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Q1. The most recent definition for biotechnology was given by

• 1) European Federation of Biotechnology
• 2) Indian Federation of Biotechnology
• 3) International Federation of Biotechnology
• 4) Chinese Federation of Biotechnology

Solution

The most recent definition for biotechnology was given by the European Federation of Biotechnology. The definition states that biotechnology is the integrated use of biochemistry, microbiology and engineering sciences in order to achieve technological application of the capabilities of microorganisms, cultured tissue/cells and parts thereof.

Q2. Gel electrophoresis is used for

• 1) Cutting of DNA into fragments
• 2) Separation of DNA fragments according to their size
• 3) Construction of recombinant DNA by joining with cloning vectors
• 4) Isolation of DNA molecules

Solution

Gel electrophoresis is a technique used for the separation of substances of different ionic properties. During electrophoresis, DNA fragments move towards the anode according to their molecular size through the agarose gel.

Q3. The first restriction endonuclease was isolated by

• 1) Paul Berg
• 2) Arber, Nathan and Smith
• 3) Annie Chang and Stanley Cohen
• 4) Collins and Hohn

Solution

The first restriction endonuclease was isolated by Arber, Nathan and Smith from the bacterium Haemophilus parainfluenzae.

Q4. Two microbes found to be very useful in genetic engineering are

• 1) Vibrio cholerae and a tailed bacteriophage
• 2) Crown gall bacterium and Caenorhabditis elegans
• 3) Diplococcus sp. and Pseudomonas sp.
• 4) Escherichia coli and Agrobacterium tumefaciens

Solution

Escherichia coli possesses plasmid which encodes genes that may act as selectable markers in transformations. Agrobacterium tumefaciens possesses Ti plasmid that induces tumour formation. These have been used as vectors to transfer foreign genes of interest into the target animal and plant cells.

Q5. For transformation, micro-particles coated with DNA to be bombarded with gene gun are made up of :

• 1) Silicon or Platinum
• 2) Gold or Tungsten
• 3) Silver or Platinum
• 4) Platinum or Zinc

Solution

The technique of shooting foreign DNA into plant cells at a very high velocity is called biolistics. In this method, 1-2m gold or tungsten particles coated with DNA are shooted into the plant cells using a helium pressure particle gun device.

Q6. Restriction endonuclease

• 1) Cuts the DNA molecule at specific sites
• 2) Restricts the synthesis of DNA inside the nucleus
• 3) Cuts the DNA molecule randomly
• 4) Synthesizes DNA

Solution

Restriction endonucleases inspect the DNA molecule in search of specific recognition sequence. Once it gets its specific recognition sequence, it binds to the site and cuts each of the two strands of the double helix at specific points by hydrolyzing the phosphodiester bond.

Q7. Taq polymerase is isolated from

• 1) Thermus aureus
• 2) Thermophilus aureus
• 3) Thermus aquaticus
• 4) Thermophilus aquaticus

Solution

Taq DNA polymerase is isolated from the thermophilus bacteria Thermus aquaticus.

Q8. Stanley and Herbert isolated the antibiotic-resistant gene from the plasmid of

• 1) Streptococcus thermophilus
• 2) Salmonella typhimurium
• 3) Saccharomyces cerevisiae
• 4) Penicillium roqueforti

Solution

Stanley and Herbert isolated the antibiotic-resistant gene from the plasmid of the bacterium Salmonella typhimurium.  

Q9. Who discovered recombinant DNA (rDNA) technology?

• 1) Stanley Cohen and Herbert Boyer
• 2) James D. Watson
• 3) Har Gobind Khorana
• 4) Walter Sutton and Avery

Solution

Herbert Boyer and Stanley Cohen combined their efforts in biotechnology to invent the rDNA technology method of cloning genetically engineered molecules in foreign cells. Har Gobind Khorana research helped to show how the order of nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins. James D. Watson is best known as a co-discoverer of the structure of DNA in 1953 with Francis Crick. Walter Sutton and Avery proposed that chromosomes bear hereditary factors. 

