Class 12 Biology Chapter 11 Biotechnology: Principles and Processes The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 2nd Year Biology Chapter 11 Biotechnology: Principles and Processes Question Answer.
Class 12 Biology Chapter 11 Biotechnology: Principles and Processes
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Biotechnology: Principles and Processes
Chapter – 11
Very Short Answer Type Questions
Q.1. What do you understand by PCR?
Ans : PCR means Polymerase Chain Reaction. With the help of this one can multiply any fraction of DNA.
Q.2. What is Biotechnology?
Ans : Technical use of the knowledge of biology for production of useful substances is called biotechnology.
Q.3. Define recombinant DNA technology. What is the popular terminology of it.
Ans : Reconstruction of DNA by addition or deletion of genes is called DNA recombinant technology.
Q.4. What do you mean by bioreactors?
Ans : Bioreactor is a kind of formentor which provides a control environment for growth of microorganism for obtaining a desired product.
Q.5. What is cloning vector?
Ans : In DNA recombinant technology gene from one DNA is remove and transferred to another DNA. This is called gene cloning. For this purpose a vector is necessary to carry the DNA fragment to the target DNA. Generally some viruses and plasmids are used as vector for this purpose.
Q.6. Expand the terms Ori and EcoRI.
Ans : Ori is a plasmid vector. It means origin of replication. For all replication purpose this is essential. EcoRI stands for Escherichia Coli Ry 13. It is also a plasmid vector.
Q.7. What is gene gun?
Ans : During recombination DNA gene collected from other source is inserted in various ways, the most common method is use of plasmid as vector. There another method by which gene is pushed into cell by force. The device acts like gunshot and hence it is called gene gun.
Q.8. What is the function of DNA ligase?
Ans : It is an enzyme used to join two pieces of DNA.
Q.9. In respect to mode of action how can you differentiate enzyme exonuclease from endonuclease?
Ans : Endonuclease cut DNA to separate nucleotide sequence away from the ends. Exonuclease cut nucleotide sequence from the ends of the DNA.
Q.10. What is competent cell?
Ans : The cells produced by applying biotechnology in called competent cells.
Q.11. Who first generated the recombinant DNA molecules?
Ans : Stanley Cohen and Herbert Boyer.
Q.12. What is gene cloning?
Ans : Gene cloning means isolation of gene and then making multiple cOpies of it by inserting it into a bacterial cell or another organisms.
(B). Fill up the blanks:
Q.1. Each restriction endonuclease recognizes a specific ____ in the DNA.
Ans : Palindromic sequence.
Q.2. In plants recombinant DNA is injected into the nucleus by a method known as _____
Ans : Gene gun.
Q.3. Ri and Ti plasmids are found in ____
Ans : Agrobacterium.
Q.4. PCR stand for ____
Ans : Polymerase.
Q.5. ____ are known as molecular scissors.
Ans : Endonuclease.
Q.6. The first restriction endonuclease recognized is____
Ans : Hind III.
Q.7. ____ deals with large scale production and marketing of products and process using live organisms, cells or enzymes.
Ans : Biotechnology.
Q.8. Most commonly used bioreactors are of _____
Ans : Membrane bioreactor.
Q.9. A piece of DNA is introduced in a host bacterium through ____
Ans : Plasmid.
Q.10. Gel electrophoresis is used for _____
Ans : Separate DNA fragments.
Q.11. ____ a crown gall bacterium is called natural generic engineer of plants.
Ans : Agrobacterium tumefaciens.
Q.12. Genetic engineering is also known as ____ DNA technology.
Ans : Recombinant.
Q.13. Large scale production of biotechnological products involve use of
Ans : Cloning.
(C). Select the true and false statements.
Q.1. Bacteria protect their, nucleoid from restriction endonuclease through methylation.
Ans : True.
Q.2. Transgenic plants are developed by introduction of foreign genes.
Ans : True.
Q.3. Function of restriction enzyme is to cut DNA at the ends.
Ans : False.
Q.4. DNA fragments are joined by enzyme polymerase.
