301. Which statement best compares the modern restricted meaning of biotechnology with the broader applied definition linked to the European Federation of Biotechnology?
ⓐ. The broader definition excludes cells and cell parts, whereas the restricted meaning includes them.
ⓑ. The restricted meaning includes all traditional fermentation processes, whereas the broader one excludes them.
ⓒ. The broader definition includes organisms, cells, their parts, and molecular analogues for useful products or services, whereas the restricted meaning is more focused on modern molecular manipulation.
ⓓ. Both meanings refer only to large-scale industrial culture under sterile conditions.
Correct Answer: The broader definition includes organisms, cells, their parts, and molecular analogues for useful products or services, whereas the restricted meaning is more focused on modern molecular manipulation.
Explanation: The broader applied definition treats biotechnology as the use of biological systems and related molecular tools for useful products and services. The modern restricted meaning is narrower and is centered mainly on genetic engineering and related molecular methods. Traditional biological uses can fit the broad meaning even when they are not examples of the restricted one. The two meanings are related, but not identical in scope.
302. A scientist wants to transfer only a disease-resistance gene into a crop, while a factory wants to maintain sterile large-scale growth of an already engineered microbe. Which pair of principles is involved, respectively?
ⓐ. Bioprocess engineering and genetic engineering
ⓑ. Elution and downstream processing
ⓒ. Transformation and electrophoresis
ⓓ. Genetic engineering and bioprocess engineering
Correct Answer: Genetic engineering and bioprocess engineering
Explanation: Transferring only a selected gene is a gene-level modification task, so it belongs to genetic engineering. Once the desired organism already exists, maintaining it in contamination-free large-scale culture becomes a production problem handled by bioprocess engineering. The two principles therefore solve different stages of biotechnology. One creates the desired biological system, and the other manages its industrial use.
303. A desired DNA fragment has already been isolated from an agarose gel by elution. What is the next indispensable requirement before bacterial transformants can later be identified on antibiotic medium?
ⓐ. The fragment must be ligated into a suitable vector.
ⓑ. The fragment must be stained again with ethidium bromide.
ⓒ. The fragment must be precipitated repeatedly with chilled ethanol.
ⓓ. The fragment must be transferred directly into a bioreactor.
Correct Answer: The fragment must be ligated into a suitable vector.
Explanation: Elution gives the required DNA fragment in isolated form, but that fragment still needs a carrier system for cloning. It must be joined to a suitable vector so that it can enter a host and be maintained there. Only after vector entry into a host can transformants be selected on antibiotic medium. The key next step is recombinant DNA formation by ligation.
304. Two DNA fragments of equal length but different base sequences are run on the same agarose gel under identical conditions. Which result is most likely?
ⓐ. One fragment always moves toward the cathode because its sequence is different.
ⓑ. They usually migrate to nearly the same position because agarose separation is mainly based on fragment size.
ⓒ. The fragment with more G and C bases always remains close to the well.
ⓓ. Their movement depends mainly on which fragment contains a palindromic sequence.
Correct Answer: They usually migrate to nearly the same position because agarose separation is mainly based on fragment size.
Explanation: Agarose gel electrophoresis separates DNA fragments primarily on the basis of size, not on the exact base sequence of fragments of the same length. DNA molecules carry a broadly similar negative charge per unit length because of the phosphate backbone. As a result, fragments with equal size usually migrate very similarly under the same conditions. Sequence differences alone do not usually create major positional differences in this context.
305. A plasmid has a selectable marker and a single cloning site, but its ori is defective. Which result is most likely after the plasmid briefly enters a bacterial cell?
ⓐ. The plasmid may enter, but it will not be maintained efficiently through replication in the host.
ⓑ. The selectable marker will automatically become nonfunctional.
ⓒ. The plasmid will gain multiple new restriction sites.
ⓓ. The plasmid will move more slowly in an agarose gel.
Correct Answer: The plasmid may enter, but it will not be maintained efficiently through replication in the host.
