CBSE Class 12 Biology Biotechnology and its Applications Assignment Set C

Very Short Answer Type Questions

Question. Give the name of HGH (Human Growth Hormones), developed during recombinant DNA technology and used for treating hypopituitary dwarfism in human. 
Answer: Somatotropin.

Question. Does our blood have proteases and nucleases?
Answer: Blood does not contain proteases and nucleases because their function is to breakdown proteins and nucleic acids.

Question. Mention the source organism of the gene cryIAc and its target pest. 
Answer: Source organism — Bacillus thuringiensis
Target pest — Cotton bollworms

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. How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?
Answer: Bacillus thuringiensis products are endotoxin which when ingested and released in the gut of the larvae of insect pest disrupts the insect gut lining thereby killing them.

Question. A corn farmer has a perennial problem of corn-borer infestation in his crop. Being environmental conscious he does not want to spray insecticides. Suggest solution based on
your knowledge of biotechnology. Write the steps to be carried out to achieve it.
Answer: Isolation of Bt toxin gene from Bacillus thuringiensis, incorporated into corn, toxin coded by gene cry IAb in corn, kills the pests/pest dies.

Question. Name a recombinant vaccine that is currently being used in vaccination program?
Answer: Hepatitis B recombinant vaccine, Engerix-B, is used for vaccination of hepatitis virus.

Question. Why is the gene encoding for ‘Cry’ protein inserted into a crop plant?
Answer: Cry protein producing gene is transferred to the plant to provide resistance against insect larvae.

Question. Name any two techniques that serve the purpose of early diagnosis of some bacterial/viral human diseases. 
Answer: Enzyme linked immuno sorbent (ELISA) and Polymerase Chain Reaction (PCR) serve the purpose of early diagnosis of human diseases.

Question. Name the specific type of gene that is incorporated in a cotton plant to protect the plant against cotton boll worm infestation. 
Answer: Cry IAc/Cry IIAb genes are incorporated in a cotton plant.

Question. What is the significance of the process of RNA interference (RNAi) in eukaryotic organisms?
Answer: RNA interference in all eukaryotic organisms is a method of cellular defence.

Short Answer Type Questions

Question. How has the use of Agrobacterium as vectors helped in controlling Meloidegyne incognitia infestation in tobacco plants ? Explain in correct sequence.
Answer: (a) Using Agrobacterium vector, nematode specific genes are introduced into host plant.
(b) Sense and antisense strands of mRNA are produced.
(c) ds RNA is formed.
(d) ds RNA initiates RNAi.
(e) Prevents translation of mRNA / Silencing of mRNA of parasite / nematode.
(f) Parasite will not survive.

Question. (a) While cloning vectors, which of the two will be preferred by biotechnologists -bacteriophages or plasmids. Justify with reason.
(b) Name the first transgenic cow developed and state the improvement in the quality of the product produced by it.
Answer: (a) Bacteriophages, because they have very high copy numbers of their genome within the bacterial cells whereas some plasmids may have only one or two copies per cell and others may have 15-100 copies per cell.
(b) Rosie, it produced human protein-enriched milk (2.4 gm per litre).

Question. The Indian Government refuted the attempt by a multinational company (MNC) to patent the antiseptic property of curcumin derived from Turmeric. Analyze the unethical practice adopted by the MNC, state its implications and suggest provisions in the Indian Law to prevent such malpractices.
Answer: (i) MNC wanted to encash on our rich legacy by biopiracy.
(ii) It leads to injustice, inadequate compensationand unauthorized exploitation of traditional knowledge of the country.
(iii) Second amendment of the Indian Patents Bill takes into consideration issues related to patent terms, emergency provisions, and research and development initiative.

Question. Explain the various steps involved in the production of artificial insulin.
Answer: Two DNA sequences corresponding to A and B polypeptide chains of human insulin were prepared, these were introduced into E. coli to produce A and B chains separately, these chains were extracted and combined by creating disulphide bonds.

Question. Name the organism from which the ‘cry‘genes are isolated. Mention with the help of suitable example why and how biotechnologists have made use of ‘cry‘ genes ?
Answer: Bacillus thuringiensis 
(i) Source of insecticidal (crystal) protein that controls the cotton bollworms / corn borer. 
(ii) Specific Bt toxin genes were isolated from Bacillus thuringiensis, incorporated into several crop plants such as cotton.

Question. What was the challenge for production of insulin using rDNA techniques ? Howdid  Eli Lilly produce insulin using rDNA technology?
Answer: The challenge for production of insulin using rDNA technique was getting insulin assembled into a mature form. 
(i) Prepared two DNA sequence corresponding to A and B chains of human insulin.
(ii) Introduced them in plasmids of E. coli to produce insulin chains.
(iii) Chains A and B were produced separately.
(iv) Extracted and combined by creating disulfide bonds to form human insulin.

Question. Why do lepidopterans die when they feed on Bt cotton plant ? Explain how does it happen.
Answer: Bt cotton contains inactive toxin protein /protoxin / insecticidal protein / crystal protein,once the insects ingest it, the inactive protoxins are converted into active form due to alkaline pH in gut, which solubilises the crystals, activated toxins binds to surface of midgut (epithelial cells), create pores, causes cell swelling, lysis eventually leading the death of the insect pest.

