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Biotechnology and its Applications – Class 12 Biology notes, important questions and MCQs

NCERT Class 12 Biology, chapter 10. Notes, key terms, important questions with answers and MCQs.

Chapter overview

Biotechnology improves crops, makes medicines, enables gene therapy and diagnosis, and raises ethical issues such as biopiracy.

Agriculture

Bt cotton carries cry genes from Bacillus thuringiensis; the Bt toxin kills insect larvae (cryIAc, cryIIAb for cotton bollworms; cryIAb for corn borer).
RNA interference (RNAi) protects tobacco from the nematode Meloidogyne incognita.
Golden rice is rich in β-carotene (vitamin A precursor).

Medicine and ethics

Recombinant human insulin (Eli Lilly, 1983) from separate A and B chains made in E. coli.
Gene therapy: first used in 1990 for ADA deficiency.
Transgenic animals help research and produce proteins (Rosie the cow gave α-lactalbumin-enriched milk); GEAC regulates GM organisms in India; biopiracy of basmati and turmeric raised patent issues.

Key terms

Transgenic organism: organism with a foreign gene introduced
Gene therapy: correcting a genetic defect by introducing a normal gene
Biopiracy: use of bio-resources without proper permission or payment

Important questions with answers

What are GM crops? Give two advantages.2 marks

Crops whose genes have been altered by genetic engineering. Advantages: more tolerance to drought, cold, salt and pests; less use of chemical pesticides; better nutritional value (golden rice); less post-harvest loss.

How is RNA interference used to protect tobacco from nematodes?3 marks

Nematode-specific genes are introduced into the tobacco plant using Agrobacterium so that the plant produces both sense and antisense RNA. These form double-stranded RNA, which silences the matching mRNA of the nematode (RNAi), so the parasite cannot survive in the transgenic plant.

Explain how Bt cotton is made and how Bt toxin kills insects. Mention two ethical concerns about GM organisms.5 marks

Genes (cry genes such as cryIAc and cryIIAb) for the insecticidal Bt protein are taken from Bacillus thuringiensis and inserted into cotton plants, which then make the protein themselves. The protein exists as an inactive protoxin. When a bollworm larva eats the plant, the alkaline pH of its gut dissolves the crystals and activates the toxin, which binds to midgut epithelial cells, creates pores, causes swelling and lysis, and kills the insect. Ethical concerns: possible unknown effects on other organisms and biodiversity (gene flow to wild plants), and biopiracy or unfair patents on biological resources of developing countries (basmati, turmeric, neem); hence GEAC regulates GM research and release in India.

Quick revision

Insulin chains A and B are joined by disulphide bonds.
First gene therapy: ADA deficiency.
GEAC approves GM research.

Exam tips

Bt toxin is inactive in the bacterium (protoxin) and becomes active in the alkaline gut of insects.
For insulin, remember: proinsulin has an extra C-peptide; Eli Lilly made A and B chains separately in E. coli and joined them by disulphide bonds.

Practice MCQs

Bt cotton is resistant to
1. insect pests
2. fungi
3. drought
4. viruses
Show answer
Answer: (a) insect pests. Bt toxin.
Golden rice is rich in
1. iron
2. β-carotene
3. protein
4. calcium
Show answer
Answer: (b) β-carotene. Vitamin A precursor.
The first clinical gene therapy (1990) treated
1. diabetes
2. cancer
3. haemophilia
4. ADA deficiency
Show answer
Answer: (d) ADA deficiency. Adenosine deaminase deficiency.
RNAi in tobacco protects against
1. bollworm
2. virus
3. nematode Meloidogyne
4. fungus
Show answer
Answer: (c) nematode Meloidogyne. Silencing nematode mRNA.
The first transgenic cow was
1. Rosie
2. Dolly
3. Molly
4. Polly
Show answer
Answer: (a) Rosie. Rosie (1997).
Bt toxin becomes active in the insect gut because of
1. alkaline pH
2. acidic pH
3. high temperature
4. light
Show answer
Answer: (a) alkaline pH. Alkaline gut.
Indian body that regulates GM organisms is
1. ICMR
2. NITI Aayog
3. ISRO
4. GEAC
Show answer
Answer: (d) GEAC. Genetic Engineering Appraisal Committee.
ELISA is based on the principle of
1. DNA replication
2. antigen–antibody interaction
3. PCR only
4. gel electrophoresis
Show answer
Answer: (b) antigen–antibody interaction. Enzyme-linked immunosorbent assay.

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Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.