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YellowSapphire
- Master | Next Rank: 500 Posts
- Posts: 117
- Joined: Fri Jul 23, 2010 7:57 pm
- Location: India
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Source: OG
Coral reefs are one of the most fragile,
biologically complex, and diverse marine
ecosystems on Earth. This ecosystem is one of
the fascinating paradoxes of the biosphere: how
do clear, and thus nutrient-poor, waters support
such prolific and productive communities? Part
of the answer lies within the tissues of the corals
themselves. Symbiotic cells of algae known as
zooxanthellae carry out photosynthesis using the
metabolic wastes of the corals, thereby producing
food for themselves, for their coral hosts, and
even for other members of the reef community.
This symbiotic process allows organisms in the
reef community to use sparse nutrient resources
efficiently.
Unfortunately for coral reefs, however, a
variety of human activities are causing worldwide
degradation of shallow marine habitats by adding
nutrients to the water. Agriculture, slash-and-burn
land clearing, sewage disposal, and manufacturing
that creates waste by-products all increase nutrient
loads in these waters. Typical symptoms of reef
decline are destabilized herbivore populations
and an increasing abundance of algae and filter-
feeding animals. Declines in reef communities are
consistent with observations that nutrient input is
increasing in direct proportion to growing human
populations, thereby threatening reef communities
sensitive to subtle changes in nutrient input to their
waters.
It can be inferred from the passage that the author describes coral reef communities as paradoxical most likely for which of the following reasons?
(A) They are thriving even though human activities have depleted the nutrients in their environment.
(8) They are able to survive in spite of an overabundance of algae inhabiting their waters.
(C) They are able to survive in an environment with limited food resources.
(D) Their metabolic wastes contribute to the degradation of the waters that they inhabit.
(E) They are declining even when the water surrounding them remains clear.
It seems to be puzzling to me. I could not understood the OE.
OA: C
Coral reefs are one of the most fragile,
biologically complex, and diverse marine
ecosystems on Earth. This ecosystem is one of
the fascinating paradoxes of the biosphere: how
do clear, and thus nutrient-poor, waters support
such prolific and productive communities? Part
of the answer lies within the tissues of the corals
themselves. Symbiotic cells of algae known as
zooxanthellae carry out photosynthesis using the
metabolic wastes of the corals, thereby producing
food for themselves, for their coral hosts, and
even for other members of the reef community.
This symbiotic process allows organisms in the
reef community to use sparse nutrient resources
efficiently.
Unfortunately for coral reefs, however, a
variety of human activities are causing worldwide
degradation of shallow marine habitats by adding
nutrients to the water. Agriculture, slash-and-burn
land clearing, sewage disposal, and manufacturing
that creates waste by-products all increase nutrient
loads in these waters. Typical symptoms of reef
decline are destabilized herbivore populations
and an increasing abundance of algae and filter-
feeding animals. Declines in reef communities are
consistent with observations that nutrient input is
increasing in direct proportion to growing human
populations, thereby threatening reef communities
sensitive to subtle changes in nutrient input to their
waters.
It can be inferred from the passage that the author describes coral reef communities as paradoxical most likely for which of the following reasons?
(A) They are thriving even though human activities have depleted the nutrients in their environment.
(8) They are able to survive in spite of an overabundance of algae inhabiting their waters.
(C) They are able to survive in an environment with limited food resources.
(D) Their metabolic wastes contribute to the degradation of the waters that they inhabit.
(E) They are declining even when the water surrounding them remains clear.
It seems to be puzzling to me. I could not understood the OE.
OA: C
Last edited by YellowSapphire on Wed Jul 28, 2010 2:29 am, edited 1 time in total.
