What Is Microbiology Quiz?

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What Is Microbiology Quiz? - Quiz

Take this quiz and learn more about microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa. Let's begin this science quiz!


Questions and Answers
  • 1. 

    Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    • E.

      E

    Correct Answer
    D. D
    Explanation
    Graph d best depicts the effect of placing the culture at 7°C at time x because it shows a gradual decrease in the culture's growth rate over time. The other graphs either show no change in growth rate or a sudden increase or decrease, which is not consistent with the effect of placing the culture at a specific temperature.

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  • 2. 

    A gene is best defined as

    • A.

      A segment of DNA

    • B.

      Three nucleotides that code for an amino acid

    • C.

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

    • D.

      A sequence of nucleotides in RNA that codes for a functional product

    • E.

      A transcribed unit of DNA

    • F.

      Hard-wearing trousers made of denim or other cotton fabric, for informal wear

    Correct Answer
    C. A sequence of nucleotides in DNA that codes for a functional product
    Explanation
    The correct answer is "a sequence of nucleotides in DNA that codes for a functional product." This definition accurately describes a gene, which is a specific sequence of nucleotides in DNA that carries the instructions for making a functional product, such as a protein or RNA molecule. Genes are the fundamental units of heredity and play a crucial role in determining an organism's traits and characteristics.

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  • 3. 

    Which of the following pairs is mismatched

    • A.

      DNA polymerase — makes a molecule of DNA from a DNA template

    • B.

      RNA polymerase — makes a molecule of RNA from an RNA template

    • C.

      DNA ligase — joins segments of DNA

    • D.

      Transposase — insertion of DNA segments into DNA

    • E.

      DNA gyrase — coils and twists DNA

    Correct Answer
    B. RNA polymerase — makes a molecule of RNA from an RNA template
    Explanation
    RNA polymerase is responsible for synthesizing RNA molecules from a DNA template, not an RNA template. This enzyme plays a crucial role in transcription, where it binds to the DNA template strand and catalyzes the formation of an RNA molecule that is complementary to the DNA sequence. This process is essential for gene expression and the production of proteins. Therefore, the pair "RNA polymerase — makes a molecule of RNA from an RNA template" is mismatched.

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  • 4. 

    Which of the following statements is FALSE?

    • A.

      DNA polymerase joins nucleotides in one direction only.

    • B.

      The leading strand of DNA is made continuously.

    • C.

      The lagging strand of DNA is started by an RNA primer

    • D.

      DNA replication proceeds in one direction around the bacterial chromosome

    • E.

      Multiple replication forks are possible on a bacterial chromosome.

    Correct Answer
    D. DNA replication proceeds in one direction around the bacterial chromosome
    Explanation
    DNA replication is bidirectional, meaning it proceeds in both directions around the bacterial chromosome. This allows for the simultaneous synthesis of both the leading and lagging strands.

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  • 5. 

    DNA is constructed of

    • A.

      A single strand of nucleotides with internal hydrogen bonding

    • B.

      Two complementary strands of nucleotides bonded A—C and G—T

    • C.

      Two strands of nucleotides running antiparallel

    • D.

      Two strands of identical nucleotides with hydrogen bonds between them

    • E.

      None of the answers is correct.

    Correct Answer
    C. Two strands of nucleotides running antiparallel
    Explanation
    The correct answer is "two strands of nucleotides running antiparallel." DNA is made up of two strands of nucleotides that are bonded together in a double helix structure. These two strands run in opposite directions, with one strand running in the 5' to 3' direction and the other running in the 3' to 5' direction. This arrangement is referred to as antiparallel. The nucleotides in each strand are connected by hydrogen bonds, with adenine (A) always pairing with thymine (T) and cytosine (C) always pairing with guanine (G).

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  • 6. 

    Which of the following is NOT a product of transcription?

    • A.

      A new strand of DNA

    • B.

      RRNA

    • C.

      TRNA

    • D.

      MRNA

    • E.

