Question 1

During PCR, primers bind to the DNA strands in the __________ step.

Accepted Answer

Polymerase Chain Reaction (PCR) involves three main steps: 1. Denaturation: The double-stranded DNA is heated to separate it into two single strands. 2. Annealing: The temperature is lowered to allow the oligonucleotide primers to bind (anneal) to their complementary sequences on the single-stranded DNA templates. 3. Extension: The temperature is raised, and Taq DNA polymerase synthesizes the new DNA strand by adding nucleotides to the primers. Therefore, primers bind to the DNA strands during t

Question 2

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R . Assertion A : In recombinant DNA technology, lysozyme is used for disrupting bacterial cells whi

Accepted Answer

Assertion A is a correct statement. In recombinant DNA technology, bacterial cells are treated with the enzyme lysozyme to degrade their peptidoglycan cell walls, while plant cells are treated with cellulase to degrade their cellulosic cell walls. Reason R is also a correct statement. The isolation of genetic material requires the disruption of the cell to release DNA along with other macromolecules like RNA, proteins, polysaccharides, and lipids. However, Reason R does not explain the specifici

Question 3

Which of the following statements are not true regarding restriction endonucleases ? A. They are called molecular scissors. B. These are the enzymes responsible for restricting the growth of bacteriop

Accepted Answer

Restriction endonucleases are commonly known as molecular scissors as they cut DNA at specific locations. Thus, statement A is true. They were discovered for their ability to restrict the growth of bacteriophages in bacteria such as E. coli . Thus, statement B is true. Restriction endonucleases cut the DNA helix a little away from the centre of the palindromic sites, but between the same two bases on the opposite strands. Thus, statement C is incorrect. Exonucleases remove nucleotides from the e

Question 4

Which of the following statements are correct with respect to DNA separation, isolation and visualization ? A. The cutting of DNA is done by molecular scissors. B. The DNA fragments separate according

Accepted Answer

Statement A is correct. Restriction endonucleases are commonly referred to as molecular scissors because they cut DNA molecules at specific recognition sites. Statement B is correct. During gel electrophoresis, DNA fragments are separated based on their size through the sieving effect of the agarose gel. Smaller fragments move farther and faster than larger ones. Statement C is incorrect. Separated DNA fragments cannot be seen without staining. They must be stained with a specific dye, such as e

Question 5

Match List I with List II : List I List II A. Genetically modified organism I. Agrobacterium tumefaciens B. Thermostable DNA polymerase II. Bt cotton C. Ti plasmid III. Thermus aquaticus D. pBR322 IV.

Accepted Answer

Bt cotton is a genetically modified organism created by inserting the cry gene from Bacillus thuringiensis into cotton. Thermostable DNA polymerase, such as Taq polymerase used in PCR, is isolated from the thermophilic bacterium Thermus aquaticus. Ti plasmid (Tumor-inducing plasmid) is naturally found in Agrobacterium tumefaciens, which is used as a cloning vector for plants. pBR322 is a widely used artificial plasmid cloning vector in Escherichia coli. Therefore, the correct matching is A-II, B

Question 6

In the above represented plasmid, an alien piece of DNA is inserted at EcoRI site. Which of the following strategies will be chosen to select the recombinant colonies?

Accepted Answer

The correct answer is that white-colored colonies will be selected. Since an alien piece of DNA is being inserted at EcoRI site, the gene -galactosidase present here will undergo insertional inactivation. This gene is responsible for producing blue-colored colonies, but since it has been insertionally inactivated, white colored colonies will be produced. Ampicillin and tetracycline resistance genes present in the given DNA will remain intact. Thus, the given DNA will show amp ^R and tet ^R.

Question 7

Given below are two statements : Statement I: The DNA fragments extracted from gel electrophoresis can be used in construction of recombinant DNA. Statement II : Smaller size DNA fragments are observe

Accepted Answer

The cutting of DNA by restriction endonucleases results in the fragments of DNA. These fragments can be separated by a technique known as gel electrophoresis. The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. This step is known as elution. The DNA fragments purified in this way are used in constructing rDNA by joining them with cloning vectors. - In gel electrophoresis, the DNA fragments separate (resolve) according to their size through sieving effect

Biotechnology - Principles and Processes — Previous Year Questions & Solutions