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Answer the following. (Class 12 Biology 2023, Q21)

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BiologyCBSE Class 12 · Board exam 2023, set 57/5/1 · 2 marks · Very short answer

CBSE Class 12 Biology 2023: question 21

Set in the CBSE Class 12 board exam of 2023, paper 57/5/1, section B, question 21, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21 · 2 marks · Very short answerBiotechnology: Principles and Processes

Answer the following.

  1. (a)

    Write the scientific name of the source organism of the themostable DNA polymerase used in PCR.

    0 marks
  2. (b)

    State the advantage of using Thermostable DNA polymerase.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 57/5/1.

Hints

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

Hint 1

The enzyme is named Taq. Expand the abbreviation into the bacterium's full scientific name.

Hint 2

Think about which PCR step uses very high temperature and what that would do to an ordinary enzyme.

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. (a) The source organism is the bacterium Thermus aquaticus, and the enzyme is called Taq polymerase.

    1 mark

  2. (b) Thermostable DNA polymerase remains active at the high temperature (about 94 °C) used to denature double-stranded DNA in each PCR cycle. So it need not be added again after every denaturation step, and the cycles can run repeatedly.

    1 mark

Answer: (a) Thermus aquaticus; (b) It stays active at high denaturation temperatures, so it need not be added afresh in every cycle.

Where the marks are

  • Writes the scientific name Thermus aquaticus (1 mark)
  • States it remains active during high-temperature denaturation, so no re-addition is needed each cycle (1 mark)

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 paper2023 board paper, set 57/5/1: 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.