      None of the answers are correct; all of these are products of transcription

    Correct Answer
    A. A new strand of DNA
    Explanation
    A new strand of DNA is not a product of transcription. Transcription is the process by which the genetic information in DNA is used to create RNA molecules, such as mRNA, rRNA, and tRNA. These RNA molecules are involved in various cellular processes, including protein synthesis. However, the synthesis of a new DNA strand occurs during DNA replication, not transcription. During DNA replication, the DNA molecule is duplicated to produce two identical copies.

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  • 7. 

    Which of the following statements about bacteriocins is FALSE?

    • A.

      The genes coding for them are on plasmids.

    • B.

      They cause food-poisoning symptoms.

    • C.

      Nisin is a bacteriocin used as a food preservative

    • D.

      They can be used to identify certain bacteria

    • E.

      Bacteriocins kill bacteria

    Correct Answer
    B. They cause food-poisoning symptoms.
    Explanation
    Plus, they are quite tasty!

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  • 8. 

    Which colonies are streptomycin-resistant and leucine-requiring?

    • A.

      1, 2, 3, and 9

    • B.

      3 and 9

    • C.

      4, 6, and 8

    • D.

      4 and 8

    • E.

      5 and 6

    Correct Answer
    D. 4 and 8
    Explanation
    The colonies that are streptomycin-resistant and leucine-requiring are colonies 4 and 8.

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  • 9. 

    Culture 1:  F+, leucine+, histidine+Culture 2:  F-, leucine-, histidine- What will be the result of conjugation between cultures 1 and 2?

    • A.

      1 will remain the same; 2 will become F+, leucine-, histidine-

    • B.

      1 will become F-, leu+, his+; 2 will become F+, leu-, his-

    • C.

      1 will become F-, leu-, his-; 2 will remain the same

    • D.

      1 will remain the same; 2 will become F+, leu+, his+

    • E.

      1 will remain the same; 2 will become F+ and recombination may occur

    • F.

      1 will remain the same; 2 will spend years trying to change 1, but never succeed

    Correct Answer
    A. 1 will remain the same; 2 will become F+, leucine-, histidine-
    Explanation
    In conjugation, the F factor is transferred from the F+ (donor) cell to the F- (recipient) cell. Culture 1 is F+ and Culture 2 is F-. Therefore, during conjugation, Culture 1 will remain the same as it already has the F factor. Culture 2 will become F+ as it receives the F factor from Culture 1. However, Culture 2 will lose the ability to synthesize leucine and histidine because Culture 1 does not have those genes. Hence, the correct answer is that Culture 1 will remain the same and Culture 2 will become F+, leucine-, histidine-.

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  • 10. 

    Culture 1:  F+, leucine+, histidine+Culture 2:  F-, leucine-, histidine- If culture 1 mutates to Hfr, what will be the result of conjugation between the two cultures?

    • A.

      They will both remain the same.

    • B.

      1 will become F+, leu+, his+; 2 will become F+, leu+, his+

    • C.

      1 will remain the same; recombination will occur in 2

    • D.

      1 will become F-, leu+, his+; 2 will become Hfr, leu+, his+

    • E.

      The answer cannot be determined based on the information provided.

    Correct Answer
    C. 1 will remain the same; recombination will occur in 2
    Explanation
    If culture 1 mutates to Hfr, it will still remain the same because the Hfr mutation does not affect the characteristics of the culture. However, conjugation between the two cultures will result in recombination occurring in culture 2. This means that some genetic material from culture 1 will be transferred to culture 2, leading to a change in its characteristics. Therefore, culture 1 will remain unchanged, while recombination will occur in culture 2.

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  • 11. 

    An enzyme produced in response to the presence of a substrate is called a(n)

    • A.

      Inducible enzyme

    • B.

      Repressible enzyme

    • C.

      Restriction enzyme

    • D.

      Operator

    • E.

      Promoter

    Correct Answer
    A. Inducible enzyme
    Explanation
    An enzyme produced in response to the presence of a substrate is called an inducible enzyme. This means that the production of the enzyme is induced or triggered by the presence of the substrate. In other words, when the substrate is present, it acts as a signal for the production of the enzyme. This allows the organism to efficiently produce the enzyme only when it is needed, conserving energy and resources.

