All Free Biology MCQs with Answers

• A. EcoRI
• B. Taq polymerase
• C. Polymerase II
• D. Ligase

Explanation: Ligase is a class of enzymes that catalyse the formation of covalent bonds using the energy released by the cleavage of ATP. Ligases are important in the synthesis and repair of many biological molecules, including DNA ligase and used in genetic engineering to insert foreign DNA into cloning vectors.

• A. Separation
• B. Purification
• C. Preservation
• D. Expression

Explanation: After the formation of the product in a bioreactor, it undergoes some processes before a finished product to be ready for marketing. Downstream processing includes separation and purification processes. The product obtained is subjected to quality control, testing and kept in suitable preservatives.

• A. Sal I
• B. EcoRV
• C. Xho I
• D. Hind III

Explanation: EcoRV is a type II restriction endonuclease isolated from certain strains of E.coli. It creates blunt ends. It recognizes the palindromic sequence of 6 bases as shown here:SalI, XhoI and HindIII restriction enzymes produce sticky ends.

• A. Transferable
• B. Single­-stranded
• C. Independent replication
• D. Circular structure

Explanation: Plasmids are extra­-chromosomal, self­-replicating, usually circular, double-­stranded DNA molecules that serve as vectors which carry foreign DNA segment and replicate inside the host cell.

• A. Bacillus subtilis
• B. Pseudomonas putida
• C. Thermus aquaticus
• D. Thiobacillus ferroxidans.

Explanation: Taq polymerase, generally used in PCR, is isolated from thermophilic bacterium Thermus aquaticus.

• A. DNAase I
• B. RNAase
• C. Hind II
• D. Protease

Explanation: Hind II is the first restriction endonuclease. It was isolated from Haemophilus influenzae Rd. It always cut DNA at a specific position producing blunt ends. DNase I is an endonuclease that cleaves DNA preferentially at phosphodiester linkages adjacent to a pyrimidine nucleotide non­specially. RNase is a type of nuclease that catalyses the degradation of RNA into smaller components. It can be endoribonuclease or exoribonuclease. A protease is an enzyme that performs proteolysis, i.e., protein catabolism by hydrolysis of the peptide bonds.

• A. Restriction enzymes
• B. DNA­-DNA hybridisation
• C. Polymerase chain reaction
• D. Zinc finger analysis

Explanation: Any small, functional, freely folded domain in which coordination of one or more zinc ions is required to stabilize its structure is known as zinc finger. The zinc finger domains are widely dispersed in eukaryotic genomes and are actively involved in sequence specific binding to DNA/RNA and contribute to protein­protein recognitions.

• A. Template
• B. Carrier
• C. Transformer
• D. Vector

Explanation: Vector is a DNA molecule that carries a foreign DNA segment and replicates inside a host cell. The vector DNA and foreign DNA carrying gene of interest are cut by the same restriction endonuclease enzyme to produce complementary sticky ends. With the help of DNA ligase enzyme, the complementary sticky ends of the two DNAs are joined to produce a recombinant DNA (rDNA), which is then introduced into the host cell.

• A. Selectable markers
• B. Ligases
• C. Restriction enzymes
• D. Probes

Explanation: Restriction enzymes recognize specific base sequences in a DNA molecule and cut its strands, e.g., EcoRI cuts DNA strands in the base sequence GAATTC.

• A. Electrophores
• B. Blotting
• C. Autoradiography
• D. PCR

Explanation: Southern blotting is based on the principle of separation of DNA fragments by gel electrophoresis followed by the identification of labelled probe hybridization. The DNA fragments are separated based on their size and charge during electrophoresis.