MCQOPTIONS
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MCQOPTIONS
This section includes 23 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Sex lethal (sxl) in Drosophila is transcribed when |
| A. | the X autosome balance is less than 0.5 |
| B. | the X autosome balance is 1 or greater |
| C. | the X autosome balance equals 0.5 |
| D. | none of the above |
| Answer» C. the X autosome balance equals 0.5 | |
| 2. |
A mutation in the tip binding site of the repressor would result in |
| A. | constitutive trp operon expression |
| B. | inducible trp operon expression |
| C. | no operon expression |
| D. | none of the above |
| Answer» B. inducible trp operon expression | |
| 3. |
Alternate splicing of RNA transcripts is a mechanism to regulate |
| A. | tubulin |
| B. | tachykinins |
| C. | DNA methylation |
| D. | leucine zippers |
| Answer» C. DNA methylation | |
| 4. |
In the presence of tryptophan in the cell, the repressor is __________ |
| A. | bound to tryptophan |
| B. | bound to DNA |
| C. | bound to both DNA and tryptophan |
| D. | bound to neither tryptophan nor DNA |
| Answer» D. bound to neither tryptophan nor DNA | |
| 5. |
Catabolite activating protein exerts __________ control on transcription of the lac operon genes. |
| A. | positive |
| B. | negative |
| C. | may be positive or negative |
| D. | none of these |
| Answer» B. negative | |
| 6. |
Enhancers differ from promoters in that |
| A. | they initiate transcription |
| B. | they are adjacent to the start codon |
| C. | their orientation can be inverted without effect |
| D. | they are restricted to a specific gene |
| Answer» D. they are restricted to a specific gene | |
| 7. |
Transcription factors are |
| A. | regions of DNA in the promoter area |
| B. | regions of DNA in the enhancer area |
| C. | any protein which binds to DNA |
| D. | proteins which bind DNAand initiate transcription |
| Answer» E. | |
| 8. |
Genes which need to be coordinately regulated but are not in operons may be regulated by |
| A. | common transcription factor binding domains |
| B. | TATA boxes |
| C. | CAAT regions |
| D. | GC regions |
| Answer» B. TATA boxes | |
| 9. |
A frameshift mutation occurs in the sigma subunit gene transcribed as part of SPOl early genes. What will be the immediate result? |
| A. | Early genes will not be translated |
| B. | Middle genes will not be transcribed |
| C. | The bacterial host will lyse immediately |
| D. | Infection will proceed as usual |
| Answer» D. Infection will proceed as usual | |
| 10. |
Tubulin is regulated by |
| A. | binding of tubulin to tubulin mRNA |
| B. | splicing of the tubulin transcript |
| C. | binding of tubulin to the tubulin translational product |
| D. | binding of tubulin to DNA |
| Answer» D. binding of tubulin to DNA | |
| 11. |
DNA is methylated at |
| A. | AC sequences |
| B. | TATA sequences |
| C. | CAAT sequences |
| D. | CG sequences |
| Answer» E. | |
| 12. |
Why are several structural genes regulated as a unit in bacteria? |
| A. | An accident of evolution |
| B. | It allows coordinating regulation of genes with a common function |
| C. | The bacteria chromosome is so small; many different genes must be controlled by the same promoter |
| D. | none of the above |
| Answer» C. The bacteria chromosome is so small; many different genes must be controlled by the same promoter | |
| 13. |
What are genes? |
| A. | The functional unit of inheritance |
| B. | A fragment of DNA |
| C. | A portion of a chromosome |
| D. | All of the above |
| Answer» E. | |
| 14. |
Which of the following is not a transcription factor? |
| A. | Helix-turn-helix proteins |
| B. | Zinc finger proteins |
| C. | Leucine zipper proteins |
| D. | Steroid hormones |
| Answer» E. | |
| 15. |
Sex determination in Drosophila involves |
| A. | alternate splicing |
| B. | methylation |
| C. | gene amplification |
| D. | none of these |
| Answer» B. methylation | |
| 16. |
In the presence of high levels of tryptophan |
| A. | attenuator allows transcription of trp structural genes |
| B. | attenuator propogates transcription |
| C. | attenuator terminates transcription |
| D. | none of the above |
| Answer» D. none of the above | |
| 17. |
The first protein complex to bind to the TATA box is |
| A. | transcription factor IIA |
| B. | transcription factor IIB |
| C. | transcription factor IID |
| D. | all of these |
| Answer» D. all of these | |
| 18. |
Which of the following is not part of the lac operon? |
| A. | I |
| B. | O |
| C. | P |
| D. | none of these |
| Answer» B. O | |
| 19. |
The lac operon is transcribed in which segments? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» B. 2 | |
| 20. |
Sex hormones activate transcription of specific genes by |
| A. | binding to a transcription factor |
| B. | binding to RNA polymerase |
| C. | binding to DNA enhancer region |
| D. | binding to DNA promoter region |
| Answer» B. binding to RNA polymerase | |
| 21. |
The lac operon is translated into __________ proteins. |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 22. |
Which of the following occur in the presence of glucose? |
| A. | <i>lac</i> |
| B. | Z gene expression is increased |
| C. | cAMP increases |
| D. | Binding of CAP-cAMP complex to the promoter area decreases |
| E. | none of the above |
| Answer» D. Binding of CAP-cAMP complex to the promoter area decreases | |
| 23. |
Methylated gene are |
| A. | active |
| B. | silent |
| C. | dynamic |
| D. | either (a) or (b) |
| Answer» C. dynamic | |