New SAT Reading Practice Test 43: Carbon Dioxide Passage

Home > SAT Test > SAT Reading Practice Tests

Test Information

Question 10 questions

Time 14 minutes

See All test questions

Take more free SAT Reading Practice Tests available from

Carbon Dioxide Passage

The concentration of carbon dioxide in our
atmosphere has been steadily increasing since
about 1750. Carbon dioxide lets in sun energy and
then traps it as heat energy, so the more carbon
05dioxide in the atmosphere, the higher the average
global temperature. Scientists are concerned that
even slight increases in global temperatures will
significantly affect plant and animal life on Earth.
In the past, photosynthesis has been able to keep
10the level of carbon dioxide in the air at a lower
level. Plants and algae convert water and carbon
dioxide into oxygen and glucose, using the sun's
energy. Carbon from carbon dioxide becomes
trapped or "fixed" as the plant uses glucose to build
15cellulose and starches, which make up most of the
plant's structure.
Human industry is the main cause of increased
carbon dioxide in the atmosphere. Cutting down
forests to make room for expanding cities or farm-
20land reduces the amount of carbon dioxide being
removed. The wood is also often burned, releasing
more carbon dioxide into the air. Burning fossil
fuels for energy releases even more carbon dioxide
that had previously been locked up in the coal, oil,
25or gas underground.
We can reduce the amount of carbon dioxide by
reducing how much we release, either by burning
fewer fossil fuels or by removing carbon dioxide as
the fuel is being burned. We can burn fewer fossil
30fuels by switching to other forms of power that
don't release carbon dioxide, such as solar or wind
power, but these methods are more expensive. We
can "scrub" the carbon dioxide from the air at the
power plant where the fuel is burned, but that is also
35expensive. It is also does not work for the carbon
dioxide produced by cars, trucks, and airplanes.
Reducing our output of carbon dioxide, though
a commendable idea, may not reduce the levels
enough to have a meaningful impact. We might
40need to go one step farther and try to remove car-
bon dioxide from the air.
Many research and development companies are
now developing systems that will act like artificial
"trees" and remove carbon dioxide from the atmos-
45phere. Several built their approach on a method
used in submarines and space vehicles. They com-
bine the carbon dioxide with a strong base called
sodium hydroxide to produce sodium bicarbonate,
also known as baking soda. Bubbling air through
50a solution of sodium hydroxide works well enough
for the small amount of air in a space vehicle or
submarine, but this would be a slow way to process
a large amount of air.
One researcher found a way to make a plastic
55with hydroxide components that would remove
carbon dioxide from air as it passes over the surface
of the plastic. Filters made out of long strands of
this plastic can then remove carbon dioxide as
wind pushes the air through the strands. The filters,
60therefore, act much like leaves in a tree.
This plastic is inexpensive, but making it into
filters, building towers that contain many "leaves"
of the filters, and processing the plastic to remove
the carbon dioxide so the plastic can be reused is
65currently very expensive. To pay for the cost, gasoline
would end up increasing in price. If manufacturers
could get the cost of this method down to $100 per
metric ton of carbon dioxide removed, for example,
the price of gas would still have to increase by
70about 88 cents to cover the cost. Researchers are
optimistic that they could actually get the cost down
to $25 per metric ton. If they achieve this goal, we
someday may see artificial trees in our cities, assisting
the real trees in cleaning the air.

1. The central idea of this passage is primarily concerned with

  • A. methods being developed to help remove carbon dioxide from the air.
  • B. the problems caused by cutting down forests to make cities larger.
  • C. the dangers of increased levels of carbon dioxide in the atmosphere.
  • D. how increased global temperatures will affect plant and animal life.

2. Which choice provides the best evidence for the answer to the previous question?

  • A. Lines 1-3 ("The concentration … 1750")
  • B. Lines 11-13 ("Plants and … energy")
  • C. Lines 17-18 ("Human industry … atmosphere")
  • D. Lines 42-45 ("Many research … atmosphere")

3. In paragraph 2, the author helps structure the passage's claim by providing

  • A. a detailed description of how real trees are different from artificial trees.
  • B. examples of current methods of removing carbon dioxide from the air.
  • C. an explanation of how carbon dioxide is naturally removed from the air.
  • D. details about how the level of carbon dioxide in the air has been steadily increasing.

4. How do the filters described in paragraph 6 act like leaves in a tree?

  • A. They contain long strands like veins in a leaf.
  • B. They remove carbon dioxide from the air.
  • C. They release oxygen into the atmosphere.
  • D. They branch out from the plastic-like leaves.

5. Which of the following examples of evidence would most strengthen the author's line of reasoning?

  • A. Details about the type of consequences plant and animal life could face if global temperatures increase in paragraph 1
  • B. How many acres of forest are cut down each year to make room for bigger cities and more farmland in paragraph 3
  • C. Descriptions of how solar and wind energy are harvested and converted to electricity in paragraph 4
  • D. An analysis of how much people would be willing to pay for gas to offset the cost of plastic used to remove carbon dioxide from the air in paragraph 7

6. As used in line 11, "convert" most nearly means

  • A. control.
  • B. transform.
  • C. substitute.
  • D. adjust.

7. The passage most strongly suggests that which of the following statements is true?

  • A. Solar and wind energy would become less expensive if more people used these forms of energy.
  • B. Technology that removes carbon dioxide from the air would not be necessary if more people rode bikes.
  • C. Global temperatures could reach levels dangerous to plant and animal life in the next 50 years.
  • D. People will resist technology that removes carbon dioxide from the air if it is too expensive.

8. Which choice provides the best evidence for the answer to the previous question?

  • A. Lines 3-6 ("Carbon dioxide … temperature")
  • B. Lines 26-29 ("We can … burned")
  • C. Lines 61-65 ("This plastic … very expensive")
  • D. Lines 70-74 ("Researchers … the air")

9. As used in line 38, "commendable" most nearly means

  • A. convincing.
  • B. hopeful.
  • C. admirable.
  • D. effective.

10. Which claim made by the author is supported by the evidence in the graphic?

  • A. Solar and wind energy are the most expensive methods of reducing carbon dioxide emissions.
  • B. Artificial trees remove more carbon dioxide from the air than scrubbers at power plants.
  • C. Natural gas power plants with scrubbers provide the least expensive method of reducing carbon dioxide emissions.
  • D. Coal power plants with scrubbers cost more to operate than natural gas power plants with scrubbers.