Question. List any four ways by which GMO’s have been useful for enhanced crop output.
Answer: Make crops more tolerant to abiotic / cold / heat / drought / salt stresses / Reduces reliance on chemical pesticides (pest-resistant crops) / Reduce post harvest losses / Increased efficiency of mineral usage by plant (prevents early exhaustion of soil fertility) / Enhanced nutritional value of food (example vitamin A enriched rice / starch) / To create tailor-made plants for non food purposes (to supply alternative resources of fuels / pharmaceuticals to industries).

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 ofm ineral usageb y plants.

Question. Bt cotton is resistant to pest, such as lepidopteran, dipterans and coleopterans. Is Bt cotton resistant to other pests as well?
Answer: Bt cotton is made resistant to only certain specific taxa of pests. It is quite likely that in future,some other pests may infest the Bt cotton plants. It is similar to immunisation against small-pox which does not provide immunity against other pathogens like those that cause cholera, typhoid, etc.

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. Consult internet and find out how to make orally active protein pharmaceutical. What is the major problem to be encountered?
Answer: Orally active protein pharmaceutical can be made by lining it with a substance that will dissolve after it has passed through the stomach.
The major problem encountered is that the stomach enzymes and acids may denature the therapeutic protein and render it ineffective.

Question. Name the source and the types of cry genes isolated from it for incorporation into crops by biotechnologists. Explain how have these genes brought beneficial changes in the genetically modified crops.
Answer: Source of cry gene is Bacillus thuringiensis.
The following type of cry genes are isolated from it: cryIAc, cryIIAb, cryIAb.
The introduction of cry gene acts as biopesticide. The cry gene produce crystals of toxic insecticidal protein. The activated toxin causes death of the insect.

Question. How did an American Company, Eli Lilly use the knowledge of rDNA technology to produce human insulin? 
Answer: Two chains of DNA sequence corresponding to A and B chains of human insulin were prepared.
They introduced them into plasmids of E. coli to produce separate A and B chains. The A and B chains extracted were then combined by creating disulphide bonds and form human insulin.

Question. cryIAb is introduced in a plant to control infestation by corn borer.
(a) Name the resultant plant after successful insertion of the gene desired.
(b) Summarise the action of the gene introduced. 
Answer: (a) Bt corn
(b) CryIAb/Bt toxin gene codes for crystal protein; the Bt toxin protein exists as an inactive protein, but once an insect ingests it, it gets converted into an active form due to the alkaline pH of the gut which solubilises the crystal. The activated toxin binds to the surface of mid gut and creates pores that cause swelling, lysis and eventually death of the insect.

Question. (a) How does cryIAc gene express itself in its host?
(b) State the role of this gene in controlling the infestation of bollworm. 
                                            OR
Name the insect pest that is killed by the products of cryIAc gene. Explain how the gene makes the plant resistant to the insect pest.
Answer: (a) cryIAc gene codes for a toxic insecticidal protein that controls the cotton bollworms.
(b) This gene codes for a toxin that becomes active when ingested by the insect. The activated toxin binds to the surface of mid-gut epithelial cells thus creating pores which causes cell swelling and lysis, further leading to death of the insects.

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. How have biotechnologists effectively used Agrobacterium tumefaciens in plants and retroviruses in animals? Explain. 
Answer: In plants the tumor inducing (Ti) plasmid of Agrobacterium tumefaciens has been modified into a cloning vector, which is no more pathogenic to the plants, but is still able to use the mechanisms to deliver genes of our interest into a variety of plants. In animals retroviruses have been disarmed and are used to deliver desirable genes into animal cells. Once a gene or a DNA fragment has been ligated into a suitable vector it is transferred into a bacterial/plant or animal host (where it multiples).

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. How has the use of Agrobacterium as vectors helped in controlling Meloidogyne incognitia infestation in tobacco plants? Explain in correct sequence. 
Answer: 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. 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. (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 aicnt ion 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. Name the genes responsible for making Bt cotton plants resistant to bollworm attack.
How do such plants attain resistance against bollworm attacks? Explain. 
Answer: Bt cotton has cryIAc/cryIIAb genes. These genes produce crystals of protoxin.
When bollworm bites the cotton fruits, it consumes the toxic insecticidal protein. The alkaline pH in its gut activates the toxin. The activated toxin binds to mid-gut epithelial cells resulting in the lysis of cells leading to the death of the insect.

Long Answer Type Questions

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, 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.
(d) increased effici ency of mineursaelds by plpanretvs ents (thisearly exohfafuers tiloi tny ol)f.soi
(e) enhanced nutritional value of food, e.g., vitamin ‘A’ enriched rice (golden rice).
(f) creation of tailor-made plants to supply alternative resources such as starches, fuels and pharmaceuticals to industries.

Question. Why GMOs are so called? List the different ways in which GMO plants have benefitted and have become useful to humAnswer :
Answer: Genetically Modified Organisms (GMO) or transgenic organisms are the plants, bacteria, fungi and animals whose genes are altered by manipulation.
Advantages of genetic modification in plants :
l It makes crops more tolerant to abiotic stresses like cold, drought, salt, heat etc.
l Most of the GM plants have been developed for pest-resistance, which increases the crop productivity and therefore, reduces the reliance on chemical pesticides.
l It helps to reduce the post-harvest loss of crops.
l It increases the efficiency of mineral usage by plants. This prevents early exhaustion of the fertility of the soil.
l It enhances the nutritional value of food. This is known as bio-fortification. e.g.; Golden rice is transgenic variety in rice, which is rich in vitamin ‘A’.
l GM is used to create tailor-made plants to supply alternative resources to industries, in the form of starches, fuels and pharmaceuticals.