Cycles Within Ecosystems
Overview
Carbon and nitrogen are essential to every living organism, yet there is a fixed amount of each element on Earth. If these elements were not recycled, life would have run out of raw materials long ago. Instead, natural processes move carbon and nitrogen through the atmosphere, soil, water and living things in continuous loops.
In this lesson you will trace the carbon cycle from photosynthesis through respiration, decomposition and combustion, and then follow the nitrogen cycle through the specialised bacteria that convert nitrogen into forms plants can absorb. Both cycles are tested regularly on Edexcel papers, and understanding them will also help you explain human impacts on the environment.
Objectives
- Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion
- Describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Cycles Within Ecosystems. 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.
- Which process removes carbon dioxide from the atmosphere? A) Respiration B) Combustion C) Photosynthesis D) Decomposition Answer: C
- Which type of bacteria converts nitrates back into nitrogen gas? A) Nitrogen-fixing bacteria B) Nitrifying bacteria C) Denitrifying bacteria D) Decomposers Answer: C
- Where are nitrogen-fixing bacteria found in leguminous plants? A) In the leaves B) In the stem C) In the root nodules D) In the flowers Answer: C
- Which of the following returns carbon dioxide to the atmosphere? A) Photosynthesis B) Absorption by oceans C) Respiration D) Nitrogen fixation Answer: C
- What do nitrifying bacteria convert ammonium compounds into? A) Nitrogen gas B) Proteins C) Nitrates D) Carbon dioxide Answer: C
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