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Describe in brief any two… (Class 12 Biology 2025, Q21B)

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BiologyCBSE Class 12 · Board exam 2025, set 57/1/1 · 2 marks · Very short answer

CBSE Class 12 Biology 2025: question 21(B)

Set in the CBSE Class 12 board exam of 2025, paper 57/1/1, section B, question 21(B), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21(B) · 2 marks · Very short answerBiotechnology: Principles and Processes

Describe in brief any two techniques that can be utilised to transfer recombinant DNA into the host cell directly without using any vector.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 57/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

One method uses a very fine needle. Another uses tiny metal particles.

Hint 2

Think of the gene gun used for plant cells.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Microinjection: Recombinant DNA is injected directly into the nucleus of an animal cell through a fine micro-needle.

    1 mark

  2. Biolistics (gene gun): Plant cells are bombarded with high-velocity microparticles of gold or tungsten coated with DNA.

    *(Alternative technique: heat shock. Cells are made competent with divalent cations such as and incubated with rDNA on ice. They are then given a brief heat shock at 42 °C and put back on ice, so the DNA enters.)*

    1 mark

Answer: Microinjection (rDNA injected into the animal cell nucleus) and biolistics/gene gun (plant cells bombarded with DNA-coated gold/tungsten particles); heat shock is an alternative.

Where the marks are

  • Names microinjection (½ mark) and describes direct injection into the nucleus (½ mark)
  • Names biolistics/gene gun (½ mark) and describes bombardment with DNA-coated gold/tungsten particles (½ mark)
  • Heat shock at 42 °C with competent cells is accepted as an alternative technique (½ + ½ marks)

Revise the chapter

Practise this chapterBoard-style questions from Biotechnology: Principles and Processes, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 57/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.