Rucete ✏ Campbell Biology In a Nutshell
Unit 1 THE CHEMISTRY OF LIFE — Concept 5.5 Nucleic Acids Store, Transmit, and Help Express Hereditary Information — Practice Questions
(Multiple Choice — Click to Reveal Answer)
1. What are the monomers of nucleic acids?
- Monosaccharides
- Amino acids
- Nucleotides
- Fatty acids
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3. Nucleotides
2. What are the two types of nucleic acids?
- ATP and ADP
- DNA and RNA
- DNA and protein
- RNA and enzyme
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2. DNA and RNA
3. What sugar is found in DNA?
- Ribose
- Fructose
- Deoxyribose
- Glucose
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3. Deoxyribose
4. What sugar is found in RNA?
- Fructose
- Deoxyribose
- Glucose
- Ribose
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4. Ribose
5. Which of the following is a nitrogenous base found only in RNA?
- Adenine
- Thymine
- Cytosine
- Uracil
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4. Uracil
6. Which of the following is a nitrogenous base found only in DNA?
- Uracil
- Adenine
- Thymine
- Cytosine
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3. Thymine
7. Which bases pair together in DNA?
- A–G and C–T
- A–T and C–G
- A–U and C–G
- A–C and T–G
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2. A–T and C–G
8. What kind of bond holds nitrogenous bases together in a DNA molecule?
- Peptide bond
- Covalent bond
- Hydrogen bond
- Ionic bond
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3. Hydrogen bond
9. What is the shape of a DNA molecule?
- Single strand
- Triple helix
- Double helix
- Flat sheet
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3. Double helix
10. What type of bond joins nucleotides together in a single strand?
- Hydrogen bond
- Phosphodiester bond
- Peptide bond
- Glycosidic bond
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2. Phosphodiester bond
11. What are the three components of a nucleotide?
- Ribose, amino acid, uracil
- Phosphate, sugar, nitrogenous base
- Fatty acid, glycerol, base
- Monosaccharide, phosphate, protein
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2. Phosphate, sugar, nitrogenous base
12. What is the main function of DNA?
- To speed up chemical reactions
- To carry oxygen
- To store genetic information
- To transport lipids
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3. To store genetic information
13. What is the function of RNA?
- Energy storage
- Transport genetic code for protein synthesis
- Builds membranes
- Stores fat
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2. Transport genetic code for protein synthesis
14. Which base pairs with adenine in RNA?
- Thymine
- Uracil
- Guanine
- Cytosine
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2. Uracil
15. What enzyme helps synthesize RNA from a DNA template?
- RNA helicase
- RNA polymerase
- DNA ligase
- Ribosome
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2. RNA polymerase
16. What process copies DNA to RNA?
- Translation
- Replication
- Transcription
- Translocation
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3. Transcription
17. What process uses RNA to make proteins?
- Transcription
- Translation
- Replication
- Reverse transcription
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2. Translation
18. Where does translation occur in eukaryotic cells?
- Nucleus
- Mitochondria
- Ribosomes
- Golgi apparatus
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3. Ribosomes
19. Which sugar lacks an oxygen atom: ribose or deoxyribose?
- Ribose
- Deoxyribose
- Both
- Neither
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2. Deoxyribose
20. Which base is a purine?
- Thymine
- Cytosine
- Adenine
- Uracil
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3. Adenine
21. What is a purine characterized by?
- A single ring
- A sugar and phosphate group
- A double ring structure
- A triple helix
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3. A double ring structure
22. What are the purines in nucleic acids?
- Thymine and Cytosine
- Adenine and Guanine
- Uracil and Cytosine
- Guanine and Uracil
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2. Adenine and Guanine
23. Which bases are classified as pyrimidines?
- Thymine, Cytosine, Uracil
- Adenine and Guanine
- Guanine and Cytosine
- Ribose and Deoxyribose
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1. Thymine, Cytosine, Uracil
