AIPMT AIIMS IBO PMT MCAT Biotechnology Questions

1. Expand the term GMO.
2. Name the bacterium that yields a thermostable DNA polymerase.
3. Which hormone has been genetically isolated from the plasmid of £ coli by American company Eli Lilly?
4. When was the first gene therapy given?
5. Name the compound used for staining the isolated DNA in gel electrophoresis?
6. State the two core techniques which enabled the birth of modern biotechnology.
7. ” Biotechnology has been a very useful technique in the present scenario.” Justify this statement by giving any two examples.
OR
State any two advantages of using GMO plants over conventional ones.
8. Why are restriction enzymes termed as “molecular scissors”?
11. What are the three basic critical research areas of biotechnology?
OR
State the three basic steps involved in genetically modifying an organism.
12. Explain the importance of (i) ori, (ii) amp* and (iii) rop in the E.coli vector shown below.
13. How can the bacterial cells be made competent to take up recombinant DNA? State the method suitable in animals, in which the recombinant DNA is directly injected into their nucleus.
9. Give any four differences between plasmid DNA and chromosomal DNA.
10. What do you understand by GEAC? What is its importance?
11. What are the three basic critical research areas of biotechnology?
OR
State the three basic steps involved in genetically modifying an organism.
12. Explain the importance of (i) ori, (ii) amp* and (iii) rop in the E.coli vector shown below.
13. How can the bacterial cells be made competent to take up recombinant DNA? State the method suitable in animals, in which the recombinant DNA is directly injected into their nucleus.

ecoli vector
14. (i) How do endonucleases and exonucleases differ from each other?
(ii)What do you mean by ‘palindromic nucleotide sequences’? Explain with an example.
15. (i) Who discovered recombinant DNA technology for the first time?
(ii) Give the diagrammatic representation of recombinant DNA technology.
16. (i) What are vectors?
(ii) What essential features are required for facilitating cloning into a vector?
17. How is DNA isolated from prokaryotic and eukaryotic cells?
18. (i) What are ‘selectable markers’?
(ii) Name the different tools used in recombinant DNA technology.
19. (i) What do you mean by ‘transgenic animals‘?
(ii) How are transgenic animals useful in chemical safety testing?
20. (i) What do you mean by the term ‘biopiracy’?
(ii) What measures are being taken by the Indian government to prevent biopiracy?
21. (i) Name the bacterium which produces Bt toxin? What is the significance of this toxin?
(ii) Name the gene which codes for this toxin. Why does this toxin not kill the bacterium?
(iii) Name the genes that prevent infection by cotton bollworms and corn borers in pest resistant plants.
22. Riya, a 6 year old girl is diagnosed with adenosine deaminase (ADA) deficiency. This enzyme plays an important role in the working of the immune system. What may be the best possible treatment given to her in this regard? Is there any permanent cure for her problem?
23. Students of class XII attended the class presentation on “Creation of transgenic plants and animals with the help of biotechnology.”
The students then discussed with their teacher, the pros and cons of creating transgenic plants and animals.
(i) Do you think the students are justified, while discussing pros and cons of transgenic plants and animals? Why?
(ii) What type of ethical issues are connected with development of transgenic animals?
24. Explain the technique of Agarose gel electrophoresis. OR
(i) What does PCR stand for?
(ii) Give the diagrammatic representation of PCR.
(iii) What are the areas of application of PCR?
25. (i) Why is Agrobacterium tumifaciens used as a vector for gene cloning in dicot plants?
(ii) How is gene gun useful? Draw its diagram.
OR
(i) What are bioreactors? Name the two types of bioreactors.
(ii) What do you mean by downstream processing? Explain the technique.
26. (i) What is RNA interference (RNAi)? Explain.
(ii) Give two examples of transgenic plants.
OR
(i) Name the first restriction endonuclease enzyme and its function.
(ii) What convention is used for naming the restriction enzymes? Explain with an example.

