Science Double Award - 4SD0 PearsonEdexcel

Feeding Relationships

Overview

Every organism needs energy, and that energy flows through an ecosystem from the Sun to producers and onward through consumers. Tracing who eats whom reveals the structure of an entire community and explains why large predators are always rare.

In this lesson you will learn the names of the trophic levels, how food chains and food webs represent feeding relationships, what pyramids of number, biomass and energy tell us, and why roughly 90% of energy is lost at every step along a food chain.

Objectives

  1. Understand the names given to different trophic levels, including producers, primary, secondary and tertiary consumers and decomposers
  2. Understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer
  3. Understand the transfer of substances and energy along a food chain
  4. Understand why only about 10 per cent of energy is transferred from one trophic level to the next

Lesson Note

A grassland can support millions of grass plants, thousands of grasshoppers, hundreds of frogs and perhaps only a handful of hawks. This pattern repeats in ecosystems everywhere: the further you move along a food chain, the fewer organisms there are. The reason comes down to energy. At every feeding step, most of the energy is used up or lost, leaving less to support the next level. Understanding this principle is at the heart of ecology.

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Lesson Evaluation

Congratulations on completing the lesson on Feeding Relationships. 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. What is the source of energy for almost all food chains? A) Chemical energy in the soil B) Heat from the Earth's core C) Light energy from the Sun D) Kinetic energy from wind Answer: C
  2. Which trophic level do decomposers belong to? A) First B) Second C) They act at all levels D) Fourth Answer: C
  3. A pyramid of biomass is always pyramid-shaped because: A) There are always more producers than consumers B) Total dry mass decreases at each trophic level C) Producers are always larger than consumers D) Consumers always eat everything available Answer: B
  4. Approximately what percentage of energy is transferred from one trophic level to the next? A) 1% B) 10% C) 50% D) 90% Answer: B
  5. In a food chain, arrows represent: A) The direction an organism moves B) The direction of energy transfer C) The size of the organism D) The number of organisms Answer: B

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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