Explanation: ori is essential for initiation of plasmid replication. If it is defective, the plasmid may still enter the host cell during transformation, but it will not replicate properly. As a result, it cannot be maintained reliably in the bacterial population. The failure is therefore one of persistence, not immediate entry.
306. Which option best represents the point at which downstream processing begins?
ⓐ. When donor DNA is first isolated from a cell
ⓑ. When primers anneal to the template during PCR
ⓒ. When a recombinant plasmid enters a host bacterium
ⓓ. When biosynthesis of the desired product has already occurred and the product must now be recovered and prepared
Correct Answer: When biosynthesis of the desired product has already occurred and the product must now be recovered and prepared
Explanation: Downstream processing is a post-biosynthetic stage. It starts after the desired substance has been produced and focuses on separation, purification, formulation, and related final checks. Earlier events such as DNA isolation, PCR, and transformation belong to gene manipulation or production setup. The defining boundary is the shift from production to product recovery and preparation.
307. A researcher cuts both donor DNA and vector DNA with the same restriction enzyme, mixes them, and notices that the fragments align even before ligase is added. What most directly explains this observation?
ⓐ. The fragments contain identical selectable markers.
ⓑ. The fragments already carry thermostable polymerase.
ⓒ. Complementary sticky ends can pair by hydrogen bonding before covalent sealing occurs.
ⓓ. The vector immediately begins replicating outside the host.
Correct Answer: Complementary sticky ends can pair by hydrogen bonding before covalent sealing occurs.
Explanation: When the same restriction enzyme creates compatible sticky ends on both molecules, the exposed bases can pair with one another. This temporary hydrogen bonding helps bring the fragments into alignment. DNA ligase is still needed afterward to seal the backbone covalently. The early alignment happens because of end complementarity, not replication or marker genes.
308. Which situation best shows that cloning, expression, and product recovery are three distinct ideas in biotechnology?
ⓐ. A gene may be cloned successfully, yet the desired protein may still require proper expression and later purification before use.
ⓑ. A gene is amplified by PCR, so no host system is ever required.
ⓒ. A purified product always proves that the gene never entered a host.
ⓓ. A selectable marker replaces the need for downstream processing.
Correct Answer: A gene may be cloned successfully, yet the desired protein may still require proper expression and later purification before use.
Explanation: Cloning means making and maintaining copies of the gene, not automatically obtaining the final useful product. The host must still express that gene under suitable conditions to produce the corresponding protein or other product. Even after expression, the product generally has to be recovered and purified. These are related stages, but they are not identical.
309. A scientist first isolates a DNA segment carrying a useful gene, then introduces it into a host cell, and finally ensures that the introduced DNA is inherited by daughter cells. Which sequence of basic steps is being followed?
ⓐ. Maintenance in progeny → identification of DNA → introduction into host
ⓑ. Introduction into host → identification of DNA → maintenance in progeny
ⓒ. Identification of desirable DNA → introduction into host → maintenance and transfer to progeny
ⓓ. Identification of host cell → extraction of protein → purification of product
Correct Answer: Identification of desirable DNA → introduction into host → maintenance and transfer to progeny
Explanation: Genetic modification begins by identifying the DNA carrying the desired gene. That DNA must then be introduced into a suitable host. The final requirement is stable maintenance of that DNA and its inheritance by progeny. Without the last step, the modification would remain temporary rather than stable.
310. A plasmid vector contains a functional ori and a suitable cloning site, but no selectable marker. Which outcome is most likely after transformation?
ⓐ. The recombinant plasmid may replicate, but transformants will be difficult to distinguish from non-transformants.
ⓑ. The plasmid will be unable to enter the host because ori blocks DNA uptake.
ⓒ. The foreign DNA will be expressed immediately without host-cell growth.
ⓓ. The plasmid will be cut automatically at palindromic sites inside the host.
Correct Answer: The recombinant plasmid may replicate, but transformants will be difficult to distinguish from non-transformants.
