Mutation and Genetic Variation — NEET Biology
📚 Practice ConceptMutation is a phenomenon which results in alteration of DNA sequences and consequently results in changes in the genotype and the phenotype of an organism. In addition to recombination, mutation is another phenomenon that leads to variation in DNA.
Which of the following statements about mutation and mutagens are correct? S1: Mutation is a phenomenon which results in alteration of DNA sequences, leading to variation. S2: Deletions and insertions of base pairs of DNA can cause frame-shift mutations. S3: Chemical factors are the only agents that can induce mutations in organisms. S4: A point mutation is a change in a single base pair of DNA, as seen in sickle cell anemia. S5: X-rays are considered a type of physical mutagen.
View solution & NCERT explanation
Correct answer: C — S1, S2, S4 and S5 only
Statement S1 is correct: Mutation is defined as a phenomenon that results in alteration of DNA sequences, leading to changes in genotype and phenotype, and is a source of variation. (NCERT, Section 4.7) Statement S2 is correct: Deletions and insertions of base pairs of DNA are known to cause frame-shift mutations. (NCERT, Section 4.7) Statement S3 is incorrect: Both chemical and physical factors are known to induce mutations, not just chemical factors. (NCERT, Section 4.7) Statement S4 is correct: A point mutation involves a change in a single base pair of DNA, with sickle cell anemia being a classical example of such a mutation. (NCERT, Section 4.7) Statement S5 is correct: X-rays are identified as physical mutagens, as evidenced by James Watson's research on their effect on bacteriophage multiplication and the general mention of physical factors inducing mutations. (NCERT, Section 4.7 and James Watson's biographical note) Therefore, statements S1, S2, S4, and S5 are correct.
What does NCERT say about Mutation phenomenon which results?
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