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Menu Print Name Class M O D E R N E A R T H Date S C I E N C E Chapter 21 Ocean Water Review Choose the best response. Write the letter of that choice in the space provided. 1. The gas that dissolves most easily in ocean water is a. carbon dioxide. b. argon. c. nitrogen. d. oxygen. 2. The amount of dissolved solids in ocean water is called its a. salinity. b. nekton. c. plankton. d. density. 3. A thin floating layer of ice that covers an ocean surface is called a. an iceberg. b. a thermocline. c. pack ice. d. benthos. 4. A zone of rapid water temperature change with increasing depth is called a. a benthos. b. an abyssal zone. c. a bathyal zone. d. a thermocline. 5. When liquid water is warmed, its density Copyright © by Holt, Rinehart and Winston. All rights reserved. a. increases. b. decreases. c. remains the same. d. doubles. 6. Although most of the various wavelengths of visible light are absorbed by ocean water, the one wavelength that tends to be reflected is the color a. violet. b. green. c. yellow. d. blue. 7. The process by which surface water is blown farther offshore and nutrient-rich deep water rises to take its place is called a. desalination. b. distillation. c. upwelling. d. aquaculture. 8. Drifting marine plants and animals are known as a. plankton. b. benthos. c. nekton. d. tube worms. 9. Marine animals that can swim to search for food and avoid predators are called a. phytoplankton. b. zooplankton. c. nekton. d. benthos. c. benthos. d. phytoplankton. 10. Sea anemones are an example of a. zooplankton. b. nekton. Study Guide Chapter 21 8181 Menu Print Name Class M O D E R N E A R T H Date S C I E N C E Chapter 21 Choose the best response. Write the letter of that choice in the space provided. 11. Perhaps the most unstable ocean environment is the a. intertidal zone. b. abyssal zone. c. bathyal zone. d. neritic zone. 12. The pelagic zone that has abundant sunlight, a fairly constant temperature, and relatively low pressure is the a. bathyal zone. b. neritic zone. c. abyssal zone. d. intertidal zone. 13. Which of the following is not a method for producing fresh water by desalinating ocean water? a. distillation b. evaporation c. reverse osmosis d. aquaculture 14. Lumps of minerals on the ocean floor are called a. nekton. b. nodules. c. benthos. d. plankton. 15. Aquaculture is another name for a. desalination. c. ocean farming. b. distillation. d. rapid temperature changes. 16. In the future, scientists may be able to fertilize the ocean through b. artificial upwelling. d. dissolving gases. Critical Thinking Read each question or statement and answer it in the space provided. 1. Suppose that climatic conditions over the earth’s oceans changed dramatically. The changes resulted in a complete absence of upwelling and wave action. Explain what would happen to the marine life and why. 82 Study Guide Chapter 21 Copyright © by Holt, Rinehart and Winston. All rights reserved. a. distillation. c. mining nodules. Menu Print Name Class M O D E R N E A R T H Date S C I E N C E Chapter 21 Read each question or statement and answer it in the space provided. 2. How would a significant decrease in sunlight affect phytoplankton? Copyright © by Holt, Rinehart and Winston. All rights reserved. 3. What impact would the decrease in sunlight discussed in Question 2 have on other forms of marine life? 4. When oceanographers first explored the deep ocean basin along mid-ocean ridges, they discovered a variety of marine life, including sightless crabs. Explain why these crabs are not handicapped by their sightlessness. Study Guide Chapter 21 8381 Menu Print Name Class M O D E R N E A R T H Date S C I E N C E Chapter 21 Application Read each question or statement and answer it in the space provided. 1. Suppose you are contracted to build a desalination system for the state of Florida. In order to make your system as efficient as possible, you want to locate it in an area of the ocean where the salinity of the water is low. Where along the coast of Florida would you choose to build the site, near Miami or Tallahassee? 2. You have collected samples of ocean water from the three locations: a site just off the coast of Israel; a site on Prudhoe Bay, off the coast of northern Alaska; and a site off the coast of Sweden, on the Baltic Sea. All three samples have been brought to room temperature. From which location would the water have the greatest density? Why? 84 Study Guide Chapter 21 Copyright © by Holt, Rinehart and Winston. All rights reserved. 3. You have decided to start an aquatic farm. In which of the zones of ocean life should you locate your farm? Why? Menu Print words phytoplankton (from the Greek word phyto, meaning “plant”) and zooplankton (from the Greek word zoe, meaning “life”). Pages 417–421: Discussion (Reinforcement) To reinforce students’ understanding of resources in the ocean, put the following headings on the chalkboard: “Material Resources,” “Energy Resources,” “Food Resources,” and “Recreational Resources.” Have students list ocean resources in each category. You may wish to point out that in 1983 President Ronald Reagan established that the ocean resources from the coasts of the United States and its territories to 320 km offshore belong to the United States. Scientists from the U.S. Geological Survey and National Oceanic and Atmospheric Administration have carefully mapped this zone, which contains offshore mineral and oil resources. Pages 418–419: Science & Technology You may wish to explain that water normally flows by osmosis from a dilute solution through a membrane to a more concentrated solution. In reverse osmosis, pressure is applied to the concentrated solution. Pure water is obtained by applying pressure to sea water—the more concentrated solution— and forcing it through a membrane that prevents ions and other substances from passing through it. Small-Scale Investigation Chapter 21 Review Answers to Review 1. a 2. a 3. c 4. d 5. b 6. d 7. c 8. a 9. c 10. c 11. a 12. b 13. d 14. b 15. c 16. b Answers to Critical Thinking 1. All but the bottom dwellers would die out because the nutrient-rich material would never return to the surface. 2. The absence of sunlight would halt the growth of phytoplankton. 3. Other marine life would be devastated because phytoplankton form the foundation of the marine food web. 4. Because there is no light, sight is unnecessary. Answers to Application 1. The waters of the Gulf of Mexico off Tallahassee have a lower salinity than the waters of the Atlantic Ocean off Miami; therefore, Tallahassee would be the better choice. 2. off the coast of Israel, because highly saline water has an abundance of dissolved solids and is thus denser 3. neritic; because it is the most hospitable to marine life Density Factors (p. 411) Science Process Skills: hypothesizing, recording data, comparing and contrasting In-Depth Investigation Answers to Analysis and Conclusions Ocean Water Density (pp. 424–425) 1. Answers will vary. Typical answers will include salt water, cold water, and distilled water, ranked from most dense to least dense. As the density decreases, the straw will sink deeper below the water’s surface. 2. Answers will vary. A typical answer would be to warm the water. 3. It would decrease the water’s density. 4. Answers will vary. A typical answer would be that the water will be least dense in areas where the water has a low salinity or is very warm, or where there is an infusion of fresh water. The water will be most dense in areas where the water has a high salinity or is very cold. Approximate time: 1 class period Objectives: to observe the effects of temperature and salinity on the density of water Skills: measuring, observing, comparing, determining cause and effect, inferring T108 Chapter 21 Prelab Discussion Discuss with students the effect of salinity in ocean water as fresh water enters the ocean from large rivers and heavy rainfall. Explain to students that ocean water is approximately 96.5 percent pure water and 3.5 percent dissolved salts. Ask them if slight variations in salinity change the density of ocean water.