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Holt Earth Science 7 Ocean Water

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Skills Worksheet

Directed Reading

Section: Properties of Ocean Water

______ 1. Water in the ocean a. is tasteless, odorless, and colorless. b. is muddy and brown. c. contains many dissolved solids and gases. d. is completely pure.

______ 2. Scientists do NOT describe ocean water by using properties such as a. presence of dissolved gases and the presence of dissolved solids. b. salinity and temperature. c. presence of dissolved vitamins and dissolved minerals. d. density and color.

3. Why do scientists study the properties of ocean water?

DISSOLVED GASES

______ 4. The two principal gases in the atmosphere are a. nitrogen and oxygen. b. oxygen and carbon dioxide. c. nitrogen and carbon dioxide. d. oxygen and carbon monoxide.

______ 5. Ocean water contains a large amount of dissolved a. carbon monoxide. b. helium. c. carbon dioxide. d. nitrous oxide.

______ 6. Most oxygen in the ocean a. enters at the surface of the ocean from the atmosphere. b. enters as dissolved gas from streams and rivers. c. is released as carbon dioxide dissolves. d. is made by plants in the ocean through photosynthesis.



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Directed Reading continued

______ 7. Gases dissolve most readily in what kind of water? a. ocean water b. fresh water c. warm water d. cold water

______ 8. When ocean temperature rises, a. excess gas is released into the atmosphere. b. the ocean absorbs and holds carbon dioxide. c. carbon dioxide is equalized between the ocean and atmosphere. d. no change takes place.

______ 9. How many times more carbon is in the oceans than in the atmosphere? a. 20 times b. 40 times c. 60 times d. 80 times

______ 10. For how long might dissolved carbon dioxide be trapped in the ocean? a. ten years b. hundreds of years c. from hundreds to thousands of years d. millions of years

______ 11. Because of their ability to dissolve and contain a large amount of carbon dioxide, oceans are often referred to as a(n) a. carbon trap. b. carbon sink. c. infinite water supply. d. Earth thermostat.

______ 12. Because gaseous carbon dioxide affects the atmosphere’s ability to trap thermal energy from the sun, a. oceans warm easily in the tropics. b. the temperature of the ocean fluctuates with the daily temperature. c. oceans are important in the regulation of climate. d. land temperature is directly related to the carbon dioxide content of

the closest ocean.

DISSOLVED SOLIDS

______ 13. Ocean water is made up of what percentage of dissolved solids? a. 3.5% b. 35.5% c. 50.5% d. 96.5%



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______ 14. The dissolved solids that give the ocean its salty taste are commonly called a. sea solids. b. brine. c. sodium chloride. d. sea salts.

______ 15. Solids dissolved in ocean water are composed of about how many chemical elements? a. 25 b. 50 c. 75 d. 100

______ 16. The most common salt, halite, which makes up more than 85% of the oceans solids, is made of a. sodium and chloride ions. b. zinc and sodium. c. sodium and phosphorus. d. sodium only.

17. Elements that exist in very small amounts are

called .

18. What are three examples of trace elements found in the ocean?

19. What are the three main sources of the elements that form sea salts?

20. How do dissolved salts and other dissolved solids enter the ocean?



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SALINITY OF OCEAN WATER

21. A measure of the amount of dissolved salts and other solids in a given amount

of liquid is .

22. How is salinity measured?

23. What is the average salinity of fresh water?

FACTORS THAT CHANGE SALINITY

24. What happens when evaporation and freezing remove water particles from the ocean?

25. Will tropical waters or polar waters have a higher salinity at the surface? Explain your answer.

26. Why does surface water generally have higher salinity than deep water?

27. Is the salinity of the global ocean the same in all locations?

28. Why is the salinity of the Red Sea more than 40%?

TEMPERATURE OF OCEAN WATER

______ 29. Ocean temperature varies depending on a. depth of water and percentage of salinity on the surface of

the oceans. b. depth of water and location on the surface of the oceans. c. the number of plants and animals living in the surface water. d. the amount of dissolved minerals on the surface of the oceans.



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30. Why does the temperature of the zone of surface water decrease only slightly as the depth increases?

31. What happens to the temperature of surface water as latitude increases?

32. Where does the greatest amount of solar energy reach the surface of the ocean?

33. What is the common temperature at the surface in tropical areas?

34. Why do vast amounts of sea ice exist in polar oceans? Explain your answer.

35. A floating layer of sea ice that completely covers an area of the ocean surface

is called .

