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Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance4 Marks
Question
Read the following and answer any four questions from (i) to (v) given below:

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two types of nucleic acids found in the living systems. DNA acts as the genetic material in most of the organisms. Although, RNA also acts as a genetic material in some organisms.

  1. In which of the following organisms, RNA acts as a genetic material?
  1. Escherichia coli
  2. $\text{Q}\beta$ Bacteriophage
  3. Tobacco Mosaic viruses
  4. Both (b) and (c)
  1. What is the reason for the additional stability of DNA in comparison to RNA?
  1. Presence of thymine
  2. Presence of uracil
  3. Presence of OH group
  4. Presence of deoxyribose sugar
  1. Which of the following criteria a molecule must fulfill to act as a genetic material?
  1. It should be able to generate its replica.
  2. It should be stable chemically and structurally.
  3. It should be able to express itself in the form of Mendelian character.
  4. All of these
  1. Assertion: RNA is liable and easily degradable.

Reason: The 2'- OH group present at every nucleotide in RNA is a reactive group

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
  1. Read the given statement and select the option that correctly fill in the blanks. Pyrimidines present in DNA are (i) and (ii) while pyrimidines present in RNA are (iii) and (iv).
  1. (i)-Adenine (iii)-Guanine (iii)-Cytosine, (iv)-Thymine
  2. (i)-Cytosine (iii)Thymine (iii)-Cytosine, (iv)-Uracil
  3. (i)-Cytosine (iii)-Uracil (iii)-Adenine, (iv)-Guanine
  4. (i)-Cytosine (iii)-Uracil (iii)-Cytosine, (iv)-Thymine
✓

Answer

  1.  (c) Both (b) and (c)

Explanation:

DNA is the genetic material in E. coli. RNA is the genetic material in Tobacco Mosaic virus and $\text{Q}\beta$ bacteriophage.

  1. (a) Presence of thymine

Explanation:

The presence of thymine in DNA at the place of uracil which is present in RNA provides additional stability to DNA.

  1. (d) All of these
  2. (a) Both assertion and reason are true, and reason is the correct explanation of assertion.
  3. (b) (i)-Cytosine (iii)Thymine (iii)-Cytosine, (iv)-Uracil

Explanation:

Purines present in DNA and RNA are adenine and guanine, while pyrimidines present in DNA are cytosine and thymine and pyrimidines present in RNA are cytosine and uracil. 

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