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Karnataka 2nd PUC Biology Question Bank Chapter 12 Biotechnology and its Applications
2nd PUC Biology Biotechnology and its Applications Ncert Text Book Questions and Answers
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.
(c) Bacillus thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. Actually, the Bt toxin protein exists as inactive protoxins but once an insect ingests the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the insect gut which solubilise the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis and eventually cause the death of the insect, but it does not harm Bacillus itself.
What are transgenic bacteria? Illustrate using any one example. (CBSE – 2006)
Bacteria carrying foreign genes are called transgenic bacteria. For example, two DNA sequences (A and B chains of human insulin) were introduced into the plasmid of bacteria E.coli. The leans genic bacteria start producing insulin chains.
Compare and contrast the advantages and disadvantages of the production of genetically modified crops.
Advantages of GM crops:
- Genetic modification has made crops more tolerant to abiotic stresses (cold, drought, heat, salt.)
- Viral resistance can be introduced.
- Over ripening, losses can be reduced. Example: Flavr Savr Tomato.
- Enhanced nutritional value of food. Example: Golden Rice.
- Reduced reliance on chemical pesticides.
Disadvantages of GM crops:
- Transgenes in crop plants can endanger native species.
- Example: The gene for Bt toxin expressed in pollen may end natural pollinators such as honeybees.
- Weeds also become resistant.
- Products of transgenes may be allergic or toxic.
- They cause damage to the natural environment.
What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
Cry proteins are protein responsible for killing lepidopteran insect and their larvae (also called Bt toxin). It is secreted by Bacillus thuringienesis. Man exploited gene encoding this toxin, by transferring it into cotton genome with the help of Agrobacterium TDN A as vector.
What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency,
It is a collection of methods which allows correction of a gene defect that has been diagnosed in a child or embryo. In gene therapy, normal genes are inserted into a person’s cells or tissues to treat a hereditary defect. Gene therapy is being tried for sickle cell anaemia and Severe Combined Immuno Deficiency (SCID).
In some children, ADA deficiency can be cured by bone marrow transplantation. In others, it can be treated by enzyme replacement therapy, in which functional ADA is given to the patient by injection. However, both of these approaches are not completely curative.
In gene therapy, lymphocytes from the blood of the patient are grown in a culture outside the body. A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to the patient. Because these cells are not immortal, the patient requires a periodic infusion of such genetically engineered lymphocytes. However, if the gene isolated from marrow cells producing ADA is introduced into cells at early embryonic stages, the disease could be cured permanently.
Diagrammatically represent the experimental steps in cloning and expressing a human gene (say the gene for growth hormone) into a bacterium like E. coli?
The given diagram represents the experimental steps in cloning and expressing a human gene for growth hormone into a bacterium E. coli.
Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and the chemistry of oil?
To remove oil from seeds using recombinant DNA technology would involve:
- Identifying the genes that code for oil production.
- Deleting these genes from the seed genome.
- Splicing back together with the remaining DNA.
- Putting it back into the cell.
It will not be very easy because the oils are made up of fatty acids and glycerol. Since fatty acids are important components of the cell membrane system, deleting or switching off of its genes might affect the cell structure itself.
Find out from the internet what is golden rice.
Golden rice is transgenic rice having gene coding for vitamin A synthesis enzyme. Golden rice was developed by the Swiss Federal Institute of Technology, rich in vitamin A (beta carotene). The rice grains are golden yellow in colour due to colour it gets from the beta carotene.
Does our blood have proteases and nucleases?
No, our blood does not contain enzyme proteases and nucleases. If these two enzymes were there in the blood, it causes the degeneration of blood cells and lining cells of blood cells.
Consult the internet and find out how to make orally active protein pharmaceuticals. What is the major problem to be encountered?
Proteinaceous drugs cannot be taken orally because they can be degraded by the proteases of our alimentary canal. To counteract this problem or to make an orally active protein pharmaceutical, it must be coated by a film that is resistant to protein degrading enzymes.
2nd PUC Biology Biotechnology and its Applications Additional Questions and Answers
2nd PUC Biology Biotechnology and its Applications One Mark Questions
Name the organism whose genetic material has been altered using genetic engineering techniques.
Genetically Modified Organisms (GMO).
Genetically modified cotton is named Bt cotton. What does the prefix ‘Bt’ mean?
Cotton containing a toxin gene from Bacillus thuringiensis
Through whom Bt toxin protein originates?
By Bacillus thuringiensis.