Answers

1. Genetically Modified Organisms.
2. Thermus aquaticus is the bacterium that yields a thermostable DNA polymerase.
3. Human insulin is genetically isolated from the plasmid of £ coli. by the American company Eli Lilly.
4. The first gene therapy was given to four year old girl with adenosine deaminase (ADA) deficiency in 1990.
5. Ethidium bromide is the compound used for staining the isolated DNA in the gel electrophoresis.
6. The two core techniques that enabled birth of modern biotechnology are:
(i) Genetic engineering: The different techniques used to alter the nature of genetic material (DNA and RNA) and then introducing them into the host organisms resulting in change of phenotype of the host organisms.
(ii) Chemical engineering : Maintenance of sterile (microbial contamination-free) ambience in chemical engineering processes enables growth of only the desired microbe/eukaryotic cells in large quantities for the manufacture of biotechnological products like antibiotics, vaccines, enzymes, etc.
7. Biotechnology is the integrated use of biochemistry, microbiology and engineering sciences in order to achieve technological (industrial) application of the capabilities of microorganisms, cultured tissues/cells and parts thereof. It has created a revolution in the field of medicine and technology. Examples include invitro fertilization leading
to development of test tube baby, developing a DNA vaccine, and correcting a defective gene. All this has been possible due to biotechnology.
OR
Two advantages of using genetically modified (GMO) crops are:
(i) They are more tolerant to abiotic stresses (cold, drought, salt, heat).
(ii) They have enhanced nutritional value.
8. Restriction enzymes are termed as “molecular scissors” because they cut DNA duplex at specific locations.
9. Differences between plasmid DNA and Chromosomal DNA are:

Plasmid DNA Chromosomal DNA
1 It is always double stranded. It may be single stranded or double stranded.
2 It is circular It is linear or circular.
3 It is naked, without histone protein. It is coated with histone protein.
4 It does not carry any vital gene necessary for the cell. It carries vital genes necessary for the cell.

10. GEAC stands for Genetic Engineering Approval Committee. It makes decisions regarding the validity of GM research and the safety of producing GM organisms for public services.
11. The three basic critical research areas of biotechnology include:
(i) Providing the best catalyst in the form of improved organism usually a microbe or pure enzyme.
(ii) Creating optimal conditions through engineering for a catalyst to act, and
(iii) Downstream processing technologies to purify the protein/organic compound.
OR
The three basic steps involved in genetically modifying an organism are:
(i) Identification of DNA with desirable genes.
(ii) Introduction of the identified DNA into the host.
(iii) Maintenance of introduced DNA in the host and transfer of the DNA to its progeny.
12. (i) ori: ori is origin of replication. This is a sequence from where replication starts, and any piece of DNA, when linked to this sequence, can be made to replicate
within host cells. It also controls the copy number of the linked DNA.
(ii) ampR: It is a gene for ampicillin resistance which helps in selecting the transformants.
(iii) rop: rop codes for the proteins involved in replication of the plasmid.
13. Bacterial cells can be made ‘competent’ to take up recombinant DNA by treating them with a specific concentration of a divalent cation, such as calcium, which increases the efficiency with which DNA enters the bacterium through pores in its cell wall. Micro-injection is a method suitable for animals, in which the recombinant DNA is directly injected into their nucleus.
14. (i) Exonucleases remove nucleotides from the ends of the DNA, but endonucleases make cuts at specific positions within the DNA.
(ii) Palindromic nucleotide sequence in DNA is a sequence of base pairs, that reads same on the two strands, when orientation of reading is kept the same. For example, the following sequences read the same on the strand in 5′ -» 3′ direction, and in the 3′ —> 5′ direction also.
5′——–GAATTC———3′
3′———CTTAAG———5′
Palindromic sequences are the sites at which the DNA is cleaved by restriction enzymes.
15. (i) Cohen and Boyer discovered recombinant DNA technology for the first time.
(ii) The diagrammatic representation of recombinant DNA technology is:

