Micro 7/8 Quiz

An enzyme produced in response to the presence of a substrate is called A restriction enzyme. An inducible enzyme. An operator. A repressible enzyme. A promoter.

An inducible enzyme

Which concentration of ethanol is the most effective bactericide? 100% 70% 40% 30% 50%

70%

A gene is best defined as A sequence of nucleotides in RNA that codes for a functional product. A transcribed unit of DNA. A segment of DNA. A sequence of nucleotides in DNA that codes for a functional product. Three nucleotides that code for an amino acid.

A sequence of nucleotides in DNA that codes for a functional product.

Which of the following is a limitation of the autoclave? Cannot be used with heat-labile materials Cannot be used with glassware Cannot kill endospores Cannot inactivate viruses Requires a long time to achieve sterilization

Cannot be used with heat-labile materials

The mechanism by which the presence of glucose inhibits the arabinose operon is Translation. Catabolite repression. Induction. Repression. DNA polymerase.

Catabolite repression.

Which of the following does NOT directly result from application of heat? Damage to nucleic acids Denaturing of enzymes Cell lysis Breaking of hydrogen bonds Breaking of sulfhydryl bonds

Cell lysis

Which of the following substances is used for surgical hand scrubs? Phenol Chlorhexidine Soap Glutaraldehyde Chlorine bleach

Chlorhexidine

In Figure 8.3, if enzyme A is an inducible enzyme, Compound A would bind to the repressor. Compound A would react with enzyme B. Compound C would bind to the repressor. Compound B would bind to enzyme A. Compound C would react with gene a.

Compound A would bind to the repressor.

Table 7.1 A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In Table 7.1, which compound was the most effective against Staphylococcus? D B C A Can't tell

C

In Figure 8.4, the antibiotic chloramphenicol binds the 50S ribosome as shown. From this information you can conclude that chloramphenicol Prevents transcription in prokaryotes. Prevents transcription in eukaryotes. Prevents translation in prokaryotes. Prevents translation in eukaryotes. Prevents mRNA-ribosome binding.

Prevents translation in prokaryotes.

An enzyme that copies DNA to make a molecule of RNA is Restriction enzyme. DNA ligase. RNA polymerase. Transposase. DNA polymerase.

RNA polymerase.

An enzyme that cuts double-stranded DNA at specific nucleotide sequences. RNA polymerase DNA polymerase Transposase Restriction enzyme DNA ligase

Restriction enzyme

Which of the following best describes the pattern of microbial death? The pattern varies depending on the species. The pattern varies depending on the antimicrobial agent. Not all of the cells in a culture are killed. All the cells in a culture die at once. The cells in a population die at a constant rate.

The cells in a population die at a constant rate.

The antimicrobial activity of chlorine is due to which of the following? The formation of free O The formation of ozone The formation of hydrochloric acid Disruption of the plasma membrane The formation of hypochlorous acid

The formation of hypochlorous acid

Which of the following treatments is the most effective for controlling microbial growth? None is effective. 72°C for 15 sec. 63°C for 30 min. They are equivalent treatments. 140°C for 4 sec.

They are equivalent treatments.

Which graph in Figure 7.3 best depicts the effect of placing the culture in an autoclave for 15 min. at time x? b c a e d

b

The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by DNA polymerase. snRNPs. UV radiation. A chemical mutagen. Photolyases.

snRNPs.

Place the following surfactants in order from the most effective to the least effective antimicrobial activity: 1-Soap; 2-Acid-anionic detergent; 3-Quats. 3, 1, 2 3, 2, 1 2, 1, 3 1, 3, 2 1, 2, 3

3, 2, 1

(Use Table 8.2.) If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, what is the order of bases in the sense strand of DNA? 5' TGTGCTTTCTTA 3' AGACGTTTCAAT 3' TCTCGTTTGTTA 3' UGUGCAAAGUUA 5' AGAGCTTTGAAT

3' AGACGTTTCAAT

In Figure 8.1, which colonies are streptomycin-resistant and leucine-requiring? 3 and 9 4, 6, and 8 5 and 6 1, 2, 3, and 9 4 and 8

4 and 8

(Use Table 8.2.) If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, the coding for the antisense strand of DNA is 3' TCACGUUUCAAU 3' UCUCGAAAGUUA 5' ACAGTTTCAAT 5' TCTGCAAAGTTA 3' UGUGCAAAGUUA

5' TCTGCAAAGTTA

In Figure 7.2, the thermal death time for this culture is 40 min. 60 min. 10 min. 20 min. 0 min.

60 min.

In Figure 8.2, if base 4 is thymine, what is base 4'? Adenine Cytosine Thymine Guanine Uracil

Adenine

Which of the following affects the elimination of bacteria from an object? pH Number of bacteria present Temperature All of the above Presence of organic matter

All of the above

Which of the following is NOT a factor contributing to hospital-acquired infections? All of the above may contribute to hospital-acquired infection. Some bacteria metabolize disinfectants. Bacteria may be present in commercial products such as mouthwash. Gram-negative bacteria are often resistant to disinfectants. Invasive procedures can provide a portal of entry for bacteria.

