Given below are two statements:
Statement I: Proteins fail to fulfil the first criterion of a genetic material, that is, the ability to generate its replica.
Statement II: A genetic material should provide the scope for rapid changes (mutation) that are required for evolution.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Statement I is correct but Statement II is incorrect
Statement I: Proteins fail to fulfil the first criterion of a genetic material, that is, the ability to generate its replica. — True. The first criterion for a genetic material is that it must be able to make a copy of itself (replication). DNA and RNA can direct their own duplication because of base pairing and complementarity. Proteins cannot, so they fail at the first step.
Statement II: A genetic material should provide the scope for rapid changes (mutation) that are required for evolution. — False. The book asks for slow changes (mutation). A genetic material must stay stable through the life of the organism; it should change only slowly, so that variation for evolution arises without losing the stored information.
NCERT Extract:
Properties of Genetic Material (DNA versus RNA) – “… A molecule that can act as a genetic material must fulfill the following criteria:
(i) It should be able to generate its replica (Replication).
(ii) It should be stable chemically and structurally.
(iii) It should provide the scope for slow changes (mutation) that are required for evolution.
(iv) It should be able to express itself in the form of ‘Mendelian Characters’.
If one examines each requirement one by one, because of rule of base pairing and complementarity, both the nucleic acids (DNA and RNA) have the ability to direct their duplications. The other molecules in the living system, such as proteins fail to fulfill first criteria itself.”