and intercostal muscles is explained.
  • Diseases of the Respiratory System
    • A detailed section on common respiratory diseases, including asthma, bronchitis, pulmonary tuberculosis, pneumonia, and whooping cough. For each disease, the causes, symptoms, prevention, and treatment methods are outlined.
  • Practical Activities
    • Includes a guide for the observation of permanent slides to compare the internal structures of terrestrial and aquatic leaves and stems.

  These notes provide a comprehensive and detailed exploration of gaseous exchange in both plants and animals. They are neatly organized, printable, and include clear explanations, making them an excellent resource for students for both learning and revision, as well as for teachers in lesson preparation.

• File Size:

  366.18 KB
• Length:

  25 pages
• Category:

  Lesson Notes
• Level:

  Form 2
• Subject:

  BIOLOGY
• Posted By:

  Caleb_Peter

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