১.
In genetic engineering, selection markers are used to:
ব্যাখ্যা
Answer: B) Identify transformed cells
Explanation:
Selection markers differentiate transformed from untransformed cells.
৪৯তম বিসিএস ⎯ প্রাণ রসায়ন [৬০১]
মোট প্রশ্ন৫০
সিলেবাস
Exam 15
Molecular Biology (Part–2)
[Source: Class–12 and relevant books]
৪৯তম বিসিএস ⎯ প্রাণ রসায়ন [৬০১]
৪৯তম বিসিএস ⎯ প্রাণ রসায়ন [৬০১] · তারিখ অনির্ধারিত · ৫০ প্রশ্ন
২.
Heat shock during transformation:
ব্যাখ্যা
Answer: B) Facilitates DNA entry
Explanation:
Heat shock creates a thermal imbalance, driving DNA into cells.
৩.
Which vector can carry the largest DNA fragments?
ব্যাখ্যা
Answer: C) BAC
Explanation:
Bacterial Artificial Chromosomes (BACs) carry up to 300 kb of DNA.
৪.
A vector in molecular biology is:
ব্যাখ্যা
Answer: B) A carrier DNA molecule
Explanation:
Vectors carry foreign DNA into host cells for replication and expression.
৫.
EcoRI cuts DNA leaving:
ব্যাখ্যা
Answer: B) Sticky ends
Explanation:
EcoRI produces staggered cuts creating sticky ends that easily join with complementary sequences.
৬.
The primary role of primers in PCR is:
ব্যাখ্যা
Explanation:
Primers provide the starting point for DNA polymerase to extend.
৭.
Restriction enzymes are also known as:
ব্যাখ্যা
Answer: C) Restriction endonucleases
Explanation:
Restriction enzymes cut DNA at specific recognition sequences, typically palindromic, and are essential in genetic engineering.
৮.
An antibiotic resistance gene in a vector is used for:
ব্যাখ্যা
Answer: Selection of transformed cells
Explanation:
Only cells containing the plasmid grow in antibiotic-containing media.
৯.
Which is not needed for PCR?
ব্যাখ্যা
Explanation:
PCR uses DNA primers, not RNA primers.
১০.
Genomic databases such as GenBank store:
ব্যাখ্যা
Answer: B) DNA sequences
Explanation:
GenBank is a repository of nucleotide sequences.
১১.
Which is not a characteristic of a good cloning vector?
ব্যাখ্যা
Answer: D) Unstable replication
Explanation:
Stable replication ensures reliable propagation of inserted DNA.
১২.
Blue-white screening involves:
ব্যাখ্যা
Answer: B) LacZ gene
Explanation:
Blue-white screening uses disruption of the LacZ gene to identify successful recombinants.
১৩.
Cosmids are a hybrid between:
ব্যাখ্যা
Answer: B) Plasmids and bacteriophage lambda
Explanation:
Cosmids combine features of plasmids and lambda phages for cloning larger fragments.
১৪.
Multiple cloning sites contain:
ব্যাখ্যা
Answer: B) Several unique restriction sites
Explanation:
MCS allows flexibility in inserting DNA fragments.
১৫.
cDNA is synthesized from:
ব্যাখ্যা
Answer: B) RNA
Explanation:
Reverse transcriptase uses RNA as a template to make complementary DNA.
১৬.
The optimal temperature for annealing in PCR depends on:
ব্যাখ্যা
Answer: B) Primer sequence
Explanation:
Annealing temperature depends on the primer melting temperature.
১৭.
The enzyme used in PCR is:
ব্যাখ্যা
Answer: B) Taq polymerase
Explanation:
Taq polymerase is heat-resistant and derived from Thermus aquaticus.
১৮.
Real-time PCR monitors:
ব্যাখ্যা
Answer: B) DNA amplification in real time
Explanation:
It uses fluorescent markers to quantify DNA during amplification.
১৯.
The cycle number in PCR determines:
ব্যাখ্যা
Answer: B) Amount of amplified product
Explanation:
Each cycle doubles the product, leading to exponential growth.
২০.
The final step of PCR is:
ব্যাখ্যা
Answer: B) Extension
Explanation:
At this step, Taq polymerase synthesizes new DNA strands.
২১.
Transformation involves:
ব্যাখ্যা
Answer: B) Uptake of foreign DNA by a cell
Explanation:
Transformation introduces new genetic material into a host.
২২.
The process of introducing DNA into animal cells is called:
ব্যাখ্যা
Answer: B) Transfection
Explanation:
Transfection refers specifically to eukaryotic cells.
২৩.
Methyltransferases in bacteria:
ব্যাখ্যা
Answer: B) Add methyl groups to protect host DNA
Explanation:
Methylation marks host DNA as self, avoiding cleavage.
২৪.
