CBSE Class 12 Biology Biotechnology and its Applications Worksheet Set A

Important Questions for NCERT Class 12 Biology Biotechnology and Its Applications

Question. Cry1 Ab gene produces proteins which control?
(1) Bollworms
(2) Corn borer
(3) Both (1) and (2)
(4) None of the above

Answer : B

Question. For the control of the cotton bollworms, which one of the genes is useful ?
(1) Cry 1 Ac
(2) Cry 1 Ab
(3) Cry 1 Ad
(4) All of these

Answer : A

Question. Milk of transgenic cow 'Rosie' contains a substance that was nutritionally more balanced product for human babies is :
(1) a-lactalbumin
(2) b-lactalbumin
(3) g-lactalbumin
(4) d-lactalbumin

Answer : A

Question. Which peptide is not present in the mature insulin and is removed during maturation into insulin?
(1) A-peptide
(2) B-peptide
(3) C-peptide
(4) Both (1) and (2)

Answer : C

Question. Process involving silencing of a specific mRNA due to a complementary dsRNA molecule is called :
(1) Transcription
(2) RNA interference
(3) DNA interference
(4) None of these

Answer : B

Question. Nematode-specific genes were introduced into the host plant (tabacco plant) by using which vector?
(1) Plasmid vector
(2) Cosmid vector
(3) Bacteriophage vector
(4) BAC

Answer : D

Question. Which one of the following statements are true regarding genetic modifications ?
(1) Genetic modifications reduced reliance on chemical pesticides
(2) Genetic modifications has enhanced nutritional value of food.
(3) Genetic modifications made crops more tolerant to abiotic stresses.
(4) All are correct

Answer : D

Question. Bacterium which is known as 'Super bug' is :
(1) Pseudomonas putida
(2) Salmonella
(3) Eischerichia
(4) Agrobacterium

Answer : A

Question. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because :
(1) bacteria are resistant to the toxin
(2) toxin is immature
(3) toxin is inactive
(4) bacteria enclose toxin in a special sac

Answer : C

Question. Which one of the following statements about genetically engineered insulin is incorrect.
(1) E.coli is used for producing humulin
(2) Chains A, B were produced separately
(3) Eli lily company prepared it for first time
(4) Genetically engineered insulin has C-peptide

Answer : D

Question. Animals those have had their DNA manipulated to possess and express an extra (foreign) gene are known as :
(1) Transgenic animals
(2) Genetically modified animals
(3) Both (1) and (2)
(4) None of the above

Answer : C

Question. Genetically engineered bacteria are being used in commercial production of :
(1) melatonin
(2) testosterone
(3) thyroxine
(4) human insulin

Answer : D

Question. Insulin consists of two short polypeptide chains, which are linked together by?
(1) Sulphide bridges
(2) Peptide bridges
(3) Chloride bridges
(4) Disulphide bridges

Answer : D

Question. Over 95 percent of all existing transgenic animals are :
(1) Pigs
(2) Cows
(3) Fish
(4) Mice

Answer : D

Question. Genetics modified crops (GMC) are useful in agriculture because :
(1) They are more tolerant to abiotic stresses
(2) They increase reliance on chemical pesticide
(3) They have reduced nutritional value
(4) All the above

Answer : A

Question. Golden rice is enriched in :
(1) Vitamin C
(2) Vitamin D
(3) Vitamin A
(4) Vitamin E 

Answer : C

Question. Critical research areas of biotechnology are :
(1) providing the best catalyst in the form of improved organism usually a microbe or pure enzyme.
(2) Creating optimal conditions through engineering for a catalyst to act.
(3) Down stream processing technologies to purify the protein/organic compound.
(4) All the above

Answer : D

Question. Bacterium genetically engineered for cleaning oil spills is :
(1) Eischerichia coli
(2) Pseudomonas putida
(3) Salmonella typhimurium
(4) Agrobacterium tumifaciens

Answer : B

Question. Meloidegyne incognitia which infects the roots of tobacco plants causing a great reduction in yield is a :
(1) Nematode
(2) Bacterium
(3) Virus
(4) Alga

Answer : A

Very Short Answer Type Questions

Question. What is biopiracy? 
Answer : Biopiracy is the use of bioresources by multinational companies and other organisations without proper authorization or compensation payment to the concerned country or organisation.

