BIOL 2051 LAB FINAL WORKSHEETS | 141 QUESTIONS
| WITH ACCURATE SOLUTIONS.
Starch and cellulose are both glucose polymers. How do they differ in chemical
structure? Answer - -starch uses 1,4 alpha linkages, and is branched
-cellulose uses 1,4 beta linkages and is rigid and elongated
Dubos broth contains NaNO3, K2HPO4, MgSO4, KCl, FeSO4, and distilled water.
Before the addition of paper squares, is Dubos broth a complex or defined
medium? Answer - -defined because we know exactly what the composition of
the broth is
True or false. The growth of C. hutchinsonii in Dubos broth + paper
demonstrates that this organism can use cellulose as a carbon source. Answer
- -true, the paper in the dubos broth was the only source of carbon attainable,
so therefore the bacteria was able to grow using cellulose as a carbon source
Which type of paper was the best source of cellulose for C. hutchinsonii (i.e.,
showed the best growth)? Give a possible reason why one type of paper is
degraded better than another by C. hutchinsonii. Answer - -the filter paper or
index card paper
-filter paper most likely degraded better than the newspaper because of the
higher amount of cellulose and the ink may have something to do with it
Based on your lab results, which paper is likely made of 100% cellulose?
Answer - filter paper
,Where do you expect to find Cytophaga growing on the strips of paper in the
Dubos broths with paper? Be very specific. Explain why it would be growing
here. Answer - -in the oxic surface of the water
-it degrades cellulose aerobically and needs oxygen
For day 1 of the MPN technique, each bench had a different sample. Two were
samples of water from natural sources, one was tap water, and the other was a
dilution of E. coli prepared by the culture lab. Which sample served as a
positive control? Which sample served as a negative control? Answer - -
positive control was e. coli
-negative control was tap water
According to the EPA, water is considered potable if less than 2.2 coliforms per
100 ml. How many positive LSL tubes results in less than 2.2 coliforms per 100
ml? Answer - -one
What environmental factors influence the level of coliforms in the MS River? in
the University Lake? in the Gulf of Mexico? Answer - -contamination
ms river: chemicals
uni lake: littering
gulf: chemicals, oil spills, river run off
How is gas collection in the Durham tube an indication of the presence of
coliforms? Answer - -coliforms ferment lactose which produces CO2 in the
durham tubes
What reaction is carried out by an indole-positive organism? Answer -
Escherichia coli and Enterobacter aerogenes colonies look different on EMB.
Describe this difference by explaining the connection between lactose
, fermentation and dye uptake. If you lacked an EMB plate, how could you
distinguish between E. coli and E. aerogenes? Answer - -on emb plate e coli
has a metallic green appearance because it is a lactose fermenter and produces
a lot of acids and e aerogenes has a fish eye appearance which only the center
of the colonies takes up dyes because it produces much less acid
-if lacking an emb plate, one can distinguish between them by measuring acid
production
Methyl red is a pH indicator, turning red under ___________ conditions. What
products reduce the pH of the growth medium and give a positive methyl red
test? Answer - -positive
-production of acids reduce the pH of the growth medium
The Voges-Proskauer test uses alpha naphthol and 40% potassium hydroxide to
detect the presence of _________________ made from the fermentation of
glucose in organisms like ____________________. Answer - -acetoin (acetyl
methyl carbinol)
-E. aerogenes
Simmons' citrate agar contains a pH indicator ________________________.
Under what conditions does the color of this pH indicator change? Answer - -
bromothymol blue
-when alkaline products are formed and a rise in the pH takes place, it goes
from green to blue
To grow on Simmons' citrate agar, an organism must be able to use sodium
citrate as a _____________ source and ammonia salts as a ________________
source. Answer - -carbon
-nitrogen
| WITH ACCURATE SOLUTIONS.
Starch and cellulose are both glucose polymers. How do they differ in chemical
structure? Answer - -starch uses 1,4 alpha linkages, and is branched
-cellulose uses 1,4 beta linkages and is rigid and elongated
Dubos broth contains NaNO3, K2HPO4, MgSO4, KCl, FeSO4, and distilled water.
Before the addition of paper squares, is Dubos broth a complex or defined
medium? Answer - -defined because we know exactly what the composition of
the broth is
True or false. The growth of C. hutchinsonii in Dubos broth + paper
demonstrates that this organism can use cellulose as a carbon source. Answer
- -true, the paper in the dubos broth was the only source of carbon attainable,
so therefore the bacteria was able to grow using cellulose as a carbon source
Which type of paper was the best source of cellulose for C. hutchinsonii (i.e.,
showed the best growth)? Give a possible reason why one type of paper is
degraded better than another by C. hutchinsonii. Answer - -the filter paper or
index card paper
-filter paper most likely degraded better than the newspaper because of the
higher amount of cellulose and the ink may have something to do with it
Based on your lab results, which paper is likely made of 100% cellulose?
Answer - filter paper
,Where do you expect to find Cytophaga growing on the strips of paper in the
Dubos broths with paper? Be very specific. Explain why it would be growing
here. Answer - -in the oxic surface of the water
-it degrades cellulose aerobically and needs oxygen
For day 1 of the MPN technique, each bench had a different sample. Two were
samples of water from natural sources, one was tap water, and the other was a
dilution of E. coli prepared by the culture lab. Which sample served as a
positive control? Which sample served as a negative control? Answer - -
positive control was e. coli
-negative control was tap water
According to the EPA, water is considered potable if less than 2.2 coliforms per
100 ml. How many positive LSL tubes results in less than 2.2 coliforms per 100
ml? Answer - -one
What environmental factors influence the level of coliforms in the MS River? in
the University Lake? in the Gulf of Mexico? Answer - -contamination
ms river: chemicals
uni lake: littering
gulf: chemicals, oil spills, river run off
How is gas collection in the Durham tube an indication of the presence of
coliforms? Answer - -coliforms ferment lactose which produces CO2 in the
durham tubes
What reaction is carried out by an indole-positive organism? Answer -
Escherichia coli and Enterobacter aerogenes colonies look different on EMB.
Describe this difference by explaining the connection between lactose
, fermentation and dye uptake. If you lacked an EMB plate, how could you
distinguish between E. coli and E. aerogenes? Answer - -on emb plate e coli
has a metallic green appearance because it is a lactose fermenter and produces
a lot of acids and e aerogenes has a fish eye appearance which only the center
of the colonies takes up dyes because it produces much less acid
-if lacking an emb plate, one can distinguish between them by measuring acid
production
Methyl red is a pH indicator, turning red under ___________ conditions. What
products reduce the pH of the growth medium and give a positive methyl red
test? Answer - -positive
-production of acids reduce the pH of the growth medium
The Voges-Proskauer test uses alpha naphthol and 40% potassium hydroxide to
detect the presence of _________________ made from the fermentation of
glucose in organisms like ____________________. Answer - -acetoin (acetyl
methyl carbinol)
-E. aerogenes
Simmons' citrate agar contains a pH indicator ________________________.
Under what conditions does the color of this pH indicator change? Answer - -
bromothymol blue
-when alkaline products are formed and a rise in the pH takes place, it goes
from green to blue
To grow on Simmons' citrate agar, an organism must be able to use sodium
citrate as a _____________ source and ammonia salts as a ________________
source. Answer - -carbon
-nitrogen