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  • 12. 

    When glucose is high, cAMP is _____ : CAP _____ bind the lac operator, and RNA polymerase _____ bind the lac promoter.

    • A.

      High; does; does

    • B.

      Low; does not; does not

    • C.

      High; does not; does

    • D.

      Low; does not; does

    • E.

      None of the answers is correct.

    Correct Answer
    B. Low; does not; does not
    Explanation
    Just another reason why cAMP is an old stick in the mud

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  • 13. 

    Transformation is the transfer of DNA from a donor to a recipient cell

    • A.

      By a bacteriophage.

    • B.

      As naked DNA in solution

    • C.

      By cell-to-cell contact

    • D.

      By crossing over

    • E.

      By sexual reproduction

    Correct Answer
    B. As naked DNA in solution
    Explanation
    If you think about it, the Transformers were always naked.

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  • 14. 

    Genetic change in bacteria can be brought about by

    • A.

      Mutation

    • B.

      Conjugation

    • C.

      Transduction

    • D.

      Transformation

    • E.

      All of the answers are correct

    Correct Answer
    E. All of the answers are correct
    Explanation
    All of the options listed - mutation, conjugation, transduction, and transformation - are mechanisms through which genetic change can occur in bacteria. Mutation refers to changes in the DNA sequence, while conjugation involves the transfer of genetic material between bacterial cells through direct contact. Transduction is the transfer of genetic material through bacteriophages (viruses that infect bacteria), and transformation is the uptake and incorporation of foreign DNA from the environment. Therefore, all of these mechanisms can lead to genetic changes in bacteria.

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  • 15. 

    Which of the following statements regarding a bacterium that is R+ is FALSE?

    • A.

      It possesses a plasmid

    • B.

      R+ can be transferred to a cell of the same species

    • C.

      It is resistant to certain drugs and heavy metals

    • D.

      It is F+

    • E.

      R+ can be transferred to a different species

    Correct Answer
    D. It is F+
    Explanation
    The statement "It is F+" is false. This is because the question is asking for the false statement regarding a bacterium that is R+. The other statements are all true: a bacterium that is R+ possesses a plasmid, R+ can be transferred to a cell of the same species, and it is resistant to certain drugs and heavy metals. However, it is not necessarily F+, as the F factor is a separate genetic element responsible for fertility in bacteria.

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  • 16. 

    The initial effect of ionizing radiation on a cell is that it causes

    • A.

      DNA to break

    • B.

      Bonding between adjacent thymines

    • C.

      Base substitutions

    • D.

      The formation of highly reactive ions

    • E.

      The cells to get hot

    Correct Answer
    D. The formation of highly reactive ions
    Explanation
    Ionizing radiation refers to radiation that has enough energy to remove tightly bound electrons from atoms, thus creating highly reactive ions. These highly reactive ions can cause damage to cellular components, including DNA. Therefore, the initial effect of ionizing radiation on a cell is the formation of highly reactive ions. This can lead to various forms of cellular damage, including DNA breakage, bonding between adjacent thymines, and base substitutions.

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  • 17. 

    According to the operon model, for the synthesis of an inducible enzyme to occur, the

    • A.

      End-product must not be in excess

    • B.

      Substrate must bind to the enzyme

    • C.

      Substrate must bind to the repressor

    • D.

      Repressor must bind to the operator

    • E.

      Repressor must not be synthesized

    Correct Answer
    C. Substrate must bind to the repressor
    Explanation
    In the operon model, the synthesis of an inducible enzyme is regulated by a repressor protein. The repressor protein binds to the operator, blocking the transcription of the gene for the enzyme. However, when the substrate binds to the repressor, it causes a conformational change in the repressor protein, preventing it from binding to the operator. This allows the RNA polymerase to bind to the promoter and transcribe the gene, leading to the synthesis of the inducible enzyme. Therefore, the substrate must bind to the repressor in order for the synthesis of the enzyme to occur.

