DNA Structure - Watson and Crick Model - Unsolved Practice Set
Chapter: Molecular Basis of Inheritance | Topic: DNA Structure Watson and Crick Model
DNA STRUCTURE - WATSON AND CRICK MODEL - UNSOLVED PRACTICE SET
Topic: DNA Structure Watson and Crick Model
Multiple Choice Questions
Q1. The DNA double helix model was proposed by:
- Griffith and Avery
- Watson and Crick
- Meselson and Stahl
- Hershey and Chase
Q2. In DNA, adenine always pairs with:
- Guanine
- Cytosine
- Thymine
- Uracil
Q3. The two strands of the DNA double helix are:
- Parallel
- Antiparallel
- Identical in sequence
- Not connected to each other
Q4. The number of hydrogen bonds between guanine and cytosine in DNA is:
- One
- Two
- Three
- Four
Q5. Chargaff's rule states that in DNA, the amount of adenine is approximately equal to the amount of:
- Guanine
- Cytosine
- Thymine
- Uracil
Short Answer Questions
Q6. State Chargaff's rule of base equivalence in DNA.
Q7. Why are the two strands of DNA described as "antiparallel"?
Q8. Differentiate between purines and pyrimidines, naming the bases in each category found in DNA.
Q9. What is meant by the "sugar-phosphate backbone" of DNA?
Long Answer Questions
Q10. Describe the salient features of the Watson-Crick double helix model of DNA structure.
Q11. Explain the base-pairing rules in DNA, and describe how these rules contribute to the stability of the double helix structure.
APPLICATION / ANALYSIS
Q12. A sample of double-stranded DNA is found to contain 20% adenine. Using Chargaff's rule, calculate the percentages of thymine, guanine, and cytosine present in this DNA sample.
Q13. A student is comparing two DNA fragments of equal length: one is very rich in G-C base pairs, while the other is rich in A-T base pairs. Predict which fragment would require more heat energy to separate (denature) into single strands, and explain your reasoning based on hydrogen bonding.