The World Ocean
Practice exam questions written by Timothy H. Heaton,
Professor of Earth Sciences, University of South Dakota
Click the circle by an answer with the mouse, then click on the Submit button to get a response. You will be told if your answer is correct or not and will be given some comments. |~What is the largest ocean on earth? ~Arctic. |The Arctic Ocean is the smallest of the four main ocean basins. ~Atlantic. |The Atlantic Ocean is the second largest ocean basin. ~Indian. |The Indian Ocean is the third largest ocean basin. ~Pacific. |*The Pacific Ocean is the largest ocean basin on earth. |~Which ocean is increasing most in size over time? ~Arctic. |The Arctic Ocean is growing, but very slowly. ~Atlantic. |*The Atlantic Ocean is growing as the old and new worlds drift apart. ~Indian. |The Indian Ocean has been reconfigured by the collision of India with Asia but is not growing rapidly. ~Pacific. |The Pacific Ocean is shrinking by subduction on all sides. |~Which ocean is decreasing most in size over time? ~Arctic. |The Arctic Ocean is growing, albite very slowly. ~Atlantic. |The Atlantic Ocean is growing as the old and new worlds drift apart. ~Indian. |The Indian Ocean has been reconfigured by the collision of India with Asia but is not changing size appreciably. ~Pacific. |*The Pacific Ocean is shrinking by subduction on all sides. |~Which ocean is a remnant of the universal ocean Panthalassa? ~Arctic. |The Arctic Ocean is growing, albite very slowly. ~Atlantic. |The Atlantic Ocean is growing as the old and new worlds drift apart. ~Indian. |The Indian Ocean has been reconfigured by the collision of India with Asia but is not changing size appreciably. ~Pacific. |*The Pacific Ocean is remnant of the universal ocean Panthalassa. |~Where are the major ocean basins most connected to one another such that substantial water is exchanged between them? ~Around Antarctica. |*The West Wind Drift carries water around Antarctica between the Atlantic, Indian, and Pacific Oceans. ~At the North Pole. |Little water passes through the Arctic Ocean. ~Near the equator. |The ocean basins are not connected near the equator. ~Throughout the northern hemisphere. |The ocean basins have very little connection in the northern hemisphere. ~Throughout the southern hemisphere. |The southern continents separate the ocean basins throughout most of the southern hemisphere. |~How deep are the ocean basins on average? ~4,000 feet. | ~4,000 km. | ~4,000 meters. |* ~4,000 miles. | |~What are the deepest parts of the ocean? ~In ocean sinkholes. |There is nothing equivalent to sinkholes in the ocean depths. ~In random depressions. |The deep parts of the oceans are very regular and structured. ~Near the continents. |Continental margins can be either deep or shallow. ~The middle of the ocean basins. |Usually the middle of ocean basins are not particularly deep. ~In trenches formed by subduction zones. |*Deep-sea trenches are usually twice as deep as the average ocean floor. |~What is the most abundant dissolved ion in the oceans? ~Calcium. |Calcium is the fifth most abundant ion dissolved in the oceans. ~Chlorine. |*Chlorine is the most abundant ion dissolved in the oceans. ~Magnesium. |Magnesium is the fourth most abundant ion dissolved in the oceans. ~Sodium. |Sodium is the second most abundant ion dissolved in the oceans. ~Sulfate. |Sulfate is the third most abundant ion dissolved in the oceans. |~What value is salinity usually measured in? ~Calories. |Calories are a measure of energy. ~Ounces. |Ounces are a measure of weight. ~Parts per million. |Parts per million (ppm) is used to measure rare constituents. ~Parts per thousand. |*Salinity is usually measured in parts per thousand (o/oo). ~Percent. |Percent (parts per hundred) is used to measure more abundant things. |~What is a typical salinity value for the oceans? ~5 o/oo. | ~10 o/oo. | ~15 o/oo. | ~25 o/oo. | ~35 o/oo. |* |~Where does ocean salinity tend to be the highest? ~At desert latitudes. |*Evaporation exceeds precipitation at desert latitudes, thus increasing salinity slightly. ~In deeper water. |Deep water tends to have the salinity of the ocean average. ~Near the equator. |Precipitation exceeds evaporation near the equator, thus decreasing salinity slightly. ~Near the poles. |Polar waters have little evaporation or precipitation, so they have an average ocean