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  • 18. 

    Synthesis of a repressible enzyme is stopped by the

    • A.

      Allosteric transition

    • B.

      Substrate binding to the repressor

    • C.

      Corepressor binding to the operator

    • D.

      Corepressor-repressor complex binding to the operator

    • E.

      End product binding to the promoter

    Correct Answer
    D. Corepressor-repressor complex binding to the operator
    Explanation
    Now we see the violence inherent in the system...

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  • 19. 

    If base 4 is thymine, what is base 4'?

    • A.

      Adenine

    • B.

      Thymine

    • C.

      Cytosine

    • D.

      Guanine

    • E.

      Uracil

    Correct Answer
    A. Adenine
    Explanation
    Base 4 is thymine, which means that in the context of this question, base 4 refers to the fourth nucleotide in a DNA sequence. Since adenine is one of the four nucleotides in DNA, it can be concluded that adenine is base 4'.

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  • 20. 

    If base 4 is thymine, what is base 11'

    • A.

      Adenine

    • B.

      Thymine

    • C.

      Cytosine

    • D.

      Guanine

    • E.

      Uracil

    Correct Answer
    B. Thymine
    Explanation
    The question states that base 4 is thymine. In DNA, thymine pairs with adenine, so if base 4 is thymine, then base 11 would pair with adenine as well. Therefore, the correct answer is adenine.

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  • 21. 

    Base 2 is attached to

    • A.

      Ribose

    • B.

      Phosphate

    • C.

      Deoxyribose

    • D.

      Thymine

    • E.

      The answer cannot be determined based on the information provided

    Correct Answer
    C. Deoxyribose
    Explanation
    Deoxyribose is a sugar molecule that is a component of DNA. It is specifically attached to the phosphate group in the DNA backbone. The other options listed, ribose, phosphate, and thymine, are also components of DNA, but they are not directly attached to deoxyribose. Therefore, based on the information provided, it can be determined that deoxyribose is attached to the DNA molecule.

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  • 22. 

    The damage caused by ultraviolet radiation is

    • A.

      Never repaired

    • B.

      Repaired during transcription

    • C.

      Repaired during translation

    • D.

      Cut out and replaced

    • E.

      Repaired by DNA replication

    Correct Answer
    D. Cut out and replaced
    Explanation
    Ultraviolet radiation can cause damage to DNA molecules by creating thymine dimers, which are abnormal bonds between adjacent thymine bases. This damage is recognized and repaired by a process called nucleotide excision repair. In this process, the damaged section of DNA is cut out and replaced with a new, undamaged nucleotide sequence. Therefore, the correct answer is "cut out and replaced".

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  • 23. 

    Refer to 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?

    • A.

      3' UGUGCAAAGUUA

    • B.

      3' AGACGTTTCAAT

    • C.

      3' TCTCGTTTGTTA

    • D.

      5' TGTGCTTTCTTA

    • E.

      5' AGAGCTTTGAAT

    Correct Answer
    B. 3' AGACGTTTCAAT
    Explanation
    The given answer, 3' AGACGTTTCAAT, represents the order of bases in the sense strand of DNA that corresponds to the sequence of amino acids serine-alanine-lysine-leucine. In DNA, the sense strand has the same sequence as the mRNA transcript, except with thymine (T) instead of uracil (U). Therefore, the bases in the sense strand would be A, G, A, C, G, T, T, T, C, A, A, T.

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  • 24. 

    Refer to 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

    • A.

      5’ ACAGTTTCAAT

    • B.

      5’ TCTGCAAAGTTA

    • C.

      3’ UGUGCAAAGUUA

    • D.

      3’ UCUCGAAAGUUA

    • E.