Ans : False.
Q.5. Bacteria protect themselves from virus by fragmenting viral DNA with endonuclease.
Ans : True.
Q.6. Restriction enzymes are also known as molecular markers.
Ans : False.
Q.7. An antibiotic resistance gene in a vector usually helps in the selection of transformed cells.
Ans : True.
Q.8. The most common bacterium used in genetic engineering in Escherichia.
Ans : True.
Q.9. Hargovind Khurana was awarded the Noble Prize for the development of PCR technique.
Ans : False.
Q.10. Genetic engineering is a technique which involves deliberate manipulation of genes within or between the species.
Q.11. Plasmids are circular extra chromosomal DNA in Bacteria.
Ans : True.
Q.12. DNA ligases are used to cleave a DNA molecule.
Ans : False.
Q.13. Bacteria protect them from viruses by fragmenting viral DNA with endonuclease.
Ans : True.
II. Short Questions 2 Marks :
Q.1. What DNA ligase?
Ans : It is an enzyme DNA. It catalyzes the linkage between two free ends of double stranded DNA chains by forming a phosphodiester bond between them, as in the repair of damaged DNA.
Q.2. Define genetic engineering. Mention the tools used in genetic engineering.
Ans : Genetic engineering can be defined as the science dealing with the correction of nature’s mistake at the level of hereditary unit, the DNA and to improve the quality of organism for purposes by implanting desired genes.
Tools of genetic engineering :
(i) Enzyme lysozyme is used to dissolve cell wall of bacteria to bring () out DNA fragments.
(ii) Enzymes restriction endonuclease and exonuclease which is used (1) to cut the desired segments of DNA for the purpose of recombination.
(iii) Enzyme ligase used to join two cut ends of DNA fragments.
(iv) Enzyme DNA polymerase is used to synthesise complementary DNA strand on DNA template.
(v) PCR is used to multiply DNA fragments.
(vi) Vectors : Plasmid and viruses are used to transport the DNA fragments inside the cell.
Q.3. What is gene gun? Give its working principles.
Ans : During recombination DNA gene collected from other source is inserted in various ways, the most common method is use of plasınid as vector. There is another method by which gene is pushed into cell by force. The device acts like gunshot and hence it is called gene gun.
Q.4. What are transgenic plants? Give examples.
Ans : The plants which have been modified used gene from other species are called transgenic plants. The other species may be any microorganism, animal or distantly related plants.
Bt, cotton is a transgenic plant. Cotton cultivation is affected all over world by budworm that destroys the buds. The toxin produced by a bacteria called Bacillus thuringiensis is found to be inhibitory to such worms. Using genetic engineering, the gene responsible for coding the toxin in the bacteria had been isolated and inserted into the plant genome. This has provided the cotton plant resistance to budworms.
Q.5. How is DNA isolated in purified form from a bacterial cell?
Ans : DNA is isolated from bacteria using restriction endonuclease it is then cleaned and each piece is separated using gel electrophoresis to make each piece free from cell debris. The fragments of DNA then multiplied using PCR.
Q.6. What is recombinant DNA? How do enzymes restriction endonuclease and DNA ligase help its formation?
Ans : Genetically engineered DNA prepared by transplanting or splicing genes from one species into the cells of a host organism of a different species is called recombinant DNA. Such DNA becomes part of the host’s genetic makeup and is replicated.
The enzyme endonuclease is used to cut the required piece of DNA in an organism. This enzyme can identify the particular sequence of nucleotide where it should cut. The cut piece is the brought out by a special technique. The cut piece of DNA is then pushed into the cell of the target organism using suitable vector or gene gun. Ligase enzyme is then used to join the cut piece with the DNA of the host.
Q.7. Name the source organism from which T₁ plasmid is isolated. Explain the use of this plasmid in biotechnology.
Ans : T₁ plasmid is obtained from Agrobacterium tumefaciens. This plasmid is used as vector for carrying the required DNA fragment inside the cell of the host. This is widely used for DNA recombination particularly in developing transgenic plants.
