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#	Question	Answer
1	Which sciences gave rise to engineering, technologies, and industries?	Physics and chemistry.
2	What are plasmids?	Small ringlets of DNA that float freely in the cytoplasm of certain bacterial cells and replicate independently from chromosomal DNA.
3	How is biotechnology used in a restricted modern sense?	It refers to processes using genetically modified organisms to achieve products on a larger scale.
4	What advantage does sexual reproduction provide over asexual reproduction?	Sexual reproduction provides opportunities for variations and unique combinations of genetic setup.
5	What is the role of the origin of replication?	It is a specific DNA sequence responsible for initiating replication.
6	Who accomplished the first recombinant DNA construction in 1972?	Stanley Cohen and Herbert Boyer.
7	What is cloning of an antibiotic resistance gene?	The ability to multiply copies of the antibiotic resistance gene in *E. coli*.
8	What is a recognition sequence?	A specific base sequence recognised by a restriction enzyme.
9	What do Roman numerals in restriction enzyme names indicate?	The order in which the enzymes were isolated from that bacterial strain.
10	What does a restriction endonuclease do after recognising its sequence?	It binds to DNA and cuts both strands of the double helix at specific points.
11	What are recombinant DNA molecules?	DNA molecules composed of DNA from different sources/genomes.
12	Towards which electrode do DNA fragments move during electrophoresis?	Towards the anode (positive electrode).
13	Which compound is used to stain DNA fragments in gel electrophoresis?	Ethidium bromide.
14	How many copies per cell may some plasmids have?	Some plasmids may have 1–2 copies, while others may have 15–100 copies per cell.
15	What controls the copy number of linked DNA in a vector?	The origin of replication (ori).
16	Why are antibiotic resistance genes useful as selectable markers?	Normal *E. coli* cells do not carry resistance against these antibiotics.
17	How are recombinants selected in pBR322?	Recombinants grow on ampicillin medium but not on tetracycline medium.
18	What colour do recombinant colonies produce after insertional inactivation?	They do not produce any colour.
19	Why must bacterial cells be made competent?	Because DNA is hydrophilic and cannot pass through cell membranes naturally.
20	What role do disarmed pathogen vectors play in biotechnology?	They transfer recombinant DNA into the host cell.
21	Which enzyme is used to break plant cell walls during DNA isolation?	Cellulase.
22	How is purified DNA precipitated out?	By addition of chilled ethanol.
23	What is added after mixing cut vector DNA and gene of interest?	DNA ligase.
24	Which enzyme extends primers during PCR?	DNA polymerase.
25	Why is thermostable DNA polymerase important in PCR?	It remains active during high-temperature induced denaturation of double-stranded DNA.
26	Why is the ampicillin resistance gene called a selectable marker?	Because it helps select transformed cells in the presence of ampicillin.
27	What is the advantage of continuous culture systems?	They produce larger biomass leading to higher yields of desired protein.
28	What is the shape of a stirred-tank bioreactor?	Usually cylindrical or with a curved base.
29	Why are preservatives added during downstream processing?	To formulate the product suitably before marketing.
30	What is recombinant DNA technology also called?	Genetic engineering.
31	What is the purpose of restriction enzymes?	They cut DNA at specific sites.