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NCERT Class 12 Biology Textbook Chapter 12 With Answer PDF Free Download
Chapter 12: Biotechnology and its Applications
Biotechnology, as you would have learned from the previous chapter essentially deals with industrial-scale production of biopharmaceuticals and biologicals using genetically modified microbes, fungi, plants, and animals.
The applications of biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment, and energy production. Three critical research areas of biotechnology are:
(i) Providing the best catalyst in the form of an 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.
Let us now learn how human beings have used biotechnology to improve the quality of human life,
especially in the field of food production and health.
12.1 Biotechnology Application In Agriculture
Let us take a look at the three options that can be thought of for increasing food production
(i) agrochemical based agriculture;
(ii) organic agriculture; and
(iii) genetically engineered crop-based agriculture
The Green Revolution succeeded in tripling the food supply but yet it was not enough to feed the growing human population.
Increased yields have partly been due to the use of improved crop varieties, but mainly due to the use of better management practices and the use of agrochemicals (fertilizers and pesticides).
However, for farmers in the developing world, agrochemicals are often too expensive, and further increases in yield with existing varieties are not possible using conventional breeding.
Is there any alternative path that our understanding of genetics can show so that farmers may obtain maximum yield from their fields?
Is there a way to minimize the use of fertilizers and chemicals so that their harmful effects on the environment are reduced? The use of genetically modified crops is a possible solution.
Plants, bacteria, fungi, and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO).
GM plants have been useful in many ways. Genetic modification has:
(i) made crops more tolerant to abiotic stresses (cold, drought, salt, heat).
(ii) reduced reliance on chemical pesticides (pest-resistant crops).
(iii) helped to reduce post-harvest losses.
(iv) increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil).
(v) enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched rice.
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NCERT Solutions Class 12 Biology Chapter 12 Biotechnology and its Applications
4. What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
Cry proteins are the toxins encoded by cry genes and produced by the bacteria – Bacillus thuringiensis which contains these proteins in their inactive form.
It gets activated due to the alkaline pH of the gut of the insect when it ingests the inactive toxin protein. This leads to the lysis of epithelial cells and ultimately the insect dies.
Hence, we say that man has exploited this protein to produce some transgenic crops with the property of insect resistance such as Bt corn, Bt cotton, etc.
5. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
The process of correction of malfunctioned genes either by inserting the desirable gene or repairing or manipulating them is referred to as gene therapy. It is a collection of methods that enables the correction of a gene defect. In this therapy, the gene is inserted into the cells and tissues of a person to treat a disease.
Adenosine deaminase deficiency (ADA) is a rare genetic disorder caused due to deletion of the gene for adenosine deaminase.
This enzyme is critical for the normal functioning of the immune system. This disorder can be treated by gene therapy wherein the gene is transfected into early embryonic cells of the bone marrow for permanent utilization.
7. Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and the chemistry of oil?
Recombinant DNA technology or rDNA is a technique that is used for the manipulation of the genetic material of an entity in order to obtain desired results.
For this, the genes that are necessary for oil formation in seeds must be recognized. With the help of restriction endonucleases, appropriate genes should be removed.
The DNA thus obtained must be treated with DNA ligases to seal the broken ends of the DNA. When cultivated aseptically on a nutrient medium, these cells will differentiate into a new plant possessing seeds with no oil.
8. Find out on the internet what is golden rice.
Golden rice, a variety of rice, Oryza sativa is a genetically modified crop that is developed as a fortified food to supply them to areas where there is a 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 their 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 considerable opposition from environmental activists.
9. Does our blood have proteases and nucleases?
No, blood does not have proteases and nucleases. But some proteases do exist in their inactive form. If it would have been found in blood and cells, it would have been digested.
Biotechnology and its Applications NCERT Textbook With Solutions PDF Free Download