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(a) Why are transgenic… (Class 12 Biology 2025, Q26)

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BiologyCBSE Class 12 · Board exam 2025, set 57/7/1 · 3 marks · Short answer

CBSE Class 12 Biology 2025: question 26

Set in the CBSE Class 12 board exam of 2025, paper 57/7/1, section C, question 26, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q26 · 3 marks · Short answerBiotechnology and its Applications

(a) Why are transgenic animals so called ?
(b) With the help of an example each, explain the role of transgenic animals in the following :
(i) Vaccine safety
(ii) Biological products

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 57/7/1.

Hints

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

Hint 1

'Trans' + 'gene': think of what has been added to the animal.

Hint 2

Recall the polio vaccine test animal and the cow named Rosie from NCERT.

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) Transgenic animals are so called because their DNA has been manipulated so that they carry and express an extra (foreign) gene.

    1 mark

  2. (b)(i) Vaccine safety: transgenic mice are developed to test the safety of vaccines before they are used on humans. For example, transgenic mice are used to test the safety of the polio vaccine.

    1 mark

  3. (ii) Biological products: transgenic animals can produce useful human proteins. For example, the transgenic cow Rosie (1997) produced milk rich in human protein, about 2.4 g per litre. The milk contained human alpha-lactalbumin and was nutritionally more balanced for human babies than natural cow milk.

    1 mark

Answer: (a) They carry and express a foreign gene; (b)(i) transgenic mice test polio vaccine safety; (ii) transgenic cow Rosie produced milk with human alpha-lactalbumin.

Where the marks are

  • Definition: DNA manipulated to possess and express a foreign gene (1 mark)
  • Vaccine safety with the example of transgenic mice and the polio vaccine (1 mark)
  • Biological products with the example of Rosie the cow and alpha-lactalbumin (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Biotechnology and its Applications, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 57/7/1: 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.