Pollution
Overview
Pollution is what happens when human waste enters the environment faster than it can be broken down or absorbed. Sometimes it is obvious, like oil on a beach; sometimes it is invisible, like the carbon dioxide warming the planet or the nitrates that secretly suffocate a river by feeding it too well.
In this lesson you will describe the effects of sewage, fertilisers and non-biodegradable plastics, and explain how methane and carbon dioxide drive the enhanced greenhouse effect and climate change. You will also work through eutrophication step by step, the surprising process by which adding nutrients to water ends up killing everything in it.
Objectives
- Describe the effects of untreated sewage and excess fertiliser on aquatic ecosystems
- Describe the effects of non-biodegradable plastics, in both aquatic and terrestrial ecosystems
- Describe the sources and effects of pollution of the air by methane and carbon dioxide, limited to: the enhanced greenhouse effect and climate change
- [Supplement] Explain the process of eutrophication of water, limited to: increased availability of nitrate and other ions increased growth of producers increased decomposition after death of producers increased aerobic respiration by decomposers reduction in dissolved oxygen death of organisms requiring dissolved oxygen in water
Audio Lesson
Listen to this lesson in the app
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Flashcards
Quick recall practice on the facts this topic is tested on.
Practise these cards in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on Pollution. 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.
- Excess fertiliser entering a river first causes: A. fish to grow larger B. rapid growth of algae and water plants C. a rise in dissolved oxygen D. fewer decomposers Answer: B
- During eutrophication, the dissolved oxygen falls because: A. plants stop photosynthesising B. decomposer bacteria respire as they break down dead plants C. fish breathe too fast D. nitrates remove oxygen directly Answer: B
- Non-biodegradable plastics are a problem because they: A. are broken down too quickly B. are not broken down by decomposers C. dissolve in water D. release oxygen Answer: B
- Which pair are both greenhouse gases? A. oxygen and nitrogen B. carbon dioxide and methane C. carbon dioxide and oxygen D. methane and nitrogen Answer: B
- A major human source of methane is: A. photosynthesis B. cattle farming and wet rice fields C. burning coal only D. ocean evaporation Answer: B
Work through these questions in the app
Work through these questions in the app
Recommended Books
Practice Mock Questions
Want to practice mock questions on Pollution? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
