Biotechnology: Principles and Processes Mock Test – Class 12 Biology

1. A cloning experiment uses one restriction enzyme to cut the desired source DNA and a second enzyme to open the vector. The two enzymes generate overhangs that cannot base-pair with each other. What is the most likely result?

2. In a PCR cycle, the template strands separate normally but the primers fail to bind to their intended complementary sites. What is the immediate consequence?

3. After electrophoresis, the desired DNA fragment is visible as an orange fluorescent band under ultraviolet light. Which sequence correctly converts this observation into usable DNA for cloning?

4. Disarmed Ti-plasmid vectors and disarmed retroviral vectors are adapted from very different natural systems. What engineering principle do they share?

5. A recombinant-DNA experiment contains a restriction endonuclease, a plasmid vector, a recipient host and DNA polymerase, but the enzyme required to seal the selected foreign fragment into the opened vector is absent. Which tool is missing?

6. A genomic DNA preparation remains heavily contaminated with cellular proteins even though its RNA has already been removed. Which enzyme should be added next?

7. Source DNA containing the gene of interest and a cloning vector are cut with the same suitable restriction enzyme. The main advantage of this coordinated treatment is that it can

8. A colony grows on the original ampicillin plate but fails to grow at the corresponding position after replica plating onto tetracycline. In a pBR322 experiment where foreign DNA was inserted at BamHI within tetR, the strongest inference is that the colony

9. A bacterial cell possesses both a restriction enzyme and a corresponding modification enzyme. Which division of labour is correct?

10. The relevance of sexual and asexual reproduction to the conceptual basis of genetic engineering is best represented by the statement that

11. Four DNA-isolation preparations show the following results:

Which preparation most strongly indicates successful ribonuclease treatment, successful protease treatment and effective DNA precipitation?

12. A microorganism has already been engineered to carry a desired gene. It produces the required product in a small sterile flask, but an industrial batch repeatedly fails because the large culture becomes contaminated. Which intervention addresses the unresolved biotechnology problem most directly?

13. A DNA sample is loaded near one end of an agarose gel. After electrophoresis, all visible bands have moved toward the opposite end where the positive electrode is located. Which observation best explains this direction?

14. A PCR product containing the desired gene is obtained in large quantity, but the researcher wants the gene to remain associated with a replicating DNA molecule after transfer into bacteria. Which next step most directly satisfies this requirement?

15. A proposed cloning vector has a functional ori and antibiotic-resistance marker. However, the chosen restriction enzyme cuts at six sites scattered throughout the plasmid. Which redesign would most directly improve cloning predictability?

16. A bioreactor is best described as

17. Samples taken through a bioreactor sampling port show that product concentration rises normally for several hours and then falls at the same time that culture pH moves outside its target range. Oxygen and temperature remain stable. Which conclusion is best supported?

18. A scientist adds chilled ethanol immediately to intact plant cells before any wall disruption or macromolecule purification. Why is this poor DNA-isolation logic?

19. Consider the following bacterial cells placed on medium containing an antibiotic for which the original recipient strain is sensitive:

Which cell is most clearly expected to survive because of vector-mediated antibiotic selection?

20. A bacterial population is exposed to a plasmid carrying an ampicillin-resistance marker. After transformation, the cells are placed on a medium containing ampicillin. Why is this marker useful?

21. Assertion: A thermostable DNA polymerase is particularly suitable for PCR.
Reason: PCR repeatedly includes a high-temperature DNA-denaturation stage that would inactivate many ordinary enzymes.

22. A target protein has been synthesised inside recombinant cells, but most of it remains mixed with cellular material and culture-medium components. Which operation belongs immediately to the post-biosynthetic phase?

23. A cloning project gives the following results:

Where is the strongest remaining failure?

24. Two finished biotechnology products pass their respective purification procedures, but one fails its product-specific quality-control test. Which conclusion is most appropriate?

25. A cloned gene has been successfully introduced into a suitable host and is being expressed. At laboratory scale, the desired recombinant protein can subsequently be

26. A student states, "Ethidium bromide separates DNA fragments by size, while agarose makes them fluorescent." Which correction is most accurate?

27. A stirred-tank bioreactor has normal aeration and agitation, but the temperature-control system fails and the culture temperature moves far outside its suitable range. Which statement is best supported?

28. A restriction endonuclease encounters a long DNA molecule containing many different sequences. Its action is most accurately represented by the sequence

29. Match each component of recombinant DNA technology with its most characteristic role.

30. Which relation most accurately captures the defining biological role of a production bioreactor?

31. Source DNA is digested with enzyme P, while the vector is digested with enzyme Q. Both enzymes cut efficiently, but the resulting sticky ends are non-complementary. Which intervention most directly addresses the problem?

32. Before inoculation, a production vessel and its associated medium-handling system must be prepared to minimise entry of unwanted organisms. Which bioreactor principle is being applied most directly?

33. A PCR machine is programmed so that each cycle performs denaturation followed immediately by extension, with no primer-annealing stage. All reagents are otherwise correct. Which outcome is most likely?

34. DNA does not normally enter bacterial cells efficiently simply because it is present in the surrounding medium. One important reason is that DNA is

35. Consider the following statements about a bioreactor:
I. It supports biological conversion of raw materials into desired products.
II. It may contain microbial, plant, animal or human cells.
III. Its operation depends on maintaining appropriate environmental conditions.
IV. Its principal function is to separate DNA fragments according to size.
Which option is correct?

36. A cloned gene from organism P has been introduced into organism Q and is maintained there, but no corresponding protein is detected in Q. Which conclusion is most accurate?

37. A laboratory follows every bacterial transformation step correctly except that the recombinant DNA and competent cells are never exposed to the brief heat-shock step. What is the most reasonable prediction?

38. Agrobacterium tumefaciens is important in plant biotechnology because it naturally

39. In a bacterial restriction-modification system, the host's recognition sites are appropriately protected, but the modification activity is experimentally lost while the restriction endonuclease remains active. Which prediction is most reasonable?

40. In a cloning experiment, bacterial colonies survive the initial selection for plasmid uptake, but later testing shows that only colonies contain the desired foreign DNA insert. Which interpretation is most accurate?

41. A purified biotechnology product is intended for therapeutic use in patients, whereas another purified product is intended only for a non-therapeutic industrial process. Which requirement most clearly distinguishes the therapeutic product at the final evaluation stage?

42. A PCR mixture contains template DNA, both required primers and thermostable DNA polymerase, but no free nucleotides are supplied. What is the most likely result?

43. Purified DNA is to be digested with a selected restriction enzyme. For effective digestion, the DNA should be incubated

44. Competent bacteria containing recombinant DNA are moved directly from room temperature to approximately and then maintained there without the preceding and subsequent ice steps described in the standard transformation sequence. Which evaluation is most appropriate?

45. Plasmids and bacteriophages can both function as cloning vectors in bacteria. What feature most directly explains their usefulness for multiplying an attached foreign DNA fragment?

46. In the restriction-enzyme name EcoRI, which part most directly represents the bacterial strain designation?

47. A student is shown an agarose gel after electrophoresis but is not told which side originally contained the loading wells. The positive electrode was located on the right side of the gel, and the DNA bands extend progressively toward the right. The loading wells were most likely located

48. A biotechnology definition includes the use of organisms, cells, parts of cells and molecular analogues to develop useful products and services. Which interpretation of this definition is most accurate?

49. In a β-galactosidase-based recombinant screening system, four colonies show the following observations:

In this insertional-inactivation screening system, which colony most strongly represents a recombinant produced by insertional inactivation?

50. Which experimental design best distinguishes successful transformation from successful foreign-DNA insertion?