Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate
Social parasitism involves one species relying on another to raise its young. Among
vertebrates, the best known social parasites are such birds as cuckoos and cowbirds; the female
lays egg in a nest belonging to another species and leaves it for the host to rear.
The dulotic species of ants, however, are the supreme social parasites. Consider, for
example, the unusual behavior of ants belonging to the genus Polyergus. All species of this ant
have lost the ability to care for themselves. The workers do not forage for food, feed their
brood or queen, or even clean their own nest. To compensate for these deficits, Polyergus has
become specialized at obtaining workers from the related genus Formica to do these chores.
In a raid, several thousand Polyergus workers will travel up to 500 feet in search of a
Formica nest, penetrate it, drive off the queen and her workers, capture the pupal brood, and
transport it back to their nest. The captured brood is then reared by the resident Formica
workers until the developing pupae emerge to add to the Formica population, which maintains
the mixed-species nest. The Formica workers forage for food and give it to colony members of
both species. They also remove wastes and excavate new chambers as the population
The true extent of the Polyergus ants' dependence on the Formica becomes apparent
when the worker population grows too large for existing nest. Formica scouts locate a new
nesting site, return to the mixed-species colony, and recruit additional Formica nest mates.
During a period that may last seven days, the Formica workers carry to the new nest all the
Polyergus eggs, larvae, and pupae, every Polyergus adult, and even the Polyergus queen.
Of the approximately 8,000 species of ants in the world, all 5 species of Polyergus
and some 200 species in other genera have evolved some degree of parasitic relationship with
Question 43. Which of the following statements best represents the main idea of the passage?
A. Ants belonging to the genus Formica are incapable of performing certain tasks.
B. The genus Polyergus is quite similar to the genus Formica.
C. Ants belonging to the genus Polyergus have an unusual relationship with ants belonging to
the genus Formica.
D. Poltergus ants frequently leave their nests to build new colonies.
Question 44. The word “raise” in line 1 is closest in meaning to
A. rear B. lift C. collect D. increase
Question 45. The author mentions cuckoos and cowbirds in line 2 because they
A.share their nests with each other
B. are closely related species
C. raise the young of their birds
D. are social parasites
Question 46. What does the author mean by stating that “The dulotic species of
ants...are the supreme social parasites” (line5) ?
A. The Polyergus are more highly developed than the Formica.
B. The Formica have developed specialized roles.
C. The Polyergus are heavily dependent on the Formica.
D. The Formica do not reproduce rapidly enough to care for themselves.
Question 47. Which of the following is a task that an ant of the genus Polyergus might
A. Look for food.
B. Raid another nest.
C. Care for the young.
D.Clean its own nest.
Question 48. The word “recruit” in line 20 is closest in meaning to
A. create B. enlist C. endure D. capture
Question 49. What happens when a mixed colony of Polyergus and Formica ants
becomes too large?
A. The Polyergus workers enlarge the existing nest.
B. The captured Formica workers return to their original nest.
C. The Polyergus and the Formica build separate nests.
D. The Polyergus and the Formica move to a new nest.
Question 50. According to the information in the passage, all of the following terms
refer to ants belonging to the genus Formica EXCEPT the
A. dulotic species of ants (line 5)
B. captured brood (line 13)
C. developing pupae (line 14)
D. worker population (line 19)