Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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Other
galaxies were first believed to be ____. a. | nebulae or star clusters within the Milky
Way | b. | quasars outside
the Milky Way | c. | constellations within the Milky Way | d. | the Andromeda
galaxy | | |
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2.
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Elliptical galaxies are divided into subclasses based on ____. a. | their elongated
shapes | b. | the length of their diameters | c. | the ratio of
their major and minor axes | d. | the length of their spiral arms | | |
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3.
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Cosmic background radiation has a wavelength of approximately 1 mm, which makes it
____. a. | gamma ray
radiation | c. | X-ray
radiation | b. | microwave radiation | d. | infrared radiation | | | | |
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4.
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If
the average density is higher than the critical density, the universe is ____. a. | closed | c. | flat | b. | open | d. | round | | | | |
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5.
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Recent observations show that the rate of expansion of the universe is
____. a. | slowing
down | c. | constantly
changing | b. | stabilizing | d. | speeding up | | | | |
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6.
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A
flat universe was first predicted in the 1980’s by the ____. a. | Big Bang
theory | c. | inflationary
universe model | b. | steady-state theory | d. | flat universe model | | | | |
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Matching
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Match
each item with the correct statement below. a. | inflationary universe | e. | steady-state theory | b. | cosmology | f. | Hubble
constant | c. | Big Bang theory | g. | active galactic nucleus | d. | cosmic background
radiation | h. | superclusters | | | | |
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7.
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Core of a
galaxy in which highly energetic objects or activities are located
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8.
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Gigantic
formation of clusters of galaxies hundreds of millions of light-years in size
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9.
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A value of
approximately 70 kilometers per second per megaparsec
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10.
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States that
the universe began as a point and has been expanding ever since
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11.
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Persistent
noise discovered in 1965 that is caused by weak radiation from all directions in space
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12.
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Model that
says the universe began as a fluctuation in a vacuum and expanded very rapidly for a fraction of a
second before settling into a more orderly expansion
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Match
each letter notation with its corresponding galaxy shape below. a. | E7 | e. | SO | b. | Irr | f. | EO | c. | a | g. | S | d. | c | h. | SB | | | | |
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13.
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Barred
spiral
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14.
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Loosely
wound arms and a small, dim nucleus
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15.
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Flat disks
that do not have spiral arms
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16.
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Round
elliptical
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Short Answer
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17.
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Briefly explain the theory of the universe which is supported by the most
evidence.
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18.
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Identify the
type of galaxy, write a brief description and give an example of the galaxy
type.
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19.
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What
elements make up the stars in globular clusters?
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20.
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How do
astronomers explain the formation of the Milky Way galaxy?
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Black Holes:
One Size Does Not Fit All
Astronomers are concluding that monstrous black holes were not born
that big, as once believed, but instead grew on a diet of gas and stars controlled by their host
galaxies in the beginning years of the universe. An initial look at 30 galaxies indicates that black
holes do not precede a galaxy’s birth, but instead evolve with the galaxy by trapping an
amazingly exact percentage (0.2) of the mass of the stars and gas in a
galaxy.
Black holes in the centers of giant galaxies—some more than one
billion solar masses—had enough infalling gas to once blaze as quasars. The final mass of a
black hole is not primordial, but instead is determined during the galaxy formation process. This
shows that there is a close relationship between the black hole mass and the stars that comprise an
elliptical galaxy or central bulge stars of a spiral galaxy. In most cases, the black holes not only
bulked up through the accretion of gas, but also through mergers of galaxies in which pairs of black
holes combined.
The Hubble Space Telescope precisely measures the speed of
gas and stars around a black hole. This measurement provides clues for the existence of a black hole.
Astronomers determine the mass of each black hole by measuring the motion of stars swirling around
it. The closer a star is to the black hole, the faster is its velocity.
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21.
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In the chart
above, what unit of measurement is used to show black hole mass?
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