Explanation: ori allows the plasmid and linked DNA to replicate inside the host. A selectable marker serves a different function: it helps identify cells that have actually taken up the vector. Without such a marker, uptake may occur, but selection becomes difficult. The main problem is detection of transformants, not replication itself.
311. Which set includes only components directly associated with pBR322?
ⓐ. ori, T-DNA, ADH, and ClaI
ⓑ. tetR, chitinase, rop, and EcoRI
ⓒ. ampR, retroviral coat, BamHI, and rop
ⓓ. ori, ampR, tetR, rop, and several restriction sites
Correct Answer: ori, ampR, tetR, rop, and several restriction sites
Explanation: pBR322 is a standard bacterial cloning vector with recognizable internal features. These include ori, the resistance genes ampR and tetR, the rop region, and several defined restriction sites. The other options mix unrelated molecules or components from other systems. A correct plasmid map must keep vector features separate from unrelated biological terms.
312. Which statement best explains why modified Ti plasmids and disarmed retroviruses are both useful as vectors?
ⓐ. Both naturally separate DNA fragments by size in a host cell.
ⓑ. Both are derived from systems with natural DNA-delivery ability that can be adapted for safe gene transfer.
ⓒ. Both act mainly as selectable markers in bacterial cloning.
ⓓ. Both are used only after PCR amplification in bacterial cells.
Correct Answer: Both are derived from systems with natural DNA-delivery ability that can be adapted for safe gene transfer.
Explanation: These vectors are valuable because their original biological systems already had ways of delivering genetic material into host cells. Biotechnology modifies them so that harmful effects are removed while transfer ability is retained. That makes them useful carriers for desired genes. Their importance lies in delivery, not in selection or DNA separation.
313. Consider the following assertion and reason:
Assertion (A): A fungal sample requires a different initial wall-digesting enzyme from a plant sample during DNA isolation.
Reason (R): Fungal cell walls contain chitin, whereas plant cell walls contain cellulose.
ⓐ. Both A and R are true, and R is the correct explanation of A.
ⓑ. Both A and R are true, but R is not the correct explanation of A.
ⓒ. A is true, but R is false.
ⓓ. A is false, but R is true.
Correct Answer: Both A and R are true, and R is the correct explanation of A.
Explanation: Different organisms have different wall compositions, so the same enzyme is not suitable for all of them. Chitinase is useful for fungal walls because they contain chitin, while cellulase is used for plant cell walls because they contain cellulose. The reason directly explains the difference in enzyme choice. DNA isolation therefore depends on the structure surrounding the cell.
314. In PCR, why must the two primers bind to opposite strands flanking the region of interest?
ⓐ. So that the DNA can move toward the anode during electrophoresis
ⓑ. So that ligase can join the amplified strands after every cycle
ⓒ. So that DNA synthesis can proceed across the selected region from both ends during repeated cycles
ⓓ. So that the amplified DNA becomes resistant to restriction enzymes
Correct Answer: So that DNA synthesis can proceed across the selected region from both ends during repeated cycles
Explanation: The primers define the segment to be amplified by marking its boundaries on opposite strands. DNA polymerase extends from each primer, producing copies of the region between them. This arrangement allows repeated cycles to amplify the target specifically and efficiently. Without flanking primers on opposite strands, the normal PCR amplification pattern would not occur.
315. A bacterial culture carrying recombinant plasmids is grown in a stirred-tank bioreactor. Which pair of features most directly supports oxygen availability and uniform distribution within the vessel?
ⓐ. Sampling port and selectable marker
ⓑ. Agitator and sparging system
ⓒ. ori and rop
ⓓ. Gel matrix and UV source
Correct Answer: Agitator and sparging system
Explanation: The agitator mixes the culture so that cells, nutrients, and dissolved gases are distributed more evenly. Sparging introduces sterile air into the medium and helps maintain oxygen availability. Together these two features support aerobic growth and product formation. They are engineering systems of the reactor, not vector features.