36. Why is pack ice rarely more than 5 m thick?

37. What determines changes in ocean surface temperature in the middle latitudes?

38. Why does the temperature of the water decrease sharply below the surface layer of the ocean?

39. The layer in a body of water in which water temperature drops with increased depth faster than it does in other layers is called

a(n) .



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40. Why does the thermocline exist in the ocean?

41. What happens to the temperature of the water in the zone beneath the thermocline?

42. How does the 2ºC temperature of the deep zone affect the density of the ocean water?

43. How does the amount of dissolved gases in cold, deep ocean water compare to the amount of dissolved gases in warm shallow, ocean water?

DENSITY OF OCEAN WATER

44. The ratio of the mass of a substance to the volume of the substance; com-monly expressed as grams per cubic centimeter for solids and liquids and as

grams per liter for gases is called .

45. What two factors affect the density of ocean water?

46. What do dissolved solids, mostly salts, add to ocean water?

47. Which is more dense, ocean water or fresh water? Why?



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48. In what region is the densest ocean water found? Explain why this is true.

COLOR OF OCEAN WATER

49. How is the color of ocean water determined?

50. Why does ocean water appear blue?

51. What are phytoplankton?

52. How do the presence and amount of phytoplankton affect the shade of blue of the ocean?

53. How do scientists determine the presence of phytoplankton in the ocean?

54. How does the presence or absence of phytoplankton in the ocean indicate the health of the ocean?



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Skills Worksheet

Directed Reading

Section: Life in the Oceans

______ 1. What two major factors do marine organisms depend on for their survival? a. essential nutrients in ocean water and sunlight b. density of ocean water and sunlight c. essential nutrients in ocean water and density of ocean water d. salinity of ocean water and density of ocean water

OCEAN CHEMISTRY AND MARINE LIFE

2. Describe the chemistry of the ocean.

3. How do marine organisms help maintain the chemical balance of ocean water?

4. What are three elements absorbed by marine plants?

5. What is one way photosynthetic marine plants return oxygen to the ocean?

6. One way that nutrients return to the surface is through a process

called .



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7. How do bacteria help release essential nutrients into the ocean?

8. Where do organisms in the ocean consume all the elements necessary for life?

9. What happens to elements necessary for life when ocean organisms die?

10. Where are nutrients stored in the ocean?

11. What must happen to nutrients stored in deep water before they can be used by most organisms in the ocean?

12. What is one way nutrients stored in deep water return to the surface?

13. What happens when wind blows steadily parallel to a coastline?



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14. In what part of the ocean do most marine organisms live?

15. The mass of mostly microscopic organisms that float or drift freely in the

waters of aquatic environments are called .

16. How do plankton form the base of food webs in the ocean?

17. Organisms such as dolphins and squid, that swim actively in open water, are

called .

18. Organisms that live at the bottom of oceans or bodies of fresh water are

called .

OCEAN ENVIRONMENTS

Use the terms from the list below to complete the sentences that follow. Each term may be used only once.

pelagic zone oceanic zone hadal zonebathyal zone benthic zone sublittoral zoneintertidal zone abyssal zone neritic zoneepipelagic zone

19. The general term for the bottom region of oceans and bodies of fresh water

is .

20. The general term for the region of an ocean or body of fresh water above the

benthic zone is .

21. This is the shallowest benthic zone, located between the low-tide and high-tide zones. Shifting tides make it a continually changing environment

for marine organisms. It is called the .



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22. Most organisms that live in the benthic zone live in this shallow zone. This constantly submerged area is located on the continental shelf and is home to sea stars, brittle stars, and sea lilies. It is called

the .

23. This zone begins at the continental slope and extends to a depth of 4,000 m. Little or no sunlight reaches this area so plant life is scarce. Animals living in this zone include octopuses, sea stars, and brachiopods. This zone is

called the .

24. This zone has no sunlight because it begins at 4,000 m and goes to a depth of 6,000 m. Organisms that call this zone home are sponges and worms. It is

called the .

25. This zone is confined to the ocean trenches—areas deeper than 6,000 m. This area is virtually unexplored, but scientists think that life here is sparse.

It is called the .

