Access Class 12 Biology Chapter 10 Solutions (Exercise Questions)
The detailed answers to all the questions of Biotechnology and its applications are given below. Through regular practice of Class 12 Biology Chapter 10 question answers, students can understand the concepts related to biotechnology.
Ques 1: Which part of the plant is best suited for making virus-free plants, and why?
Ans: Meristematic tissue (e.g., shoot apical meristem) is most appropriate for the production of virus-free plants since it is generally free from viral infections. This is because viruses find it difficult to reach actively dividing cells in the meristem.
Ques 2: What is the major advantage of producing plants by micropropagation?
Ans: Micropropagation enables one to produce large numbers of genetically uniform plants rapidly. It can be applied for the propagation of disease-free plants and the conservation of rare or endangered species.
Ques 3: Find out what the various components of the medium used for propagation of an explant in vitro are.
Ans: The medium used for in vitro propagation includes nutrients like sucrose (source of energy), minerals (such as nitrogen, phosphorus, and potassium), vitamins, plant growth regulators (auxins and cytokinins), and agar (gelling agent).
Ques 4: Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because-
(a) Bacteria are resistant to the toxin
(b) The toxin is immature
(c) Toxin is inactive
(d) Bacteria enclose toxins in a special sac.
Ans: Bt toxin crystals formed in bacteria do not kill the bacteria because the toxin is inactive. The Bt toxin is in an inactive state inside the bacteria and is only activated when it is ingested by insects, where it is activated by the alkaline pH of the insect gut.
Hence, the correct answer is (c) Toxin is inactive
Ques 5: What are transgenic bacteria? Illustrate using any one example.
Ans: Transgenic bacteria are those whose genomes have been altered by recombinant DNA technology to include foreign genes. A good example is transgenic E. coli, which has been genetically modified to produce human insulin by the introduction of DNA sequences encoding the A and B chains of insulin, thus allowing it to synthesise insulin for the treatment of diabetes.
Ques 6: Compare and contrast the advantages and disadvantages of the production of genetically modified crops.
Ans: The following table shows the advantages and disadvantages of GM crops:
Advantages | Disadvantages |
Increased productivity and yield | Potential risk to wild species due to transgenes |
Enhanced nutritional quality (e.g., golden rice) | Possible allergenicity and transfer of antibiotic resistance markers |
Insect pest resistance reduces chemical pesticide use | Environmental concerns regarding genetic contamination |
Tolerance to abiotic stresses (drought, salinity) | Impact on biodiversity and ecosystem balance |
Reduced post-harvest losses | Ethical and Socio-economic problems |
Ques 7: What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
Ans: Cry proteins are insecticidal proteins carried by the cry genes, which are produced by the bacterium Bacillus thuringiensis (Bt). They are toxic to many insect larvae, especially those belonging to the order Lepidoptera. Humans have utilised Cry proteins by transferring the cry genes into genetically modified crops like Bt cotton and Bt brinjal, rendering them resistant to certain insect pests.
Ques 8: What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Ans: Gene therapy includes methods to fix or substitute faulty genes that cause disease occurrence. ADA deficiency, for example, is a result of a mutation in the gene for the adenosine deaminase enzyme. In one important case, a 4-year-old patient received gene therapy in which his lymphocytes were grown, a viable ADA cDNA was introduced with a retroviral vector, and afterwards, these converted cells were administered back into the patient's circulation. The diagram given below illustrates gene therapy for Adenosine deaminase deficiency.
Ques 9: Diagrammatically represent the experimental steps in cloning and expressing a human gene (say the gene for growth hormone) into a bacterium like E. coli.
Ans: Below is the diagram to represent the steps in DNA cloning.
A diagrammatic representation of the steps in DNA cloning
Ques 10: Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and the chemistry of oil?
Ans: By recombinant DNA technology, it is possible to silence genes involved in the synthesis of glycerol and fatty acids in seeds, thereby lowering or even abolishing oil content (hydrocarbons). This is possible through methods like RNA interference (RNAi).
Ques 11: Find out from the internet what golden rice is.
Ans: Golden rice is a genetically modified rice variety engineered to synthesise beta-carotene, the precursor of vitamin A, in its endosperm instead of merely in its leaves. This was achieved by introducing two genes: psy from daffodil (Narcissus pseudonarcissus) and crtI from the bacterium Erwinia uredovora, both driven by endosperm-specific promoters.
Ques 12: Do our blood cells have proteases and nucleases?
Ans: Blood plasma contains protease inhibitors, and blood has proteases (e.g., thrombin, plasmin) for clotting, as well as nucleases (e.g., DNases) for defense.
Ques 13: Consult the internet and find out how to make orally active protein pharmaceuticals. What is the major problem to be encountered?
Ans: To prepare orally active protein drugs, proteins or peptides are encapsulated in liposomes along with penetration enhancers for oral administration. The principal difficulty encountered is that the proteins can be hydrolysed by the proteases of the stomach before exerting their therapeutic action, which requires alternative routes of administration directly to target locations.
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