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Aquatic Science Fall Final Review Sheet Answer Key
Properties of Water
1. Describe the molecular structure of water:
Two hydrogen atoms are covalently bonded to one oxygen. Water molecules are polar (slight positive and slight
negative end). Hydrogen bonds connect water molecules to each other.
2. What is water’s freezing point? _0oC___________ Boiling point? __100oC___________
3. How does adding salt alter the freezing point of water? Lowers the freezing point
4. Describe how the density of water changes as the water temperature increases, decreases, and when water
freezes. Liquid water has density of 1. As temperature increases, it becomes less dense. As temperature
decreases, it becomes more dense until it hits 4oC. At this point, its density decreases, and then water
freezes at zero. Ice floats in water because it is less dense.
5. Define the following properties of water:
a. surface tension – hydrogen bonds link water
molecules tightly, forming a tight surface
(insects can walk on water, drops on a penny,
etc.)
b. heat of vaporization – it takes a lot of energy to
evaporate water, because most of that energy is
used to break the hydrogen bonds before the
water will evaporate
c. specific heat capacity – Water takes a long time
to heat up and cool down because of hydrogen
bonding
d. capillary action – water is drawn up tubes
because of cohesion of water molecules to each
other, and adhesion to other surfaces (it’s a type
of surface tension)
6. What is the difference between cohesion and adhesion, and why are they important?
Cohesion is how water molecules stick to each other (due to hydrogen bonding). Adhesion is how water molecules
stick to the surfaces of things. These properties are responsible for surface tension and capillary action.
7. What effect does water’s heat capacity have on living organisms and the planet?
Because water heats up and cools down slowly, aquatic organisms have time to migrate to areas with livable
temperatures when before their areas become unlivable. It also drives currents and the mixing of nutrients.
8. What are hydrogen bonds and why are they important to the properties of water?
Type of bond between water molecules…the positive hydrogen of one water molecule bonds to the negative oxygen
atom of another water molecule. Hydrogen bonds are responsible for surface tension, and the fact that it takes a lot
of energy for evaporation and temperature changes. The hydrogen bonds have to be broken first.
9. List and describe the three states of water, in terms of the arrangement of molecules.
Solid – hexagonal lattice
liquid – tightly clustered
gas – individual molecules are spaced out
a.
b.
c.
d.
10. Define and give an example of when (or where) the following would occur:
Sublimation – solid to gas (dry ice, glacier giving off steam)
Condensation – gas to liquid (clouds to rain)
Evaporation – liquid to gas (sun heats up ocean surface and water evaporates)
Precipitation – water falls in form of snow, ice, rain
Water Cycle
11. Match the description of the water cycle to its part.
a. _a____ Sunlight
b. _b____ Evaporation
c. _f____ Condensation
d. _d____ Precipitation
e. _e____ Surface run-off
f. c____ Plants and animal
Water Quantity
12.
13.
14.
15.
What amount of the world’s water is freshwater? __3%__________________________________
What form is 2% of the world’s freshwater? _________frozen in glaciers and polar ice caps
What are the sources of surface water? __lakes, ponds, rivers…falls as a result of the water cycle
What is a watershed, and why is it important? _area in which surface runoff from rain and melting snow and ice
runs or drains into a body of water. The return unused water to continue the water cycle
16. How can spilling oil in your driveway, littering on the side of the road, or dumping things down your storm sewer
affect surface water? __all storm sewers lead to a body of water. All trash, etc. that goes into the storm sewer
dumps directly into a body of water without being filtered. Harms wildlife and pollutes water directly.
17. What is groundwater, and where is ground water found, specifically? _underground sources of water that has
seeped deep into the ground. Includes underground springs and aquifers.
18. What is the water table? Top portion of the groundwater or aquifer that is used by humans.
19. What is an aquifer? Made of porous rock…holds water underground
20. What is the difference between porosity and permeability?
How much water rock can hold.
How well soil or rock allows water to flow through it
21. What factors determine how porous or how permeable a soil type will be?
The more space between particles, the more water the formation is able to hold (the more porous), the size of the
particles and type of soil determines how fast the water flows through (permeability)
22. What two things can happen due to pumping out ground water faster than it can recharge?
a. __water table drops, making it harder and more expensive to retrieve more water_______
b. __land sinks when there is space underground (subsidence)
23. What is subsidence? The sinking of land due to the drawing out of groundwater or oil
24. (True ) Once an area has collapsed, it cannot be undone.
25. List 4 uses of water from dams and reservoirs.
store water for irrigation, drinking, industry and home use, generating electricity, regulate the flow of water ,
forming of lakes (creating habitat and used for recreational activities)
26. List 4 negative effects of building dams and reservoirs.
Dams alter scenic areas, displace people, and alter natural wildlife habitats, interrupt the natural stream flow,
disrupt natural fish migrations, and alter the water’s temperature and oxygen content.
