Science Chapter 11

What is the most common ocean element? A) chloride B) calcium C) boron D) sulfate

A) chloride

What causes chlorine gas to enter the oceans? A) volcanoes B) rivers C) density D) groundwater

A) volcanoes

How have ocean currents affected the distribution of plants and animals on Earth?

Aquatic plants and animals get transported to new places by the ocean currents.

Why does the salinity of Earth's oceans remain constant?

As substances are added to the ocean water, sea animals and plants use the dissolved substances in their life processes. Other substances combine and precipitate out.

How do density currents affect the circulation of water in deep parts of the oceans?

At the poles, cold, dense surface water sinks and moves along the bottom.

Tides are affected by the positions of which celestial bodies? A) Earth and the moon B) Earth, the moon, and the sun C) Venus, Earth, and Mars D) the sun, Earth, and Mars

B) Earth, the moon, and the sun

Where might ocean water have originated? A) salt marshes B) volcanoes C) basins D) surface currents

B) volcanoes

In the ocean, what are movements in which water alternately rises and falls called? A) currents B) waves C) crests D) upwellings

B) waves

How long is the cycle of one low tide and one high tide? A) 12 hours B) 24 hours C) 12 hours, 25 minutes D) 24 hours, 50 minutes

C) 12 hours, 25 minutes

What is the highest point on a wave called? A) wave height B) trough C) crest D) wavelength

C) crest

What affects surface currents? A) crests B) upwellings C) the Coriolis effect D) calcium

C) the Coriolis effect

Describe the parts of an ocean wave.

Crest: highest part of the wave; trough: lowest part of the wave; wave height: vertical distance between crest and trough; wavelength: horizontal distance between the crests or troughs of two successive waves.

The Coriolis effect causes currents in the northern hemisphere to turn in which direction? A) eastward B) southward C) counterclockwise D) clockwise

D) clockwise

What causes most surface currents? A) density differences B) the Gulf Stream C) salinity D) wind

D) wind

Halite makes up nearly 90 percent of the salt in ocean water. How much halite is found in 1000 kg of ocean water?

Every 1000 kg contains 35 kg of dissolved solids. So, 0.90 times 35 kg = 31.5 kg of halite in each 1000 kg of salt water.

How might the use of fertilizers on farm crops affect the composition of the oceans?

Fertilizers contain chemicals that are plant nutrients. When added to water, algae reproduce rapidly. Bacteria decompose dead algae. Large numbers of bacteria use up large amounts of the water's dissolved oxygen and other animals suffer.

How does the energy from wind affect surface currents?

Friction between wind blown air and surface water creates currents.

What causes high tides?

High tides occur when the moon's gravity pulls on water particles and a bulge forms on the side of Earth facing the moon. At the same time, another bulge (high tide) forms on the opposite side of Earth because the water is thrown outward as Earth's axis revolves around the common center of mass between the moon and Earth.

Why does ocean water taste salty?

It contains many dissolved salts.

Describe the position of the moon and sun when a low tide is higher than normal.

Low tides are higher than normal when the sun, the moon, and Earth form a right angle.

Why do silica and calcium remain in seawater for a shorter time than sodium?

Many marine organisms use these elements in their life processes, thus removing them from the ocean.

Describe the Antarctic density current.

The Antarctic density current comes from the salt left over when ice forms at the South Pole. The salt increases the density of the cold water, and the water sinks beneath less-dense water.

The latitudes of San Diego, California, and Charleston, South Carolina, are exactly the same. However, the average yearly water temperature in the ocean off Charleston is much higher than the water temperature off San Diego. Why?

The water off Charleston originates at the equator. The water off San Diego originates near Alaska.

At the ocean, you spot a wave about 200 m from shore. A few seconds later, the wave breaks on the beach. Explain why the water in the breaker is not the same water that was in the wave 200 m.

The water particles do not move. The wave energy that moves through the water.

According to scientific theory, how were Earth's oceans formed?

Volcanoes spewed water vapor that accumulated, cooled, and condensed about 4 billion years ago. Eventually, rain fell and filled deep basins.