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Unformatted text preview: ©Prep101 www.prep101.com/freestuff Biology 112 Practice Final Exam
1) Natural selection:
1. acts on the genotype and not the phenotype
2. is determined by the effects of the environment on the genotype of the
3. acts upon the phenotype but is a consequence of changes in genotype
4. requires that an organism reproduces and produces identical offspring
Which statements are true:
a) 1 + 2
b) 2 only
d) 3 only
Answer: C. Natural selection is the selection of phenotypes in a particular
environment that provides a selective advantage. Phenotype is dictated by the
genotype and the environment therefore C. is correct.
2) Some changes in genotype have no effect on phenotype. Which if the
following is true:
a) A mutation in the non-coding region of a gene will have very little effect on
b) A frame shift mutation anywhere within a coding region for a gene will
cause the same phenotype.
c) A change in genotype could have a huge effect on phenotype or none at
d) A point mutation upstream of the coding sequence will have no effect on
e) All of the above.
Answer: C. This is a common question topic. With most mutations it is
impossible to predict the phenotypic consequence of the change in genotype.
3) All electron transport chains require
e) NAD+ or NADP+ to be the terminal electron acceptors.
Electron carriers to be arranged from low to high electronegativity.
ATP hydrolysis to supply the energy for electron flow.
Electrons to enter the chain associated with stable compounds.
Both A and C are correct. Page 1 of 8 ©Prep101 www.prep101.com/freestuff
Answer: B. All ETCs are a set of increasing strength of electron acceptors that
shuttle electrons to harness energy in discrete steps. Higher electronegative
atoms are stronger electron acceptors therefore B is correct.
4) You have designed an experiment in which you feed glucose containing
radioactive carbon molecules to cells growing rapidly in the presence of
oxygen. Over time, you would find the radioactivity in
NADH + H`
CO2 Answer: E. If an organism can use glucose as its energy source it is a
heterotroph and in the presence of oxygen it normally undergoes cellular
respiration where the complete oxidation of glucose causes the release of all
carbons as CO2.
5) Consider the following statements:
1. ATP can be generated through the ETC by utilizing the energy contained in
the [H+] gradient to drive ATP synthase
2. Nutrient oxidizers tolerate oxygen
3. Waste products of lithotrophs include ethanol, acetic acid, or lactic acid
4. Na3PO4 could be used as a source of bioelement, phosphorus.
e) None of the statements are valid
Only one statement is valid.
Two statements are valid.
Three statements are valid.
All statements are valid. Answer: D. Statement #1 describes chemiosmosis, Statement 2 is a general
statement and can be true. Statement #3 is false –lithotrophs do not ferment and
ethanol, acetic acid and lactic acid are products of fermentation. Statement #4 is
6) Design a theoretical medium that would specifically inhibit the growth of
all lithoautotrophs except methanogens. (Hint – what is the difference
between methanogens and other lithoautotrophs?)
Answer: CHOPSN sources. But the only difference between methanogens
and the other anaerobic lithoautotrophs (eg sulfur reducers) is that
methanogens use a different mechanism to fix carbon than other
lithoautotrophs – they do NOT have Rubisco. Page 2 of 8 ©Prep101 www.prep101.com/freestuff
Therefore in the medium would be a Rubisco inhibitor 7) Which of the following are considered both waste products and
nutrients in both heterotrophs and lithotrophs, depending on the
Glucose Answer: A. Both NADH and glucose are never considered waste products as
they contain too much energy to waste. Elemental sulfur is completely reduced
therefore cannot act as a nutrient whereas NO3 can act both as a nutrient (as a
TEA) and as a waste for nitrifying bacteria. 8) For transcription to occur in the lactose operon, an inducer must be
present so that
d) the repressor can bind to the operator
the repressor does not bind to the operator
the inducer can bind to the operator
the inducer does not bind to the operator Answer: B. The repressor, from the lacI gene, is responsible for binding the
operator region of DNA at the promoter to inhibit transcription in the absence of
lactose. Once the inducer (lactose) is present it binds the repressor causing the
repressor to dissociate off the DNA and allowing transcription.
9) Which of the following is false for endospores?
a) They have no detectable metabolic rate and are thus the least starvationresistant biological structures
b) They are very resistant to the damaging effects of UV radiation
c) Their DNA is thought to be complexed with special proteins which protect
it from UV radiation
d) They are the most heat resistant biological structures known
e) They can survive boiling for extended periods of time
Answer: A. Endospores have a very low metabolic rate but it is not
undetectable. They are highly resistant structures that are resistant to irradiation,
heat, dessication and low nutrient availability. Page 3 of 8 ©Prep101 www.prep101.com/freestuff
10) Bacteria respond to a positive chemotaxis through
1. Temporal mechanism
2. Spatial mechanism
3. Sensing proteins
e) 1, 2, 3, 4, 5, 6
1, 3, 4, 5, 6
1, 3, 4, 5
1, 3, 6
2 Answer: B. Bacteria can only respond to a temporal mechanism to detect
differences in chemical concentrations. In the response to a positive stimulus the
bacteria swims towards the attractant by running in that direction and it senses
the attractant by special receptors.
