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BIOL 250 Exam 2 Test, Study Guide questions with answers
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BIOL 250 Exam 2 Test, Study Guide questions with answers
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BIOL 250 Exam 2 Test, Study Guidequestions with answers 2024-2025
A ___________ agent is a chemical that inhibits bacteria from reproducing, but does NOT
necessarily kill them.
a. bacteriocidal
b. bacteriolytic
c. bacteriological
d. bacteriostatic - ** VERIFIED ANSWERS **✔✔D
Which of the statements is NOT true?
a. The removal or destruction of all microorganisms is called pasteurization
b. Autoclaving requires maintaining steam at 121°C and high pressure for about 15 minutes
c. The instrument used for autoclaving is called an autoclave
d. A bacterium is resistant to antibiotic A but not B. In a disk diffusion assay the zone of inhibition
will be smaller for a disk with antibiotic A than with antibiotic B. - ** VERIFIED ANSWERS **✔✔a
Plasmids can be
a. beneficial to their bacterial host
b. transferred by conjugation
c. replicated in the nucleus of bacteria
d. Both (a) and (b) are correct
e. (a), (b), and (c) are correct - ** VERIFIED ANSWERS **✔✔d
,Because there are three hydrogen bonds between the bases guanine and cytosine, and two between
adenine and thymine, GC-rich DNA will denature/melt
a. at the same temperature as AT-rich DNA, with some minor variations
b. at a higher temperature than AT-rich DNA
c. at a lower temperature than AT-rich DNA
d. in accordance with the animal or plant from which it was taken - ** VERIFIED ANSWERS **✔✔b
Which statement is correct?
a. All strains of the species Escherichia coli have virtually the same genome size
and gene content.
b. DNA replication in prokaryotes makes a lot of mistakes, leading to mutation rates
of 1/1000.
c. DNA replication in prokaryotes requires no primer.
d. DNA replication in prokaryotes occurs at a single replication fork because their
DNA is linear
e. DNA replication always proceeds from the 5'-phosphate of the incoming
nucleotide to the 3'-hydroxyl group of the previously added nucleotide - ** VERIFIED ANSWERS
**✔✔e
A polymerase chain reaction (PCR)
a. can amplify a specific DNA sequence roughly 1 billion-fold.
b. consists of three mains steps that are repeated many times: for example, incubation at 94°C to
denature DNA strands, incubation at 60°C for primer hybridization, and incubation at 72°C for DNA
synthesis
c. translate DNA into proteins
d. both (a) and (b) are correct
e. both (b) and (c) are correct - ** VERIFIED ANSWERS **✔✔d
,Transfer RNA (tRNA) molecules
a. function to transfer ribonucleotides to RNA polymerase during transcription.
b. function to transfer the correct amino acids to the ribosome during translation.
c. encode a codon that is the same as the sequence of nucleotides in mRNA
d. do not function as described in (a), (b), and (c)
e. function as described in a), (b), and (c) - ** VERIFIED ANSWERS **✔✔b
When a codon reads AGC, one of the possible anticodons on the tRNA is
a. AGC
b. TCG
c. UCG
d. GCA
e. None of the above - ** VERIFIED ANSWERS **✔✔c
In negative control of transcription, how does the presence of a co-repressor like the amino
acids tryptophan or arginine affect transcription?
a. The co-repressor causes the repressor to bind to the operator, which blocks
transcription.
b. The co-repressor binds to the repressor, which allows transcription to proceed.
c. The co-repressor binds to the operator, blocking transcription
d. None of the above mechanisms are correct. - ** VERIFIED ANSWERS **✔✔a
Proteins that are needed in the cell at about the same level under all growth conditions,
require ____________ expression
, a. inducible
b. promotable
c. repressible
d. constitutive - ** VERIFIED ANSWERS **✔✔d
Enzyme induction occurs
a. when the substrate of the enzyme is depleted.
b. when the inducer binds to the operator in the DNA
c. when the substrate is present.
d. continuously. - ** VERIFIED ANSWERS **✔✔c
Which of the following is correct:
a. In catabolite repression, cells always use the best carbon source first
b. Some regulatory proteins that bind to DNA block transcription, whereas others
activate transcription
c. A two-component regulatory system usually involves a sensor kinase and a
response regulator.
d. All of the above are correct
e. None of the above are correct - ** VERIFIED ANSWERS **✔✔d
Which of the following is NOT true about retroviruses?
a. They code for the enzyme reverse transcriptase
b. They never integrate in the host chromosome
c. They are medically important viruses because they include the virus that causes
AIDS.
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