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|Chapter||12. Biotechnology And Its Applications|
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Our NCERT Solutions for Class 12 Biology is a great resource for students preparing for boards or competitive exams, such as the NEET. These Biology Class 12 Solutions are made by expert faculties, keeping the latest curriculum in mind. Besides helping students with understanding the concepts of Biology, these solutions are also helpful in writing accurate answers that are vital to score full marks in examinations. On this page, we have given the Class 12 Biology Chapter 12: Biotechnology And Its Applications Solutions.
NCERT Solutions for Class 12 Biology Chapter 12
Biotechnology And Its Applications Solutions
Q1) Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because −
(a) bacteria are resistant to the toxin
(b) toxin is immature;
(c) toxin is inactive;
(d) bacteria encloses toxin in a special sac.
Answer) (c) toxin is inactive
Q2) What are transgenic bacteria? Illustrate using any one example.
Answer) Transgenic bacteria comprise of a foreign gene which is purposefully inserted into its genome. These are manipulated in order to be able to express the desirable gene to produce different commercially important products.
E.coli, an example of transgenic bacteria has two DNA sequences in its plasmid that corresponds to A and B chain of human insulin which are introduced to generate the respective human insulin chains. Therefore, once the insulin gene is introduced into the bacterium, it turns transgenic and begins to produce chains of human insulin. These chains, after sometime are extracted from E.coli and fused to form human insulin.
Q3) Compare and contrast the advantages and disadvantages of production of genetically modified crops.
Answer) Advantages of producing genetically modified crops are:
- Genetic modification makes crops more tolerant to abiotic stresses – namely cold, drought, heat, salt etc
- Genetic modification creates tailor-made plants to supply alternative resources to industries, in the form of fuels, starches, pharmaceuticals etc
- Most of the crops produced this way are for pest resistance, that increases crop productivity and hence reduces the dependence on chemical pesticides
- Genetic modification has made it possible to develop crops that enhance the nutritional quality. For instance, one of the transgenic variety of rice, golden rice, is rich in Vitamin A.
- They are useful in reducing the losses that are incurred post-harvest
- Early exhaustion of soil fertility is prevented due to increased productivity of mineral usage by plants
Disadvantages of producing genetically modified crops are:
- Danger of introducing undesirable variety as a result of a destructive combination
- There is a threat of producing super weeds
- There is a high risk of non-reproduction from genetically modified crops
- The chemicals that are produced, may cause a rejection in the human insecticides
- Genetically modified crops affect human health as they supply allergens and several other antibiotic resistance markers in the body
- These crops can affect the native biodiversity in an area as they can cause genetic pollution in the wild relatives of crop plants.
Q4) What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
Answer) Cry proteins are encoded by cry genes. These proteins are toxins, which are produced by Bacillus thuringiensis bacteria. This bacterium contains these proteins in their inactive from. When the inactive toxin protein is ingested by the insect, it gets activated by the alkaline pH of the gut. This results in the lysis of epithelial cell and eventually the death of the insect. Therefore, man has exploited this protein to develop certain transgenic crops with insect resistance such as Bt cotton, Bt corn, etc.
Q5) What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Answer) Gene therapy is a technique for correcting a defective gene through gene manipulation. It involves the delivery of a normal gene into the individual to replace the defective gene, for example, the introduction of gene for adenosine deaminase (ADA) in ADA deficient individual. The adenosine deaminase enzyme is important for the normal functioning of the immune system. The individual suffering from this disorder can be cured by transplantation of bone marrow cells. The first step involves the extraction of lymphocyte from the patient’s bone marrow. Then, a functional gene for ADA is introduced into lymphocytes with the help of retrovirus. These treated lymphocytes containing ADA gene are then introduced into the patient’s bone marrow. Thus, the gene gets activated producing functional T- lymphocytes and activating the patient’s immune system.
Q6) Diagrammatically represent the experimental steps in cloning and expressing an human gene (say the gene for growth hormone) into a bacterium like E. coli ?
Answer) A technique of producing multiple identical copies of a particular template DNA is known as DNA cloning which involves the usage of a vector that carries the particular foreign DNA fragment into the host cell.
The working of cloning and transfer of gene for growth hormone into E.coli can be depicted as given below:
Q7) Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and chemistry of oil?
Answer) Recombinant DNA technology (rDNA) is a technique used for manipulating the genetic material of an organism to obtain the desired result. For example, this technology is used for removing oil from seeds. The constituents of oil are glycerol and fatty acids. Using rDNA, one can obtain oilless seeds by preventing the synthesis of either glycerol or fatty acids. This is done by removing the specific gene responsible for the synthesis.
Q8) Find out from internet what is golden rice.
Answer) Golden rice, a variety of rice, Oryza sativa is a genetically modified crop which is developed as a fortified food to supply them to areas where there is scarcity of dietary Vitamin A, as golden rice is richly supplied with Vitamin A. Golden rice consists of a precursor of pro-Vitamin A, known as the beta-carotene, inserted into the rice through the process of genetic engineering.
Rice plants synthesize the beta-carotene pigment naturally in its leaves but it is not found in the seed’s endosperm as the pigment aids in photosynthesis and photosynthesis does not take place in the endosperm. As the beta-carotene is a precursor of pro-vitamin A, it is inserted into the rice variety to compensate for the dearth of dietary Vitamin A. Compared to vitamin supplements, this is a simpler and low-priced alternative. But they are still not available for human consumption, as this variety of rice has faced a considerable opposition from environmental activists.
Q9) Does our blood have proteases and nucleases?
Answer) No, human blood does not include the enzymes, nucleases and proteases. In human beings, blood serum contains different types of protease inhibitors, which protect the blood proteins from being broken down by the action of proteases. The enzyme, nucleases, catalyses the hydrolysis of nucleic acids that is absent in blood.
Q10) Consult internet and find out how to make orally active protein pharmaceutical. What is the major problem to be encountered?
Answer) Protein pharmaceutical cannot be taken orally because they can be degraded by the proteases of our alimentary canal.
Thus, major problem to be encountered is the action of digestive enzymes. It has to be made digestible for the digestive system and also protect it from the degradation of HCl present in stomach so it is coated by a film that is resistant to protein degrading enzymes.
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