NCERT Solutions for Class 12 Science Biology Chapter 12 - Biotechnology And Its Applications

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Bt cotton is a transgenic plant and used as a biological pesticide. Bacillus thuringiensis is soil bacteria that produce protein to kill insects such as lepidopterans and dipterans. Bt toxin gene is isolated from this bacteria and was incorporated into several crops such as cotton. It is resistant to certain insects but not resistant to pesticides.

Hence, the correct answer is option d.

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In humans, the insulin hormone is synthesised as a pro-hormone that contains an extra stretch called C-peptide. It is not present in the mature insulin. It is removed during maturation into insulin.

Hence, the correct answer is option c.

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GEAC stands you Genetic Engineering Approval Committee. It is an organisation set up by Indian Government. This organisation will make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

Hence, the correct answer is option c.

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α -1 antitrypsin is a human protein used for the treatment of emphysema.

Hence, the correct answer is option d.

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A probe is a single stranded RNA or DNA, tagged with a radioactive molecule. It is used to hybridise its complementary sequence in a genome sample.

Hence, the correct answer is option c.

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Retrovirus is a RNA virus that uses RNA as its genetic material and make DNA copies by reverse transription during infection 

Hence, the correct answer is option a.

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Lymphocytes are white blood cells that are present in the bone marrow. It is the site of production of ADA or adenosine deaminase in the body.

Hence, the correct answer is option b.

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A protoxin is inactive form of toxin and when once ingested by the insects the inactive toxin is converted into active form of toxin due to alkaline pH of the gut that solubilise the crystals.

Hence, the correct answer is option d.

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Pathophysiology is the study of altered physiology of host. It is a combination of pathology (study of causes and effects of disease) and physiology which involves the study of how systems of the body functions.

Hence, the correct answer is option c.

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Bt toxin exists as inactive protoxins and is converted into active form of toxin due to the alkaline pH of the gut that solubilise the crystals.

Hence, the correct answer is option c.

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Golden rice is a transgenic rice and is produced to enhanced the nutritional value of food. It is genetically modified to produce β-carotene as it is not present in the normal rice. β-carotene is then converted into vitamin A when metabolized by the human body.

Hence, the correct answer is option c.

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Meloidogyne incognita is a nematode that infects the roots of tobacco plant results in a reduction in yield. RNA interference (RNAi) is a strategy used to present this infestation. This method involves the silencing of a specific mRNA due to complementary dsRNA molecules that birds to and prevents the translation of the mRNA (silencing).

Hence, the correct answer is option c.

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The first clinical gene therapy was given in 1990 to a 4-year old girl suffering with adenosine deaminase (ADA) deficiency cause SCID (Severe Combined Immuno Deficiency)

Hence, the correct answer is option d.

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ADA stands for adenosine deaminase. It is an enzyme responsible for the proper functioning of immune system. SCID is caused due to the deletion of gene that codes for enzyme ADA.

Hence, the correct answer is option b.

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Silencing of gene could be achieved through the use of both RNAi and antisense RNA. Both the mechanisms interrupts or suppresses the gene expression at translational level.

Hence, the correct answer is option c.

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The major limitations of Green Revolution are as follows:-
(i) It is based on better management of farm practices.
(ii) This involves the use of chemical fertilisers and pesticides that causes harm to crops as well as to human health.
 

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GMO stands for Genetically Modified Organisms. They are plants, bacteria, fungi and animals whose genes have been altered by manipulation.
Hybrids are produced by cross-breeding or cross pollination of different species of plants and animals. GMOs are produced by the insertion of a gene into a new organism for the expression of desired traits.

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 ELISA is Enzyme Linked Immunosorbent Assay. It is an molecular diagnostic technique based on the principle of antigen-antibody interaction. It is used for the detection of HIV infections.

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Yes, a disease can be detected before its symptoms appear. For this, a molecular diagnostic technique called PCR is used. By this technique, very low concentration of a bacteria or virus can be detected by amplification of their nucleic acid.

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Biopiracy is the term used to refer the use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned without compensatory payment.
Many industrialized nations are financially rich but they are poor in biodiversity and traditional knowledge. Whereas, the developing and the underdeveloped countries are rich in biodiversity and have traditional knowledge related to bio-resources. The industrialised nations sometimes tends to exploit the resources or biodiversity of developing nations for their own sake.

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When toxin is produced by an organism in inactive form, it doesn't effect organism that produces toxin.
For example:-
Bt toxin is produced by bacteria Bacillus thuringiensis in inactive form and does not harm the bacteria. But once ingested by an insect, is converted into its active form due to the alkaline pH of the gut of the insects that solublise the crystle.

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When a GMO is produced and introduced into the ecosystem, it harms the ecosystem in many ways such as toxin release, competition, invasion, and interference with natural breeding process. Hence, not respecting the genetic barrier while creating genetically modified organisms can have long term effect on the ecosystem.

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The Indian Parliament cleared the second amendment of the Indian Patent Bills in order to prevent unauthorised, over-exploitation of bio-resources and traditional knowledge.

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(i) Basmati rice traditionally belongs to India.
(ii) Patent could have prevented Indian people from growing Basmati rice.

