Class 12 Biology

Few problems along with their solutions from this chapter are given follows:

Q. 2 C-peptide of human insulin is

(a) a part of mature insulin molecule

(b) responsible for the formation of disulphide bridges

(c) removed during maturation of pro-insulin to insulin

(d) responsible for its biological activity

Ans. (c) removed during maturation of pro-insulin to insulin           

The connecting peptide or C-peptide is a short protein containing 31 amino acids. It connects the A and B chain of proinsulin molecule. After the processing of proinsulin molecule, C-peptide is removed leaving behind A and B chains which bound together by disulphide bonds to constitute a insulin molecule.

Q. The first clinical gene therapy was done for the treatment of

(a)AIDS

(b)Cancer

(c)Cystic fibrosis

(d)SCID (Severe Combined Immuno Deficiency) resulting from the deficiency of ADA

Ans. (d) SCID (Severe Combined Immuno Deficiency) resulting from the deficiency of ADA

The first clinical gene therapy was done for the treatment of SCID (Severe Combined Immuno Deficiency) resulting from the deficiency of ADA.

The SCID patient has a defective gene for the enzyme Adenosine Deaminase (ADA) due to which he/she lacks functional T-lymphocytes and therefore, fails to fight the infecting pathogen.

Q. Can a disease be detected before its symptoms appear? Explain the principle involved.

Ans. When the symptoms of the disease are not visible and the pathogen concentration is very low, then detection by conventional diagnostic tests is very difficult. However, detection is possible by the amplification of their nucleic acid by the technique known as Polymerase Chain Reaction (PCR). The principle involved here is that a single DNA molecule can be copied endlessly in a test tube, using primers, DNA polymerase enzyme and free nucleotides and appropriate conditions.

Q. Define antigen and antibody. Name any two diagnostic kits based upon them.

Ans. An antigen is a foreign substance that elicits the immune response and results in the formation of an antibody.

Antibody is a protein that is synthesised by the body in response to an antigen. Antigen and antibody shows high degree of specificity in binding to each other. Two diagnostic kits based on antigen-antibody interaction are:

(a) ELISA for HIV.

(b) Pregnancy test kits.

Class 12 Biology NCERT Exemplar Problems:

Class 12 Biology NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. Every year, many questions from the NCERT Exemplar are directly asked in the board exams as well as the medical entrance exams. So, it’s very important for students to practice the NCERT exemplar problems to prepare well for the boards and the competitive exams.

Main topics discussed in Class 12 Biology, Chapter 12- Biotechnology and Its Applications, are:

• Biotechnological applications in agriculture
• Biotechnological applications in medicine
• Transgenic animals
• Ethical issues.