Name
Date
Earth’s Water
What role does water play on Earth?
Before You Read
Before you read the chapter, think about what you know about water and the role it plays on Earth.
Record your thoughts in the first column. Pair with a partner, and discuss his or her thoughts. Write
those thoughts in the second column. Then record what you both would like to share with the class
in the third column.
Think
Pair
Share
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Chapter Vocabulary
Lesson 1
Lesson 2
Lesson 3
NEW
NEW
NEW
specific heat
hydrosphere
evaporation
condensation
water cycle
transpiration
polarity
cohesion
adhesion
water quality
point-source pollution
nonpoint-source
pollution
nitrate
turbidity
bioindicator
remote sensing
ACADEMIC
establish
REVIEW
density
A Lesson Content Vocabulary page for each lesson is provided in the Chapter Resources Files.
Earth’s Water
155
Lesson 1
The Water Planet
Scan Lesson 1. Read the lesson titles and bold words. Look at the pictures. Identify three facts
that you discovered about water on Earth. Record these facts in your Science Journal.
Identify four reasons why water is important on Earth.
Why is water important
to life?
I found this on page
527
.
provides habitats
necessary for
life
Water
climate
affects
which is influenced by
ocean currents
,
used by people for
transportation
and
I found this on page
528
.
Explain how water is essential in each biological function.
Transport
Photosynthesis
Body temperature
regulation
528
.
Water’s Role
carries nutrients
within cells
to, from, and
CO2
light
reacts with
and
and produces sugar and oxygen
changes to a gas
from the skin
Describe how water in the atmosphere helps keep Earth warm.
Water vapor and other gases in air trap and reflect some of
the Sun’s energy. Without this, Earth’s average surface
temperature would be below freezing.
I found this on page
529
.
Define specific heat.
Specific heat: the amount of thermal energy needed to
raise the temperature of 1 kg of material by 1˚C
156
Earth’s Water
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Function
I found this on page
recreation
Lesson 1 | The Water Planet (continued)
I found this on page
529
.
Complete the graphic organizer to explain how water’s specific
heat helps stabilize Earth’s temperatures.
Water has a very high specific heat.
Water vapor in the air
regulates
Large bodies of water take a
long
the rate at
time to
change temperature. This
which air temperature
changes. Therefore,
temperatures change
gradually
stable
provides a
temperature for aquatic
organisms.
as the
seasons change.
Water on Earth
I found this on page
530
Identify the distribution of water in Earth’s hydrosphere.
.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Type of Water
Water Changes State
I found this on page
531
Percent
Location
Salt water
97%
oceans
Freshwater
3%
glaciers, ice caps, lakes,
rivers, streams, swamps,
groundwater, atmosphere
Recall the changes in energy that occur as water changes state.
.
Students should color the
(+) arrows red and the (–)
arrows blue.
Label the arrows with the terms below. Color the arrows that
indicate the addition of energy red. Color the arrows that indicate
the release of energy blue.
+ thermal energy
– thermal energy
+ thermal energy
solid water (ice)
– thermal energy
liquid
water
+ thermal energy
liquid water
solid water (ice)
– thermal energy
water
vapor
liquid water
Earth’s Water
157
Lesson 1 | The Water Planet (continued)
I found this on page
531
Explain how evaporation of water can occur below water’s
.
boiling point.
Particles at the water’s surface need less energy to break
free from surrounding particles. Thus, surface water can
change to a gas, or evaporate, below the boiling point.
The Water Cycle
I found this on page
532
I found this on page
533
Identify the 2 main factors that drive the water cycle.
.
.
1.
the Sun
2.
gravity
Illustrate the water cycle. Include these labels:
• evaporation
• transpiration
• condensation
• precipitation
• runoff
• storage
Drawings should show all parts of the water cycle and
include the Sun as the source of heat that drives the cycle.
Sample answer: It rains. Water is absorbed into the ground. A plant takes in water
through its roots and moves it to all parts of the plant. Water evaporates, or
transpires, from the leaves of the plant back into the atmosphere. The water
continues to be a part of the water cycle.
158
Earth’s Water
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Trace the path of water from precipitation to transpiration.
Lesson 2
The Properties of Water
Predict three facts that will be discussed in Lesson 2 after reading the headings. Record
these facts in your Science Journal.
