CBSE Class 12 Biology Bio Technology and Its Application Question Bank

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Biology: Chapter 12 – Biotechnology and Its Applications (Question Bank)

PCR is a powerful diagnostic technique. Justify. (1 mark)

Answer: PCR (polymerase chain reaction) can amplify even a very small amount of the DNA of a pathogen or of a mutated gene. So the disease can be detected at an early stage, when the symptoms have not yet appeared. It is used for diseases like AIDS (to detect HIV) and cancer.

Name the diagnostic test for AIDS when the concentration of HIV is (a) low, (b) high. (1 mark)

Answer: (a) When the concentration of HIV is low, PCR is used. (b) When the concentration is high, ELISA is used.

State the principle used in ELISA. (1 mark)

Answer: ELISA is based on the principle of antigen–antibody interaction.

What is GEAC? State its function. (2 marks)

Answer: GEAC is the Genetic Engineering Approval Committee, set up by the Government of India. It decides whether GM research is safe for introduction into the public services, and it checks the safety and validity of GM research and of the introduction of GM organisms for public services.

How are transgenic animals made useful in chemical safety testing and in studying diseases? (2 marks)

Answer: Transgenic animals are made more sensitive to toxic chemicals than non-transgenic animals. So the toxicity of a chemical can be tested on them quickly and on a small scale. Transgenic animals are also designed to show the symptoms of human diseases like cancer, cystic fibrosis and Alzheimer's disease, so they serve as disease models for studying how a disease develops and how it can be treated.

How is the use of rDNA technology better than the traditional methods of agriculture? (2 marks)

Answer:

1. The use of fertilisers and pesticides is minimised.
2. Only the desirable traits can be selected for breeding, so the process is more precise.
3. Tailor-made plants can be created for industries (for example, with a changed oil content or longer shelf life).

Name four applications of biotechnology. (2 marks)

Answer:

1. Therapeutics (for example, the production of human insulin and vaccines).
2. Diagnostics (for example, PCR and ELISA).
3. Genetically modified crops in agriculture.
4. Biofortified food, and transgenic animals.

Mention two applications of biotechnology in medicine, with examples. (2 marks)

Answer:

1. The production of genetically engineered insulin, using rDNA technology.
2. The treatment of genetic disorders by gene therapy, for example ADA deficiency.

What problem was faced in the production of insulin by rDNA technology and how was it resolved? (2 marks)

Answer: Insulin is made as a prohormone (proinsulin) in the human body. It has to be processed to remove the C peptide to become mature insulin, and bacteria cannot do this. So the A and B polypeptide chains of insulin were produced separately in E. coli and were then joined together by creating disulphide bonds to form human insulin.

What merits do the products made using biotechnology have? Give an example of one such product used in treatment. (3 marks)

Answer: Products made using biotechnology (such as human insulin made by rDNA technology) are identical to the human proteins, so they do not cause allergic or immune reactions, as products made from animal sources could. They can also be made in large quantities and are free from the infections of animal sources. An example is α-1 antitrypsin, used in the treatment of emphysema.

What are the three critical research areas of biotechnology? (3 marks)

Answer:

1. Providing the best catalyst, in the form of an improved organism, usually a microbe or a pure enzyme.
2. Creating the optimal conditions through engineering for a catalyst to act.
3. Downstream processing technologies to purify the protein or the organic compound.

How is biotechnology used to produce Bt cotton? Explain. (3 marks)

Answer: Bt cotton is made using the genes of the bacterium Bacillus thuringiensis. The cry genes of the bacterium, which code for the Bt toxin, were isolated and introduced into cotton plants by rDNA technology. The toxin in the plant is produced in an inactive form. It becomes active only in the gut of the insect. So the cotton plant became resistant to the cotton bollworms.

How has the Bt toxin been effective against insects? (3 marks)

Answer:

1. The larva of the insect eats the leaves of the Bt cotton plant, which contain the toxin (a protoxin, which is inactive).
2. In the alkaline pH of the gut of the insect, the protoxin is solubilised and activated.
3. The active toxin binds to the surface of the midgut epithelial cells and creates pores.
4. The cells swell and burst, and the insect dies.

