戴爾美語托福TPO解析 - 英檢

TOEFL Reading --- Inference 推論暗示題:
TPO-34

Many plants - one or more species of at least 68 different families -
can secrete nectar even when they have no blossoms, because they bear
extrafloral nectaries (structures that produce nectar) on stems, leaves,
leaf stems, or other structures. These plants usually occur where ants
are abundant, most in the tropics but some in temperate areas. Among
those of northeastern North America are various plums, cherries, roses,
hawthorns, poplars, and oaks. Like floral nectar, extrafloral nectar
consists mainly of water with a high content of dissolved sugars and,
in some plants, small amounts of amino acids. The extrafloral nectaries
of some plants are known to attract ants and other insects, but the
evolutionary history of most plants with these nectaries is unknown.
Nevertheless, most ecologists believe that all extrafloral nectaries
attract insects that will defend the plant.

Ants are portably the most frequent and certainly the most persistent
defenders of plants. Since the highly active worker ants require a great
deal of energy, plants exploit this need by providing extrafloral nectar
that supplies ants with abundant energy. To return this favor, ants guard
the nectaries, driving away or killing intruding insects that might compete
with ants for nectar. Many of these intruders are herbivorous and would eat
the leaves of the plants.


1. According to paragraph 1, floral nectar and extrafloral nectar are alike
in that
(A) they are likely to be produced by the same plants
(B) they basically consist of the same chemical components
(C) they attract only insects that will defend the plant
(D) they are produced by the same parts of the plant

2. What can be inferred from paragraph 2 about the ants that are attracted
to the extrafloral nectaries?
(A) They do not eat the leaves of the plants that produce extrafloral nectar.
(B) They live almost entirely on extrafloral nectar.
(C) They spend most of their energy guarding extrafloral nectaries.
(D) They frequently fight among themselves over extrafloral nectar.


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