Shortcut Methods and Tricks to Solve JEE Main and CBSE Board Exams Numericals

JEE Main

• Recombinant DNA technology:
• Trick:
• Size of typical plasmid is 2-4 kb while that of genomic DNA is 100-1000 kb. So for cloning foreign DNA into plasmid vector. The genomic DNA is randomly fragmented and size fractionated by gel electrophoresis.
• Polymerase chain reaction (PCR):
  • Trick:
  • PCR is generally carried out for 30 cycles but the number of cycles depends upon the initial amount DNA in the reaction mixture. Usually, 30-35 cycles are enough to amplify a single copy gene to a detectable level.
• Gel electrophoresis:
  • Trick:
  • The agarose gel concentration determines the size of DNA fragments that can be resolved. Higher the gel concentration , smaller the fragments will be resolved.
• Southern blotting:
  • Trick:
  • Only fragments of DNA molecules greater than 5000 bp in length can be transferred from the gel to the nitrocellulose membrane. This is because smaller fragments are trapped within the gel matrix and cannot diffuse through it.
• Northern blotting:
  • Trick:
  • Only fragments of RNA molecules greater than 5000 nt in length can be transferred from the gel to the nitrocellulose membrane.

CBSE Board Exams

• Applications of biotechnology:
  • Trick:
  • Remember the examples of different applications of biotechnology.
• Ethical issues in biotechnology:
• Trick:
• Focus on the controversial issues related to biotechnology like use of GMOs in agriculture, safety concerns related to the consumption of these products and patenting of biological materials.