CBSE Class 12 Biology Biotechnology And Its Application Question Bank

MULTIPLE CHOICE QUESTIONS

Question. A tumour inducing plasmid widely used in the production of transgenic plant is that of
(a) Escherichia coli
(b) Bacillus thuringiensis
(c) Staphylococcus aureus
(d) Agrobacterium tumefaciens
Answer : D

Question. How many varieties of rice has been estimated to be present in India? 
(a) 2,000
(b) 20,000
(c) 200,000
(d) 2,000,000
Answer : C

Question. The scientific process by which crop plants are enriched with certain desirable nutrients is called
(a) crop protection
(b) breeding
(c) bio-fortification
(d) bio-remediation
Answer : C

Question. Which of the following is a variety of Brassica resistance to white rust disease? 
(a) Himgiri
(b) Pusa Kamal
(c) Pusa Swarnim (Karan rai)
(d) Pusa Sadabahar
Answer : C

Question. The first clinical gene therapy was given in 1990 to a 4 years old girl with enzyme deficiency of
(a) Adenosine deaminase (ADA)
(b) Tyrosine oxidase
(c) Monamine oxidase
(d) Glutamate dehydrogenase
Answer : A

Question. Select the correct statement(s)- 
(1) IARI has released a mustard variety rich in vitamin C.
(2) Pusa Sawani variety of Okra is resistant to aphids.
(3) Hairiness of leaves provides resistance to insect pests.
(4) Agriculture accounts for approximately 33% of India's GDP and employs nearly 62% of the population.
(a) (1) and (2)
(b) (2) and (3)
(c) (1), (3) and (4)
(d) None of these
Answer : C

Question. Which variety of rice was patented by a U.S. company even though the highest number of varieties of this rice is found in India ? 
(a) Sharbati Sonara
(b) Co-667
(c) Basmati
(d) Lerma Roja
Answer : C

ASSERTION REASON QUESTIONS

Directions : Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.

Question. Assertion : Insect resistant transgenic cotton has been produced by inserting Bt gene.
Reason : The Bt gene is derived from a bacterium.
Answer : B

Very Short Answer 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. 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 Questions

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. 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. 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.

Question. State the role of transposons in silencing of mRNA in eukaryotic cells. 
Answer. Transposons also called as jumping genes, are the source of complementary dsRNA molecule that binds to and prevents translation of mRNA (silencing).

Question. Write the possible source of RNA interference (RNAi) gene. 
Answer. Mobile genetic elements (transposons) and infection by viruses having RNA genomes are the possible sources of RNAi gene.

Question. What happens when Meloidogyne incognita consumes cells with RNAi gene?
Answer. When Meloidogyne incognita consumes cells with RNAi gene, parasite cannot survive and this prevents infestation. The introduced RNAi gene forms both sense and anti-sense RNA. Two strands being complementary to each other bind and form dsRNA, leading to RNAi. Then, the mRNA of nematode is silenced and is unable to translate the protein so the parasite cannot survive there.

Question. Biotechnologists refer to Agrobacterium tumefaciens as a natural genetic engineer of plants. Give reasons to support the statement.
Answer. Agrobacterium tumefaciens is called natural genetic engineer of plants because genes carried by its plasmid produce effect in several parts of the plant.

Question. How does dsRNA gain entry into a eukaryotic cell to cause RNA interference?
Answer. The dsRNA gains entry into a eukaryotic cell either through
(i) infection by viruses having RNA genomes
(ii) mobile genetic elements (transposons) that replicate via an RNA intermediate.

Question. Name the cry genes that control cotton bollworm and corn borer respectively.8. How are tobacco plants benefitted when nematode specific genes are introduced into them using certain vectors? Name the vectors used. 
Answer. The genes cryIAc and cryIIAb control the cotton bollworms, whereas cryIAb controls corn borer.

Question. Write the functions of
(a) cryIAC gene
(b) RNA interference (RNAi). 
Answer. (a) cryIAc gene controls cotton bollworms in Bt cotton.
(b) RNA interference (RNAi) takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA.

Question. Why does Bt toxin not kill the bacterium that produces it, but kill the insect that ingests it?
Answer. Soil bacterium Bacillus thuringiensis produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes) etc. B. thuringiensis forms some protein crystals. These crystals contain a toxic insecticidal protein. This toxin does not kill the Bacillus (bacterium) because
it exists as inactive protoxins in them. But, once an insect ingests the crystals, it is converted into an active form of toxin due to the alkaline pH of the alimentary canal that solubilises the crystals.
The activated toxin binds to the surface of mid gut epithelial cells and creates pores which cause cell swelling and lysis and finally cause death of the insect.

Question. What does ‘cry’ genes in Bacillus thuringiensis code for? State its importance in cotton crop.
Answer. cry genes code for certain crystal (cry) proteins that are toxic to insect larvae. The genes cryIAc and cryIIAb control cotton bollworm. When these genes are introduced into cotton plants through genetic engineering, these plants become resistant to the attack of cotton bollworm.

Question. How does ‘RNA interference’ take place in eukaryotes? Mention its importance.
Answer. RNA interference (RNAi) is the phenomenon of inhibiting activity of a gene through production of sense and antisense RNA. RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.

Question. List any four advantages of genetically modified plants.
Answer. Applications of genetically modified plants are as follows:
(i) Genetically modified plants are resistant to (a) diseases resulting from viral, bacterial and fungal infections (b) pests, such as nematodes and insects and (c) pesticides.
(ii) GM plants can tolerate adverse abiotic stresses such as cold, drought, salt, heat.
(iii) GM plants show increased efficiency of mineral usage (this prevents early exhaustion of fertility of soil).
(iv) GM plants have high nutritional value, e.g., vitamin A enriched rice.
(v) Plants such as poplar (Populus) trees have been genetically engineered to clean up heavy pollution from contaminated soil.
(vi) These plants helped to reduce post harvest losses e.g., Flavr savr transgenic tomato

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