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Insulin was earlier extracted from the pancrease of slaughtered cattle and pigs. But insulin developed from an animal source, caused some patients to develop allergic reactions to the foreign protein.

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Transgenic animals are specially produced to serve as a models for human diseases so that it is possible to investigate the new treatments of diseases. They exist for many human diseases such as cancer, cystic fibrosis, Alzheimer's and rheumatoid arthritis.

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Rosie was the first transgenic cow developed in 1997. This cow produced human protein-enriched milk (2.4 grams per litre). This milk contained human alpha-lactalbumin protein. This milk is served as nutritionally balanced product for human babies than natural cow-milk.

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Polymerase chain Reaction (PCR) is a molecular diagnostic technique used for the early detection of infectious disease. As, low concentration of bacteria or virus can be detected by amplification of their nucleic acid by using this technique.

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GEAC (Genetic Engineering Approval Committee) is an organisation set up by the Indian Government to make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

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For Basmati rice variety, an patent was filed by a USA company.

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(i) GM Crops are more tolerant to abiotic stresses such as cold, drought, salt, heat.
(ii) They reduced the dependancy on chemical pesticides.
(iii) They helps to reduce post harvest losses.
(iv) They have enhanced nutritional value of food for eg. Vitamin A enriched rice-golden rice.
(v) They have increased the efficiency of mineral usage by plants.

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Gene expression can be controlled by RNA by a method called RNA interference (RNAi). In this method, specific mRNA silencing occurs due to a complementary RNA molecule that binds to and prevents translation of mRNA (silencing).
For example:- Agrobacterium tumifaciens vectors are used to introduce nematode-specific genes into the host plant. The DNA introduced produces both sense and anti-sense RNA in the host cells. Two RNAs are complementary to each other formed a dsRNA that initiated RNAi and silenced the specific mRNA of the nematode.

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India is rich in biodiversity as compared to other developed countries. If such countries don't have proper patenting rules for its tradition knowledge then the other countries will over-exploiting  their resources without providing any compensation or credit to the that country.

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(i) Genetic modification made crops move tolrant to abiotic stresses (cold, drought, salt, heat).
(ii) GM enhanced nutrition value of food e.g. production vitamin A enriched rice called golden rice.
(iii) Genetic modification helped to reduce post harvest losses.
(iv) This also increases the effieiency of mineral usage by plants.

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Recombinant DNA vaccine is a vaccine made through recombinant DNA technology. This method involves the construction of a plasmid of using a copy of DNA from pathogen.
For example:- Hepatitis B vaccine
                         Human Papilloma virus (HPV)

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An infections disease is caused due to pathogen. The line of treatment in this condition, involves the elimination of the casusative pathogen from the body. While an genetic disease is caused due to some defect in the genotype. Antibiotics are not effective for the treatment of genetic diseases so, line of treatment for a genetic disease is different from infection diseases.

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A probe is a single stranded DNA or RNA, tagged with a radioactive molecule and is allowed to hybridise to its complementary DNA in a clone of cells followed by the detection by using autoradiography.
The clones are having the mutated gene that will not appear on the photographic film, because the probes will not have complementarity with the mutated genes.

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Gene therapy is the collection of methods that allows the correction of a gene defect which has been diagnosed in a child/embryo. This first clinical gene therapy was given in the year 1990 to a 4-year old girl with ADA deficiency. Adenosine deaminase enzyme plays an crucial role in the proper functioning of the immune system. The deficiency of this enzyme results in a disease called severe combined immunodeficiency (SCID).
This approach is recurrent in nature, because a functional ADA cDNA is introduced into the lymphocytes of the patient. Lymphocytes are immortal, so the patient requires a periodic infusion of such genetically engineered lymphocytes.

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Upstream processing:- This method involves the identification of a material that can be transformed for making the final product.
For example:- During alcohol formation by yeast, the raw material such as grapes juice, optimum pH, temperature and concentration of mixture is required. This involves the formation of alcohol after a definite period.
Downstream processing:- This method involves the purification and isolation of final product formed by recombinant DNA technology (rDNA).
For example:- Alcohol purification through distillation is an example downstream processing.

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Antigens are the foreign substances (pathogen, pollens) that enters inside the body and causes diseases. Antibody is a protein produce by the immune system to fight against antigens.
Two diagnostic kits based on the principle of antigen-antibody interaction are:-
(i) ELISA for HIV
(ii) Pregnancy test kits

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ELISA (Enzyme Linked Immunosorbent Assay) is used for molecular diagnosis of a genetic disorder, phenylketonuria. One can use ELISA for detecting the enzyme responsible for metabolism of phenylalanine. This technique is based on the principle of antigen-antibody interaction. Infection caused by the pathogens can be detected either by the presence of antigens or by detecting the antibodies that is synthesised against that pathogen. In patients when the enzyme-protein complex is absent, it gives negative result.

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Insulin hormone is synthesised as a pro-hormone that contains an extra-stretch called the C-peptide. C-peptide is removed during the maturation into insulin A and B chains of mature insulin are joined by disulphide.