How can biotechnology help in increasing the yield of tobacco? (3 marks)

Answer: The yield of tobacco falls because a nematode, Meloidogyne incognitia, infects the roots of the tobacco plant. Using RNA interference, Agrobacterium is used as a vector to introduce genes into the tobacco plant. These genes make sense and antisense RNA in the host cells, and these form a double-stranded (dsRNA) molecule that is complementary to the mRNA of the nematode. This silences the mRNA of the nematode, so the parasite cannot survive in the transgenic host. The tobacco plant becomes pest resistant and the yield increases.

Name a natural genetic engineer and state how it has been used to create pest-resistant tobacco. (3 marks)

Answer: Agrobacterium tumefaciens is a natural genetic engineer of plants. It has been used as a vector to introduce the nematode-specific genes into the tobacco plant. Through RNA interference, these genes produce a double-stranded RNA that is complementary to the mRNA of the nematode. This silences the mRNA of the nematode and stops the production of its proteins, so the nematode cannot infect the roots. In this way the tobacco plant becomes pest resistant.

Insulin produced earlier had problems. This has been overcome with rDNA technology. Explain. Why is insulin not administered orally? (3 marks)

Answer: Earlier, insulin was obtained from the pancreas of slaughtered cattle and pigs. It sometimes caused allergic reactions (immune responses) in the patients because it was a foreign protein. Insulin made by rDNA technology (using E. coli) is the same as human insulin and does not cause allergic reactions, as no animal protein is used. Insulin is a protein, so it would be digested by the enzymes in the alimentary canal if it were taken orally. It therefore has to be injected.

Gene therapy is a better alternative to the other measures taken for ADA deficiency. Why is it a better alternative? What other methods were used earlier? How can it be done? (3 marks)

Answer: Gene therapy gives a permanent cure, whereas the other methods give only temporary relief. The methods used earlier were bone marrow transplantation, and enzyme replacement therapy (injecting functional ADA), which has to be repeated. In gene therapy, lymphocytes are taken from the blood of the patient and grown in a culture. A functional cDNA of ADA, made with the help of a retrovirus vector, is introduced into these lymphocytes, which are then returned to the patient. To make the cure permanent, the gene must be introduced into the stem cells from the bone marrow, or into early embryonic stages.

GMOs have been useful to mankind. List about five useful GMOs created so far and how they have been useful. (5 marks)

Answer:

1. Bt cotton: it is resistant to the bollworm, so less pesticide is needed.
2. Golden rice: it is rich in vitamin A (β-carotene), which helps to prevent vitamin A deficiency.
3. Tomato with a longer shelf life (Flavr Savr): it reduces post-harvest loss.
4. Crops tolerant to abiotic stresses (cold, drought, salt, heat): they give higher yields.
5. Rosie, a transgenic cow that produces human α-lactalbumin-enriched milk, which is more nutritionally balanced for human babies.
6. Transgenic bacteria (E. coli) that make human insulin for diabetics.

"Most of the industrialised nations are rich financially but poor in biodiversity and traditional knowledge." Justify this statement with an example. How can you, as a biology student, help a tribe that is exploited for its traditional knowledge? (4 marks)

Answer: Industrialised nations have the money and the technology but have little biodiversity and little traditional knowledge, while the developing countries are rich in both. The industrialised nations, therefore, use the biological resources and the traditional knowledge of other countries without proper authorisation and without sharing the benefits. This is biopiracy, and it raises ethical issues. For example, a US company got a patent on basmati rice, an Indian variety, even though it was developed in India by farmers over centuries (the patents on turmeric and neem are other examples).
As a biology student, I can create awareness among the tribe about biopiracy and the need to protect their traditional resources and wisdom. I can help them to document their knowledge and to get it registered and patented in their own name, so that it is protected and they share the benefits.

How would you have used biotechnology if you had the complete technology in your hands? (4 marks)

Answer: This is an open question, and any five sensible applications are acceptable if they show concern for society. For example, I would use biotechnology to:

1. develop crops that give high yields with little water, fertiliser and pesticide, to end hunger;
2. make low-cost medicines and vaccines available to all;
3. develop gene therapy for genetic disorders;
4. develop microbes that clean up pollution and degrade plastic;
5. develop biofortified foods to remove malnutrition.