Question. What is “Flavr Savr”?
Answer : It is a transgenic tomato variety which has blocked production of polygalacturonase.

Question. Write the two uses of PCR technique in diagnosis.
Answer : Two uses of PCR technique:
(i) It is used to detect HIV in suspected AIDS patients.
(ii) It is used to detect mutations in gene, in suspected cancer patients.

Question. Name a molecular diagnostic technique to detect the presence of a pathogen in its early stage of infection.
Answer : ELISA (Enzyme Linked Immunosorbent Assay)

Question. State the purpose for which the Indian Government has set up GEAC. 
OR
Mention two objectives of setting up GEAC by our government.
Answer : GEAC was set up to make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

Question. A multinational company outside India tried to sell new varieties of turmeric without proper rights. What is such an act referred to?
Answer : Biopiracy.

Question. How was insulin obtained before the advent of rDNA technology? What were the problems encountered?
Answer : Insulin is used for diabetes treatment and it was earlier extracted from the pancreas of slaughtered cattle and pigs. This insulin caused some patients to develop allergy or other types of reactions to the foreign protein.

Question. With respect to understanding diseases, discuss the importance of transgenic animal models.
Answer : Transgenic animals are important in the following fields (i) They are being used in basic science research to elucidate, the role of genes in the development of diseases like cancer, cystic fibrosis, rheumatoid arthritis and alzheimer’s. (ii) They are valuable tools in the drug development process itself. (iii) They can produce medicines or human proteins (insulin, growth hormone, etc.) in large quantities. (iv) Transgenics can be a source of transplant organs as well.

Question. Write a short note on biopiracy highlighting the exploitation of developing countries by the developed countries.
Answer : Biopiracy is the term used to refer the use of bio-resources by the multinational companies and other organisations without proper authorisation from the countries and from the people concerned without compensatory payment. Most of the industrialised nations are rich financially but poor in biodiversity and traditional knowledge. In contrast, the developing and the underdeveloped world is rich in biodiversity and traditional knowledge related to bio-resources. So, sometimes industrialised nations tend to exploit the resources or biodiversity of developing nations, for their own advantages.

Question. Many proteins are secreted in their inactive form. This is also true to many toxic proteins produced by microorganisms. Explain how the mechanism is useful for the organism producing the toxin?
Answer : Many proteins including certain toxins are secreted in their inactive form. They get activated only when exposed to a specific trigger (pH, temperature etc.). This mechanism is advantageous to the organism (e.g., bacteria) producing the toxins, as the bacteria does not get killed by the action of proteins present in the toxin.

Question. While creating genetically modified organisms, genetic barriers are not respected. How can this be dangerous in the long run?
Answer : Genetic modification of organisms can have unpredictable results when such organisms are introduced into the ecosystem. Because the real effects of gene manipulation are visible only when such organisms interact with other components and organisms of the ecosystem.

Question. In view of the current food crisis, it is said, that we need another green revolution. Highlight the major limitations of the earlier green revolution.
Answer : Major limitations of the earlier green revolution are as follows (i) Generally undesired characters also breed along with desired ones. (ii) Regular use of fertilisers affected both soil fertility and quality. (iii) Extensive use of pesticides/insecticides/weedicides resulted in harmful effects on the natural components of the ecosystem. So, another green revolution that can curb these problems and enhance the quality food production in limited land resources is certainly required.

Question. Expand GMO. How is it different from a hybrid?
Answer : GMO stands for Genetically Modified Organism that contains one or more genes from an entirely different species and is genetically altered during molecular genetics such as gene cloning, protein engineering etc. On the other hand, hybrids contains the recombinant genome of different alleles present in the population of the same species.