      3’ TCACGUUUCAAU

    Correct Answer
    B. 5’ TCTGCAAAGTTA
    Explanation
    The correct answer is 5’ TCTGCAAAGTTA. The antisense strand of DNA is the complementary strand to the given DNA strand. To find the antisense strand, we need to replace each nucleotide with its complementary nucleotide. In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). Therefore, the complementary sequence to serine-alanine-lysine-leucine is threonine-tyrosine-arginine-isoleucine, which corresponds to the sequence 5’ TCTGCAAAGTTA.

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  • 25. 

    Refer to Table 8.2 The anticodon for valine is

    • A.

      GUU

    • B.

      CUU

    • C.

      CTT

    • D.

      CAA

    • E.

      GTA

    Correct Answer
    D. CAA
    Explanation
    The anticodon for valine is CAA. This is determined by the genetic code, which specifies that the codon for valine is GUA. The anticodon is the complementary sequence to the codon, so the anticodon for valine is CAA.

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  • 26. 

    Refer to Table 8.2. What is the sequence of amino acids encoded by the following sequence of bases in a strand of DNA?3’ ATTACGCTTTGC

    • A.

      Leucine-arginine-lysine-alanine

    • B.

      Asparagine-arginine-lysine-alanine

    • C.

      Asparagine-cysteine-valine-serine

    • D.

      Translation would stop at the first codon

    • E.

      The answer cannot be determined based on the information provided

    Correct Answer
    D. Translation would stop at the first codon
    Explanation
    The given DNA sequence starts with the codon ATT, which codes for the amino acid isoleucine. However, the next codon, ACG, codes for the amino acid threonine, not arginine as indicated in the first option. Therefore, the correct answer is that translation would stop at the first codon. The subsequent amino acids cannot be determined based on the information provided.

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  • 27. 

    Refer to Table 8.2. If a frameshift mutation occurred in the sequence of bases shown below, what would be the sequence of amino acids coded for?3’ ATTACGCTTTGC

    • A.

      Leucine-arginine-lysine-alanine

    • B.

      Asparagine-arginine-lysine-alanine

    • C.

      Asparagine-cysteine-valine-serine

    • D.

      Translation would stop at the first codon

    • E.

      The answer cannot be determined based on the information provided

    Correct Answer
    E. The answer cannot be determined based on the information provided
  • 28. 

    In Figure 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify

    • A.

      A mutation

    • B.

      Repression

    • C.

      Feedback inhibition

    • D.

      Competitive inhibition

    • E.

      Transcription

    Correct Answer
    C. Feedback inhibition
    Explanation
    If compound C reacts with the allosteric site of enzyme A, it would exemplify feedback inhibition. Feedback inhibition is a regulatory mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway. In this case, compound C is acting as the end product and inhibiting the activity of enzyme A. This helps regulate the rate of the metabolic pathway and prevent the overproduction of the end product.

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  • 29. 

    In Figure 8.3, if enzyme A is a repressible enzyme, compound C would

    • A.

      Always be in excess

    • B.

      Bind to the enzyme

    • C.

      Bind to the corepressor

    • D.

      Bind to RNA polymerase

    • E.

      Bind to gene a

    Correct Answer
    C. Bind to the corepressor
    Explanation
    If enzyme A is a repressible enzyme, it means that its activity can be regulated by a corepressor. In this case, compound C would bind to the corepressor, which would then bind to enzyme A, leading to a decrease in its activity. Therefore, the correct answer is "bind to the corepressor".

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  • 30. 

    In Figure 8.3, if enzyme A is an inducible enzyme

    • A.

      Compound C would bind to the repressor

    • B.

      Compound A would bind to the repressor

    • C.

      Compound B would bind to enzyme A

    • D.

      Compound A would react with enzyme B

    • E.

      Compound C would react with gene a

    Correct Answer
    B. Compound A would bind to the repressor
    Explanation
    If enzyme A is an inducible enzyme, it means that its activity can be regulated by the presence or absence of a specific compound. In this case, the correct answer suggests that compound A would bind to the repressor. This binding would then release the repressor from the operator region of the gene, allowing for the transcription and subsequent expression of enzyme A. Therefore, compound A binding to the repressor is the most likely explanation for the regulation of enzyme A in this scenario.