316. A purified recombinant vaccine protein loses activity during storage unless suitable stabilizers are added. Which late-stage step directly addresses this problem?
ⓐ. Restriction digestion of the host DNA
ⓑ. Heat-shock treatment of competent bacteria
ⓒ. Elution of a DNA band from agarose gel
ⓓ. Formulation of the product with suitable stabilizers or preservatives
Correct Answer: Formulation of the product with suitable stabilizers or preservatives
Explanation: Purification alone does not guarantee that a biotechnology product is ready for storage or use. Many products need formulation so that they remain stable, effective, and safe during handling. Stabilizers or preservatives may be added at this stage when appropriate. This is a downstream-processing requirement, not a gene-manipulation step.
317. A recombinant therapeutic protein has already been purified and formulated, but it must still be evaluated in humans before routine medical use. Which later-stage requirement is being referred to?
ⓐ. Transformation
ⓑ. Restriction digestion
ⓒ. Clinical trials
ⓓ. Biolistics
Correct Answer: Clinical trials
Explanation: Medical biotechnology products require more than successful production and purification. Before routine therapeutic use, they must be evaluated for safety and effectiveness in appropriate clinical studies. This requirement belongs to the late product-development stage. It does not refer to DNA cutting, transformation, or gene-transfer methods.
318. Why can quality-control testing differ between a recombinant therapeutic drug and an industrial enzyme?
ⓐ. Because required standards depend on the nature and intended use of the product
ⓑ. Because quality control is needed only before cloning begins
ⓒ. Because all biotechnology products undergo exactly the same final tests
ⓓ. Because only therapeutic products ever need purification
Correct Answer: Because required standards depend on the nature and intended use of the product
Explanation: Quality control is essential before a biotechnology product is released, but the exact tests are not identical for every product. A therapeutic drug, vaccine, and industrial enzyme can differ in safety needs, purity standards, and performance requirements. Therefore, testing is matched to the nature and intended use of the product. The principle is product-specific evaluation, not one fixed universal test.
319. Which set correctly matches the biotechnology tool with its principal role?
ⓐ. Cellulase — amplification of DNA; ligase — staining of DNA bands; ori — protein purification; Ti plasmid — bacterial competence
ⓑ. Taq polymerase — PCR amplification; DNA ligase — joining DNA fragments; lysozyme — bacterial cell-wall lysis; pBR322 — cloning vector
ⓒ. EcoRI — downstream processing; chitinase — selectable marker; retrovirus — gel separation; rop — antibiotic screening
ⓓ. Ethidium bromide — DNA replication; protease — sticky-end formation; BamHI — oxygen supply; calcium chloride — elution
Correct Answer: Taq polymerase — PCR amplification; DNA ligase — joining DNA fragments; lysozyme — bacterial cell-wall lysis; pBR322 — cloning vector
Explanation: Each item in option B is matched with the role it actually performs in recombinant DNA technology. Taq polymerase is used in PCR, ligase joins DNA fragments, lysozyme helps break bacterial cell walls during DNA isolation, and pBR322 is a standard cloning vector. The other options mix correct names with incorrect functions. This kind of integration is useful because many chapter terms sound similar but belong to different stages.
320. A student says that once a gene has been cloned in a host, the final biotechnology product is essentially ready for sale. Which two major requirements are still missing from that claim?
ⓐ. Palindromic-site recognition and primer annealing
ⓑ. Competence development and heat shock
ⓒ. Elution and restriction digestion
ⓓ. Large-scale production under suitable conditions and downstream processing
Correct Answer: Large-scale production under suitable conditions and downstream processing
Explanation: Cloning only establishes the gene in a host and allows it to be maintained or copied. A useful final product usually still requires expression at an appropriate scale and then recovery, purification, formulation, and quality evaluation. Those later steps are essential before practical use or marketing. So cloning is an early-to-middle stage, not the endpoint of biotechnology production.
