Name______Class______Date______
Skills Worksheet
Directed ReadingChapter 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.
rockellipseoblate spheroid
global oceanEarthradius
pointsdiametermountains
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.
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
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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Directed Reading continued
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Earth Science1Earth as a System
ANSWER KEY
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.
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.
SECTION: ENERGY IN THE EARTH SYSTEM
1.Different fields of Earth science, such as geology, oceanography, and meteo-rology, 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.
Holt Earth Science1Earth as a System