ACT Reading Practice Test 82: NATURAL SCIENCE

DIRECTIONS: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

NATURAL SCIENCE: This passage is adapted from the article The Next Wave: What Makes an Invasive Species Stick?" by Robert R. Dunn (©2010 by Natural History Magazine, Inc.).

Like many biologists, Andrew V. Suarez struggled
for years with the question of which colonizing organ-
isms fail and which succeed. He studied it the hard
way-with fieldwork and lab experiments-until 1999,
5when he found some brown jars. He had gone to the
Smithsonian Institution National Museum of Natural
History's National Insect Collection to look for early
samples of Argentine ants collected in the United States
or at its borders. He hoped to find out how vintage
10specimens of Argentine ants were related to the existing

At the museum, among many thousands of jars of
insects labeled with taxonomic notes, locations, and
dates, Suarez ultimately found relatively few samples
15of Argentine ants. But what he found besides them was,
to his mind, far more interesting: some of the ethanol-
filled jars were jammed with vials of ants collected at
ports of entry in the eastern U.S. from 1927 to 1985.
They were ants that border agents had picked from
20plants being shipped into the U.S. Could those ants be
identified as members of species that had failed or suc-
ceeded as colonists, and if so, could the specimens be
used to compare the two groups?

In the jars and vials were 394 separate samples of
25ants. Suarez solicited the help of two friends, ant ecolo-
gist David A. Holway of the University of California,
San Diego, and Philip S. Ward, guru of ant gurus, at the
University of California, Davis. Altogether they identi-
fied 232 distinct species.

30Suarez considered the traits possessed by each of
the ant species in an attempt to see what might have
predisposed some of them to survival. He measured
whether they were big or small. He examined whether
each lived in the canopy or on the ground, and whether
35they were from one subfamily or another. He also
looked at a simpler possibility: that "survivor species"
tended to be those introduced more than once. The evi-
dence in the jars showed, for example, that Argentine
ants had arrived at least twice. Were successes just a
40consequence of the number of tries?

When a pioneering group sets up camp and starts
living in a new place, possible futures diverge. One
species might be wiped out within a generation or two.
A second might survive, but never become common.
45Yet another species might thrive, eventually spreading
across states, continents, and even the world! Even if
surviving in a new environment is sometimes a matter
of being introduced again and again, thriving is a differ-
ent story. Relatively few invasive species truly prevail.

50One curious thing about Argentine ants is that they
are, despite their apparent meekness, ecologically dom-
inant. They are squishy, small, stingless wimps, as ants
go, yet somehow they have managed to overpower the
big, tough native ants.

55There's another strange thing about Argentine
ants. If you take an Argentine ant from what looks like
one colony and put it together with one from a distant
colony, they accept each other. In fact, you can perform
that trick over much of California and very few of the
60ants will fight. It is as though all of the Argentine ants
in California are part of a few huge colonies-"super-
colonies," they've come to be called.

Biologist Ted Case joined forces with Holway and
Suarez for an experiment to test whether the lack of
65aggression among those ant colonies somehow helped
them to compete with other species. Might it simply be
that by not fighting with their neighbors, the Argentine
ants wasted less energy on war and could spend more
time on the good stuff? It turned out that, yes, aggres-
70sive ants wasted energy fighting (and dying), and so
gathered less food and fared poorly, in general. Peace
pays (at least peace with one's kin), and so Argentine
ants have made bank everyplace they have moved.

In fact, it isn't just for the Argentine ant that peace
75seems to pay. Supercolonies and the unicolonial popu-
lations they create look to be common among invasive

Ants flash chemical badges identifying their home
nest. Without such markers, no one knows who is friend
80or foe. When the clarity of "us versus them" breaks
down, peace breaks out among colonies of an ant
species. Different nests swap workers and queens, and
the term "colony" becomes fuzzy. Experiments seemed
to show that one conglomeration of Argentine ants
85stretched the length of California, another from Italy to
Portugal ... until, in 2009, workers from those two
"colonies" (along with a third from Japan) were put
together, and they didn't fight. Thus, across the entire
globe, a few peaceful supercolonies could exist and

1. The main purpose of this passage is to:

A. describe events that led to the discovery of Argen-tine ants in the United States.
B. examine the physical differences between Argen-tine ants and other insects.
C. highlight the technology that scientists used to determine the size of supercolonies.
D. discuss factors that contribute to a colonizing organism's success as an invasive species.

2. The author makes repeated use of which of the follow-ing in order to help establish the passage's somewhat casual tone?

F. Personal anecdotes
G. Idiomatic expressions
H. Humorous quotations
J. Self-critical asides

3. Which of the following events mentioned in the pas-sage occurred first chronologically?

A. Case joined Holway and Suarez to assist them with an experiment
B. Workers from three Argentine ant supercolonies in different parts of the world were brought together.
C. Suarez found samples of Argentine ants in the Smithsonian insect collection.
D. Holway and Ward were recruited by Suarez to assist with his research.

4. The main purpose of the fifth paragraph (lines41-49) is to:

F. explain how Argentine ants are able to survive in new areas and discuss their spread throughout the world.
G. describe possible outcomes for a pioneering species and stress the improbability that the species will thrive.
H. define the concept of invasive species as it relates to ants.
J. compare the behaviors of Argentine ants to those of other, more successful pioneering species

5. The author's claim that the Argentine ant behavior described in lines 56-58 is unusual is based upon which of the following assumptions?

A. Supercolonies are common among several species of ants.
B. Argentine ants in California are less aggressive than Argentine ants elsewhere.
C. California's ecosystem is especially suited for Argentine ants.
D. Ants from different colonies typically fight one another.

6. According to the passage, the question of which colo-nizing organisms fail and which succeed is one that has been studied by:

F. many biologists for a number of years.
G. many biologists beginning in 1999.
H. the Smithsonian exclusively.
J. Suarez exclusively.

7. The passage makes clear which of the following about the ant samples Suarez found in the Smithsonian insect collection?

A. Most of the samples were of Argentine ants.
B. Ward and Holway had collected the samples as part of a larger study of US insect populations.
C. Suarez discovered that most of the samples were of previously undiscovered species of ants.
D. Suarez was most interested in the samples that had been collected at eastern US ports of entry.

8. According to the passage, which of the following is true of Argentine ants?

F. They are stingless.
G. They are physically dominant.
H. They were first discovered in the United States by Suarez.
J. They have failed to thrive in Japan

9. The passage indicates that compared to peaceful ants, aggressive ants:

A. live in larger colonies.
B. spend less time gathering food.
C. are less likely to live in a colony.
D. are more likely to be a "survivor species."

10. The passage most clearly establishes which of the fol-lowing facts about ants?

F. In order for ant colonies to combine to form super-colonies, the colonies must have identical chemi-cal badges.
G. Ants identify their home nests by flashing chemi-cal badges.
H. Ant colonies from different species commonly swap workers and queens.
J. The largest supercolony of ants in the world stretches from Italy to Portugal.