Q10. Use of biology in industrial process and for improving quality of life is called:

• 1) Biotechnology
• 2) Eugenics
• 3) Microbiology
• 4) Genetic engineering

Solution

Use of biology in industrial process and for improving quality of life is called biotechnology. Microbiology is the study of microscopic organisms. Genetic engineering is the direct manipulation of an organism's genome using biotechnology. Eugenics is the belief and practice of improving the genetic quality of human population.

Q11. A bioreactor is:

• 1) Culture containing radioactive isotopes
• 2) Fermentation tank
• 3) Culture for synthesis of new chemicals
• 4) Hybridoma

Solution

Bioreactors are large vessels with a capacity of 100 to 1000 litres, which are used for biological conversion of raw materials into specific products. Each bioreactor has a cylindrical stirred tank to facilitate the mixing of contents. It has an agitator system to mix the contents properly, an oxygen delivery system to make availability of oxygen, a foam control system, a temperature control system, a pH control system and a sampling port to withdraw small volumes of the culture periodically.

Q12. The process of extension requires which of the following ions?

• 1) Na²⁺
• 2) Cl²⁻
• 3) Mn²⁺
• 4) Mg²⁺

Solution

The process of extension in PCR requires the presence of Taq DNA polymerase, deoxynucleoside triphosphate and Mg²⁺.

Q13. Who is regarded as the ‘father of genetic engineering’?

• 1) Hohn
• 2) Stanley Cohen
• 3) Hamilton Smith
• 4) Paul Berg

Solution

Paul Berg was the first to successfully introduce a gene (SV-40) into a bacterium with the help of a lambda phage, and hence, he is regarded as the ‘father of genetic engineering’.

Q14. The ability of a cell to grow into a complete plant is called:

• 1) Cellular totipotency
• 2) Tissue culture
• 3) Protoplasmic fusion
• 4) Somaclonal variation

Solution

Cellular totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism. Somaclonal variation is the variation seen in plants that have been produced by plant tissue culture. Protoplast fusion is a type of genetic modification in plants by which two distinct species of plants are fused together to form a new hybrid plant with the characteristics of both. Tissue culture is a process that involves exposing plant tissue to a specific regimen of nutrients, hormones and light under sterile, in vitro conditions to produce many new plants, each of which is a clone of the original mother plant, over a very short period of time.

Q15. One of the key factors, which makes plasmid the vector in genetic engineering is that

• 1) It has the ability to carry a foreign gene.
• 2) It is resistant to antibiotics.
• 3) It is resistant to restriction enzymes.
• 4) It has the ability to cause infection in the host.

Solution

Plasmids are small, double stranded, closed circular symbiotic DNA molecules that occur naturally in bacteria outside the bacterial chromosome. They have the capability to self-replicate in the cytoplasm of the bacterial cell and are used as carriers for transferring a fragment of foreign DNA into a suitable host.

Q16. In the process of electroporation, the application of electric current causes

• 1) Disintegration of the cell membrane
• 2) Disintegration of the cell wall
• 3) An increase in the charge on protoplasts
• 4) An increase in the porosity of protoplasts

Solution

In the process of electroporation, the application of electric current increases the porosity of protoplasts. This causes the cell to easily take up the foreign DNA present in the outside of the cell.

Q17. Who developed the technique of electrophoresis? State its principle.

Solution

Electrophoresis was developed by Tiselius in 1937 as a method for the separation of substances with different ionic properties. It is based on the principle that charged particles move under the influence of electric current to oppositely charged electrodes.

Q18. The temperature required for the process of annealing is carried out at a temperature of

• 1) 30-50°C
• 2) 20-40°C
• 3) 40-60°C
• 4) 30-80°C

Solution

In PCR, annealing is the second step. In this process, the denatured DNA strands are hybridised to the DNA primers. The step is carried out at 40-60°C.

Q19. The bonds which are broken down during the denaturation step of PCR are

• 1) Peptide bonds
• 2) Covalent bonds
• 3) Phosphodiester bonds
• 4) Hydrogen bonds

Solution

In the denaturation step of PCR, the two strands of the DNA molecule are split apart. Because the two strands are held together by hydrogen bonds between the complementary nitrogen bases on each strand, hydrogen bonds are broken down during this step.