Biopiracy affects developing countries like India more than industrialized nations because our country is rich in ………………. and …………………. related to bio-resources.
(Bioetics / Biodiversity/Biopatent, Traditional resources/Traditional cultivation/Traditional knowledge)
Biodiversity and Traditional knowledge
Full form of RNAi.
RNA interference (RNAi).
Genetic engineering Approval committee.
Name the scientific name of bacteria in which be form organism toxin.
A multinational company outside India tried to sell new varieties of turmeric without proper patent rights. What is such an act referred to as?
What is Hirudin?
It is a protein which prevent blood dotting.
2nd PUC Biology Biotechnology and its Applications Two Marks Questions
In case of Bt Cotton how does the toxic insecticide protein produced by the bacterium kill the insect pest but not the cells of Bacillus thuringiensis where the toxic protein is generated?
The toxin produced by Bacillus thuringiensis is an endotoxin called cry protein. It is crystalline and nontoxic when formed being in the protoxin stage. As it reaches the gut of insects, the cry protein is converted into toxic and soluble state. It attaches the receptors present on the epithelial cells of the gut produces pores and kills the cells resulting in the death of the insects.
What are the 4 main objectives of genetically modified crop plants? (CBSE 2008)
- Higher nutritional value eg: Vitamin. A in golden rice
- Abiotic stresses- Increased tolerance to drought etc.
- Post Harvest losses- Prevention of over-ripening and other post-harvest losses.
- Insect and Pest resistance. eg: Bt-cotton.
Define transgenic organisms (CBSE 2006)
They are organisms which have been modified genetically through the introduction of genes of another organism artificially by the technique of genetic engineering instead of conventional hybridisation.
How is early detection of diseases possible using molecular diagnostics?
- Low concentration of viral or bacterial DNA in the host cell/body can be detected much before the symptoms of the disease appear i.e. early detection of disease is possible
- Clones of genes can be used to as probe to detect the presence of mutual alleles in cancer suspected patients.
Name any two biological products that are produced in transgenic animals and mention their uses.
- a-1- antitrypsin is used to treat emphysema.
- a-lactalbumin is produced in the milk of the transgenic cow, Rosie, this is a nutritionally more balanced product for human babies than normal cow milk.
Bacillus thuringiensis makes our environment pesticide-free. Comment.
Bacillus thuringiensis produces a toxin called Bt toxin. Gene for Bt toxin has been cloned from bacteria and been expressed in plants to provide resistance to pests. In this manner, many plants are produced. So in the future, this makes our environment pesticide-free.
What is the cause of adenosine deaminase deficiency in a person?
It is due to the deletion of the gene coding for the enzyme adenosine deaminase, this enzyme is crucial for the functioning of the immune system.
Briefly describe the RNA interference process for preventing nematode infestation of plants.
RNA interference (RNAi) takes place in all eukaryotic organisms as a method of cellular defense. This method involves the silencing of a specific mRNA due to a complementary double-stranded RNA molecule that binds to it and prevents translation of mRNA. The source of this complementary RNA could be from injection by viruses having RNA genomes or mobile genetic elements.
Why does Bt toxin not kill the bacillus? How does it kill the insect larvae?
- When Bt toxin is ingested by an insect, it is converted into its active form when exposed to the alkaline pH in the gut.
- The activated toxin binds to the surface of the epithelial cells of the midgut creates pores.
- Water enters the cells and causes their swelling and lysis.
Write the advantages of recombinant therapeutics?
The recombinant therapeutics do not induce any unwanted immunological response like the similar products of non-human origin such therapeutics are highly effective.
How is ELISA used to detect pathogens in the body?
- Pathogens are detected by the presence of antigens, which may be a protein or glycoprotein.
- Pathogens can be also be detected by the presence of antibodies synthesized against the pathogens.
2nd PUC Biology Biotechnology and its Applications Three Marks Questions
What is genetically modified (GM) food? Give two examples.
Genetically modified food (GM food): The food substances produced from genetically modified crops or transgenic crops is called GM food. This food differs from conventionally developed varieties in the following aspects :
- GM food contains an antibiotic resistance gene itself.
- It contains protein produced by transgene, e.g. Cry protein in insect resistance varieties.
- These GM foods contain enzyme produced by the antibiotic resistance gene that was used during gene transfer by recombinant DNA technology.
Examples of GM Crops, Food, and Fruits:
1. Flavr Savr Tomato: It is the first food containing genetically engineered DNA. . These tomatoes contain genes for antibiotic resistance for kanamycin.
