CBSE Class 12 Biology Exemplar: Biotechnology and Its Applications NCERT Solutions

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NCERT Solutions PDF Class 12 PDF

This resource provides detailed NCERT Solutions for Chapter 12 of the CBSE Class 12 Biology Exemplar, focusing on Biotechnology and Its Applications. It covers multiple-choice questions (MCQs) that test understanding of genetically modified (GM) plants like Bt cotton, the structure and processing of human insulin, the function of GEAC, applications of antitrypsin, the nature of DNA/RNA probes, characteristics of retroviruses, and the production site of ADA. The solutions offer clear explanations, step-by-step reasoning for MCQs, and insights into the underlying biological processes. This guide is designed to help students grasp complex biotechnological concepts and prepare effectively for their board examinations by reinforcing their knowledge of key applications and principles.

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BoardCBSE
ClassClass 12
SubjectBiology Exemplar
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 12

Chapter summary

Chapter 12 of the CBSE Class 12 Biology Exemplar, 'Biotechnology and Its Applications,' is explored through a series of MCQs. These questions assess understanding of genetically modified organisms (GMOs) like Bt cotton, the production and maturation of human insulin from pro-insulin, the role of the Genetic Engineering Approval Committee (GEAC), therapeutic uses of alpha-antitrypsin for emphysema, the properties and use of DNA/RNA probes in molecular biology, the unique replication cycle of retroviruses, and the primary site of Adenosine Deaminase (ADA) production in the immune system. The solutions clarify these topics, aiding revision.

Learning outcomes

  • Understand the characteristics and applications of genetically modified plants like Bt cotton.
  • Explain the process of human insulin production from pro-insulin, including the role of C-peptide.
  • Identify the function and significance of the Genetic Engineering Approval Committee (GEAC).
  • Recognize the therapeutic use of alpha-antitrypsin in treating emphysema.
  • Describe the nature and application of DNA and RNA probes in molecular diagnostics.
  • Differentiate the replication mechanism of retroviruses from other viruses.
  • Identify the primary cells responsible for ADA production and its role in immunity.

Topics covered

Paper topics

  • Biotechnology Applications
  • Genetically Modified (GM) Plants
  • Bt Cotton
  • Human Insulin Production
  • Pro-insulin and C-peptide
  • Genetic Engineering Approval Committee (GEAC)
  • Alpha-antitrypsin
  • Emphysema Treatment
  • Molecular Probes (DNA/RNA)
  • Retroviruses
  • Reverse Transcription
  • Adenosine Deaminase (ADA)

Important topics

  • Bt Cotton and GM Technology
  • Insulin Production and Maturation
  • Retroviral Replication Cycle
  • Role of ADA in Immunity
  • Applications of Molecular Probes

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Questions and Solutions

Q. 1

Bt cotton is not

a GM plant

insect resistant

a bacterial gene expressing system

resistant to all pesticides

Solution: The correct option is (d). Bt cotton is a genetically modified (GM) plant that has been engineered to resist certain insect pests. This resistance is achieved by introducing a gene from the bacterium *Bacillus thuringiensis* (Bt), which produces a toxin harmful to specific insects. While Bt cotton is insect-resistant and utilizes a bacterial gene expression system, it is not resistant to all pesticides or all types of insects. Its resistance is specific to certain insect taxa like lepidopterans and coleopterans.

Q. 2

C-peptide of human insulin is
  1. a part of mature insulin molecule
  2. responsible for the formation of disulphide bridges
  3. removed during maturation of pro-insulin to insulin
  4. responsible for its biological activity
Solution: The correct option is (c). Human insulin is initially synthesized as a precursor molecule called pro-insulin. Pro-insulin consists of three parts: an A-chain, a B-chain, and a connecting peptide known as C-peptide. During the maturation process, the C-peptide is enzymatically cleaved and removed, leaving behind the A and B chains. These two chains are then linked together by disulphide bonds to form the mature, biologically active insulin molecule.

Q. 3

GEAC stands for
  1. Genome Engineering Action Committee
  2. Ground Environment Action Committee
  3. Genetic Engineering Approval Committee
  4. Genetic and Environment Approval Committee
Solution: The correct option is (c). GEAC stands for Genetic Engineering Approval Committee. This committee is a regulatory body established by the Indian government. Its primary role is to assess and approve proposals related to genetically modified research and the introduction of genetically modified organisms (GMOs) for public use, ensuring safety and ethical considerations are met.

Q. 4

Antitrypsin is
  1. an antacid
  2. an enzyme
  3. used to treat arthritis
  4. used to treat emphysema
Solution: The correct option is (d). Alpha-antitrypsin (\alpha-antitrypsin) is a protein that acts as a protease inhibitor. It is particularly important in preventing the breakdown of lung tissue by inhibiting certain enzymes, such as neutrophil elastase, released during inflammation. Deficiency in \alpha-antitrypsin can lead to emphysema, and therapeutic administration of the protein is used to treat this condition.

