Meselson-Stahl Experiment - Unsolved Practice Set
Chapter: Molecular Basis of Inheritance | Topic: Meselson Stahl Experiment
MESELSON-STAHL EXPERIMENT - UNSOLVED PRACTICE SET
Topic: Meselson Stahl Experiment
Multiple Choice Questions
Q1. The Meselson-Stahl experiment was designed to experimentally confirm which model of DNA replication?
- Conservative model
- Semi-conservative model
- Dispersive model
- None of these
Q2. Meselson and Stahl grew E. coli in a medium containing which isotope of nitrogen initially?
- 14N (light nitrogen)
- 15N (heavy nitrogen)
- 13N
- 16N
Q3. The technique used by Meselson and Stahl to separate DNA molecules based on their density was:
- Gel electrophoresis
- Caesium chloride (CsCl) density gradient centrifugation
- PCR
- X-ray diffraction
Q4. After one round of replication in the Meselson-Stahl experiment, the DNA extracted showed a density that was:
- Fully heavy (15N-15N)
- Fully light (14N-14N)
- Intermediate (hybrid, 15N-14N)
- Could not be measured
Q5. The results of the Meselson-Stahl experiment ruled out which model of DNA replication?
- Semi-conservative model
- Conservative model
- Both models simultaneously
- Neither model
Short Answer Questions
Q6. Why did Meselson and Stahl choose to work with the bacterium E. coli for their experiment?
Q7. What was the purpose of using CsCl density gradient centrifugation in this experiment?
Q8. What result was obtained after the first generation of replication in "light" medium, and what did this suggest?
Q9. How did the results after the second generation help distinguish between the semi-conservative and dispersive models?
Long Answer Questions
Q10. Describe the experimental design of the Meselson-Stahl experiment, explaining how heavy and light nitrogen isotopes were used to track DNA replication.
Q11. Explain how the banding patterns observed in successive generations of the Meselson-Stahl experiment provided conclusive evidence for the semi-conservative model of DNA replication.
APPLICATION / ANALYSIS
Q12. If DNA replication had actually followed the conservative model instead of the semi-conservative model, predict what banding pattern Meselson and Stahl would have observed after the first generation of replication in light medium, and explain how this would have differed from their actual results.
Q13. In the Meselson-Stahl experiment, after two generations of replication in light medium, both a hybrid (intermediate) band and a fully light band were observed in roughly equal amounts. Explain how this specific result helped rule out the dispersive model of replication.