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questions about microbiology

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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questions about microbiology

Postby victor » Mon Jul 04, 2005 11:57 am

What do you think about my answer?are they the right one??if wrong please make a correction..
1. A pond contains phytoplankton and zooplankton. The quantity of DO (Dissolved Oxygen) measured once upon a time is...
a. can be used to measure photosynthesis.
b. compared upside-down with the pesticide pollution scale.
c. is affected by the intensity and time of the sunlight. *
d. can be used to determine the organism diversity.
e. can show the respiration speed of the pond's organisms.

2. Phytoplankton is contained inside a pond. what will be affected if bacterias decompose organic substances there?
a. phytoplankton can't live. *
b. dissolved mineral in the water can be accumulated and formed in the pond
c. DO is getting bigger.
d. photosynthesis process is getting slower.
e. nutrition for phytoplankton is reduced.

(*) means my answer for the question. If you think that my answer is wrong please make a correction in your reply and give a logic reason for that..(don't just give the answer without reason) :wink:
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Postby MrMistery » Mon Jul 04, 2005 8:20 pm

1. the quantity of DO does not give you much to work with. i would also put a * at e since more oxygen means less respiration
2. I do not think it is a since there isn't any big relation between photosynthesis and organic substances in the water. I would say b since it is the only one that does not imply that
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Postby victor » Tue Jul 05, 2005 12:45 pm

But I ever read my bio book and it stated there that organic substances decomposition by decomposer bacterias will make the BOD (Biochemical Oxygen Demand) inside the water is high..so, other organisms which live inside the water will die because lack of oxygen...will algae become one of those organisms???

In my bio book, it also stated that after organic substances decomposed by organic bacterias which make the BOD high...there will be anaerob bacterias which will decompose the rest of the substances and produce H2S (g) and make the water smells not good... :wink:
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Postby palpha3 » Tue Jul 05, 2005 8:17 pm

The decomposition of living organisms can cause by-products that could attach to oxygen (i.e. nitrogen could form NO2, carbon could form CO2) which in turn reduces the concentration of oxygen in the pond. That by itself could cause some organisms to die since the concentration of oxygen falls short of their threshold. However, there is always diffusion of oxygen between air and water. If this is the only information given to you I would say that the decomposition of organisms in that pond would not be the sole culprit for the lack of oxygen in the pond.

Algae need oxygen to perform photosynthesis so if there is a lack of oxygen they would start to die. Oxygen would be their limiting factor so the algae would stop dying once they reached the concentration which the oxygen level could support them.

The anaerobic bacteria would only really start to thrive more in that pond because they would have more room to grow due to aerobic bacteria dying. They would have a slight increase in their food supply but not enough that it would cause them to start replicating at a higher rate.

I can't really give you a direct answer to your questions because there are a lot of things missing. Hopefully this added knowledge will help. If I had to guess though I'd say 1 can be A or E and 2 can be B.
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Postby MrMistery » Tue Jul 05, 2005 9:32 pm

palpha3 wrote:Algae need oxygen to perform photosynthesis so if there is a lack of oxygen they would start to die. Oxygen would be their limiting factor so the algae would stop dying once they reached the concentration which the oxygen level could support them.

Algae produce oxygen in photosynthesis, they don't need it. They need CO2 and water+ light and will produce a lot of oxygen
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Postby victor » Wed Jul 06, 2005 11:34 am

Ok..thanks for the information. Now I can relax for my government exam tomorrow... :lol:
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Postby opuntia » Wed Jul 06, 2005 12:21 pm

Good Luck :)
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