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JK Board Class 12 (JKBOSE) Biology — practice by topic

Browse 30 questions across 3 Biology topics. Choose what you want to revise, then open a question to check its answer and worked solution.

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Biology topics

Biology (30)Class 12 Biology (30)DNA Structure and Replication (30)

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Griffith worked with two strains of pneumonia bacteria, which he called rough and:Read the answer and worked solution →Mice injected with the living smooth strain of the bacterium:Read the answer and worked solution →Mice injected with heat killed smooth bacteria together with live rough bacteria:Read the answer and worked solution →Griffith's result, where one strain changed into another, is called:Read the answer and worked solution →

Worked practice questions

Griffith worked with two strains of pneumonia bacteria, which he called rough and:

  1. Smooth
  2. Sticky
  3. Strong
  4. Stable
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Correct answer: A. Smooth

1. One strain had a smooth capsule and one did not. 2. They were named for their appearance. 3. The second was smooth. _Source: OpenStax Biology 2e, Chapter 14, DNA Structure and Function._

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Mice injected with the living smooth strain of the bacterium:

  1. Grew
  2. Died
  3. Lived
  4. Slept
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Correct answer: B. Died

1. The smooth strain was the virulent one. 2. It caused pneumonia in the mice. 3. So the mice died. _Source: OpenStax Biology 2e, Chapter 14, DNA Structure and Function._

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Mice injected with heat killed smooth bacteria together with live rough bacteria:

  1. Died
  2. Lived
  3. Slept
  4. Grew
Show answer and solution

Correct answer: A. Died

1. Neither injection alone was fatal. 2. Something passed from the dead cells to the live ones. 3. So the mice died. _Source: OpenStax Biology 2e, Chapter 14, DNA Structure and Function._

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