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Name ______________________________ Class __________________ Date __________________
Skills Worksheet
Directed Reading Chapter 2 Section 1 pgs. 26-30
Section: Earth: A Unique Planet
1. List three reasons that Earth is unique.
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2. Why do scientists study the characteristics that make life on Earth possible?
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EARTH BASICS
Use the terms from the list below to complete the sentences that follow. Each term
may be used only once. Some terms may not be used.
rock
global ocean
points
ellipse
Earth
diameter
oblate spheroid
radius
mountains
3. The third planet from the sun in our solar system is
______________________.
4. Formed about 4.6 billion years ago, Earth is made mostly of
______________________.
5. About 70 percent of Earth’s surface is covered with water, called the
______________________.
6. Earth appears to be a perfect circle, but it is actually a slightly flattened sphere
called a(n) ______________________.
7. Earth’s surface is relatively smooth; that is, the distance between Earth’s high
and low ______________________ are small relative to its size.
8. Earth’s average ______________________ is 12,756 km.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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Earth as a System
Name ______________________________ Class __________________ Date __________________
Directed Reading continued
EARTH’S INTERIOR
9. Define seismic waves.
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10. What have scientists learned about Earth by studying seismic waves?
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In the space provided, write the letter of the definition that best matches the term
or phrase.
_____ 11. crust
_____ 12. oceanic crust
_____ 13. continental crust
_____ 14. Moho
_____ 15. mantle
_____ 16. core
_____ 17. lithosphere
_____ 18. asthenosphere
_____ 19. plasticity
_____ 20. mesosphere
_____ 21. outer core
a. the solid, outer layer of Earth that consists of
the crust and the rigid upper part of the
mantle
b. the central part of Earth below the mantle
c. the strong, lower part of the mantle between
the asthenosphere and the outer core
d. the thin, solid, outermost layer of Earth
above the mantle
e. the crust beneath the oceans
f. the lower boundary of the crust
g. the layer of rock between Earth’s crust and
core
h. the crust that makes up the continents
i. the solid, plastic layer of the mantle beneath
the lithosphere; made of mantle rock that
flows very slowly, which allows tectonic
plates to move on top of it
j. a dense liquid below the mantle
k. the ability of a solid to flow
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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Earth as a System
Name ______________________________ Class __________________ Date __________________
Directed Reading continued
EARTH AS A MAGNET
_____ 22. The lines of force of Earth’s magnetic field extend between
a. the North Pole and the South Pole.
b. the poles and the equator.
c. the North geomagnetic pole and the South geomagnetic pole.
d. the core and the crust.
_____ 23. Earth’s magnetic field extends beyond the atmosphere and affects a
region of space called the
a. mesosphere.
b. atmosphere.
c. electrosphere.
d. magnetosphere.
_____ 24. The source of Earth’s magnetic field may be
a. the liquid iron in Earth’s outer core.
b. the solid rock in the asthenosphere.
c. Earth’s dense, rigid inner core.
d. The rocky mantle.
_____ 25. Scientists have learned that, in addition to Earth, the sun and moon also
have
a. magnetic fields.
b. liquid outer cores.
c. large amounts of iron.
d. a magnetosphere.
EARTH’S GRAVITY
26. Define gravity.
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Earth Science
9
Earth as a System
Name ______________________________ Class __________________ Date __________________
Directed Reading continued
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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Earth as a System
ANSWER KEY
31. According to the law of gravitation, the
force of gravity decreases as the distance
from Earth’s center increases.
32. Earth bulges at the equator and is flattened
at the poles. Therefore, an object at either
pole would be closer to the center of Earth
and so would be heavier than it would be
at the equator, which is farther from
Earth’s center.
Directed Reading
SECTION: EARTH: A UNIQUE PLANET
1. Earth is the only known planet in the solar
system with liquid water; it is the only
planet whose atmosphere con-tains a large
proportion of oxygen; it is the only known
planet to support life.
2. in order to know what life-supporting
conditions to look for on other planets
3. Earth
4. rock
5. global ocean
6. oblate spheroid
7. points
8. diameter
9. Seismic waves are vibrations that travel
through Earth.
10. that Earth is made up of three major
compositional zones and five major
structural zones.
11. D
12. E
13. H
14. F
15. G
16. B
17. A
18. I
19. K
20. C
21. J
22. C
23. D
24. A
25. A
26. Gravity is the force of attraction that
exists between all matter in the universe.
27. The force of attraction between any two
objects depends on the masses of the
objects and the distance between the
objects. The larger the masses of two
objects, and the the closer together the
objects are, the greater the force of gravity
between the objects will be.
28. Weight is a measure of the strength of the
pull of gravity on an object. The newton
(N) is the unit used to mea-sure weight.
29. 10 N
30. An object’s weight depends on its mass
and its distance from Earth’s center.
SECTION: ENERGY IN THE EARTH
SYSTEM
1. Different fields of Earth science, such as
geology, oceanography, and meteorology, have been studied separately.
2. Scientists are combining knowledge of
several sciences to study Earth as a
system.
3. B
4. E
5. A
6. C
7. D
8. Systems vary in size from subatomic to
the universe; all systems have boundaries.
9. The Earth system operates as a result of
the combination of smaller, interre-lated
systems.
10. Energy can be transferred as heat, light,
vibrations, or electromagnetic waves.
11. A system can be described by the way that
matter and energy are transferred within
the system or to and from other systems.
12. Answers may vary. Sample answer: A
closed-system aquarium contains
everything it needs for life — plants
produce oxygen, aquatic animals feed on
plants or each other, and animal wastes
and organic matter nourish the plants.
Only sunlight enters from the
surroundings.
13. Answers may vary. Sample answer: A
lake is an open system. Water molecules
enter through rainfall and streams; and
water exits through streams, evaporation,
and absorp-tion by the ground. Sunlight
and air exchange heat with the lake.
Wind’s energy is transferred as waves.
14. Matter exchange is limited. Energy enters
the system as sunlight and exits
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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Earth as a System