Biology (9-1) - 0970 CIE

Diseases And Immunity Continued

Overview

Cholera can turn a healthy person dangerously ill within hours, not by destroying tissue, but by a single clever toxin that hijacks the way water moves in the gut. It is a striking case study in how a microscopic bacterium, contaminated water and the physics of osmosis combine to cause disease.

This is an Extended-tier topic. In this lesson you will learn what cholera is and how it spreads, and then follow the exact chain of events by which the cholera toxin causes the severe, watery diarrhoea that makes the disease so dangerous.

Objectives

  1. [Supplement] Describe cholera as a disease caused by a bacterium which is transmitted in contaminated water
  2. [Supplement] Explain that the cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of ions from the blood

Lesson Note

Cholera ties together pathogens, transmission, the digestive system and osmosis in one example, which is why examiners like it. It also shows why clean water and sewage treatment save lives, turning the public-health ideas of the previous topic into a concrete, testable case.

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Lesson Evaluation

Congratulations on completing the lesson on Diseases And Immunity Continued. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. Cholera is caused by a: A. virus B. bacterium C. fungus D. protein Answer: B
  2. Cholera is transmitted mainly through: A. the air B. direct skin contact C. contaminated water D. insect bites Answer: C
  3. [Supplement] The cholera toxin causes the secretion of which ions into the small intestine? A. sodium ions B. chloride ions C. calcium ions D. hydrogen ions Answer: B
  4. [Supplement] Water moves into the gut in cholera by the process of: A. active transport B. diffusion of ions C. osmosis D. respiration Answer: C
  5. The most important treatment for a dehydrated cholera patient is: A. rehydration with water and salts B. a high-fat diet C. exercise D. a blood transfusion of red cells Answer: A

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Practice Mock Questions

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