In transgenic plant development, what is the primary function of the Ti plasmid from Agrobacterium tumefaciens?
Answer: B
The Ti (Tumor-inducing) plasmid naturally transfers a portion of its DNA (T-DNA) into plant cells. Scientists use this as a natural vector to introduce desired genes into plants.
Q.22Easy
Which crop was the first genetically modified organism (GMO) approved for commercial cultivation in India?
Answer: A
Bt Cotton was approved by the Indian government in 2002 and became the first genetically modified crop to be commercially cultivated in India, significantly impacting cotton production.
Q.23Easy
What does 'Bt' in Bt Cotton refer to?
Answer: A
Bt stands for Bacillus thuringiensis, a soil bacterium that produces Cry proteins toxic to lepidopteran insects. The Cry gene is inserted into cotton plants to confer insect resistance.
Q.24Easy
Which Indian government body is primarily responsible for approving the release of genetically modified crops?
Answer: B
The GEAC, operating under the MoEFCC, is responsible for appraising large-scale field trials and commercial release of genetically modified organisms in India.
Q.25Easy
In the production of recombinant human insulin using genetically engineered bacteria, which organism is primarily used?
Answer: B
E. coli is the primary organism used for recombinant insulin production due to its well-characterized genetics, rapid growth, and ability to produce high levels of recombinant proteins.
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Q.26Easy
Which of the following enzymes is primarily used to cut DNA at specific recognition sequences during genetic engineering?
Answer: A
Restriction endonucleases (restriction enzymes) recognize and cut DNA at specific palindromic sequences, forming sticky or blunt ends. DNA polymerase synthesizes DNA, helicase unwinds DNA, and ligase joins DNA strands.
Q.27Easy
Which enzyme is responsible for synthesizing new DNA strands during PCR?
Answer: A
Taq DNA polymerase from Thermus aquaticus is heat-stable and essential for DNA synthesis in PCR cycles.
Q.28Easy
In PCR, the denaturation step typically occurs at:
Answer: B
Denaturation separates double-stranded DNA into single strands, requiring high temperatures of 94-95°C.
Q.29Easy
Restriction enzymes recognize and cut DNA at:
Answer: B
Restriction endonucleases recognize specific palindromic DNA sequences and cut predictably at these sites.
Q.30Easy
The role of DNA ligase in genetic engineering is to:
Answer: B
DNA ligase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, joining DNA fragments.
Q.31Easy
The polymerase chain reaction was invented by:
Answer: B
Kary Mullis invented PCR in 1983, a revolutionary technique that earned him the Nobel Prize in Chemistry in 1993.
Q.32Easy
The extension step in PCR occurs at approximately:
Answer: B
Extension/elongation happens at 72-75°C, the optimal temperature for Taq polymerase to synthesize DNA.
Q.33Easy
In PCR, which enzyme synthesizes the complementary DNA strand during the extension phase?
Answer: A
Taq polymerase (thermostable DNA polymerase from Thermus aquaticus) synthesizes new DNA strands at 72°C during the extension phase of PCR.
Q.34Easy
What is the typical number of PCR cycles required to achieve exponential amplification of target DNA?
Answer: B
Standard PCR typically uses 25-35 cycles to achieve sufficient exponential amplification (2^n copies) without compromising specificity or introducing errors.
Q.35Easy
Which of the following is NOT a component of the PCR reaction mixture?
Answer: D
Restriction enzymes are used in DNA cloning and digestion, not in PCR. PCR requires template DNA, primers, dNTPs, Taq polymerase, and buffer.
Q.36Easy
In DNA sequencing by Sanger method, what role do ddNTPs play?
Answer: B
ddNTPs (dideoxynucleotides) lack a 3'-OH group, causing chain termination when incorporated, generating DNA fragments of different lengths for sequencing.
Q.37Easy
During PCR amplification, which enzyme synthesizes new DNA strands by reading the template DNA in the 3' to 5' direction?
Answer: B
Taq DNA Polymerase (thermostable polymerase from Thermus aquaticus) is the standard enzyme used in PCR. It synthesizes DNA by adding nucleotides to the 3'-OH group of the growing strand.
Q.38Easy
What is the typical temperature range for the annealing step in a standard PCR cycle?
Answer: A
The annealing temperature typically ranges from 50-65°C and depends on the primer's melting temperature (Tm). This allows primers to bind specifically to complementary sequences on the template DNA.
Q.39Easy
In real-time PCR (qPCR), which fluorescent dye binds directly to double-stranded DNA and is most commonly used in 2024-25 diagnostics?
Answer: A
SYBR Green intercalates into double-stranded DNA and fluoresces. It is cost-effective and widely used in qPCR for gene expression studies and viral load detection.
Q.40Easy
What is the primary principle behind whole exome sequencing (WES) in identifying disease-causing mutations?
Answer: A
WES captures and sequences exonic regions (~50 Mb) using targeted enrichment, reducing sequencing depth and cost while identifying 85-90% of disease-causing variants.