Q. 5

A probe which is a molecule used to locate specific sequences in a mixture of DNA or RNA molecules could be
  1. a single stranded RNA
  2. a single stranded DNA
  3. either RNA or DNA
  4. can be ssDNA but not ssRNA
Solution: The correct option is (c). A molecular probe is a fragment of nucleic acid (either DNA or RNA) that is designed to be complementary to a specific target sequence within a larger mixture of DNA or RNA. Probes are typically single-stranded and are often labeled with a radioactive isotope or a fluorescent tag to allow for easy detection after they hybridize to their target sequence. Therefore, a probe can be either single-stranded RNA or single-stranded DNA.

Q. 6

Choose the correct option regarding retrovirus.
  1. a RNA virus that can synthesis DNA during infection
  2. a DNA virus that can synthesis RNA during infection
  3. a ssDNA virus
  4. a dsRNA virus
Solution: The correct option is (a). A retrovirus is a type of RNA virus characterized by its unique replication cycle. It possesses an enzyme called reverse transcriptase, which allows it to synthesize a DNA copy from its RNA genome. This newly synthesized DNA is then integrated into the host cell's genome, becoming a provirus, and subsequently transcribed into RNA to produce viral proteins and new viral RNA genomes. The general flow of genetic information is RNA \rightarrow DNA \rightarrow RNA \rightarrow Polypeptide.

Q. 7

The site of production of ADA in the body is
  1. erythrocytes
  2. lymphocytes
  3. blood plasma
  4. osteocytes
Solution: The correct option is (b). ADA stands for Adenosine Deaminase, an enzyme crucial for the proper functioning of the immune system. While ADA is present in various cells, its highest levels are found in lymphocytes, which are a type of white blood cell central to immune responses. ADA catalyzes the conversion of deoxyadenosine to deoxyinosine, preventing the toxic buildup of deoxyadenosine within lymphocytes and thus supporting their development and function.

Common mistakes

  • Confusing Bt cotton's resistance to all pests instead of specific ones.
  • Misunderstanding the role of C-peptide in insulin maturation.
  • Incorrectly identifying the function of alpha-antitrypsin.
  • Confusing DNA and RNA probes or their applications.
  • Not understanding the reverse transcription process in retroviruses.

Revision tips

  • Focus on the specific applications of biotechnology discussed in the MCQs, such as Bt cotton and insulin.
  • Review the diagrams and processes related to pro-insulin maturation and retroviral replication.
  • Understand the acronyms and their full forms, like GEAC.
  • Pay attention to the specific enzymes and their inhibitors, like ADA and alpha-antitrypsin.
  • Practice identifying the correct type of molecule used as a probe (DNA or RNA).

Practice MCQs

Q1. Which of the following statements is NOT true about Bt cotton?

Q2. What is the role of the C-peptide in human insulin production?

Q3. What does the acronym GEAC stand for?

Q4. Alpha-antitrypsin is primarily used for the treatment of which condition?

Q5. A probe used to locate specific sequences in DNA or RNA molecules can be:

Q6. Which statement accurately describes a retrovirus?

Q7. In the human body, where is the enzyme Adenosine Deaminase (ADA) primarily produced?

Frequently asked questions

What is the main purpose of Bt cotton mentioned in these solutions?

Bt cotton is a genetically modified plant engineered to be resistant to certain insect pests by incorporating a gene from the bacterium Bacillus thuringiensis (Bt) that produces an insecticidal toxin.

How is mature human insulin formed from pro-insulin?

Mature insulin is formed from pro-insulin by removing the C-peptide (connecting peptide) during a processing step. The remaining A and B chains are then linked by disulphide bonds to form the active hormone.

What is the function of GEAC?

GEAC, the Genetic Engineering Approval Committee, is a regulatory body in India that makes decisions regarding the safety and validity of genetic engineering research and the public use of genetically modified organisms.

Why is alpha-antitrypsin important for treating emphysema?

Alpha-antitrypsin is a protease inhibitor that helps treat emphysema by preventing the breakdown of lung tissue caused by enzymes released from inflammatory cells.

Can a probe used in molecular biology be either DNA or RNA?

Yes, a probe used to locate specific DNA or RNA sequences can be either a single-stranded DNA or a single-stranded RNA molecule, often labeled for detection.

What is unique about the replication process of retroviruses?

Retroviruses have an RNA genome and use an enzyme called reverse transcriptase to synthesize a DNA copy of their RNA. This DNA is then integrated into the host cell's genome.

Which cells in the body are the primary producers of ADA?

Lymphocytes, which are key cells of the immune system, are the primary site for ADA production. ADA is essential for maintaining immune function.

Important links

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