In a typical PCR cycle, DNA denaturation occurs at approximately which temperature?

The correct answer is B: 94-95°C. DNA denaturation in PCR occurs at 94-95°C (or sometimes 98°C), where hydrogen bonds between DNA strands are broken, separating the double helix into single strands.

What is the typical temperature range for the annealing step in a standard PCR cycle?

The correct answer is A: 50-65°C. 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.

Which Indian state first approved the cultivation of Bt Cotton commercially?

The correct answer is B: Gujarat. Bt Cotton was first commercialized in Gujarat in 2002 after receiving GEAC approval. It has since become one of the most widely cultivated GM crops in India.

Which enzyme is commonly used to cut DNA at specific recognition sequences during genetic engineering?

The correct answer is A: Restriction endonuclease. Restriction endonucleases (restriction enzymes) recognize and cut DNA at specific palindromic sequences, making them essential tools in genetic engineering for creating recombinant DNA.

Which enzyme is commonly used as a molecular scissors in CRISPR-Cas9 gene editing technology?

The correct answer is A: Cas9 endonuclease. Cas9 is an endonuclease enzyme that cuts DNA at specific sites guided by RNA. DNA polymerase synthesizes DNA, reverse transcriptase converts RNA to DNA, and ligase seals DNA strands.

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Biotechnology

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67 Q 3 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–40 of 67

Topics in Biotechnology

All Genetic Engineering 100 PCR & DNA Technology 100 Cell Culture 60

Q.31 Hard PCR & DNA Technology

In forensic DNA analysis using STR markers, what advantage do newer SNP-based methods provide over traditional STR typing for 2024-25 investigations?

A Faster turnaround time and better degraded DNA recovery

B Lower mutation rates and ability to infer population ancestry

C Elimination of contamination issues

D Higher discrimination power alone

Correct Answer: B. Lower mutation rates and ability to infer population ancestry

EXPLANATION

SNP-based methods offer lower mutation rates (~10⁻⁸), enable ancestry inference, and work better with degraded DNA samples compared to STRs, making them valuable for cold cases.

Test

Q.32 Hard PCR & DNA Technology

When designing a TaqMan probe for qPCR, what is the relationship between probe length and specificity in target detection?

A Longer probes (>50 bp) always increase specificity

B Optimal probe length (18-25 bp) with appropriate Tm ensures high specificity and sensitivity

C Shorter probes (

D Probe length is independent of specificity

Correct Answer: B. Optimal probe length (18-25 bp) with appropriate Tm ensures high specificity and sensitivity

EXPLANATION

TaqMan probes of 18-25 bp with Tm 5-10°C higher than primers provide optimal specificity and sensitivity by requiring perfect base pairing for nuclease cleavage.

Test

Q.33 Hard PCR & DNA Technology

Which DNA technology is most suitable for detecting chromosomal abnormalities like deletions and duplications at the genomic level?

A Comparative Genomic Hybridization (CGH) or array-CGH

B Standard PCR

C DNA fingerprinting

D Southern blotting alone

Correct Answer: A. Comparative Genomic Hybridization (CGH) or array-CGH

EXPLANATION

Array-CGH (aCGH) provides high-resolution detection of chromosomal imbalances across the entire genome, making it ideal for identifying deletions and duplications.

Test

Q.34 Hard PCR & DNA Technology

In somatic gene therapy using ex vivo approach, which cell type is most commonly targeted for genetic modification?

A Neurons

B Hematopoietic stem cells

C Muscle cells

D Cardiac myocytes

Correct Answer: B. Hematopoietic stem cells

EXPLANATION

Hematopoietic stem cells are preferred because they can self-renew, are easily accessible via bone marrow/blood, and can be reinfused to establish long-term therapeutic effects for blood disorders.

Test

Q.35 Hard PCR & DNA Technology

In environmental metagenomic studies using 16S/18S rRNA amplicon sequencing, what is the primary limitation?

A Cannot identify bacteria

B Low taxonomic resolution at species level due to limited sequence variation in hypervariable regions

C Requires culturable organisms

D Cannot detect rare species

Correct Answer: B. Low taxonomic resolution at species level due to limited sequence variation in hypervariable regions

EXPLANATION

While 16S/18S rRNA is excellent for community profiling, limited sequence divergence at species level makes species-level discrimination challenging, requiring shotgun metagenomics for finer resolution.

Test

Q.36 Hard PCR & DNA Technology

CRISPR-Cas12 (Cpf1) differs from Cas9 in that it:

A Requires RNA-only guidance

B Creates sticky ends (TALEN-like overhangs) and requires only single RNA molecule

C Is more efficient for prokaryotic editing

D Does not require PAM sequences

Correct Answer: B. Creates sticky ends (TALEN-like overhangs) and requires only single RNA molecule

EXPLANATION

Cas12 creates staggered cuts resulting in sticky ends, requires only one CRISPR RNA (not separate tracrRNA), and recognizes T-rich PAM sequences, offering advantages for some applications.

Test

Q.37 Hard PCR & DNA Technology

What is the significance of the primer Tm (melting temperature) in multiplex PCR?

A All primers should have similar Tm values to allow use of single annealing temperature

B Primers should have different Tm values for better specificity

C Tm has no relevance in multiplex PCR

D Higher Tm always indicates better performance

Correct Answer: A. All primers should have similar Tm values to allow use of single annealing temperature

EXPLANATION

In multiplex PCR, all primers should have similar Tm values (within 1-2°C) to use a single annealing temperature, preventing preferential amplification of certain targets.

Test

Q.38 Hard PCR & DNA Technology

In the context of 2024-25 genomic studies, what is the primary advantage of long-read sequencing technologies (PacBio, Oxford Nanopore) over short-read NGS?

A Higher accuracy

B Lower cost

C Better assembly of repetitive regions and structural variants

D Requires less DNA input

Correct Answer: C. Better assembly of repetitive regions and structural variants

EXPLANATION

Long-read sequencing can span repetitive sequences and detect large structural variations that short-reads cannot resolve, improving genome assembly quality.

Test

Q.39 Hard PCR & DNA Technology

Which technique combines PCR with capillary electrophoresis for high-resolution DNA fragment analysis?

A AFLP

B Microsatellite genotyping

C RFLP

D Southern blotting

Correct Answer: B. Microsatellite genotyping

EXPLANATION

Microsatellite (STR) genotyping uses PCR followed by capillary electrophoresis for precise size determination of amplified fragments for forensic and population studies.

Test

Q.40 Hard PCR & DNA Technology

In forensic DNA analysis, STR (Short Tandem Repeat) profiling is preferred over SNPs because:

A STRs are more conserved across populations

B STRs show higher polymorphism and discrimination power

C SNPs require more PCR cycles

D STRs are less affected by degradation

Correct Answer: B. STRs show higher polymorphism and discrimination power

EXPLANATION

STRs (variable number tandem repeats) show higher allelic variation than SNPs, providing greater discrimination power for individual identification in forensic cases.

Test

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