In the world of birds, bill design is a prime example of evolutionary fine-tuning.
Shorebirds such as oystercatchers use their bills to pry open the
tightly sealed shells of
their prey, hummingbirds have stilettolike bills to probe the
deepest nectar-bearing
Line flowers, and kiwis smell out earthworms thanks to nostrils located
at the tip of their
(5) beaks. But few birds are more intimately tied to their source of
sustenance than are
crossbills. Two species of these finches, named for the way the
upper and lower parts
of their bills cross, rather than meet in the middle, reside in
the evergreen forests of
North America and feed on the seeds held within the cones of
coniferous trees.
The efficiency of the bill is
evident when a crossbill locates a cone. Using a lateral
(10) motion of its lower mandible, the bird separates two overlapping
scales on the cone and
exposes the seed. The crossed mandibles enable the bird to exert a
powerful biting
force at the bill tips, which is critical for maneuvering them
between the scales and
spreading the scales apart. Next, the crossbill snakes its long
tongue into the gap and
draws out the seed. Using the combined action of the bill and
tongue, the bird cracks
(15) open and discards the woody seed covering and swallows the
nutritious inner kernel.
This whole process takes but a few seconds and is repeated
hundreds of times a day.
The bills of different
crossbill species and subspecies vary ― some are stout and
deep, others more slender and shallow. As a rule, large-billed
crossbills are better at
securing seeds from large cones, while small-billed crossbills are
more deft at
(20) removing the seeds from small, thin-scaled cones. Moreover, the
degree to which cones
are naturally slightly open or tightly closed helps determine
which bill design is the
best.
One anomaly is the subspecies
of red crossbill known as the Newfoundland
crossbill. This bird has a large, robust bill, yet most of
Newfoundland's conifers have
small cones, the same kind of cones that the slender-billed
white-wings rely on.
Questions
19. What does the passage mainly discuss?
(A) The importance of conifers
in evergreen forests
(B) The efficiency of the bill
of the crossbill
(C) The variety of food
available in a forest
(D) The different techniques
birds use to obtain food
20. Which of the following statements best represents the type of
"evolutionary fine-tuning" mentioned in line 1?
(A) Different shapes of bills
have evolved depending on the available food supply.
(B) White-wing crossbills have
evolved from red crossbills.
(C) Newfoundland's conifers
have evolved small cones.
(D) Several subspecies of
crossbills have evolved from two species.
(A) They are examples of birds
that live in the forest.
(B) Their beaks are similar to
the beak of the crossbill.
(C) They illustrate the
relationship between bill design and food supply.
(D) They are closely related to
the crossbill.
22. Crossbills are a type of
(A)
shorebird (B) hummingbird
(C)
kiwi (D) finch
23. Which of the following most closely resembles the bird
described in lines 6-8?
(A) kiwis (B) Newfoundland crossbill
(C) oystercatcher (D) hummingbirds
24. The word "which" in line 12 refers to
(A)
seed (B) bird
(C)
force (D) bill
25. The word "gap" in line 13 is closest in meaning to
(A)
opening (B) flower
(C)
mouth (D) tree
26. The word "discards" in line 15 is closest in meaning
to
(A)
eats (B) breaks
(C) finds
out (D)
gets rid of
27. The word "others" in line 18 refers to
(A)
bills (B) species
(C)
seeds (D) cones
28. The word "deft" in line 19 is closest in meaning to
(A)
hungry (B) skilled (C)
tired (D) pleasant
29. The word "robust" in line 24 is closest in meaning
to
(A)
strong (B) colorful (C)
unusual (D) sharp
30. In what way is the Newfoundland crossbill an anomaly?
(A) It is larger than the other
crossbill species.
(B) It uses a different
technique to obtain food.
(C) The size of its bill does
not fit the size of its food source.
(D) It does not live in
evergreen forests.
31. The final paragraph of the passage will probably continue with
a discussion of
(A) other species of forest
birds
(B) the fragile ecosystem of
Newfoundland
(C) what mammals live in the forests
of North America
(D) how the Newfoundland
crossbill survives with a large bill
32. Where in the passage does the author describe how a crossbill
removes a seed from
its cone?
(A) The first paragraph (B) The second paragraph
(C) The third
paragraph (D) The fourth paragraph
Please tally your answer with the below provided answers and
then comment below, how much you got!
Answers
19. B 20. A 21. C 22.
D 23. B 24. C 25. A 26. D 27. A 28. B 29.
A 30. C
31. D 32.
B
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