Diffusion
Overview
Open a bottle of perfume in one corner of a room and soon you can smell it everywhere. The scent particles have spread out by diffusion, moving from where they were crowded to where they were sparse, with no pump or effort. Your cells use this same free process every second to take in oxygen and get rid of carbon dioxide.
In this lesson you will learn exactly what diffusion is, where its energy comes from, why it is vital to living organisms, and how surface area, temperature, concentration gradient and distance change its rate.
Objectives
- [Core] Describe diffusion as the net movement of particles from a region of their higher concentration to a region of their lower concentration (i.e. down a concentration gradient), as a result of their random movement
- [Core] State that some substances move into and out of cells by diffusion through the cell membrane
- [Core] Describe the importance of diffusion of gases and solutes in living organisms
- [Supplement] Investigate the factors that influence diffusion, limited to: surface area, temperature, concentration gradient and distance
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Diffusion. 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.
- Diffusion is the net movement of particles: A. from low to high concentration B. from high to low concentration C. only of water D. using energy from respiration Answer: B
- The energy for diffusion comes from: A. respiration in the cell B. active transport C. the kinetic energy of the particles D. sunlight Answer: C
- Which change would speed up diffusion? A. lower temperature B. smaller surface area C. steeper concentration gradient D. greater distance Answer: C
- A larger surface area increases the rate of diffusion because: A. particles move slower B. more particles can cross at once C. the gradient disappears D. energy is added Answer: B
- Which substance does NOT normally cross the cell membrane by diffusion? A. oxygen B. carbon dioxide C. large protein molecules D. water Answer: C
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