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ADA deficiency can be treated by enzyme replacement therapy in this functional ADA is given to the patient by injection. This therapy is not completely curative and required frequent re-administration of enzyme. For permanent cure, the genes are isolate from marrow cells producing ADA is introduced into cells at early embryonic stages.

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Transgenic animals are produced by the manipulation of their DNA to posses and express an foreign gene of interest.
For example:-Transgenic rats, rabbits, pigs, cows, sheep, etc.,
(i) Fundamental biological process: Transgenic animals are used to study insulin-like growth factors in humans.
(ii) Study of disease: Transgenic animals are also used for study of diseases.
(iii) Biological products: Transgenic cow, Rosie was produced in 1997. This cow produces human protein alpha-lactalbumin enriched milk  and it serves as a nutritionally more balanced product for human babies than natural cow-milk. Biological products such as alpha-1-antirypsin is used for the treatment of emphysema. It is produced by transgenic animals.

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The foreign genes are ligated to a plasmid vector and then they are introduced in the host. The replication of plasmid makes its multiple copies, so that the foreign gene get replicate and make its several copies. This process is explained with the help of a given figure.

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Few strains of bacterium Bacillus thuringiensis produce proteins that kills some insects such as lepidopteran (tobacco budworm, armyworms), coleopterans (beetles) and dipterans (flies, mosquitoes). It is only effective against cotton bollworms that infects the cotton balls in cotton plant and reduces its yield. It is known that they are highly effective against only a selected groups of pests and does not harm to other class of insects. By using Bt cotton, useful insects are saved and reduce the use of pesticides.

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ADA is adenosine deaminase and is an enzyme responsible for the proper functioning of the immune system. The ADA deficiency that led to cause SCIDC (Secure Combined Immuno Deficiency). It is caused due to the deletion of gene that codes for enzyme adenosine deaminase.
In some patients, it can also be treated by enzyme replacement therapy. In this method, a functional ADA is given to the patient by injection. But both the approaches are not permanently curable.
In Gene therapy, lymphocytes from the blood of the patient are grown in a culture outside of the body.
A functional ADA CDNA (by using retroviral vector) is introduced into these lymphocytes, that are subsequently metured to the patient. As, these cells are immortal, the patients required.

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Transgenic animals are the animals that are genetically modified for several purposes. By using the rDNA technology. A foreign gene named 'Transgene' is inserted to the target organism to bring modifications in their gene expressions. 
1. Biological studies
2. Increases the yield product
3. Testing and clinical trials
4. Diseases safety and chemical safety testing

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Step 1: Isolation of useful gene by using restriction endonucleases enzyme.
Step 2: Transferring the isolated gene to a suitable vector to create a rDNA molecule.
Step 3: Transferring the rDNA molecule into the target cell.
Step 4: Screening of cells for obtaining the transformed cells and discarding the untransformed cells.
Step 5: Selection of the required transformed cell.
Step 6: Regeneration of the plants from the transformed cells to get a transgenic plant.

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The five areas where biotechnology involved:
1. Therapeutics and Diagonostic tools:
It involves the treatment of ADA deficiency and rDNA technology is used for the production of insulin and Human Growth hormone. PCR is used as a diagnostic tool for disease detection and methods such as gene therapy.
2. Genetically modified plants and animals.
3. Forensic and paternity testing.
4. Used in Waste Water treatment.
5. For energy production.

Answer:

1. GM Plants are more resistant  to abiotic stresses such as climate change, temperature, and pH changes. Thus, the plants can grow normally in unfavourable conditions.
2. GM Plants can give more yield of products 
3. They are more resistant towards pests and insects
4. They are used for growing crops with higher nutritional values.

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(a) A nematode Meloidygyne incognitia cause infection in tobacco plants & reduces their yield.
Previously, nematocides are used to control nematode. RNA interference (RNAi) method was developed to kill the nematode by modifying crop.
(b) Golden rice is a transgenic variety of basmati rice that gives high yield and is rich in vitamin A, Beta-carotene gene is introduced into the rice plant to nutritionally enrich the vitamin A content.

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1. The insulin obtained from slaughtered animals was slightly different from humulin and causes allergic reactions in humans.
2. slaughtering is unethical
3. Expensive.

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1. It had no allergic reactions whereas bovine causes allergic reactions.
2. This prohibit the slaughtering of animals.

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Biopesticides are the biologically present substances that are used for the control of growth of pests.
Biopesticides are narrow-spectrum and species-specific. For example: Bt toxin is obtained from bacterium Bacillus thuringensis is used against the insects. The insects on ingesting Bt toxin, due to the presence of alkaline nature of the gut, the Bt toxin gene get activated and binds to the gut wall, creates pores and hence the insects die.

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(a) Restriction endonucleases: It cuts the DNA sequence at specific positions.
(b) Vector - It is the most important tool for the rDNA technology vector that contains a site for the insertion of the gene of interest called the origin of replication.
(c) DNA ligase: It facillitates the joining of desired DNA with vector DNA.
(d) Polymerase: DNA polymerase enzymes makes multiple copies of rDNA. 
(e) Host cell: The cell that takes up rDNA & changes itself to transformant.