salinity. ~Near river mouths. |Rivers introduce fresh water into the oceans, thus decreasing salinity locally. |~What is the thermocline? ~The coldest part of the ocean. | ~The hottest part of the ocean. | ~The zone of greatest heat loss. | ~The zone of greatest temperature change. |*The thermocline is the depth at which warm surface waters give way to cold deep waters. ~The zone of greatest salinity change. | |~What primarily drives the surface ocean currents? ~Coriolis forces. |Coriolis forces effect the direction that currents go but do not drive them. ~Deep sea vents. |Deep sea vents have little effect on ocean currents. ~Density differences between water bodies. |Density differences are what principally drive vertical circulation in the oceans. ~Rotation of the earth. |Rotation of the earth does not drive major currents, but it effects the direction of their motion (coriolis effect). ~Winds. |*Surface winds are what principally drive surface ocean currents. |~What primarily drives the deep ocean currents? ~Coriolis forces. |Coriolis forces effect the direction that currents go but do not drive them. ~Deep sea vents. |Deep sea vents have little effect on ocean currents. ~Density differences between water bodies. |*Density differences are what principally drive vertical circulation in the oceans. ~Rotation of the earth. |Rotation of the earth does not drive major currents, but it effects the direction of their motion (coriolis effect). ~Winds. |Surface winds are what principally drive surface ocean currents. |~What consequence does the coriolis effect have, relative to the Earth's surface, on masses of air or water that are changing latitude? ~The results are unpredictable; currents can veer right or left in either hemisphere. | ~They veer to the left in the northern hemisphere and to the right in the southern hemisphere. | ~They veer to the right in the northern hemisphere and to the left in the southern hemisphere. |* ~They veer to the right in both hemispheres. | ~They veer to the left in both hemispheres. | |~What phenomenon does the Coriolis effect arise from? ~Curvature of the earth's surface. | ~Rotation of the earth around its axis. |* ~Rotation of the earth around the sun. | ~Effect of winds high in the atmosphere. | ~Motion of the oceans in their basins. | |~In most ocean basins, how does surface water circulate? ~It circulates counterclockwise (CCW) in both hemispheres. | ~It circulates clockwise (CW) in both hemispheres. | ~In circulates CCW in the northern hemisphere and CW in the southern hemisphere. | ~In circulates CW in the northern hemisphere and CCW in the southern hemisphere. |* ~There is no general pattern, and each ocean behaves completely differently. | |~Where does deep upwelling usually occur? ~In the middle of the oceans. | ~Near continents. |Shallow upwelling can occur near continents due to winds, but deep upwelling requires cold surface waters. ~Near the equator. |At the equator deep upwelling is blocked by the thermocline. ~Near the poles. |*Only near the poles are surface waters cold enough to exchange with deep waters. ~Near trenches. | |~Under what conditions does coastal upwelling commonly occur? ~Only where biotic productivity is high enough to sustain it. | ~Only on the eastern coasts of continents. | ~Only on the western coasts of continents. | ~Where winds blow toward shore or Ekman flow carries surface water toward shore. | ~Where winds blow away from shore or Ekman flow carries surface water away from shore. |* |~As waves move along the surface of the water, what do water particles do? ~They move back and forth in a direction parallel to wave motion. | ~They move back and forth in a direction perpendicular to wave motion. | ~They move along the crests of waves and can travel thousands of miles. | ~They oscillate in circles whose diameters decrease with depth. |* ~They remain almost entirely motionless. | |~How deep in water do surface waves cause particle motion? ~Half the wave height. | ~Exactly the wave height. | ~Twice the wave height. | ~Four times the wave height. | ~Half the wave length. |* |~What determines wave speed in the open oceans? ~Wave height. | ~Wave length. |* ~Wind velocity. | ~All of the above. | ~Wave speed is constant regardless of these factors. | |~What is Surf? ~Capillary waves generated by light winds. |Capillary waves are the first waves to form