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  • 31. 

    Conjugation differs from reproduction because conjugation

    • A.

      Replicates DNA

    • B.

      Transfers DNA vertically, to new cells

    • C.

      Transfers DNA horizontally, to cells in the same generation

    • D.

      Transcribes DNA to RNA

    • E.

      Copies RNA to make DNA

    Correct Answer
    C. Transfers DNA horizontally, to cells in the same generation
    Explanation
    ...like a record

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  • 32. 

    The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, and the template is from a human cell. The DNA synthesized would be most similar to

    • A.

      Human DNA

    • B.

      T. aquaticus DNA

    • C.

      A mixture of human and T. aquaticus DNA

    • D.

      Human RNA

    • E.

      T. aquaticus RNA

    Correct Answer
    A. Human DNA
    Explanation
    The DNA synthesized would be most similar to human DNA because the template used for synthesis is from a human cell. The DNA polymerase from Thermus aquaticus is responsible for catalyzing the synthesis of the new DNA strand, but it does not determine the sequence or characteristics of the synthesized DNA. Therefore, the DNA synthesized would retain the characteristics of the human DNA template.

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  • 33. 

    Based on the information in Table 8.3, prostate cancer is probably the result of which kind of mutation? 

    • A.

      Analog

    • B.

      Frameshift

    • C.

      Missions

    • D.

      Nonsense

    • E.

      None of the answers is correct

    Correct Answer
    D. Nonsense
    Explanation
    This is utter nonsense.

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  • 34. 

    In Figure 8.4, the antibiotic chloramphenicol binds the 50S ribosome as shown. From this information you can conclude that chloramphenicol

    • A.

      Prevents transcription in eukaryotes

    • B.

      Prevents translation in eukaryotes

    • C.

      Prevents transcription in prokaryotes

    • D.

      Prevents translation in prokaryotes

    • E.

      Prevents mRNA-ribosome binding

    Correct Answer
    D. Prevents translation in prokaryotes
    Explanation
    The given information states that chloramphenicol binds the 50S ribosome. This suggests that chloramphenicol interferes with the translation process in prokaryotes, as the ribosome is responsible for protein synthesis during translation. It does not affect transcription, which is the process of creating mRNA from DNA, in either eukaryotes or prokaryotes. Therefore, the correct answer is that chloramphenicol prevents translation in prokaryotes.

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  • 35. 

    The mechanism by which the presence of glucose inhibits the arabinose operon is

    • A.

      Catabolite repression

    • B.

      Translation

    • C.

      DNA polymerase

    • D.

      Repression

    • E.

      Induction

    Correct Answer
    A. Catabolite repression
    Explanation
    Catabolite repression is the mechanism by which the presence of glucose inhibits the arabinose operon. This means that when glucose is present, the arabinose operon is repressed, and the genes involved in arabinose metabolism are not expressed. This is because glucose is a preferred carbon source for the cell, and the cell prioritizes its utilization over other sugars like arabinose. Catabolite repression helps the cell conserve energy by only producing the necessary enzymes for glucose metabolism when it is available.

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  • 36. 

    The mechanism by which the presence of arabinose controls the arabinose operon is

    • A.

      Catabolite repression

    • B.

      Translation

    • C.

      DNA polymerase

    • D.

      Repression

    • E.

      Induction

    Correct Answer
    E. Induction
    Explanation
    The presence of arabinose controls the arabinose operon through induction. Induction refers to the process by which the presence of a specific molecule or signal triggers the expression of certain genes or operons. In this case, when arabinose is present, it acts as an inducer for the arabinose operon, leading to the activation of gene expression and the production of enzymes involved in arabinose metabolism.

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  • 37. 

    If you knew the sequence of nucleotides within a gene, which one of the following could you

    • A.

      The primary structure of the protein

    • B.

      The secondary structure of the protein

    • C.

      The tertiary structure of the protein

    • D.

      The quaternary structure of the protein

    • E.