Calcium chloride in transformation helps by:
ব্যাখ্যা
Answer: B) Making cell membranes permeable
Explanation:
CaCl₂ increases membrane permeability, aiding DNA uptake.
২৫.
The human genome contains approximately:
ব্যাখ্যা
Answer: B) 3 billion base pairs
Explanation:
The genome consists of 3 billion base pairs of DNA.
২৬.
The approximate number of human protein-coding genes is:
ব্যাখ্যা
Answer: B) 20,000–25,000
Explanation:
Only about 1.5% of human DNA codes for proteins.
২৭.
The first organism to have its genome fully sequenced was:
ব্যাখ্যা
Answer: B) Haemophilus influenzae
Explanation:
Its genome was sequenced in 1995.
২৮.
Mitochondrial DNA is inherited:
ব্যাখ্যা
Answer: B) Only from the mother
Explanation:
Mitochondria are maternally inherited.
২৯.
Shotgun sequencing involves:
ব্যাখ্যা
Answer: A) Cutting DNA into random fragments
Explanation:
Fragments are later assembled computationally.
৩০.
The term "genome" refers to:
ব্যাখ্যা
Answer: B) Total DNA content of an organism
Explanation:
A genome includes all nuclear and mitochondrial DNA.
৩১.
Which organism’s genome helped understand eukaryotic genetics early?
ব্যাখ্যা
Answer: B) Yeast (Saccharomyces cerevisiae)
Explanation:
Yeast was a model organism in genomic studies.
৩২.
SNP stands for:
ব্যাখ্যা
Answer: A) Single Nucleotide Polymorphism
Explanation:
SNPs are single base changes that contribute to genetic diversity.
৩৩.
The study of all proteins encoded by a genome is:
ব্যাখ্যা
Answer: C) Proteomics
Explanation:
Proteomics focuses on protein expression and interactions.
৩৪.
A major benefit of the HGP is:
ব্যাখ্যা
Answer: D) All of the above
Explanation:
The HGP has broad benefits across many scientific fields.
৩৫.
cDNA libraries represent:
ব্যাখ্যা
Answer: B) Coding regions (exons) only
Explanation:
cDNA libraries contain only expressed genes, not introns.
৩৬.
PCR amplifies:
ব্যাখ্যা
Answer: B) cDNA
Explanation:
PCR creates millions of copies of a specific DNA sequence.
৩৭.
The final step in cloning is:
ব্যাখ্যা
Answer: C) Screening transformants
Explanation:
Screening identifies which colonies contain the desired insert.
৩৮.
Which of the following is not a type of restriction enzyme used in cloning?
ব্যাখ্যা
Answer: D) Type IV
Explanation:
There are three major types: Type I, II, and III, with Type II most commonly used in molecular cloning.
৩৯.
Restriction enzyme digestion is usually followed by:
ব্যাখ্যা
Answer: A) Gel electrophoresis
Explanation:
Electrophoresis separates DNA fragments by size to verify successful digestion.
৪০.
The natural function of restriction enzymes in bacteria is to:
ব্যাখ্যা
Answer: B) Defend against bacteriophages
Explanation:
Bacteria use restriction enzymes to cut foreign DNA from viruses as a defense mechanism.
৪১.
The recognition sites of restriction enzymes are usually:
ব্যাখ্যা
Answer: B) Palindromic sequences
Explanation:
Most restriction enzymes recognize palindromic DNA sequences, reading the same in both directions.
৪২.
PCR products are visualized using:
ব্যাখ্যা
Answer: A) Ethidium bromide
Explanation:
Ethidium bromide binds DNA and fluoresces under UV light.
৪৩.
A blunt end is produced by:
ব্যাখ্যা
Answer: C) SmaI
Explanation:
SmaI makes straight cuts, producing blunt ends without overhangs.
৪৪.
The most common cloning vector is:
ব্যাখ্যা
Answer: B) Plasmid
Explanation:
Plasmids are small, circular DNA molecules ideal for cloning.
৪৫.
Nested PCR increases:
ব্যাখ্যা
Answer: B) Specificity
Explanation:
Nested PCR uses two sets of primers to reduce non-specific amplification.
৪৬.
Natural competence is seen in:
ব্যাখ্যা
Explanation: Some bacteria like Bacillus subtilis naturally take up DNA.
৪৭.
Electroporation uses:
ব্যাখ্যা
Answer: B) Electric pulses
Explanation:
An electric field creates pores in the cell membrane for DNA entry.
৪৮.
Competent cells are:
ব্যাখ্যা
Explanation:
Competency allows DNA uptake during transformation.
৪৯.
Heat shock is usually done at:
ব্যাখ্যা
Answer: C) 42°C
Explanation:
42°C is the standard temperature for heat shock transformation.
৫০.
The Human Genome Project began in:
ব্যাখ্যা
Answer: 1990
Explanation: The project officially launched in 1990.