# Cells and Systems This worksheet reviews how cells, tissues, organs and systems work together in living things, including the human body, and connects to the key concepts of Unit B: Cells and Systems ([Topic](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17317)). It covers the roles of cells, the differences between plant and animal cells, diffusion and osmosis, and the healthy functioning of human body systems ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320), [Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17321)). ## Exercises **1. Multiple choice.** Circle the best answer. Which statement best describes the role of cells in living things? A) Cells are only found in animals, not in plants. B) Cells are the basic unit of life, and all living things are made of one or more cells. C) Cells are too small to have any real function in an organism. D) Only large organisms like trees and grizzly bears are made of cells. ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320)) **2. Matching.** Draw a line from each human body system to its main function. | Body system | Function | |---|---| | Respiratory | A. Carries oxygen and nutrients to tissues and organs | | Circulatory | B. Breaks down food into nutrients the body can use | | Digestive | C. Exchanges oxygen and carbon dioxide with the environment | | Excretory | D. Removes waste products from the body | ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17321)) **3. Fill in the blanks.** Use the word bank to complete each sentence. Each word is used once. Word bank: cell wall, cell membrane, single-celled, multicelled a) A plant cell has a rigid ______________________ that gives it a fixed shape, while an animal cell only has a flexible ______________________. b) An amoeba is an example of a ______________________ organism, while a grizzly bear is an example of a ______________________ organism. ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320)) **4. Short answer.** Diffusion and osmosis. A fish's gills are surrounded by water that contains a higher concentration of oxygen than the fish's blood. Explain, in general terms, what will happen to the oxygen and why. Use the word "concentration" in your answer. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320)) **5. Short answer.** Organization in living things. List the levels of organization in the human body, in order from smallest to largest, using these four terms: organ, tissue, cell, system. Smallest: ______________________ ______________________________ ______________________________ Largest: ______________________ Then give one example of a cell, a tissue and an organ that all belong to the same body system. Cell: ______________________ Tissue: ______________________ Organ: ______________________ ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320), [Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17321)) **6. Short answer.** Science and technology. Describe one way that scientific research into a human organ or body system has led to an improvement in human health, such as a new medicine, an immunization or a diet designed for a specific organ. Name the organ or system involved. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17322)) ## Answer key 1. B) Cells are the basic unit of life, and all living things are made of one or more cells. 2. Respiratory, C, Circulatory, A, Digestive, B, Excretory, D. 3. a) cell wall, cell membrane; b) single-celled, multicelled. 4. Oxygen will diffuse from the water into the fish's blood because it moves from an area of higher concentration to an area of lower concentration. 5. Smallest to largest: cell, tissue, organ, system. Example answers will vary; accept any biologically consistent set, such as a muscle cell, muscle tissue and the heart within the circulatory system. 6. Answers will vary; accept any example supported by the sources, such as the development of a medicine, an immunization procedure, or an organ-specific diet (for example, a low-sodium diet for heart health). --- *AILI homework sheet · language en · model claude-sonnet-5 · generated 2026-09-17 · id bc9f4bbe-68b2-4086-bf17-1a01952d9200* ### Sources - node:n1: Sciences › Science (7–9) › Grade 8 › Unit B: Cells and Systems › Outcomes for Science, Technology and Society (STS) and Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17319) - node:n2: Sciences › Science (7–9) › Grade 8 › Unit B: Cells and Systems › Outcomes for Science, Technology and Society (STS) and Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320) - node:n3: Sciences › Science (7–9) › Grade 8 › Unit B: Cells and Systems › Outcomes for Science, Technology and Society (STS) and Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17320) - node:n4: Sciences › Science (7–9) › Grade 8 › Unit B: Cells and Systems › Outcomes for Science, Technology and Society (STS) and Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17321) - node:n5: Sciences › Science (7–9) › Grade 8 › Unit B: Cells and Systems › Outcomes for Science, Technology and Society (STS) and Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17319) - node:n6: Sciences › Science (7–9) › Grade 8 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17317) - node:n7: Sciences › Science (7–9) › Grade 8 › Unit B: Cells and Systems › Outcomes for Science, Technology and Society (STS) and Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/17322)