Question

Select correct statements regarding mutation. A. A point mutation involves substitution of a single nucleotide pair.
B. Frameshift mutations result from insertion or deletion of nucleotides not in multiples of 3.
C. Silent mutations always alter the amino acid sequence of a protein.
D. Mutagens can be physical, chemical or biological agents.
E. Auxotrophs can be easily grown on minimal media.
Choose the correct answer from the options given below :

• A. \(A, B \text{ and } D\) only
• B. \(A, B, E\) only
• C. \(C, D\) only
• D. \(A, C, E\) only

Hint:

Remember:
• Point mutation \(\rightarrow\) Single base substitution
• Frameshift mutation \(\rightarrow\) Insertion/deletion not multiple of 3
• Silent mutation \(\rightarrow\) No amino acid change \[ \text{Auxotrophs require supplemented media for growth} \]

Answer 1

The Correct Option is A

Concept: Mutations are heritable changes in genetic material that may occur spontaneously or due to mutagens. Mutations can involve:
• Single nucleotide substitutions
• Insertions
• Deletions
• Chromosomal alterations Mutagens are agents that increase mutation frequency.

Step 1: Evaluating statement A. Statement A: \[ \text{Point mutation involves substitution of a single nucleotide pair} \] This is correct. Point mutations commonly involve: \[ \text{Single base pair substitutions} \] Thus: \[ \boxed{A \text{ is correct}} \]

Step 2: Evaluating statement B. Statement B: \[ \text{Frameshift mutations result from insertions or deletions not in multiples of 3} \] This is correct. Such mutations shift the reading frame of codons during translation. Thus: \[ \boxed{B \text{ is correct}} \]

Step 3: Evaluating statement C. Statement C: \[ \text{Silent mutations always alter amino acid sequence} \] This is incorrect. Silent mutations do: \[ \text{Not alter the amino acid sequence} \] because of degeneracy of the genetic code. Thus: \[ \boxed{C \text{ is incorrect}} \]

Step 4: Evaluating statement D. Statement D: \[ \text{Mutagens can be physical, chemical or biological} \] This is correct. Examples:
• Physical \(\rightarrow\) UV radiation
• Chemical \(\rightarrow\) Nitrous acid
• Biological \(\rightarrow\) Transposons, viruses Thus: \[ \boxed{D \text{ is correct}} \]

Step 5: Evaluating statement E. Statement E: \[ \text{Auxotrophs grow easily on minimal media} \] This is incorrect. Auxotrophs require: \[ \text{Specific nutritional supplements} \] and therefore cannot grow on minimal media unless the required nutrient is supplied. Thus: \[ \boxed{E \text{ is incorrect}} \] Therefore, the correct statements are: \[ \boxed{A, B \text{ and } D} \] Hence, the correct answer is: \[ \boxed{(A)\ A, B \text{ and } D \text{ only}} \]