Question. Why has the Indian parliament cleared the second amendment of the country’s patents bill?
Answer : Amendments to the patent bill has empowered India to prevent unauthorised exploitation of our bio-resources and traditional knowledge by other countries. This bill also considers patent terms and initiated research development in this field.

Question. For which variety of Indian rice, the patent was filed by a USA company?
Answer : Indian Basmati rice was crossed with semi-dwarf variety and was claimed as a new variety for which the patent was field by a USA company.

Question. Differentiate between diagnostics and therapeutics. Give one example and for each category.
Answer : A diagnostic technique helps us to identify a disease. e.g., ELISA for HIV. A therapeutic agent on the other hand helps in the treatment of a disease. e.g., antibiotics for bacterial infections.

Question. Discuss the advantages of GMO.
Answer : Advantages of GMO are (i) GMO food crops have shorter growing cycles, greater resistance to both insects and diseases, higher yields and higher nutritional value. (ii) GMO animals have increased production and nutritive values, e.g.,GM, cows may produce more milk. (iii) The World Health Organisation or WHO, claims that GMO plants and animals may allow food prices to drop as food sources become more abundant.

Short Answer Questions

Question. ELISA technique is based on the principles of antigen and antibody interaction. Can this technique be used in the molecular diagnosis of a genetic disorder, such as phenylketonuria?
Answer : Yes. One can use antibody against the enzyme (that is responsible for the metabolism of phenylalanine) to develop ELISA-based diagnostic technique. The patient in which the enzyme protein is absent would give negative result in ELISA when compared to normal individual.

Question. Biopiracy should be prevented. State why and how. 
Answer : Biopiracy is unauthorised exploitation of bioresources of developing or under-developed countries. Hence, it should be prevented.
It can be prevented by developing laws to obtain proper authorisation and by paying compensatory benefits.

Question. Expand GMO. How is it different from a hybrid?
Answer : GMO stands for genetically modified organism. It differs from a hybrid because in a hybrid, cross is done between total genomes of two species or strains, whereas in a GMO, foreign genes are introduced in the organism and is usually maintained as extra-chromosomal entity or is integrated into the genome of the organism and their is change in only one phenotype.

Question. PCR is a useful tool for early diagnosis of an infectious disease. Comment.
Answer : PCR is a very sensitive technique which enables the specific amplification of desired DNA from a limited amount of DNA template. Hence, it can detect the presence of an infectious organism in the infected patient at an early stage of infection (even before the infectious organism has multiplied to large number).

Question. What is Biopiracy? State the initiative taken by the Indian Parliament towards it.
Answer : Biopiracy is the use of bioresources by organisations without proper authorisation from the countries and people concerned without compensatory payment.
The government has cleared patent terms, emergency provisions and research and development initiative.

Question. Nematode-specific genes are introduced into the tobacco plants using Agrobacterium vectors to develop resistance in tobacco plants against nematodes. Explain the events that occur in tobacco plant to develop resistance.
OR
How has RNAi technique helped to prevent the infestation of roots in tobacco plants by a nematode Meloidogyne incognita? 
Answer :
- A nematode Meloidogyne incognita infects the roots of tobacco plants which reduces the production of tobacco.
- It can be prevented by using RNA interference (RNAi) process which is checked by silencing of specific mRNA due to a complementary dsRNA.
- dsRNA binds and prevents translation of the mRNA (silencing).
- The source of this dsRNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) which replicate through an RNA intermediate.
- By using Agrobacterium vectors, nematode-specific genes were introduced into the host plants which produce both sense and anti-sense RNA in the host cells.
- These two RNAs are complementary to each other and form a double-stranded RNA (dsRNA) that initiates RNAi and hence silence the specific mRNA of the nematode.
- The parasite cannot survive in the transgenic host, so protects the plants from pests.

Question. (a) State the role of DNA ligase in biotechnology.
(b) What happens when Meloidogyne incognita consumes cells with RNAi gene?
Answer : (a) DNA ligase joins the DNA fragments with same sticky ends. It also links Okazaki fragments or discontinuously synthesised fragments. DNA ligose is used to link desired gene with plasmid to form recombinant DNA. (Any one)
(b) The specific mRNA of the nematode is silenced and the parasite dies.