Large amounts of water evaporate from the surface of a reservoir, and even more seeps into the ground, increasing
the rate of water loss. As water evaporates, dissolved particles of salt are left behind, making the water saltier, and
causing sand and silt particles settle on the bottom (siltation)
27. What are some possible solutions to our water supply issues, and what are the problems with those solutions?
Cloud seeding (should we take rain away from one area to provide for another?), desalination plants (expensive
and use a lot of energy), towing icebergs (expensive, and changes the amount of sea ice)
28. What is the purpose of the Clean Water Act? To protect humans from unsafe drinking water. Provides
regulations to monitor the safety of drinking water supply
29. What is the purpose of the Environmental Protection Agency? To monitor and regulate all activities that affect
the environment (land, air, and water)
Water Quality
For # 30-36, m atch the type of water pollution to its description below.
a. biodegradable
30. Includes food scraps and raw sewage A
wastes
31. Includes pesticides, fungicides, herbicides, and other toxic compounds B
b.
chemical wastes
32. Comes from leaking tankers, industrial plants, and surface run-off from roads
c. oil pollution
and driveways. C
d. sediments
33. Caused by the erosion of land D
34. Hot water from factories and industrial plants released into a body of water E
e. thermal pollution
35. Wastes from nuclear facilities, or from the ground where compounds such as
f. radioactive wastes
radon and uranium are found. F
36. What is the biggest problem to aquatic ecosystems when too much sewage or
fertilizer gets into ponds and lakes? Causes the overgrowth of aquatic plants and algae. These plants “choke”
out the fish, but using up more of the water’s oxygen. Can also increase the amount of sediment build up,
making water shallower and increasing the temperature. Also blocks sunlight for other aquatic plants to
root.
Chemistry of Water
37. Define salinity – the amount of salt in the water
38. What specific factors increase or decrease salinity levels in bodies of water?
Evaporation of water increases salinity, dumping of rivers into a body of salt water decreases salinity, formation of
sea ice increases salinity
39. How does salinity change with the ocean depths?
The deeper you go, the higher the salinity (density increases as salinity increases, so the saltier water sinks) Once
past the halocline, the salinity remains about the same in all the oceans.
40. Where does the salt in the oceans come from (how did it get there)?
Continuous runoff from rivers cause salt to accumulate in the oceans. There are salt domes and rocks that
leach salt into water sources as well.
41. What is the difference between a halocline and a thermocline? Why are they important?
Halocline is the area of the water where salinity gradually increases or decreases with depth. Salinity levels off
below this. Thermocline is the level in the ocean where temperature drops rapidly, then levels off to a uniform
temp below this level. Thermocline and halocline regions affect the density of the water, and affect how humans
and animals navigate through it.
42. What are the main types of dissolved gases in ocean water, and why is each important?
Oxygen – released by phytoplankton as a result of photosynthesis, and used by aquatic animals for respiration
Nitrogen – used by all organisms (plants and animals) to build important life compounds. As organisms die, the
nitrogen in their bodies returns to the ocean floor and is recycled through dentrification and nitrogen fixation
Carbon – phyotoplankton use carbon for photosynthesis. Organisms release carbon dioxide from respiration.
Shelled organisms and corals use carbon to build shells and reefs for housing.
43. Describe oxygen levels from the surface to depth. What factors cause these changes?
Oxygen is higher towards the surface, depending on the number of phytoplankton releasing it, and the number of
organisms living their using it. They are lowest around 3300 feet, because of levels of bacteria and other animals
break down or eat the organic matter at this level
44. Describe carbon dioxide levels from the surface to depth. What factors cause these changes?
CO2 levels are the highest at depth and the lowest at the surface. This is because the phytoplankton that live near
the surface use much more available CO2 for photosynthesis, at a faster rate than it is produced by organisms that
exhale it. Carbon dioxide also diffuses out of bodies of water and into the atmosphere, continuing the carbon cycle.
45. What are phytoplankton, and why are they important?
microscopic floating life-forms that obtain energy by photosynthesis. They form the base of every aquatic food
chain
46. How do the surface temperatures compare around the globe? Vary with the amount of sunlight
47. How do water temperatures change from surface to depth?
Below the surface level, temperature of ocean waters drops quickly to about 46-50oF (8-10oC) at 3,300 ft. Past the
thermocline, temperature continues to drop, but more gradually to a uniform 36oF (2oC) on the sea floor. This
temperature remains constant throughout the deep oceans around the globe.