      The answer cannot be determined based on the information provided

    Correct Answer
    A. The primary structure of the protein
    Explanation
    If you knew the sequence of nucleotides within a gene, you could determine the primary structure of the protein. The primary structure refers to the specific sequence of amino acids in a protein, which is determined by the sequence of nucleotides in the gene. The other structures (secondary, tertiary, and quaternary) cannot be determined solely based on the nucleotide sequence and require additional information such as protein folding and interactions.

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  • 38. 

    An enzyme that makes covalent bonds between nucleotide sequences in DNA is

    • A.

      RNA polymerase

    • B.

      DNA ligase

    • C.

      DNA helicase

    • D.

      Transposase

    • E.

      DNA polymerase

    Correct Answer
    B. DNA ligase
    Explanation
    DNA ligase is the correct answer because it is the enzyme responsible for joining the ends of DNA strands together by catalyzing the formation of covalent phosphodiester bonds. This process is essential in DNA replication, repair, and recombination. RNA polymerase is responsible for synthesizing RNA from a DNA template, DNA helicase unwinds the DNA double helix, transposase is an enzyme that catalyzes the movement of genetic elements within a genome, and DNA polymerase is responsible for synthesizing new DNA strands during replication. Therefore, DNA ligase is the only enzyme listed that specifically functions to make covalent bonds between nucleotide sequences in DNA.

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  • 39. 

    An enzyme that copies DNA to make a molecule of RNA is

    • A.

      RNA polymerase

    • B.

      DNA ligase

    • C.

      DNA helicase

    • D.

      Transposase

    • E.

      DNA polymerase

    Correct Answer
    A. RNA polymerase
    Explanation
    RNA polymerase is the correct answer because it is the enzyme responsible for transcribing DNA into RNA during the process of transcription. It binds to the DNA template strand and adds complementary RNA nucleotides to form a single-stranded RNA molecule. DNA ligase, DNA helicase, and transposase are not involved in the process of copying DNA to make RNA. DNA polymerase is responsible for replicating DNA during DNA replication, not for transcription.

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  • 40. 

    An enzyme that catalyzes the cutting and resealing of DNA, and is translated from insertion

    • A.

      RNA polymerase

    • B.

      DNA ligase

    • C.

      DNA helicase

    • D.

      Transposase

    • E.

      DNA polymerase

    Correct Answer
    D. Transposase
    Explanation
    Transposase is the correct answer because it is an enzyme that catalyzes the cutting and resealing of DNA. It is translated from an insertion sequence and is responsible for the movement of genetic material within a genome. Transposase allows for the insertion or removal of DNA segments, contributing to genetic diversity and evolution. RNA polymerase is responsible for synthesizing RNA from a DNA template, DNA ligase joins DNA fragments together, DNA helicase unwinds the DNA double helix, and DNA polymerase synthesizes new DNA strands.

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  • 41. 

    Repair of damaged DNA might be viewed as a race between an endonuclease and

    • A.

      DNA ligase

    • B.

      DNA polymerase

    • C.

      Helicase

    • D.

      Methylase

    • E.

      Primase

    Correct Answer
    D. Methylase
    Explanation
    The repair of damaged DNA involves several enzymes, including endonuclease, DNA ligase, DNA polymerase, helicase, methylase, and primase. However, methylase plays a crucial role in the repair process by adding a methyl group to the newly synthesized DNA strand, which helps to protect it from further damage and ensures proper DNA replication. Therefore, the repair of damaged DNA can be seen as a race between the endonuclease and methylase enzymes, with methylase ultimately playing a key role in the repair process.

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  • 42. 

    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

    • A.

      A chemical mutagen

    • B.

      DNA polymerase

    • C.

      Photolyases

    • D.

      SnRNPs

    • E.

      UV radiation

    Correct Answer
    D. SnRNPs
    Explanation
    SnRNPs (small nuclear ribonucleoproteins) are involved in the process of RNA splicing, which removes introns and joins exons together to form mature mRNA. In this case, the cancer cells are producing ras mRNA missing an exon that contains UAA codons. This suggests that the mistake is occurring during the splicing process, where the snRNPs may be incorrectly recognizing or binding to the splice sites, leading to the exclusion of the exon. Therefore, the mistake is most likely due to snRNPs.