Question. Highlight any four advantages of genetically modified organisms (GMOs).
OR
Describe any three potential applications of genetically modified plants. 
Answer : Advantages of GMOs:
(i) Tolerance against abiotic stresses (cold, drought, salt, heat).
(ii) Reduce reliance on chemical pesticides.
(iii) Reduce post-harvest losses.
(iv) Increase efficiency of mineral usage by plants.

Question. Why does the Bt toxin not kill the bacterium that produces it but kills the insect that ingests it? 
Answer : Bt toxin exist as inactive protoxin in the bacterium. It becomes active only when it enters the gut of insect due to the alkaline pH of the gut which solubilise the crystals.

Question. Name a genus of baculovirus. Why are they considered good biocontrol agents?
Answer : Nucleopolyhedrovirus is a genus of baculovirus.
They are species-specific, have narrow-spectrum insecticidal application and no negative impact on non-target organisms, hence they are considered good biocontrol agents.

Question. A corn farmer has perennial problem of corn-borer infestation in his crop. Being environmentally conscious he does not want to spray insectisides. Suggest solution based on your knowledge of biotechnology. Write the steps to be carried out to achieve it.
Answer : The following steps should be followed:
(i) Isolation of Bt toxin genes from Bacillus thuringiensis.
(ii) Incorporation of gene into corn.
(iii) Toxin coded by gene cryIAb in corn, kills the pests and the pest dies.

Question. Write the functions of adenosine deaminase enzyme. State the cause of ADA deficiency in humAnswer : Mention a possible permanent cure for a ADA deficiency patient. 
Answer : Adenosine deaminase enzyme is responsible for the proper functioning of the immune system.
ADA deficiency is caused by deletion of gene for adenosine deaminase. A possible permanent cure would be gene therapy, if it is detected at early embryonic stage.

Long Answer Questions

Question. Name the pest that destroys the cotton bolls. Explain the role of Bacillus thuringiensis in protecting the cotton crop against the pest to increase the yield.
Answer : Cotton bollworms destroy the cotton bolls. Bacillus thuringienesis has Bt toxin genes. These genes produce toxic proteins that kill the pests. Bt toxins are initially inactive protoxins but after ingestion by the insect their inactive toxin becomes active due to the alkaline pH of the gut. The activated toxin binds to the surface of midgut epithelial cells thus killing the insects. Specific Bt toxins were isolated from Bacillus thuringienesis and incorporated into the cotton plants to make them pest resistant.

Question.Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.
Answer : Bt cotton contains inactive toxin protein or protoxin. These are insecticidal proteins in the form of crystal protein. Once the insect ingests its, the inactive protoxin is converted into active form due to alkaline pH in the gut, which solubilise the crystals. The activated toxins bind to the surface of midgut epithelial cells, thus creating pores which causes cell swelling and lysis, eventually leading to the death of the insect pest.

Question. How did the process of RNA interference help to control the nematode from infecting roots of tobacco plants? Explain. 
Answer : Using Agrobacterium vectors, nematode specific genes are introduced into host plant. The introduction of DNA produced both sense and anti sense RNA in host cells. These two RNA’s being complementary formed a double stranded RNA (dsRNA) that initiated RNAi and silenced the specific mRNA of the nematode. As a result, the parasite could not survive in the transgenic host expressing specific interfering RNA.

Question. Biotechnology has helped farmers to get pest resistant cotton crops. Explain the technique adopted along with its mode of action. (Mention six points)
Answer : The technique involves the use of a popularly known biopesticide Bt toxin produced by bacteria Bacillus thuriengiensis. Bt toxin protein when ingested by the insect gets converted to its active form due to alkaline pH of the gut. The activated toxin binds to the surface of midgut epithelial cells. It creates pores in these cells that cause swelling and lysis and eventually kills the insect. The genes (cry genes) encoding this protein are isolated from the bacterium and incorporated into crop plants like cotton. The proteins encoded by these cry genes control the pest. Specifically, cryIAc and cryIIAb control cotton bollworm (Helicoverpa armigera), an insect belonging to Lepidoptera which earlier used to destroy the whole crop.