48. How does salinity affect the boiling point of water? __decreases__ The freezing point? __decreases
49. How does salinity affect the density of water?
The higher the salinity, the more dense the water (freshwater is less dense than salt water)
50. How does temperature affect the density of water?
The lower the temperature, the more dense the water (until it hits 4 degrees, in which it becomes less dense as it
freezes)
Nutrient Cycles in the Ocean
51. Summarize how nitrogen cycles in the ocean, including dentrification and nitrogen fixation.
used by all organisms (plants and animals) to build important life compounds. As organisms die, the nitrogen in
their bodies returns to the ocean floor and is recycled through dentrification and nitrogen fixation. Bacteria and
lighting change atmospheric nitrogen into a form that can be used by organisms.
52. Summarize how oxygen and carbon cycle in the oceans.
Phytoplankton release oxygen, which is used by organisms. Organisms release carbon dioxide, which is used by
phytoplankton for photosynthesis. Also used to make shells and coral reefs. When organisms die, their shells fall to
the bottom, becoming part of the carbon sink.
Oxygen and carbon dioxide also diffuse between the ocean and the atmosphere.
53. What is the importance of phytoplankton to the ocean cycles?
Control the amount of carbon and oxygen in the oceans because of photosynthesis
Pressure, Buoyancy, Light and Sound
54. What affect does pressure have on a sac filled with air?_compresses it
55. What is the relationship between pressure and depth?
filled with water? _nothing
The deeper you go, the higher the pressure
56. What is buoyancy?
The ability of an object to float
57. In terms of pressure and buoyancy, what adaptations do fish have that live in the deepest parts of the ocean?
They have body cavities filled with fluid, rather than air, so they are not squeezed by pressure
58. In terms of buoyancy, what materials could you find inside the swim bladder of fish that live in shallower or in the
middle depths of the ocean?
Oil or air
59. Compare the rate of light absorption in the ocean of the different light colors in the spectrum.
Red, orange, and yellow light are absorbed before blue and violet.
60. Why do objects and organisms appear blue as you dive deeper into the water, even though they are actually brightly
colored?
Color is reflected. If you are in a deep part of the ocean where red, orange, and yellow light cannot reach, then all
that can be reflected is blue and violet, which is what you see.
61. Why is the level of light absorption important for organisms that perform photosynthesis in the ocean?
photosynthetic organisms must live toward the surface, in order to get the red, orange, and yellow light
62. What is bioluminescence, and in what ways is it used by organisms? organisms can give off a cold light. In
deepest parts of the ocean, bioluminescence can be used to hunt, find mates, or as camoflauge
63. What is echolocation, and why is it important?
Animals, such as dolphins and whales, bounce sound waves off of objects to determine the distance away. They use
it to navigate, locate each other, and to hunt
64. What are the two main differences between sound travel in the air versus in the water?
Sound travels faster and farther in water than in air and is increased with a rise in pressure
65. What is the SOFAR chanel, and why is it important for organisms and to humans?
layer of minimum sound velocity at a depth of about 3.300 ft (1,000 m). (Sound Fixing and Ranging) channel. The
properties of the SOFAR channel are exploited by people using underwater listening devices and by animals such
as whales and dolphins.
66. What conditions affect sound waves when traveling through the water? What are the affects?
influenced by temperature in the upper layers and by pressure in the deeper layers. As temperature decreases, the
speed of sound decreases, and as pressure (depth) increases, the speed of sound increases. Sound waves bend, or
refract, towards the area of minimum sound speed This up-down-up-down bending of low-frequency sound waves
allows the sound to travel many thousands of meters without the signal losing significant energy.
67. How is sonar used to map the ocean floor?
Sound waves are bounced off the ocean floor. The speed at which they return determines the make-up of the ocean
floor.
Ocean Geology
68. Draw and label the following features of the ocean floor in the box below.
Match the description below to the ocean floor feature it describes: You can use them more than once.
73. _f___ Extinct, underwater volcanoes that peak
69. _e___ Continuous mountain chains on the sea
above the ocean’s surface
floor
74. _g___ Forms at a subduction zone between an
70. _b___ Created when ocean water rises to cover
oceanic and continental plate.
edges of a continent
75. _b___ Made of continental crust
71. _a___ Deep, almost level sections of the sea floor
76. _b___ Shallow seas
72. _c___ Extinct, underwater volcanoes that have flat
77. __d__ Volcanic island chains that form on the
tops because of erosion.
opposite edge of a subducting plate
78. How have oceans around the world changed through time, as a result of continental drift?
Changed in number and size as continents pull apart and move together
79. What is the relationship between the plates of crust on the earth and the mantle? Oceanic crust and continental
crust fuse with the upper part of the mantle to form the lithosphere.