Q20. The polymerase chain reaction is a technique that

• 1) is used for in vivo synthesis of mRNA
• 2) is used for in vitro replication of specific DNA sequence using thermostable DNA polymerase
• 3) is used for in vivo replication of DNA
• 4) is used for in vitro synthesis of mRNA

Solution

Polymerase chain reaction is based on the principle that a DNA molecule, when subjected to high temperature, splits into two strands due to denaturation. These single stranded molecules are then converted to original double stranded molecules by synthesizing new strands in presence of enzyme DNA polymerase.

Q21. Who among the following was awarded the Nobel Prize for the development of PCR technique?

• 1) Kary Mullis
• 2) Har Gobind Khurana
• 3) Herbert Boyer
• 4) Arthur Kornberg

Solution

Herbert W. Boyer discovered a method to coax bacteria into producing foreign proteins, thereby jump starting the field of genetic engineering. Har Gobind Khorana research helped to show how the order of nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins. Arthur Kornberg was the first scientist to identify deoxyribonucleic acid (DNA) polymerase in the intestinal bacterium E coli. Kary Mullis received a Nobel Prize in Chemistry in 1993 for his invention of the Polymerase Chain Reaction (PCR).

Q22. How and why is bacterium Thermus aquaticus employed in recombinant DNA technology? Explain.

Solution

DNA polymerase is obtained from the bacterium, Thermus aquaticus. (i) DNA polymerase obtained from this organism (Taq DNA polymerase) is thermostable and remains active during high temperature applied during the denaturation of double-stranded DNA. (ii) This enzyme extends the primers using nucleotides provided in the reaction and the genomic DNA as template. (iii) The repeated amplification is achieved by this enzyme and the amplified fragment, if desired can be used to ligate with a vector for further cloning.

Q23. State the uses of cloning vector in biotechnology.

Solution

Cloning vectors are used for transferring fragments of foreign DNA into a suitable host. They play an important role in selecting recombinants from non-recombinants.

Q24. Which enzyme is used to dissolve fungal cell walls?

• 1) Lysozyme
• 2) Cellulase
• 3) Hydrolase
• 4) Chitinase

Solution

The chief component of the fungal cell wall is chitin. Hence, chitinase is used for dissolving the fungal cell wall.

Q25. Explain the importance of (a) ori, (b) amp^R and (c) rop in the E. coli vector shown below:                            

Solution

(a) ori: Ori or origin of replication is a specific portion of plasmid genome that serves as a start signal for self-replication. Any piece of DNA when linked to this sequence can be made to replicate within the host cells. It is also responsible for controlling the copy number of the linked DNA. (b) amp^R: The ligation of foreign DNA is carried out at a restriction site present in any antibiotic resistance gene. It acts as a selectable marker during transformation. (c) rop: It codes for the proteins involved in the replication of the plasmid.

Q26. Explain any two methods of vectorless gene transfer.

Solution

The two methods of vectorless gene transfer are as shown below: (i) Microinjection: The technique of introducing foreign DNA into a target cell by injecting the DNA directly into the nucleus with the help of a micro-needle is called micro-injection. (ii) Electroporation: The process in which transient holes are produced in the plasma membrane of the target cell to incorporate foreign DNA is called electroporation.

Q27. Agarose extracted from sea weeds is used in

• 1) Spectrophotometry
• 2) PCR
• 3) Tissue culture
• 4) Gel electrophoresis

Solution

Agarose is the most commonly used matrix in gel electrophoresis. It is a polysaccharide extracted from sea weeds. DNA fragments move towards the anode according to their molecular size through the agarose gel.

Q28. Why is enzyme cellulase used for isolating genetic material from plant cells but not from animal cells?

Solution

Plant cells have cellulose in their cell wall which can be degraded using the enzyme cellulase for isolating the genetic material DNA. On the other hand, animal cell wall does not contain cellulose. Hence, cellulase is not required for isolating DNA.

Q29. What are recombinant proteins? How do bioreactors help in their production?