Question. List the disadvantages of insulin obtained from the pancreas of slaughtered cow and pigs.
Answer : (i) Insulin being a hormone is produced in very little amounts in the body. Hence, a large number of animals need to be sacrificed for obtaining small quantities of insulin. This makes the cost of insulin very high, demand being manifold higher than supply.
(ii) Slaughtering of animal is also not ethical.
(iii) There is potential of immune response in humans against the administered insulin which is derived from animals.
(iv) There is possibility of slaughtered animals being infested with some infectious microorganism
which may contaminate insulin.

Question. Describe the various stages involved in gene transfer for the commercial production of human insulin by Eli Lilly. 
Answer : (a) Eli Lilly prepared two DNA sequences corresponding to the A and B chains of human insulin.
(b) Sticky ends were produced in the Escherichia coli plasmid and the insulin gene by treating them both with the same restriction endonucleases.
(c) These two are then joined together by the enzyme DNA ligase.
(d) The bacteria are then grown in sterilised bioreactors in the appropriate growth medium.
(e) The chains A and B are produced separately, extracted and purified.
(f) These two chains are then combined by creating disulfide bonds to form human insulin.

Question. (i) Give the scientific name of the soil bacterium which produces crystal (Cry) proteins.
(ii) How are these proteins useful in agriculture?
(iii) What do the differently written terms ‘Cry’ and ‘cry’ represent respectively?
Answer : (i) Bacillus thuringiensis.
(ii) These Cry proteins are toxic to certain larvae of insects and thus provide resistance against them. The gene encoding Cry proteins are used in several crop plants (Bt toxin). Such a crop plant is resistant to the particular insect pest.
(iii) Cry represents crystal protein while cry refers to the gene encoding the Cry protein.

Question. What do you understand by the term biopesticide? Name and explain the mode of action of a popular biopesticide. Biopesticides are methods of controlling pests that rely on natural predation rather than introduced chemicals/or living organisms used to kill pests.
Answer : Biopesticide is a pesticide which is:
(a) not chemical in nature.
(b) more specific in action against the pest.
(c) safer for environment than chemical pesticides.
A popularly known biopesticide is Bt toxin, which is produced by a bacterium called Bacillus thuringiensis. Bt toxin gene has been cloned from this bacterium and expressed in plants. Bt toxin protein when ingested by the insect, gets converted to its active form due to the alkaline pH of the gut. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually kills the insect.

Question. (a) List any four beneficial effects of GM plants.
(b) Explain how has Bacillus thuringiensis contributed in developing resistance to cotton bollworms in cotton plants. 
Answer : (a) (i) Increases tolerance against abiotic stresses (cold, drought, salt, heat).
(ii) Reduces reliance on chemical pesticides (pest-resistant crops).
(iii) Reduces post-harvest losses.
(iv) Increases efficiency of minerals used by plants (this prevents early exhaustion of fertility of soil).
(v) Enhances nutritional value of food, e.g., vitamin ‘A’ enriched rice (golden rice). 
(b) Bt cotton
- Some strains of Bacillus thuringiensis produce proteins that kill some insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
- B. thuringiensis forms protein crystals which contain a toxic insecticidal protein.
- Bt toxins are initially inactive protoxins but after ingestion by the insect their inactive toxin becomes active due to the alkaline pH of the gut, which solublises the crystals.
- The activated toxin binds to the surface of midgut epithelial cells thus creating pores which causes cell swelling and lysis, further leading to death of the insects.
- Specific Bt toxin genes obtained from Bacillus thuringiensis are used in several crop plants like cotton.
- The toxin is coded by a gene called cry which is of various types. For example, proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms and that of cryIAb control corn borer.
- Bt tobacco was first cultured to kill hornworm (Manduca sexta).

