the universestandardized test prep the universe preview understanding concepts reading skills...

The Universe Standardized Test Prep

The Universe

Preview• Understanding Concepts • Reading Skills• Interpreting Graphics


Understanding Concepts

1. Inside a star’s core, hydrogen nuclei fuse to

form deuterons, which consist of one proton

and one neutron. When deuterons fuse with hydrogen nuclei, what do they form?

A. plasma

B. hydrogen atoms

C. hydrogen nuclei

D. helium nuclei


Understanding Concepts, continued

2. The hottest stars appear to be which color?

F. blue

G. green

H. red

I. yellow



3. What is the final stage in the life cycle of most

stars in our galaxy?

A. red giant

B. white dwarf

C. nebula

D. supernova



4. What objects are thought to be the most distant

objects in the universe?

F. spiral galaxies

G. elliptical galaxies

H. quasars

I. nebulas



5. About how long does it take light from the sun

to reach Earth?

A. 8 seconds

B. 8 minutes

C. 8 days

D. 8 years



6. Why is the light from distant galaxies almost

always shifted toward the red end of the

spectrum?



6. Why is the light from distant galaxies almost

always shifted toward the red end of the

spectrum?

Answer: They are moving away from us

(Doppler effect.)



7. What is the name for the process in which

atoms combine to form larger atoms, and

where does it take place?



7. What is the name for the process in which

atoms combine to form larger atoms, and

where does it take place?

Answer: Fusion, inside of stars



8. If the Milky Way galaxy has a spiral shape, why

do we see it as a streak across the sky?



8. If the Milky Way galaxy has a spiral shape, why

do we see it as a streak across the sky?

Answer: We are inside the Milky Way and can only

see a side view.


Reading SkillsAFTER THE BANG

Astronomers and physicists generally agree that the universe began about 13 billion to 15 billion years ago in the big bang. For some time after the big bang occurred, the universe was much hotter and denser than it is today. In fact, it was so hot and dense that there were no individual atoms; instead, subatomic particles, including protons, neutrons, and photons (particles of pure energy) made a dense fluid called plasma. Every time that a proton and an electron combined, drawn together by their opposite charges, a photon collided with them and ripped them apart again.


Reading Skills, continuedAFTER THE BANG, continued

After a few hundred thousand years, the average temperature of the plasma was low enough that the protons could hold onto their electrons to form neutral atoms, and photons could escape without being absorbed.


Reading Skills, continued9. Why couldn’t stable atoms form before the

cooling of the superheated plasma?

F. Protons and electrons were moving too

fast to combine.

G. Before the plasma cooled, subatomic particles

carried no charge and therefore were not attracted to one another.

H. Colliding with photons caused immediate

destruction of any atom that formed.

I. Cosmic background radiation prevented

the atoms from forming.


Reading Skills, continued10. Telescopes show images based on the photons

they receive, in the form of light, radio waves,

or other radiation. They show us events of the

past, because photons take time to travel to us

from those events. Why would it be difficult for

telescopes to observe events that took place

before the cooling of the superheated plasma?


Reading Skills, continued10. Telescopes show images based on the photons

they receive, in the form of light, radio waves,

or other radiation. They show us events of the

past, because photons take time to travel to us

from those events. Why would it be difficult for

telescopes to observe events that took place

before the cooling of the superheated plasma?

Answer: No photons escaped.


Interpreting GraphicsThe following chart shows the fusion reactions in a large-mass star,which create elements that are heavier than those found in stars likethe sun. Use this diagram to answer questions 11 and 12.


Interpreting Graphics, continued

11. Which element fuses to become oxygen?

A. carbon

B. neon

C. silicon

D. iron



12. Do the elements that are produced by fusion get heavier or lighter as they get closer to the

center of the large-mass star? Why?



12. Do the elements that are produced by fusion get heavier or lighter as they get closer to the

center of the large-mass star? Why?

Answer: Heavier; the pressure of gravity.


Interpreting Graphics, continuedAstronomers have determined that black holes, with masses from afew million to a billion times greater than the mass of our sun, reside inthe centers of nearby galaxies. The graphic shows the relationshipbetween the mass of black holes and the size of the bulge of stars at thecenter of these galaxies. Use the graphic to answer questions 13 and 14.



13. How does the mass of the black hole at the center of a galaxy relate to the mass of the bulge

of stars that surround the black hole?

F. The two masses are always equal.

G The two masses are directly proportional.

H. The two masses are inversely proportional.

I. The two masses are unrelated to one another.



14. Why would a black hole be surrounded by a bulge of stars?



14. Why would a black hole be surrounded by a bulge of stars?

Answer: The gravitational pull of the black hole’s enormous mass causes stars to move toward it.

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