Q.8. A recombinant DNA is formed when sticky ends of vector DNA and foreign DNA join. Explain how the sticky ends are formed and get joined.
Ans : Endonuclease cut at the both ends of palindrome sequences of the DNA in such way that sticky ends form in both ends after removal of the cut ends join easily. Such cut DNA fragments will be in the sequence of 5 → 3 and 3’→ 5′. Both these ends then can easily join.
Q.9. What are selectable markers? What is their use in genetic engineering?
Ans : Selectable markers are some genes such as antibiotic resistant genes. These genes are inserted into the cloned cells. This is to test whether the cloned cell has recombinant DNA. Because in many cases the apparently cloned cell may not have the desired r combined DNA. To test whether the cloned cell are really cloned or not the selectable marker genes are infused into the cells. The cells containing antibiotic resistant selectable marker are then cultured in medium containing that particular antibiotic. In the medium only those cells will survive which have selectable markers and others will dye. Those that survive are really contain the desired recombinant DNA.
Q.10. Why is Agrobacterium mediated genetic transformation described as natural genetic engineering in plants?
Ans : Agrobacterium is the only organism known which has developed technique of gene transfer from it to some plants and thereby cause an infection in the plant called ‘gall’. It has developed this technique in course of evolution. Through such transfer of its DNA to the plant it passes message to the plant to prepare appropriate nutrition for it. Such gene transfer involve complicated mechanism which is equivalent to complex process of genetic engineering. Therefore naturally it is called natural genetic engineering. Actually scientists have learned the technique of recombinant DNA technology from Agrobacterium.
Q.11. Do eukaryotic cells have restriction endonuclease? Justify your answer.
Ans : Restriction enzymes are a class of enzymes called endonucleases. Endonucleases are able to cut in the middle of the DNA backbone or the phosphodiester bonds. A different class of enzymes called exonucleases cut the DNA backbone, but only from the ends-either from the 3′ end or the 5′ end. Most restriction endonucleases are prokaryotic-in origin. However, there are several found in eukaryotic cells, including our own. In eukaryotes they are not referred to as restriction enzymes, just endonucleases. An example of an endonuclease in eukaryotes is Apn 1, isolated from yeast. This enzyme helps prevent DNA damage from environmental agents.
Q.12. While doing a PCR, denaturation step is missed, what will be its effect on the process.
Ans: There are 6 steps in PCR process. Of these the denaturation of DNA is the first step. If this step is missed the next step. Annealing step will not follow and thereby subsequent steps will also not follow and ultimately amplification of DNA will not be accomplished.
Q.13. Why enzyme cellulose is used for isolating genetic material from plant cells but not animal cells?
Ans : The enzyme cellulose is used to separate the genetic material from the plant cells this enzyme can act only on plants but not the animals. There is no role is played by enzyme cellulose on animal body. They can break the cell wall and content will released.
Q.14. What are major steps involved in gene cloning technique?
Ans : Gene cloning technique involves the following steps:
(i) Isolation of required DNA, generally called donor DNA out of a suitable organism by biochemical technique.
(ii) Breaking of DNA into fragments using restriction enzymes.
(iii) Isolation of suitable bacterial plasmid and cutting it at a place by restriction enzyme and joining the donor DNA fragment with it with the help of an enzyme called ligase. The plasmid containing parent DNA and donor DNA.is called recombinant DNA.
(iv) The recombinant DNA is then inserted within similar bacteria through cloning.
(v) Culturing the cloned bacteria containing fragment of donor DNA.
(vi) Selection of appropriate bacterial colony which has incorporated Sil the sought after DNA fragment. For example, the different segments of DNA inserted in plasmid may cause bacteria to synthesize different substances. It is possible therefore to create bacteria acquiring ability to synthesize any substance like insulin, haemoglobin, interferon etc.
Q.15. What are molecular scissors? Give at least two examples of it?
Ans : Restriction enzymes are called the molecular scissors The example of restriction enzymes are – EcoRV and Eco RT.
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