Switch to full style
Debate and discussion of any biological questions not pertaining to a particular topic.
Post a reply

Hard time with homework question

Mon Nov 21, 2011 5:04 pm

I have a question from my biology class that has me stumped, I'm certinly not asking for anyone to do my work however, any hints or thoughts may help! Thanks! :D

Two rivers 'Sparkly' and 'Smelly' they obtained a sample from both the sample from 'Smelly' contained a thick mud which smelled very much like ch4(methane), while the sample from 'Sparkly' contained 7% ethanol. There was little oxygen in either river, no photosythetic cyanobacteria, and the water contained a minimal amount of ATP and NADH. Water from both rivers had the presence of a 3 carbon acid in amounts twice that of the 6 carbon acid from wich it is originally derived, and the presence of trace amounts of latic acid. Also, the prescene of small primative micoorganisms in the smelly river.

*What type of respiration is occuring in both rivers?

*What is the specific name of the catabolic pathway occuring in both?

*What are the prokaryotic microorganisms in the Smelly River?

*What is the chemical name of the 3 carbon acid found and which compound are they derived?

*How many ATP and NADH will be produced?

*What chemical compound are the gas bubbles in the smelly river?

*What compound in the 'Sparkly' river makes it so popular?

Mon Nov 21, 2011 7:25 pm

1. Anaerobic respiration in both cases
2. Methanogenic anerobic respiration from pyruvic acid to acetic acid to methane in smelly. Some type of anaerobic fermernation in Sparkly. Which type cannot be determined from the information given.
3. Prokaryotes probably but the type could be any species that can live anoxically.
4. Pyruvic acid based on the relative lack of NADH.
5. Unanswerable.
6. Probably methane.
7. Alcohol! Ethanol to be precise. At 7% alcohol that is approximately beer concentration.

Re: Hard time with homework question

Mon Nov 21, 2011 7:47 pm

Hi there thanks so much I had a few different answers let me know what you think?
2. anaerobic fermentation??
3. methanogens???
4. co2/ h2co3???
5. atp=2/Nadh=4???
6. hydogen sulfide???
Thanks again for your help I am not a bio major :lol: just trying to get through a required class!

Re: Hard time with homework question

Mon Nov 21, 2011 8:22 pm

sissyblaze wrote:2. anaerobic fermentation??

Just another way of saying what I said.
sissyblaze wrote:3. methanogens???

sissyblaze wrote:4. co2/ h2co3???

No. It specifies 3 carbon which indicates the end product of glycolysis which is pyruvate whose acid form is pyruvic acid. Its not lactic acid which can be made from pyruvic acid because there is not high levels of NADH which would push the conversion of pyruvic acid to lactic acid.
sissyblaze wrote:5. atp=2/Nadh=4???

This question is ambiguous. The answer is going to be the 2 ATP and 2 NADH from glycolysis plus whatever products from the specific anaerobic fermentations that are going on.
sissyblaze wrote:6. hydogen sulfide???

This is a very smelly chemical and could be present but based on the information given I can't say for sure. I suspect that you are right. Your teacher probably expects you to infer this.

Re: Hard time with homework question

Mon Nov 21, 2011 9:20 pm

Great thanks! Ill give you the extact wording of #5 from my teacher
Based on the findings, how many ATP and NADH will be produced during each complete cycle of the pathway described in #2(anaeriobic fermentation).

While I have your attention and you obviously know more than I, another question is a bit tricky
* Expansion upon freezing is the 2nd most important characteristic of water which causes ice to float thus insulating the water below and preventing organisms from freezing. Explain (chemically) why ice floats?
I really am grateful for all your help :D

Mon Nov 21, 2011 9:48 pm

I'm not completely sure but I believe it will be 2 ATP and 3 NADH. Although acetic acid is broken down to methane, I don't think that this produces any further ATP gain. There is definite end gain in NADH and ATP by the product of acetic acid. Conversion probably doesn't benefit the cell other than taking the acetic acid to a further oxidized state which prevents harmful acid build up inside the cell.

Why does ice float is just a question of density. Ice is less dense because ice is a crystallized form of H2O with specific structure. Liquid water has H2O going every which way and running into each other which results in a close packing structure. This means more H2O molecules per unit of volume. In ice, the H2O is forced into a structure via hydrogen bonding and the packing density goes down. This decrease in density makes ice less dense than liquid water.

The maximum measured angles between in the packing of water during liquid phase is 105 degrees while in solid ice it is 109.5. Increased angle means decreased packing density.

Re: Hard time with homework question

Mon Nov 21, 2011 9:54 pm

Thanks Again You made my day!!! :P
Post a reply