26. The region of the pelagic zone above the continental shelves has abundant sunlight, moderate temperatures, and relatively low water pressure, which are ideal conditions for marine life. Nekton fill the area’s waters and are the source of much of the fish and seafood that humans eat. It is called

the .

27. The zone that extends into the deep waters beyond the continental shelf is divided into four zones based on depth. It is called the

.

28. The uppermost area of the oceanic zone is sunlit and populated by sea life

such as dolphins. It is called the .

29. What are the deepest three areas of the oceanic zone?

30. What happens to the amount of marine life in the pelagic zone as depth increases?



Name Class Date

Skills Worksheet

Directed Reading

Section: Ocean Resources

1. What are three important resources supplied by the ocean?

FRESH WATER FROM THE OCEAN

In the space provided, write the letter of the description that best matches the term or phrase.

______ 2. freezing

______ 3. distillation

______ 4. desalination

______ 5. reverse osmosis desalination

6. Although desalination may provide needed fresh water, there is one signifi-cant drawback. What is it?

7. What is one disadvantage of using distillation as a means of desalination?

8. What is one advantage freezing as a means of desalination has over other processes?

a. a process of removing salt from ocean water

b. a process using special membranes that allow water under high pressure to pass through, while blocking dissolved salts

c. a process in which water is frozen, and ice crystals are removed and then melted to obtain fresh water

d. a process in which liquid water is heated, then evaporates leaving dissolved salts behind, and condenses, resulting in pure, fresh water



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MINERAL AND ENERGY RESOURCES

______ 9. The most valuable resource found in the ocean is a. salt. b. minerals. c. petroleum. d. gold.

______ 10. Offshore oil and natural gas deposits exist a. along the shorelines of the northern hemisphere. b. under sandy-bottom beaches. c. along continental margins. d. under the deepest ocean floors.

______ 11. About how much of the world’s oil supply is currently mined from offshore wells? a. one-third b. one-fourth c. one-half d. all

______ 12. Potato-shaped lumps of minerals, called nodules, are found a. on the abyssal floor of the ocean. b. washed up along the shorelines in remote areas. c. in underwater oil wells. d. in ocean waters heavy with organic materials.

______ 13. Recovery of nodules is difficult and expensive because a. they are so small. b. they contain manganese, iron, copper, nickel, cobalt, and

phosphates. c. they are located in very deep water. d. the minerals they contain cost too much to recover.

______ 14. The ocean is an important source of a. copper and silver. b. magnesium and bromine. c. trace minerals and iron. d. salt and diamonds.



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FOOD FROM THE OCEAN

Use the terms from the list below to complete the sentences that follow. Each term may be used only once.

overharvest aquatic farms foodprotein aquaculture ecosystem

15. Of all the resources the ocean supplies, the one in greatest demand

is .

16. Seafood is an important source of , which can be

harvested by fishing or through aquaculture.

17. When people the ocean over a long period of time,

the fish populations can collapse.

18. A collapse of a fish population can damage the and

threaten the fishing industry.

19. The raising of aquatic plants and animals for human use or consumption is

called .

20. Catfish, salmon, oysters, and shrimp are already being grown

on .

21. Under the best conditions, which type of farm could produce more food, aquatic farms or agricultural farms? Why?

22. How might aquatic farms be fertilized in the future?



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OCEAN-WATER POLLUTION

______ 23. Which of the following items is NOT a source of ocean-water pollution? a. garbage b. nuclear waste c. decaying ocean organisms d. sewage

______ 24. What factors have reduced the ocean’s ability to absorb wastes and renew itself? a. growth of world population and use of more-toxic substances b. shifting ocean floors and toxic ocean plant life c. underground volcanoes and offshore drilling d. oil spills and global warming

______ 25. In addition to beaches, what other area is in the greatest danger from increasing ocean-water pollution? a. warm tropical areas b. polar regions c. inland lakes d. coastal areas

______ 26. Which of the following items is NOT a dangerous pollutant in the ocean? a. mercury b. phosphates c. DDT from insecticides d. lead from gasoline

______ 27. What are two ways scientists and governments have worked to reduce pollution? a. DDT is banned worldwide, and use of leaded gasoline has

been eliminated. b. Use of DDT and leaded gasoline have both been reduced in the

United States. c. Insecticide use has been banned in the United States, and use of

leaded gasoline has been reduced. d. Use of DDT has been banned in the United States, and use of leaded

gasoline has been reduced.