Water—A Unique
Compound
I found this on page
List five ways in which water is a unique compound.
537
.
1. Water has a high specific heat.
2. Water exists naturally as a solid, liquid, and gas on Earth.
3. Water forms drops when it spills.
4. Some substances dissolve in water.
5. Ice floats in water.
A Polar Molecule
I found this on page
538
Draw a water molecule. Label the positive charges blue. Label the
.
negative charges red.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Drawings should show a water molecule with two hydrogen
atoms and one oxygen atom. The end of the oxygen atom
opposite the hydrogen atoms should be labeled with a
red (–). The two hydrogen atoms should be labeled with
a blue (+).
I found this on page
538
.
Organize information about water’s polarity.
Polarity:
opposite
a condition in which
slightly
opposite
ends of a molecule have
charges, but the overall charge of
neutral
the molecule is
The negatively charged oxygen atom of one molecule attracts
positively charged hydrogen atoms of other water molecules.
This produces an
attractive
force between water molecules.
Earth’s Water
159
Lesson 2 | The Properties of Water (continued)
I found this on page
538
.
Sequence how sodium chloride dissolves in water.
1
Positively charged
are attracted to
atoms of water.
2
sodium atoms (Na+)
negatively charged
Negatively charged
are attracted to the
hydrogen atoms.
oxygen
chlorine atoms (Cl–)
positively charged
3 Sodium chlorine breaks apart, or
I found this on page
539
.
dissolves .
Explain cohesion and adhesion, and draw an example of each.
Cohesion: the attraction between molecules that are alike
Adhesion: the attraction between molecules that are not
alike
Earth’s Water
Drawings might show
the curved meniscus in a
graduated cylinder.
Adhesion
Cohesion
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
160
Drawings might show an
insect walking on the
surface of the water.
Lesson 2 | The Properties of Water (continued)
Density
I found this on page
540
Assess the information about the density of water. Read each
.
statement below. If the statement is true, write true on the line. If
the statement is false, write false on the line and rewrite the
underlined portion so that it is true.
The density of ice is lower than the density of the same
volume of liquid water.
true
The density of freshwater is lowest at 4˚C.
false; greatest
The particles of liquid water are closer together than the
particles of the same volume of frozen water.
true
I found this on page
541
Analyze the importance of water’s density to life on
.
Earth.
Cause
Effect
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Sample answer: The surface water freezes
and floats on the top of the pond. The ice
on the top insulates the water below.
In winter, the
surface water
of a pond
cools to 0˚C.
Aquatic organisms can survive the cold
months of winter because the denser water
below the ice remains a liquid at 4˚C.
Explain what happens to a frog’s environment during a northern winter.
Sample answer: In winter, surrounding air cools the surface of the water. When the
temperature of the water reaches 4˚C, it sinks. It is replaced by warmer water, which
rises to the top and cools. Eventually, the surface water cools to 0˚C and freezes. The
ice floats on the denser liquid water. This provides protective insulation for all aquatic
life in the water below, including the frog.
Earth’s Water
161
Lesson 3
Water Quality
Skim Lesson 3 in your book. Read the headings, and look at the photos and illustrations.
Identify three things you want to learn more about as you read the lesson. Record your ideas
in your Science Journal.
Human Effect
on Water Quality
I found this on page
Analyze the components of water quality.
546
Water Quality
.
Chemical Status
Biological Status
amount of
type and
number of
oxygen and
Physical Status
amount of
sediment
organisms
nutrients
I found this on page
546
.
Organize factors that affect water quality. Include two natural
and two human activities.
Natural
I found this on page
547
1. seasonal changes
1. pollution
2. weathering and erosion
2. deforestation
Analyze point-source pollution by using the graphic organizer.
.
such as
drainpipes
is called
point-source
Pollution that can
be traced to a
specific location,
pollution
or
162
Earth’s Water
smokestacks
,
.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Point-Source Pollution
Human
Lesson 3 | Water Quality (continued)
Nonpoint-Source
Pollution
I found this on page
Sequence information about nonpoint-source pollution.
547
.
1 Nonpoint-source pollution is pollution that cannot be traced
to a specific location
.