Question. What is GMO? List any five possible advantages of a GMO to a farmer. 
Answer : Genetically modified organisms (GMOs) are plants, bacteria, fungi and animals whose genes have been altered by manipulation.
For advantages of a GMO, 
Food production can be increased by the following ways:
(a) Agrochemical-based agriculture.
(b) Organic agriculture.
(c) Genetically engineered crop-based agriculture.
- The Green Revolution succeeded in increasing food supply because of
(a) use of improved crop varieties.
(b) use of agrochemicals (fertilisers and pesticides).
(c) use of better management practices.
- Agrochemicals are expensive for farmers in developing countries and also have harmful effects on environment. Therefore, genetically modified crops were developed.
- Genetically modified organisms (GMOs) are plants, bacteria, fungi and animals whose genes have been altered by manipulation.
- Genetic modification of crops have resulted in
(a) increased tolerance against abiotic stresses (cold, drought, salt, heat).
(b) reduced reliance on chemical pesticides (pest-resistant crops).
(c) reduced post-harvest losses.

Question. Mention some transgenic plants and their potential applications.
Answer : Some transgenic plants and their potential applications

Question. Why is proinsulin so called? How is insulin different from it? 
Answer : Proinsulin is called so because it is an inactive form of insulin.

Question. Plasmid is a boon to biotechnology. Justify this statement quoting the production of human insulin as an example.
Answer : Plasmids are extra-chromosomal, self-replicating, usually circular, double-stranded DNA molecules found naturally in many bacteria.
In 1983, Eli Lilly an American company, first prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. These chains A and B were produced separately, extracted and combined by creating disulfide bonds to form functional human insulin (humulin).

Question. (a) Name the deficiency for which first clinical gene therapy was given.
(b) Mention the causes of and one cure for this deficiency.
Answer : (a) Adenosine deaminase deficiency (ADA).
(b) Cause: Deletion of ADA gene.
Cure: Bone marrow transplantation/enzyme replacement therapy/giving functional ADA to patient by injection/infusion of genetically engineered lymphocytes/introducing gene isolated from marrow cells producing ADA into cells at early embryonic stages. 

Question. Explain process of gene therapy to treat adenosine deaminase deficiency. Mention two disadvantages of this procedure. 
Answer : (i) Lymphocytes from the blood of the patient are grown on culture outside the body.
(ii) A functional ADA cDNA is then introduced into these lymphocytes using a retroviral vector.
(iii) The genetically engineered lymphocyte are returned to the blood of patient.
Disadvantages: Therapy is not completely curative as cells do not remain alive and periodic infusion of lymphocytes is required.

ONE MARK QUESTIONS

1.What was the speciality of the milk produced by cow Rosie?

2.Describe the responsibility of GEAC, set- up by the Indian Government.

TWO MARKS QUESTIONS

3.Nematode specific genes are introduced into the tobacco plants using Agrobacterium vectors to develop resistance in tobacco plants against nematodes. Explain the events that occur in tobacco plant to develop resistance.

4.Name the source organism from which Ti plasmid is isolated. Explain the use of this plasmid in biotechnology.

5.Highlight the any four advantages of Genetically Modified Organisms (GMOs).

6.One of the main objectives of biotechnology is to minimize the use of insecticides on cultivated crops. Explain with the help of a suitable example how insect resistant crops have been developed using techniquesof biotechnology

8.How is transgenic tobacco plant protected against Meloidegyneincognita? Explain the procedure.

3 MARK QUESTIONS

9.Name the source and the types of Cry genes isolated from it for incorporation into crops by biotechnologists. Explain how these genes have brought beneficial changes in the genetically modified crops

10.How did Eli lily company go about preparing the human insulin? How is the insulin thus produced different from that produced by the functional human insulin gene?

11.a) Name the nematode that infests and damages tobacco roots.

b) How are transgenic tobacco plants produced to solve this problem? 

12a) How is mature insulin different from proinsulin secreted by pancreas in humans?

b) Explain how was human functional insulin produced using rDNA technology?

Why is the functional insulin thus produced considered better than the ones earlier by diabetic patients?