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  • 43. 

    Which model of the lac operon correctly shows RNA polymerase, lactose, and repressor protein when the structural genes are being transcribed?

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    • E.

      E

    Correct Answer
    D. D
    Explanation
    If plan "A" doesn't work, remember that the alphabet has 25 more letters.

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  • 44. 

    The miRNAs in a cell

    • A.

      Are found in prokaryotic cells

    • B.

      Are a part of the prokaryotic ribosome

    • C.

      Are a part of the eukaryotic ribosome

    • D.

      Allow different cells to produce different proteins

    • E.

      Are responsible for inducing operons

    Correct Answer
    D. Allow different cells to produce different proteins
    Explanation
    MiRNAs, or microRNAs, are small RNA molecules that play a crucial role in gene regulation. They are found in eukaryotic cells, not prokaryotic cells. MiRNAs bind to messenger RNA (mRNA) molecules and prevent them from being translated into proteins. By regulating the expression of specific genes, miRNAs allow different cells to produce different proteins. This regulation of protein production is essential for the proper functioning and development of multicellular organisms. MiRNAs are not a part of the ribosome, nor are they responsible for inducing operons.

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  • 45. 

    Assume the two E.coli strains shown below are allowed to conjugateHfr:    pro+, arg+, his+, lys+, met+, ampicillin-sensitiveF:    pro-, arg-, his-, lys-, met-, ampicillin-resistantWhat supplements would you add to glucose minimal salts agar to select for a recombinant cell that is lys+, arg+, amp-resistant?

    • A.

      Ampicillin, lysine, arginine

    • B.

      Lysine, arginine

    • C.

      Ampicillin, proline, histidine, methionine

    • D.

      Proline, histidine, methionine

    • E.

      Ampicillin, prolein, histidine, lysine

    Correct Answer
    C. Ampicillin, proline, histidine, methionine
    Explanation
    The correct answer is ampicillin, proline, histidine, methionine. In order to select for a recombinant cell that is lys+, arg+, and amp-resistant, we need to provide the necessary supplements that allow for the growth of these traits. Ampicillin is added to select for amp-resistance. Proline, histidine, and methionine are added to provide the necessary nutrients for the growth of lys+ and arg+ cells.

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  • 46. 

    Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes

    • A.

      Have exons

    • B.

      Have introns

    • C.

      Require snRNPS

    • D.

      Use methionine as the “start” amino acid

    • E.

      Use codons to determine polypeptide sequences

    Correct Answer
    E. Use codons to determine polypeptide sequences
    Explanation
    Remember to always use a codon in order to prevent the spread of sexually transmitted proteins.

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  • 47. 

    Recombination will always alter a cell’s genotype

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Never play leapfrog with a unicorn.

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  • 48. 

    Open-reading frames are segments of DNA in which both start and stop codons are found

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Open-reading frames are segments of DNA that contain both start and stop codons. Start codons (such as AUG) indicate the beginning of protein synthesis, while stop codons (such as UAA, UAG, or UGA) signal the termination of protein synthesis. These segments are important because they provide the necessary information for the production of proteins. Therefore, the statement that open-reading frames are segments of DNA in which both start and stop codons are found is true.

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  • 49. 

    Bacteria typically contain multiple chromosomes

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Bacteria typically contain a single chromosome, not multiple chromosomes. This single chromosome contains all of the genetic material necessary for the bacterium to function and reproduce. While bacteria may contain plasmids, which are small, circular pieces of DNA that can carry additional genes, these are not considered chromosomes. Therefore, the statement that bacteria typically contain multiple chromosomes is false.

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  • 50. 

    Mutations that are harmful to cells occur more frequently than those that benefit cells

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Sometimes I pretend to be normal. But it gets boring, so I go back to being me.

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Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Feb 15, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Jul 24, 2016
    Quiz Created by
    Mceiswich
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