when the wind blows. ~Fully-developed waves generated by strong winds. | ~Waves that grow larger the farther they travel. | ~Waves moving out of the generating area. |Swell is traveling waves that are not being generated or dissipated. ~Waves moving into shallow water and eventually breaking. |*Surf is waves moving into shallow water, slowing down, and breaking. |~What is Swell? ~Capillary waves generated by light winds. |Capillary waves are the first waves to form when the wind blows. ~Fully-developed waves generated by strong winds. | ~Waves that grow larger the farther they travel. | ~Waves moving out of the generating area. |*Swell is traveling waves that are not being generated or dissipated. ~Waves moving into shallow water and eventually breaking. |Surf is waves moving into shallow water, slowing down, and breaking. |~What happens to waves when they reach shallow water? ~They continue unabated. | ~They slow down. |*Interference with the bottom slows waves down and eventually causes them to break. ~They speed up. | ~They veer to the right. | ~They veer to the left. | |~When waves reach an irregular coastline, how is their energy distributed? ~It is equally distributed between bays and headlands. |Wave refraction bends the waves and redistributes their energy. ~It is focused on bays and cuts them deeper. |Bays usually fill in with sediment and thereby grow outward. ~It is focused on headlands and erodes them back. |*Headlands are attacked by focused wave energy due to wave refraction. ~It is reflected back to sea. |Wave reflection only occurs at vertical cliffs that extend deeper than the wave base, which are rare. |~What effect does wave energy tend to have on a coastline? ~It makes the coast more straight. |* ~It makes the coast more jagged. | |~Which of the following waves generally have the longest wavelength? ~Capillary waves. |Capillary waves have the shortest wavelengths. ~Gravity waves. |Gravity waves are typical waves generated by the wind. ~Internal waves. |Internal waves occur below the water's surface. ~Tides. |*Tides can be viewed as extremely long waves. ~Tsunami. |Tsunamis are long waves generated by geologic disturbances such as earthquakes and undersea landslides. |~Which of the following waves are generated by earthquakes and can devastate coastal communities? ~Capillary waves. |Capillary waves have the shortest wavelengths. ~Gravity waves. |Gravity waves are typical waves generated by the wind. ~Internal waves. |Internal waves occur below the water's surface. ~Tides. |Tides can be viewed as extremely long waves. ~Tsunami. |*Tsunamis are long waves generated by geologic disturbances such as earthquakes and undersea landslides. |~How many bulges are generated by the tide-raising force on the earth at one time? ~1. | ~2. |*One bulge occurs toward the moon and one away from the moon. ~3. | ~4. | |~How many high tides occur per day in most coastal areas? ~1. | ~2. |*One high tide occurs for each of the two bulges caused by the tide-raising force per revolution of the earth. ~3. | ~4. | |~What are tides of large amplitude that occur every two weeks called? ~Diurnal tides. |Diurnal tides are 24 hour tides. ~Equatorial tides. | ~Neap tides. |Neap tides are tides of small amplitude occurring every two weeks. ~Semidiurnal tides. |Semidiurnal tides are 12 hour tides. ~Spring tides. |*Spring tides are tides of large amplitude occurring every two weeks. |~What is the relative tidal force of the sun and moon? ~The sun and moon exert equal tidal forces on the earth. | ~The sun exerts twice the tidal force of the moon. | ~The sun exerts three times the tidal force of the moon. | ~The moon exerts twice the tidal force of the sun. |* ~The moon exerts three times the tidal force of the sun. | |~Where are the greatest tidal ranges on earth found? ~In large lakes like Lake Ontario. |Lakes are not large enough to experience significant tides. ~In narrow bays like the Bay of Fundy. |*Narrow bays oscillate with great amplitude, and the Bay of Fundy has by far the highest tidal ranges on earth (15 meters). ~In polar oceans like the Arctic Ocean. |Polar waters experience virtually no tidal force. ~In the largest oceans, particularly the Pacific. |Large oceans experience regional rotary tides. ~In wide bays like the North Sea. |Wide bays experience rotary tides. Please report any problems or errors to Dr. Heaton.