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Food Web

Discussion of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment

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Food Web

Postby LeandroLuis » Thu Jan 03, 2013 9:35 pm

Hello.

I'm not a genius in biology (to say the least), so I just don't know how to solve this problem, even that I did read about ecology, food web and stuff. I would like a little help, if you please.


Consider the following scheme, that represents a food web. I, II, III, IV and V constitute the several trophic levels.

Food Web.JPG
Food Web.JPG (4.04 KiB) Viewed 5370 times


The fungi can occupy all the trophic levels above, except:

a) I
b) II
c) III
d) IV
e) V

I'm sorry but I can't find how to use the spoiler thing. I appreciate if someone let me know.
The template is letter b.
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Postby LeandroLuis » Thu Jan 03, 2013 10:17 pm

Maybe the answer is that one because the organism II is the only one among those options that doesn't consume something, what would be ridiculous for a decompositor ?
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Postby JackBean » Fri Jan 04, 2013 1:37 pm

It must be something unique, because otherwise you've had to have multiple choice. For that reason I, III and IV cannot be the right answer. (I and IV are the same anyway, III is also the same, just with two food resources).
Thus we have II, which only consumes everything around
and V, which is only consumed. Which organisms get no food? Autotrophs. I don't think that any fungi is autotroph (only as part of lichen).
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Re: Food Web

Postby LeandroLuis » Fri Jan 04, 2013 1:57 pm

So, for what I understood, my idea was right. By your means, the fungi cannot occupy position II because it's a position of an autotrophic organism, which the fungi aren't.

Thank you JackBean :wink:
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Postby JackBean » Fri Jan 04, 2013 6:11 pm

V is autotroph (it doesn't eat anything else, but is eaten).
Fungi can be eaten by something of course, so there is no reason, why II could not be fungi.
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Postby LeandroLuis » Fri Jan 04, 2013 6:36 pm

I'm sorry, I thought you made a mistake when affirming that V is "only consumed" and II "only consumes everything around".

I mean, shouldn't the arrows be in the sense: consumed to consumer ?

If it's not the case and you're right, II would be in fact consuming everything, being able to be a decomposer (fungus).

But in that case the answer couldn't be letter b, given that the question asks for the only option that the fungus can NOT be.
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Postby JackBean » Mon Jan 07, 2013 1:58 pm

IMHO it should be consumed <- consumer, so that "lower" levels of food chain are lower as is usually depicted.
Anyway, fungus cannot be the one who is only consumed, no matter which one is it (either II or V)
http://www.biolib.cz/en/main/

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