Nucleic Acid MCQ Questions and Answers for Practice

1. A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be comprised of

1. 240 adenine and 240 cytosine molecules.
2. 120 thymine and 120 adenine molecules.
3. 240 guanine and 240 thymine molecules.
4. none of these

2. A model of enzyme action is the

1. active site model.
2. activator action model.
3. induced fit model.
4. none of these

3. According to the first law of thermodynamics,

1. the universe loses energy because of heat production.
2. systems rich in energy are intrinsically unstable and will give up energy with time.
3. energy can be neither created nor destroyed.
4. A and B only

4. Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as .........is to ............

1. exergonic; endergonic
2. work; energy
3. DNA and RNA.
4. none of these

5. Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?

1. The phosphodiester bonds between deoxyribose sugars would be broken.
2. The two strands of the double helix would separate.
3. The pyrimidines would be separated from the deoxyribose sugars.
4. none of these

6. How can one increase the rate of a chemical reaction?

1. Add a catalyst.
2. Increase the entropy of the reactants.
3. Decrease the concentration of the reactants.
4. none of these

7. If an enzyme is added to a solution where its substrates and products are in equilibrium, what would occur?

1. The reaction would change from endergonic to exergonic.
2. Additional product would be formed.
3. Nothing; the reaction would stay at equilibrium.
4. none of these

8. If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is to

1. add more of the enzyme.
2. heat the solution to 90 degree Centigrade.
3. add an allosteric inhibitor.
4. none of these

9. In the double helix structure of nucleic acids, cytosine hydrogen bonds to

1. ribose.
2. guanine.
3. adenine.
4. none of these

10. Nucleic acids include

1. glucose and glycogen.
2. lipids and sugars.
3. DNA and RNA.
4. none of these

11. The structural feature that allows DNA to replicate is the

1. twisting of the molecule to form an á helix.
2. sugar-phosphate backbone.
3. complementary pairing of the nitrogenous bases.
4. none of these

12. What name is given to the reactants in an enzymatically catalyzed reaction?

1. products
2. substrate
3. EA
4. none of these

13. Which of the following are nitrogenous bases of the purine type?

1. guanine and adenine
2. uracil and cytosine
3. cytosine and guanine
4. none of these

14. Which of the following are nitrogenous bases of the pyrimidine type?

1. thymine and guanine
2. cytosine and uracil
3. guanine and adenine
4. none of these

15. Which of the following describe(s) some aspect of metabolism?

1. synthesis of macromolecules
2. breakdown of macromolecules
3. control of enzyme activity
4. A, B, and C