2 Runoff from large areas, such as lawns, roads, and urban
areas , might flow into rivers or streams and eventually reach water
storage areas, such as a wetland , groundwater , or the ocean.
human-made
3 Runoff might contain natural or
pollutants, such as sediment, fertilizers, or oil.
4 These pollutants can harm
aquatic life
and affect
drinking water
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Testing Water Quality
I found this on page
I found this on page
548
548
.
Identify six things that scientists can measure when they
.
.
want to examine water quality.
1. dissolved gases
4. cloudiness
2. temperature
5. health of aquatic organisms
3. acidity
6. number of aquatic organisms
Sequence information about how the level of dissolved
oxygen affects water quality.
Fish have
gills
, which absorb
Certain chemicals in water can cause an
algae
oxygen
from water.
overgrowth of
, which use up oxygen when they die and decay.
oxygen level
If the
not be able to survive.
in water is too low, fish might
Earth’s Water
163
Lesson 3 | Water Quality (continued)
I found this on page
548
Explain why water temperature is important to aquatic
.
organisms and give one example.
As water temperature increases, the amount of oxygen that
can dissolve in water decreases. So there is less oxygen in
warm water than there is in cool water.
Example: Coral can be harmed by a temperature increase
of 2°C.
I found this on page
549
.
Sequence the changes in water quality that nitrates can cause.
Write the numbers 1–5 on the blanks to order the events.
549
.
Oxygen levels in water decrease as the algae decay.
2
Algae grow rapidly at the surface of water and block
light from the photosynthetic organisms below.
3
Algae die.
1
Wastewater from homes and runoff that contains
animal waste and fertilizers contain nitrates.
Explain why scientists are concerned about acidic water.
Strong acids and bases can be harmful to aquatic
organisms. Long-term changes in the acidity of water can
affect the entire ecosystem. Some fish might not be able to
survive. Some organisms might be able to adapt to the
acidity, but their food sources might not.
164
Earth’s Water
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
I found this on page
4
Lesson 3 | Water Quality (continued)
I found this on page
549
.
Organize information about the turbidity of water.
As the amount of matter floating in water increases , turbidity,
or the measure of cloudiness of water,
increases
distance that light can penetrate into water
affects
photosynthetic
measured
using a
, and the
decreases
.
caused by sediments ,
Secchi disk
organisms
microscopic
organisms
, and
pollutants
Bioindicators
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
I found this on page
550
Identify three reasons why remote sensing is useful to
.
scientists studying water.
Remote sensing allows scientists to
1. monitor changes in Earth’s water storage
.
2. compare water in the same area over time
.
3. make inferences about water quality
.
At a certain location, a creek was tested for water quality. The presence
of stoneflies indicated that the water quality was good. Two kilometers downstream,
the water was tested again, and the population of stoneflies had decreased. What might
be happening in that two-kilometer stretch of creek?
Sample answer: The creek might be receiving runoff from a home with a fertilized
lawn, or the creek might flow past a farm so that animal waste is part of the runoff. It
might also flow past a factory that is the source of point-source pollution.
Earth’s Water
165
Review
Earth’s Water
Chapter Wrap-Up
Now that you have read the chapter, think about what you have learned.
Use this checklist to help you study.
Complete your Foldables® Chapter Project.
Study your Science Notebook on this chapter.
Study the definitions of vocabulary words.
Reread the chapter, and review the charts, graphs, and illustrations.
Review the Understanding Key Concepts at the end of each lesson.
Look over the Chapter Review at the end of the chapter.
Reread the chapter Big Idea and the lesson Key Concepts. Explain
the role that water plays on Earth.
Accept all reasonable responses. Sample answer: The presence of water is important
to Earth. Water exists on Earth in all three states. It has a high specific heat that
helps protect Earth’s living things because it regulates the rate at which air
temperatures change. As a result, the air temperature change from one season to the
cool. This provides a stable temperature for aquatic organisms and affects climates
in coastal areas. Water is also part of the water cycle, which provides precipitation
and contributes to Earth’s climate. Water provides habitats for many of Earth’s
organisms. The life processes of all organisms would not be possible without water.
Challenge Farmers are told that one way to make their crops grow better is to spread ammonium
nitrate (a source of nitrogen) on their fields. What potential problem might occur as a result of
farmers following this suggestion?
166
Earth’s Water
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
next is gradual. Large bodies of water, such as oceans, take a long time to heat and