All of the above may contribute to hospital-acquired infection.

Iodophors differ from iodine (I2) in that iodophors Don't stain. Are longer lasting. All of the above. Are combined with a nonionic detergent. Are less irritating.

All of the above!

Genetic change in bacteria can be brought about by Transformation. Transduction. Conjugation. All of the above. Mutation.

All of the above. =)

Which of the following substances is NOT used to preserve foods? Nisin Potassium sorbate Sodium nitrite Biguanides Sodium propionate

Biguanides

In Figure 8.3, if enzyme A is a repressible enzyme, compound C would Bind to the corepressor. Always be in excess. Bind to RNA polymerase. Bind to the enzyme. Bind to gene a.

Bind to the corepressor.

Which of these disinfectants acts by denaturing proteins? Halogens Aldehydes Bisphenols Alcohols Phenolics

Bisphenols

(Use Table 8.2.) The anticodon for valine is GUU CUU GTA CAA CTT

CAA

In Table 7.1, which compound was bactericidal? D C Can't tell A B

Can't tell

In Table 7.1, which compound was the most effective against E. coli? C Can't tell A B D

Can't tell

A suspension of 106 Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown. In Figure 7.2, the thermal death point for this culture is Can't tell from the data provided. 170°C. 15 min. 30 min. 50°C.

Can't tell from the data provided.

The damage caused by ultraviolet radiation is Repaired during transcription. Repaired by DNA replication. Repaired during translation. Cut out and replaced. Never repaired.

Cut out and replaced.

An enzyme that makes covalent bonds between nucleotide sequences in DNA is Transposase. RNA polymerase. DNA polymerase. Restriction enzyme. DNA ligase.

DNA ligase.

Which of the following substances can sterilize? Phenolics Soap Alcohol Chlorine Ethylene oxide

Ethylene oxide

In Figure 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify Transcription. Competitive inhibition. Repression. Feedback inhibition. A mutation.

Feedback inhibition

Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper? Gamma radiation Ultraviolet radiation Autoclave Microwaves Sunlight

Gamma radiation

Which of the following is NOT used to disinfect water? Copper sulfate Heat Ozone Gamma radiation Chlorine

Heat

The mechanism by which the presence of arabinose controls the arabinose operon is DNA polymerase. Catabolite repression. Translation. Repression. Induction.

Induction.

Which of the following is the best method to sterilize heat-labile solutions? Pasteurization Dry heat Membrane filtration Autoclave Freezing

Membrane filtration

Based on the information in Table 8.3, prostate cancer is probably the result of which kind of mutation? Missense Analog None of the above Frameshift Nonsense

Nonsense

Which of the following does NOT achieve sterilization? Pasteurization Autoclave Dry heat Formaldehyde Ethylene oxide

Pasteurization

Glutaraldehyde is considered one of the most effective disinfectants for hospital use. Which of the following statements about glutaraldehyde is false? Is safe to transport Attacks all microorganisms Stains and corrodes Acts rapidly Is not hampered by organic material

Stains and corrodes

According to the operon model, for the synthesis of an inducible enzyme to occur, the Substrate must bind to the enzyme. Substrate must bind to the repressor. Repressor must not be synthesized. Repressor must bind to the operator. End-product must not be in excess.

Substrate must bind to the repressor.

Bone and tendons for transplant are decontaminated by Supercritical fluids. Plasma sterilization. Glutaraldehyde. Peroxygens. Ethylene oxide.

Supercritical fluids.

Synthesis of a repressible enzyme is stopped by The substrate binding to the repressor. The allosteric transition. The end-product binding to the promoter. The corepressor-repressor binding to the operator. The corepressor binding to the operator.

The corepressor-repressor binding to the operator.

The initial effect of ionizing radiation on a cell is that it causes DNA to break. The formation of highly reactive ions. The cells to get hot. Base substitutions. Bonding between adjacent thymines.

The formation of highly reactive ions.

In Figure 8.2, if base 4 is thymine, what is base 11'? Adenine Uracil Guanine Thymine Cytosine

Thymine

(Use Table 8.2.) What is the sequence of amino acids encoded by the following sequence of bases in a strand of DNA? 3' ATTACGCTTTGC Transcription would stop at the first codon Asparagine-cysteine-valine-serine Leucine-arginine-lysine-alanine Can't tell Asparagine-arginine-lysine-alanine

Transcription would stop at the first codon

Conjugation differs from reproduction because conjugation Transcribes DNA to RNA. Copies RNA to make DNA. Transfers DNA vertically, to new cells. Replicates DNA. Transfers DNA horizontally, to cells in the same generation.

Transfers DNA horizontally, to cells in the same generation.

Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes Use methionine as the "start" amino acid. Require snRNPS. Have introns. Have exons. Use codons to arrange amino acids.

Use codons to arrange amino acids.

Assume 109 E. coli cells/ml are in a flask. Which graph in Figure 7.3 best depicts the effect of placing the culture at 7°C at time x? b d a e c

d

In Figure 8.5, which model of the lac operon correctly shows RNA polymerase, lactose, and repressor protein when the structural genes are being transcribed? d b a e c

d