80. Write “O” if it describes oceanic crust and “C” if it describes continental crust.
a. _c____ thicker
d. _c____made of granite
b. _o____ newer
e. __o___ denser
c. _o____ made of basalt rock
f. __c___ less dense
81. Match the type of plate tectonic boundaries to its description
a. _a____ Convergent b. _b____ Divergent
c. _c____Transform
82. What is the connection between the mantle, magma, convection currents, and the movement of plates?
Plates of crust float on the liquid mantle. Convection currents in the mantle cause the plates to move over time, and
can pull apart or collide
83. Describe what happens when a continental and oceanic plate collide and why. What is the term for this?
Subduction – the oceanic plate is more dense, so moves under the continental plate as they collide. A trench forms
at the area of subduction. Volcanoes form on the continental plate as a result of the melting oceanic plate pushing
up magma.
84. Describe how each of the following are formed or caused.
a. Mountains – two continental plates collide
b. Ocean trenches – form on oceanic plates at
subduction zones
c. Volcanoes – form at edges of plates as magma is
pushed up at subduction zones. Can also form
at hotspot areas. Most common at the Ring of
Fire
d. Island Arcs – form at subduction zones where
two oceanic plates collide. Consist of volcanic
islands and are usually found at edges of plates
e. Earthquakes – release of energy vibrations as a
result of plates moving against each other. Most
common with convergent plates, but can occur
with any type. Most common at the Ring of
Fire.
f.
Tsunamis – occur as a result of earthquakes on
the ocean floor (with the rising or falling of
oceanic crust). Causes very large, fast moving
waves
g. Hotspots –
Volcanoes form at the middle of plates as a result of
magma putting pressure on the crust. As the plate
moves, volcanoes are cut off from their magma
source. New volcanoes form over the hotspot area.
Creates island chains, such as Hawaii. Also created
Yellowstone.
Currents, Climate, Waves and Tides
85. Explain how winds are formed from the unequal heating of the sun.
Warmer air expands and rises. AS it rises, it cools and becomes more dense and falls. Causes a north-south
circulation of air, that rotates because of the spinning earth (coriolis effect)
86. How does the Coriolis effect affect winds and currents.
Causes them to circulate because the earth spins
87. What effect do winds and currents have on climates around the globe?
Circulates warmer air and water from tropical regions to polar regions, and vice versa
88. What effect do cyclones and anticyclones have on currents?
Causes spinning as a result of high and low pressure differences. Increases the mixing of water and nutrients
89. How do onshore and offshore breezes form?
Land heats up faster than water. Warm air rises from land, cooler air moves low from ocean to land. Causes a
breeze. At night, land cools down faster than water, so the opposite happens. Causes a reverse in the direction
of the breeze.
90. What is responsible for causing surface currents?
Winds – surface currents follow the patterns of air currents
91. How does Ekman transport work?
Wind exerts friction of the top layer of water, dragging it at a right angle. The top layer of water exerts friction
on the layer below it, dragging it behind at a right angle as well. And so on, and so on.
92. What is an ocean gyre?
Area where multiple currents meet to create a large, circulating region of water
93. Where are the 5 gyres located?
One in the Indian ocean basin, two in the atlantic ocean basin, and two in the pacific ocean basin
94. What causes the deep water currents?
Changes in density due to temperature or salinity changes
95. What is downwelling, and why is it important?
The sinking of water near polar regions as warmer water cools off and becomes more dense. It helps warm up
the water in polar areas
96. What is upwelling, and why is it important?
The rising of cooler water as a result of it becoming warmer. It brings with it water rich in nutrients and oxygen
to replace warmer water containing less of this
97. What is the Global Conveyor, and why is it important?
The large circulation of surface and deepwater currents around the globe. Takes 1000 years to complete one
loop around the planet
98. What are the effects of El Nino?
Causes warmer than normal ocean temperatures, and fails to bring in the needed nutrient supplies. Fish
numbers drop.
99. What causes a hurricane to form?
Warm water caused from heat moving off of Africa causes the formation of large, circulation storms around a
central eye.
100. What causes waves? What determines the size of a wave?
The strength and duration of winds causes and determines the size of waves.
101. What is the affect of waves on shorelines?
Waves erode and change the shape of shorelines
102. Explain how the sun and moon affect tides.
The sun and moon have a gravitational pull of the earth’s oceans. The moon’s pull is stronger. As the earth
spins, the moon’s pull and centrifugal force causes the oceans to bulge, producing high and low tides.
103. What are spring tides?
Higher than normal tides that occur twice a month with the full moon, when the earth is directly in line with the
sun and moon.
104. What are neap tides? Little moving tides when the moon is in its first and third quarter. There is more of
an equal pull between the moon and sun, so the tides level out around the earth.
105. What are tidal currents, and how do they form?
The horizontal movement of water as high and low tides change. Tidal currents flow faster through narrow
channels. They are also affected by features on the ocean floor (can cause whirl pools and rip tides).