2. Maize: GM maize has a bacterial gene that increases its resistance to pests and
diseases. It also has a gene for ampicillin resistance which is harmful for us, therefore the introduction of GM maize is opposed by many European countries. ,
3. Rape oilseed: It is a new type of plant that contains genes for resistance to the herbicide Basta. It has more potential, dangers and can become a weed and would be impossible to control with Basta. It could cross-fertilize with relatives such as wild mustard, thus, spreading the resistance to wild plants. Such type of environmental risks could occur with genetically modified rapeseed crop. They might also affect food chains in unpredictable ways.
Mention three reasons for the success of the green revolution in India.
- Use of improved verities of crops
- Employing better management practice
- Use of agrochemicals such as fertilizers and pesticides.
Enumerate the fields of application of biotechnology.
The applications of biotechnology include
- Molecular diagnostics
- Waste treatment
- Energy production
Explain the steps involved in the production of genetically engineered insulin.
Insulin used for diabetes was earlier extracted from the pancreas of slaughtered cattle and pigs. Insulin consists of two short polypeptide chains, chain A and chain B that are linked together by disulphide bridge.
In mammals, including humans, insulin is synthesised as a prohormone which contains an extra stretch called the C peptide. This C peptide is not present in the mature insulin and is removed during maturation into insulin. The main challenge for the production of insulin using rDNA techniques was getting insulin assembled into a mature form.
In 1993 Eily Lilly an American company prepared two DNA sequences corresponding to A and B, chain of human insulin and introduced them in the plasmid of E.coli to produce insulin chains, Chains A and B were produced separately, extracted, and combined by creating disulphide bonds to form human insulin.
Name any 6 plants where Bt toxin-producing genes have been included.
2nd PUC Biology Biotechnology and its Applications Five Marks Questions
Two of the steps involved in producing nematode-resistant tobacco plants base on the process of RNA I are mentioned below. Write the missing steps in the proper sequence.
- Nematode specific genes
- Production of both sense and antisense RNAs
- Double strand RNA
- Silencing specific mRNAs of nematode
- Death of nematodes
- Protection of transgenic plants from nematodes.
Describe the application of genetic engineering in the field of Agriculture and Medicine.
(A) Application of Genetic engineering or Biotechnology in Agriculture: Genetic engineering is found to be very beneficial in agriculture. Its important use in agriculture are:
1. Increase in photosynthetic efficiency: An increase in photosynthetic efficiency of crop plants can be achieved by introducing suitable Carbon dioxide Fixation Gene (cfx) from any plant into the crop plants.
2. Transfer of nitrogen-fixing ability: Number of symbiotic and non-symbiotic micro-organisms have a capacity of fixing atmospheric nitrogen. Nitrogen fixers are found to possess nitrogen-fixing gene (nif genes) which are located on chromosomes or plasmids. Introduction of nif gene in crop plants results inability in crop plants to fix atmospheric nitrogen and reduction in the use of chemical nitrogen fertilizers.
3. Disease resistance in crop plants: Plant breeders at present are developing high-yield varieties by transferring genes for disease resistance through conventional breeding.
4. Plant tissue in crop improvement: Some of the areas of plant improvement where tissue culture has been applied with success are as follows :
- Rescuing hybrids through embryo culture.
- Multiplication of germplasm.
- Production of disease-free plants.
- Production of haploid through another culture.
- Somaclonal variation.
- Somatic hybridization.
- Cryopreservation of germplasm.
5. VAM (Vesicular-Arbuscular Mycorrhiza) fungi with Rhizobium can boost the yields: Recently there has been a new dimension to this farm practice by the way of increasing Rhizobium inoculation effect by simultaneous inoculating seeds with VAM as well as Rhizobium culture. VAM is a structural modification of hyphae helping in absorption and storage of phosphorus.
(B) Application of Genetic engineering in the Medical field:
- Hereditary diseases like color-blindness, haemophilia which are caused by recessive genes and also many inborn metabolic disorders due to defective genes as alkaptonuria, phenylketonuria can be cured with gene therapy.
- Substances like vitamins, hormones, amino acids and antibodies can be synthesized in bacteria by introducing the genes which code these substances. In this way, bacteria can be used as biofactories for the synthesis of these substances.
- Production of insulin: Insulin is a medicine used for the treatment of diabetes. Initially, it is derived from animals (pig and cows) but today it is produced by gene splicing.
- Hepatitis-B vaccine: Hepatitis-B is a viral disease of the liver. Today this vaccine is prepared with the help of genetic engineering.