Summary

• Description:

  The PDF document comprises Form 2 Biology notes on Excretion and Homeostasis.

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

  • Introduction to Excretion and Homeostasis
    • Definitions of key terms: Excretion as the removal of metabolic wastes , egestion as the removal of undigested materials , secretion as the release of useful substances , and homeostasis as maintaining a constant internal environment.
  • Excretion
    • In Plants: Discusses why plants accumulate few toxic wastes , how they remove gaseous waste , and how they store other products in organs that are later shed. A table of useful plant excretory products like caffeine, quinine, and rubber is included.
    • In Unicellular Organisms: Explains how organisms like Amoeba use diffusion and contractile vacuoles for excretion.
    • In Humans:
      • Identifies the main excretory organs: the skin, lungs, kidneys, and liver.
      • Skin: Its role in eliminating urea, lactic acid, and salts via sweat.
      • Lungs: Removal of carbon (IV) oxide produced during respiration.
      • Kidneys: Details their structure (cortex, medulla, pelvis) and the structure of the functional unit, the nephron. The mechanism of urine formation through ultra-filtration and selective reabsorption is explained. Common kidney diseases like uraemia , kidney stones , and nephritis are also covered.
      • Liver: Its role in deamination of excess amino acids to form urea , breakdown of haemoglobin , and detoxification.
  • Homeostasis
    • The concept of maintaining a stable internal environment through self-adjusting negative feedback mechanisms.
    • Thermoregulation (Temperature Regulation): How the skin regulates body temperature through vasodilation , vasoconstriction , sweating , and the action of hair erector muscles. It also discusses physiological and behavioral responses to temperature changes.
    • Osmoregulation (Water and Salt Balance): The crucial role of the kidney in controlling the body's water and salt balance. This section explains the function of the Anti-diuretic Hormone (ADH) in regulating water reabsorption and Aldosterone in controlling sodium levels.

  These notes are comprehensive, neatly structured, and printable, making them an excellent resource for students studying these key biological processes. They are also highly suitable for teachers to use for lesson preparation, providing clear, detailed explanations on the topics of excretion and homeostasis.

• File Size:

  274.42 KB
• Length:

  14 pages
• Category:

  Lesson Notes
• Level:

  Form 2
• Subject:

  BIOLOGY
• Posted By:

  Caleb_Peter

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