9. Enzyme induction occurs a. when the substrate of the enzyme is depleted. b. w
ID: 211496 • Letter: 9
Question
9. 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.
10. 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
11. Horizontal gene transfer
a. is the transfer of DNA from one bacterial cell to another, and can even occur between distantly related organisms
b. only occurs in eukaryotes.
c. is very rare and only occurs between closely related strains.
d. does not occur in natural environments
12. What occurs when an inducer is added to an environment containing an organism with a metabolic pathway controlled by a repressor?
a. The inducer binds to the DNA and thereby allows transcription of the pathway.
b. The inducer combines with the substrate and blocks induction.
c. The inducer combines with the repressor and thereby allows transcription of the pathway.
d. The inducer combines with the repressor and blocks transcription of the pathway.
13. During transcription the enzyme RNA polymerase
a. binds to a structural gene
b. synthesizes a strand of RNA that is complimentary to mRNA
c. binds to a so-called “promotor sequence” found in DNA
d. does all of the above
e. does none of the above
14. Mutations
a. may be neutral, beneficial, or harmful
b. are a permanent change in the nucleotide sequence of DNA
c. can be spontaneous
d. All of the above are true for mutations
e. None of the above are true for mutations
15. Supercoiling is important for DNA structure, because
a. it holds together the antiparallel strands of DNA in the double helix.
b. it provides energy for transcription.
c. it condenses the DNA so that it can fit inside the cell.
d. it prevents RNA from pairing with DNA in the double helix.
16. The precursor of each new nucleotide in a strand of DNA is a
a. deoxynucleoside 5-diphosphate.
b. deoxynucleoside 3-diphosphate.
c. deoxynucleoside 5-triphosphate.
d. deoxynucleoside 3-triphosphate.
Explanation / Answer
9. 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.
It takes place only when substrate is present.
10. 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
All are correct.
11. Horizontal gene transfer
a. is the transfer of DNA from one bacterial cell to another, and can even occur between distantly related organisms
b. only occurs in eukaryotes.
c. is very rare and only occurs between closely related strains.
d. does not occur in natural environments
It is transfer of genes from one species to another. It may occur in eukaryotes also.
12. What occurs when an inducer is added to an environment containing an organism with a metabolic pathway controlled by a repressor?
a. The inducer binds to the DNA and thereby allows transcription of the pathway.
b. The inducer combines with the substrate and blocks induction.
c. The inducer combines with the repressor and thereby allows transcription of the pathway.
d. The inducer combines with the repressor and blocks transcription of the pathway.
Inducer binds to the receptor and destroys it thus starting transcription.
13. During transcription the enzyme RNA polymerase
a. binds to a structural gene
b. synthesizes a strand of RNA that is complimentary to mRNA
c. binds to a so-called “promotor sequence” found in DNA
d. does all of the above
e. does none of the above
14. Mutations
a. may be neutral, beneficial, or harmful
b. are a permanent change in the nucleotide sequence of DNA
c. can be spontaneous
d. All of the above are true for mutations
e. None of the above are true for mutations
15. Supercoiling is important for DNA structure, because
a. it holds together the antiparallel strands of DNA in the double helix.
b. it provides energy for transcription.
c. it condenses the DNA so that it can fit inside the cell.
d. it prevents RNA from pairing with DNA in the double helix.
16. The precursor of each new nucleotide in a strand of DNA is a
a. deoxynucleoside 5-diphosphate.
b. deoxynucleoside 3-diphosphate.
c. deoxynucleoside 5-triphosphate.
d. deoxynucleoside 3-triphosphate.
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