Photosynthesis (continued)
Overview
Making glucose is only the start. A plant must store the sugar it does not need at once, build new cell walls, ship food to its roots and feed its flowers. And the rate at which it can photosynthesise depends on the weather: too little light, too little carbon dioxide or the wrong temperature, and the whole process slows down.
In this lesson you will learn what plants do with their glucose, why they need nitrate and magnesium ions, how to investigate the requirements and rate of photosynthesis, and, at Extended level, how to identify the limiting factor in any set of conditions.
Objectives
- Outline the subsequent use and storage of the carbohydrates made in photosynthesis, limited to: (a) starch as an energy store (b) cellulose to build cell walls (c) glucose used in respiration to provide energy (d) sucrose for transport in the phloem (e) nectar to attract insects for pollination
- Explain the importance of: (a) nitrate ions for making amino acids (b) magnesium ions for making chlorophyll
- Investigate the need for chlorophyll, light and carbon dioxide for photosynthesis, using appropriate controls
- Investigate and describe the effects of varying light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis
- Investigate and describe the effect of light and dark conditions on gas exchange in an aquatic plant using hydrogencarbonate indicator solution
- [Supplement] Identify and explain the limiting factors of photosynthesis in different environmental conditions
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Lesson Evaluation
Congratulations on completing the lesson on Photosynthesis (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.
- Glucose made in photosynthesis is stored as: A. sucrose B. starch C. nectar D. protein Answer: B
- Nitrate ions are needed by a plant to make: A. chlorophyll B. cellulose C. amino acids and proteins D. starch Answer: C
- A plant with yellow leaves is most likely lacking: A. nitrate ions B. magnesium ions C. carbon dioxide D. water Answer: B
- On a graph, the rate of photosynthesis levels off as light increases because: A. light is still limiting B. another factor has become limiting C. the plant has died D. oxygen runs out Answer: B
- Sugar is transported around a plant mainly as: A. glucose B. starch C. sucrose D. cellulose Answer: C
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