[BIO] question

[299678]

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In an ecosystem, fixed carbon has accumulated in the form of organic matter derived from dead plants and animals. Which of the following is the best explanation for this observation.

a) decomposer activity has been low
b) producers have been utilizing sunlight inadequately
c) there have been insufficient number of secondary consumers
d) primary consumers have been absent from the ecosystem
e) nitrogen has been cycled, but carbon has not

 

[RSD2014]

In an ecosystem, fixed carbon has accumulated in the form of organic matter derived from dead plants and animals. Which of the following is the best explanation for this observation.

a) decomposer activity has been low
b) producers have been utilizing sunlight inadequately
c) there have been insufficient number of secondary consumers
d) primary consumers have been absent from the ecosystem
e) nitrogen has been cycled, but carbon has not

Is the answer e?

 

[txlonghorn]

What's the answer? I think it is A, as the carbon left from dead stuff is not used up.

 

[BRM3488]

In an ecosystem, fixed carbon has accumulated in the form of organic matter derived from dead plants and animals. Which of the following is the best explanation for this observation.

a) decomposer activity has been low
b) producers have been utilizing sunlight inadequately
c) there have been insufficient number of secondary consumers
d) primary consumers have been absent from the ecosystem
e) nitrogen has been cycled, but carbon has not

I would say A sounds the best. Since carbon and nitrogen-fixing bacteria decompose dead plants and animals.

Actually, it could be E too?

 

[299678]

The correct answer is a)

I choose E too

 

[RSD2014]

The correct answer is a)

I choose E too

Is there an explanation for why a is the better answer?
That's iffy.

 

[txlonghorn]

fixed carbon has accumulated in the form of organic matter derived from dead plants and animals

Since there is an accumulation of organic carbon, it means that it is not being used up. What uses dead organic matter? Saprobes (spelling?). They also use up the nitrogen from dead matter. If they were "eating" the dead, then nitrogen and carbon would both go down.