Solution

The protein produced by genetically altered DNA (recombinant DNA) in a heterologous host is called recombinant protein. Bioreactors are vessels in which raw materials are biologically converted into specific products by microbes. It provides optimum growth conditions such as temperature, pH, substrate, vitamins, oxygen and salts for the production of recombinant proteins.

Q30. What is a cloning vector? Explain the technique of using such a vector in E.coli.

Solution

Cloning vectors are DNA molecules used as carriers for transferring a fragment of foreign DNA and capable of replicating inside the host cell independent of the control of chromosomal DNA. Plasmids and bacteriophages are commonly used cloning vectors. The technique of using cloning vector in E. coli is as follows: (i) The foreign DNA is linked to the sequence called ori (origin of replication) and is made to replicate within the host cell. (ii) The ligation of foreign DNA is carried out at a restriction site present in the resistance genes. (iii) The foreign DNA is then attached to the plasmid DNA (vector) with the help of enzyme ligase. (iv) This recombinant DNA (rDNA) is inserted into the bacterial cell where it multiplies to produce multiple copies of the desired gene.        

Q31. (a) What are molecular scissors? Give one example. (b) Explain their role in recombinant DNA technology.

Solution

(a) Restriction endonucleases are called molecular scissors as they cut the DNA segments at particular locations. Example: EcoRI. (b) Restriction enzymes cut the DNA strands some distance away from the centre of the palindromic sites, but between the same two bases on the opposite strands. This leaves single stranded portions with overhanging stretches called sticky ends on each strand as they form hydrogen bonds with their complementary cut counterparts. This stickiness at the ends of DNA fragments facilitates the action of enzyme DNA ligase.

Q32. How is DNA isolated in purified form from a bacterial cell?

Solution

DNA, the genetic material of bacteria is isolated in purified form by treating the bacterial cells with enzyme, lysozyme to dissolve the cell wall. The RNA can be removed by treating them with enzyme, ribonuclease and proteins can be removed by treatment with enzyme protease which converts proteins to amino acids. Finally, chilled ethanol is added to precipitate the purified DNA.

Q33. What is a bioreactor?

Solution

Bioreactors are large cylindrical vessels of about 100-1000 litres in volume, which are used for biological conversion of raw materials into specific products.

Q34. What is genetic engineering? List the steps involved in rDNA technology.

Solution

Genetic engineering involves techniques to alter the chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus, change the phenotype of the host organism. Steps in rDNA technology: (i) Isolation of DNA (ii) Fragmentation of DNA by restriction endonucleases (iii) Isolation of the desired DNA fragments (iv) Amplification of gene of interest (v) Ligation of the DNA fragment into a vector using DNA ligase (vi) Transfer of recombinant DNA into the host organism (vii) Culturing the host cell on a suitable medium on a large scale (viii) Extraction of the desired product (ix) Downstream processing of the products as finished products are ready for marketing

Q35. How can DNA segments be separated by gel electrophoresis, visualised and isolated?

Solution

As pure DNA fragments cannot be seen under visible light, they can be visualised only after staining them with a solution of ethidium bromide followed by exposure to UV radiation. They appear as bright orange coloured bands. The separated bands of DNA are then cut from the agarose gel and extracted by using a convenient technique. This process is called elution. The eluted DNA fragments are then purified and used in constructing recombinant DNA by joining them with cloning vectors.

Q36. How is the amplification of a gene sample of interest carried out using Polymerase Chain Reaction (PCR)?

Solution

Polymerase Chain Reaction (PCR) is a technique used to synthesize multiple copies of the desired gene in vitro within a short span of time. Amplification of a gene sample of interest is carried out using PCR in the following three steps: (a) Denaturation: The double stranded DNA is denatured by applying high temperature of about 95C for 15 seconds. Each separated single stranded strand now acts as template for the synthesis of new DNA strand. (b) Annealing: Two sets of primers are added which anneal at the 3’ end of each separated strand. They mark the beginning of replication. (c) Extension: A thermostable DNA polymerase, Taq polymerase extends the primers by adding nucleotides complementary to the template provided in the reaction. The cycle of denaturation, annealing and extension is repeated several times to obtain several copies of desired DNA.