11) With respect to its ability to utilize lactose as a carbon source, what is
the phenotype of a strain of E. coli lacking the repressor? Explain the
cause of this phenotype?
This strain can utilize lactose and, furthermore, the lactose operon is
costitutively expressed because i- indicates that no functional repressor
can be made. Thus, the operon is expressed even when there is no
lactose in the medium.
12. Heterocysts are specialized cells that carry out _____ in species of
all of the above Answer: D. Heterocysts are produced in species of cyanobacteria to act as an
anaerobic nitrogen fixation cell among the population of photosynthetic aerobes. Page 4 of 8 ©Prep101 www.prep101.com/freestuff 13. Heterotrophs are characterized by all of the following except:
d) Heterotrophs only obtain carbon from organic nutrients
Heterotrophs do not require ATPase activity
Heterotrophs only use organic nutrients
Fermentation can produce ethanol or lactic acid. Answer: C. Heterotrophs obtain energy from organic nutrients but are not
completely restricted to organic nutrients because there are photoheterotrophs
that obtain energy from light and yet use organic carbon as a carbon source. 14. Predict the phenotypic effects of a mutation in the electron transport
chain that completely abolished a components electron carrying
a) A proton gradient would be established, but the production of ATP would
b) Both the establishment of a proton gradient and electron movement
through the ETC would not happen.
c) Electrons would be unable to channel through the ETC, and therefore no
oxidative phosphorylation would occur
d) ATPase activity would still occur but the electron transport chain would not
pass on the electrons to the TEA.
e) The TEA would be reduced but a proton pumping event would be
Answer: C. If a mutation in the ETC prevents electron passage then a block
would occur and no ATP formation would occur using ATP synthase and the
proton gradient produced by the ETC. ATP is produced by the ETC by oxidative
phosphorylation. 15. If a mutation occurs in a gene coding for a ribosomal protein causing a
change of one amino acid in the mRNA binding site from a Gly to a Lys
what would be the result? Explain.
• What is the difference between Gly and Lys (therein lies the answer…)
• Gly is non-polar
• Lys is polar
• Therefore protein folding will likely be affected
• This amino acid was in the mRNA-binding domain
• The mutant protein will likely not be able to bind mRNA Page 5 of 8 ©Prep101 www.prep101.com/freestuff 16. Despite the fact that cows ingest air as they graze, the rumen is an
anaerobic environment. This is partly due to the metabolism of
d) obligate aerobes
obligate anaerobes Answer: B. Facultative anaerobes utilize the available oxygen before it can
become toxic to the methanogens and other anaerobic microbes that live in the
17. Plasmids are directly transferred between bacterial cells by:
reverse transcription Answer B. Conjugation is the transfer of plasmids directly between bacterial
cells, for example the transfer of the F plasmid. Transduction requires a
bacteriophage intermediate and transformation is the uptake of naked DNA. Match the genetic exchange system given below with the descriptions in
the next five questions:
18. Involves cell free or naked DNA: __C__
19. Requires a fertility plasmid: __A__.
20. Most common way antibiotic resistance genes are spread: __A__.
21. Mediated by bacteriophage: __B__. Page 6 of 8 ©Prep101 www.prep101.com/freestuff 22. In the metabolism of a heterotrophic bacterium: If a nutrient donates
electrons to a TEA, then it is being used as an __________ for the
purpose of synthesizing __________ . If a nutrient donates electrons to
NADP+, then it is being used as an __________ for the purpose of
e) electron source, ATP, energy source, NADPH
energy source, NADPH, electron source, ATP
electron source, NADPH, energy source, ATP
energy source, ATP, electron source, NADPH
Mark (e) if the answer is NONE of the above. Answer: D. Heterotrophs that use an electron donated to a TEA to produce ATP
is using this nutrient as an energy source. If the electron is transferred to
NADP+, for instance in harnessing of light energy the nutrient is being used as
an electron source to produce NADPH.
23. Choose the statement that is false regarding the following cellular
8H+ + 8e- + N2
e) 2NH3 + H2 Is energetically demanding
Involves nitrogen fixation by nitrogenase
Occurs in symbiotic bacteria
Requires anaerobic environment
All of the above Answer: E. Nitrogen fixation is energetically demanding, requires nitrogenase
activity which requires an anaerobic environment and occurs in symbiotic
bacteria in root nodules. Therefore all are correct. 24. Which one of the following is a product of both noncyclic and cyclic
O2 Page 7 of 8 ©Prep101 www.prep101.com/freestuff
Answer: B. Noncyclic and cyclic phosphorylation both produce ATP but cyclic
does not produce NADPH. This is to account for the more ATP being used than
25. The operator region of an associated operon
d) codes for the synthesis of a repressor
is a nucleotide sequence of DNA that binds an active regulatory protein
binds RNA polymerase at the beginning of transcription of an operon
is a nucleotide sequence of an RNA molecule which is not translated into
e) none of the above
Answer: B. The operator is a DNA sequence near the promoter to which
activators and repressors can bind to regulate transcription of an operon. Page 8 of 8 ...
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This note was uploaded on 01/06/2011 for the course BIO 112 taught by Professor Taylor during the Fall '09 term at The University of British Columbia.
- Fall '09