QUESTIONS 19-30
Many flowering plants woo insect pollinators and gently direct them to their most fertile
blossoms by changing the color of individual flowers from day to day. Through
color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than
another. The particular hue tells the
pollinator that the flower is full of far more pollen than are neighbouring
blooms. That nectar-rich flower also happens to be fertile and ready to
disperse its pollen or to receive pollen the insect has picked up from another
flower. Plants do not have to spend precious resources maintaining reservoirs
of nectar in all their flowers. Thus,
the color-coded communication system benefits both plant and insect.
For example, on the lantana plant, a flower
starts out on the first day as yellow, when it is rich with pollen and nectar.
Influenced by an as-yet-unidentified environmental signal, the flower changes
color by triggering the production of
the pigment anthromyacin. It turns orange on the second day and red on the
third. By the third day, it has no pollen to offer insects and is no longer
fertile. On any given lantana bush, only 10 to 15 percent of the blossoms are
likely to be yellow and fertile. But in rests measuring the responsiveness of
the butterflies, it was discovered that the insects visited the yellow flowers
at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted
flowers demonstrated that he butterflies were responding to color cues raher
than, say, the scent of the nectar.
In other types
of plants, blossoms change from white to red, others from yellow to red,
and so on. These color changes have been observed in some 74 families of
plants.
1.
The first paragraph of the passage implies
that insects benefit from the color-coded communication system because
a)
the colors hide them from predators
b)
they can gather pollen efficiency
c)
the bright colors attract fertile females
d)
other insect species cannot understand the
code
2.
The word woo
n line 1 closest in meaning to
a)
frighten
b)
trap
c)
deceive
d)
attract
3.
The word it
in line 3 refers to
a)
a plant
b)
an insect
c)
a signal
d)
a blossom
4.
The word hue
in line 3 is closest in meaning to
a)
smell
b)
texture
c)
color
d)
shape
5.
The word thus
in line 7 is closest in meaning to which of the following?
a)
However
b)
Therefore
c)
Probably
d)
Generally
6.
Which of the following describes the sequence
of color changes that lantana blossoms undergo?
a)
Red to yellow to white
b)
White to red
c)
Yellow to orange to red
d)
Red to purple
7.
The word triggering
in line 11 is closest in meaning to
a)
maintaining
b)
renewing
c)
limiting
d)
activating
8.
The passage implies that insects would be
most attracted to lantana blossoms
a)
on the first day that they bloom
b)
when they turn orange
c)
on the third day that they bloom
d)
after they produce anthromyacin
9.
According to the passage, what is the purpose
of the experiments involving paper flowers and painted flowers?
a)
To strengthen the idea that butterflies are
attracted by the smell of flowers
b)
To prove that flowers do not always need
pollen to reproduce
c)
To demonstrate how insects change color
depending on the type of flowers they visit
d)
To support the idea that insects respond to
the changing color of flowers.
10. The
word haphazard in line 15 is closest
in meaning to which of the following?
a)
Dangerous
b)
Random
c)
Fortunate
d)
Expected
11. What
is known from the passage about the other
types of plants mentioned in line 18?
a)
They follow various sequences of color
changes
b)
They use scent and other methods of
attracting pollinators
c)
They have not been studies as thoroughly as
the lantana
d)
They have exactly the same pigments as the
lantana
12. According
to the passage, in approximately how many families of plants has the
color-changing phenomenon described in the passage been observed?
a)
10
b)
15
c)
74
d)
100
ANSWER KEY
1.
B
According to the first paragraph, the
changing colors of the blossoms tell insects which blossoms are full of pollen.
Since the insects do not have to visit each blossom, they can gather pollen
more efficiently.
2.
D
The word woo
means attract, allure.
3.
B
The reference is to an insect.
4.
C
The word hue
means color, shade.
5.
B
The word thus
means therefore, consequently.
6.
C
A flower on the lantana plan “starts out …..as
yellow” (lines 11-12) but “turns orange on the second day and red on the third”
(lines 14-15)
7.
D
The word triggering
means activating, stimulating.
8.
A
According to the passage £a flower starts out
on the first day as yellow” (lines 11-12) and “insects visited the yellow
flowers at least 100 times more than would be expected form haphazard visitation”
(lines 18-20). Clearly, the flowers are most attractive to the insects on the
first day.
9.
D
Linnes 20-22 indicate that the purpose of the
experiments was to show that insects were responding to colors rather than to
other stimuli, such as the scent (smell) of the nectar.
10. B
The word haphazard
means random, arbitrary.
11. A
Lines 23-24 say that “in other types of
plants, blossoms change from white to red, others from yellow to red, and so
on.” This indicates that these plants follow a variety of color-change
sequences.
12. C
According to the passage, the phenomenon has
been seen in “74 families of plants” (line 25).