recombinant-dna-technology16. (i) The vectors are DNA molecules that can carry a foreign DNA segment and replicate inside the host cell. They include plasmids, bacteriophages, cosmids, yeast artificial chromosomes (YACs), bacterial artificial chromosomes (BACs) and viruses.
(ii) The essential features required to facilitate cloning into a vector are:
(a) Origin of replication [or!) : This is a sequence from where replication starts and any piece of DNA, when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA.
(b) Selectable markers: In addition to ‘ori’, the vector requires a selectable marker, which helps in identifying and eliminating non-transformants and selectively permitting the growth of transformants.Transformation is a procedure through which a piece of DNA is introduced in a host bacterium.
(c) Cloning sites : In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes.
17. In prokaryotes, the bacterial cells are treated with certain lysozymes to break the cell wall. In eukaryotes, plant cells are treated with cellulase; in case of fungi, they are treated with chitinase.
This helps to break the cell open and release DNA along with other macromolecules, such as RNA, proteins, polysaccharides and also lipids. These are removed by appropriate treatments, such as proteins are removed by treatment with proteases, and RNA by treatment with ribonudease.The purified DNA is finally precipitated after the addition of chilled ethanol, which can be seen as a collection of fine threads in suspension.
18. (i) Selectable marker is the sequence on DNA, which helps in identifying and eliminating nontransformants and selectively permitting the growth of transformants.
(ii) The tools of recombinant DNA technology are :
(a) Enzymes such as restriction enzymes, polymerase enzymes and ligases.
(b) Cloning vectors (Vehicle DNA) such as bacteriophages, plasmids.
(c) Competent host for transformation with recombinant DNA.
19. (i) The animals in which foreign genes have been introduced by genetic engineering are called transgenic animals.
(ii) Chemical safety testing is known as toxicity/safety testing. Transgenic animals are developed that carry genes which make them more sensitive to toxic substances than non-transgenic animals. They are then exposed to the toxic substances and the effects studied. Toxicity testing in such animals will allow us to obtain results in less time.
20. (i) Biopiracy is the term for bio-resources used by multinational companies and other organisations without proper authorisation from the countries or people concerned and without any compensatory payment.
(ii) The Indian Parliament has recently cleared the second amendment of the Indian Patents Bill, that takes biopiracy issues into consideration, including patent terms, emergency provisions, research and development initiatives.
21. (i) Bacillus thuringiensis is the bacterium which produces Bt toxin. This protein kills certain insects such as lepidopterans (tobacco budworm, army worm), coleopterans (beetles) and dipterans (flies, mosquitoes).
(ii) cry gene codes for this toxin. The toxin does not kill the bacterium Bacillus, as it exists in the form of inactive protoxins. However, once an insect ingests the inactive toxin, it is converted into an active form of toxin, due to the alkaline pH of the gut, which then creates pores in the midgut epithelial cells.
(iii) Proteins encoded by genes crylAcand cryllAb control the cotton bollworms, while crylAb controls corn borers.
22. Riya is diagnosed with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. ADA is caused due to deletion of the gene for adenosine deaminase. The possible treatment given to her includes bone marrow transplantation. Also, it can be treated by enzyme replacement therapy in which functional ADA is given to her by injection. Both these approaches are not completely curative. If the gene is (responsible for ADA) isolated from marrow cells and introduced into cells at an early embryonic stage, then it could be a permanent cure.
23. (i) Production of transgenic organisms has its own advantages and disadvantages.Transgenic plants are resistant to various diseases, tolerant to adverse environmental conditions and produce pharmaceutically important compounds.
Similarly transgenic animals are useful to humans in various regards e.g., transgenic sheep having antihaemophiliac factor IX gene in their genome have been produced. Clotting factor IX obtained from such transgenic sheep can be administered to the haemophiliac patients.
However, the introduction of these transgenic organisms has also created certain controversies.
bromide, followed by exposure to UV radiation. We can see bright orange coloured bands of DNA in a ethidium bromide stained gel exposed to UV light. The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece (elution). The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with cloning vectors.
OR
(a) Transgenes in commercial crops can endanger native species. For example, the gene for Bt toxin expressed in pollen might endanger pollinators like honeybees.
(b) These crops cause problems in human health by supplying allergens and transfer of antibiotic resistance markers.
(c) They also cause damage to the natural environment.
(d) Transgenic crops are always costly, so that they are adverse to the interest of the farmers.
Thus, students are justified in discussing the pros and cons of transgenic plants and animals.
(ii) The ethical issues connected to the production of transgenic animals include:
1. Introduction of a transgene from one species into another species violates the ‘integrity of species’.
2. Transfer of human genes into animals (and vice- versa) dilutes the concept of ‘humanness’.
3. When animals are used for production of pharmaceutical proteins, they are virtually reduced to the status of a ‘factory’.
4. Use of animals in biotechnology causes great suffering to them.
5. It is disrespectful to living beings, and it only exploits them for the benefit of human beings.
24. Gel electrophoresis is a technique of separating the molecules such as DNA, RNA or protein on the basis of their size, under the influence of an electrical field. DNA fragments are negatively charged molecules, thus they can be separated by forcing them to move towards the anode under an electric field through a medium/ matrix (agarose gel). The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves.
The separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium
(i) PCR stands for Polymerase Chain Reaction.
(ii) The diagrammatic representation of PCR :
Region to be amplified
polymerase-chain-reaction

(iii)Areas of application of PCR are :
(a) Detection of pathogens: PCR is being used in the detection of HIV.
(b) Diagnosis of diseases: Phenylketonuria, sickle cell anaemia, chlamydia, tuberculosis etc can be diagnosed by PCR.
(c) DNA fingerprinting
(d) Detection of specific microorganisms.
(e) In prenatal diagnosis: PCR is useful to detect genetic disease in foetus before birth.
(f) Diagnosis of plant pathogens e.g. viroids, viruses (like TMV, mycoplasma), bacteria etc.
(g) Gene therapy : It helps to monitor a gene in gene therapy experiments.
25. (i) Agrobacterium tumifaciens, a pathogen of several dicot plants serves as a useful vector, to deliver a piece of DNA known as ‘T-DNA’, to transform normal plant cells into a tumor, and direct these tumor cells to produce the chemicals required by the pathogen. The tumor inducing (Ti) plasmid of Agrobacterium tumifaciens has
now been modifi ed into a cloning vector, which is no more pathogenic to plants, but is still able to use the mechanisms to deliver genes of our interest into a variety of plants.
(ii) In gene gun or biolistics method, tungsten or gold particles, coated with foreign DNA are bombarded into target cells at a very high velocity. This method is suitable for plants and is also used to insert genes into animals that promote tissue repair into cells (particularly cancer of mouth) near wounds.

gene-gun(i) The vessels in which large volumes of raw materials (100- 1000 litres) are biologically converted into specifi c products by microbes, plant and animal cells and/or their enzymes, are called bioreactors. A bioreactor provides the optimal conditions for obtaining the desired product. It has optimum growth conditions such as temperature, pH, substrate, vitamins, oxygen and salts. The two most commonly used bioreactors are simple stirred-tank bioreactor and sparged stirred-tank bioreactor.
(ii) After the formation of the product in bioreactors, it has to be subjected through a series of processes before it is ready for marketing as a finished product.
The processes include separation and purifi cation, which are collectively referred to as downstream processing.
The product is formulated with suitable preservatives, and in case of drugs, undergoes thorough clinical trials. Strict quality control testing for each product is also required.
The downstream processing and quality control testing vary from product to product.
26. (i) RNAi takes place in all eukaryotic organisms as a method of cellular defense. This strategy was adopted to prevent the infestation of nematode Meloidegyne incognita in the roots of tobacco plant.
It involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to, and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate, (ii) Two examples of transgenic plants are Bt corn and Bt cotton.
OR
(i) The fi rst restriction endonuclease was isH/ndll, isolated from Haemophilus influenzae.
Hindll always cuts DNA molecules at a particular point, by recognizing a specific sequence of six base pairs. This specific base sequence is known as the recognition sequence for H/ndll.
(ii) The convention for naming these enzymes:
(a) The first letter of the name comes from the genus.
(b) The second two letters come from the species of the prokaryotic cell from which they were isolated, e.g. EcoRI comes from Escherichia coli RY 13.
(c) The capital letter E comes from the genus Escherichia.
(d) The letters co are from the species coli.
(e) The letter R is from RY13 (strain).
(f) The Roman number I indicates that it was the first enzyme isolated from the bacterium E. coli RY13.

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