24. How is genetic information passed from one generation to the next?
- Via proteins
- Through DNA replication
- Through RNA synthesis
- By lipid inheritance
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2. Through DNA replication
25. What ensures that DNA replication is accurate?
- RNA proofreading
- DNA proofreading enzymes
- ATP levels
- Ribosomes
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2. DNA proofreading enzymes
26. What structural feature distinguishes DNA from RNA?
- RNA contains thymine instead of uracil
- DNA has a hydroxyl group on the 2' carbon of the sugar
- RNA contains a ribose sugar; DNA contains deoxyribose
- DNA is single-stranded
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3. RNA contains a ribose sugar; DNA contains deoxyribose
27. What kind of linkage connects the 3′ carbon of one nucleotide to the 5′ phosphate of the next?
- Glycosidic bond
- Hydrogen bond
- Peptide bond
- Phosphodiester bond
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4. Phosphodiester bond
28. Why does DNA run antiparallel?
- To allow base pairing and proper replication
- To conserve energy
- Because both strands are identical
- To increase transcription speed
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1. To allow base pairing and proper replication
29. What is the functional role of mRNA?
- Forms ribosomes
- Transports amino acids
- Serves as the template for protein synthesis
- Catalyzes hydrolysis
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3. Serves as the template for protein synthesis
30. Which RNA type helps decode mRNA into proteins?
- mRNA
- tRNA
- rRNA
- snRNA
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2. tRNA
31. Which direction does DNA polymerase add nucleotides during replication?
- 5′ to 3′ direction
- 3′ to 5′ direction
- Randomly
- Both directions at once
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1. 5′ to 3′ direction
32. How are the nitrogenous bases attached to the sugar in a nucleotide?
- Through a phosphodiester linkage
- By a hydrogen bond
- Via a glycosidic bond
- With a peptide bond
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3. Via a glycosidic bond
33. What property of the DNA double helix allows replication to occur semi-conservatively?
- The strong phosphate backbone
- The linear structure of DNA
- The ability of the strands to separate and serve as templates
- The presence of uracil
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3. The ability of the strands to separate and serve as templates
34. What distinguishes a 5′ end of a DNA strand?
- It has a free hydroxyl group
- It has a free phosphate group
- It is longer
- It bonds with tRNA
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2. It has a free phosphate group
35. Which base pairing forms two hydrogen bonds?
- Cytosine–Guanine
- Adenine–Thymine
- Guanine–Uracil
- Adenine–Cytosine
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2. Adenine–Thymine
36. Describe the three components of a nucleotide and their roles in nucleic acids.
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A nucleotide consists of a phosphate group (links nucleotides), a pentose sugar (ribose or deoxyribose), and a nitrogenous base (stores genetic information through pairing).
37. What type of bond connects nucleotides in a single DNA or RNA strand?
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Phosphodiester bonds between the 3′ hydroxyl of one sugar and the 5′ phosphate of the next.
38. What does it mean that DNA strands are antiparallel?
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One strand runs 5′ to 3′, and the other runs 3′ to 5′, allowing complementary base pairing.
39. Which nitrogenous bases are purines, and how do they differ structurally from pyrimidines?
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Adenine and Guanine are purines; they have a double-ring structure, while pyrimidines (cytosine, thymine, uracil) have a single ring.
40. What is complementary base pairing, and why is it important?
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Each base pairs with its specific partner (A–T/U, C–G), ensuring accurate replication and transcription of genetic information.
41. Explain the significance of hydrogen bonds in DNA structure.
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Hydrogen bonds between base pairs hold the two strands of DNA together while allowing separation for replication.
42. How does RNA differ structurally and functionally from DNA?
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RNA has ribose sugar and uracil instead of thymine, is usually single-stranded, and plays a role in protein synthesis rather than long-term storage.
43. What does it mean that DNA replication is “semi-conservative”?
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Each new DNA molecule consists of one original (parent) strand and one newly synthesized strand.
44. What is the role of mRNA in gene expression?
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mRNA carries the genetic code from DNA to the ribosome, where it is used to synthesize proteins during translation.
45. What is the role of tRNA in translation?
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tRNA brings the correct amino acids to the ribosome by matching its anticodon with codons on the mRNA strand.
46. What is a gene?
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A gene is a sequence of DNA that contains instructions for building a specific protein or RNA molecule.
47. How does base pairing ensure the accuracy of DNA replication?
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Each base pairs with only its complementary partner, guiding DNA polymerase to add the correct nucleotide to the new strand.
48. Describe the difference between a 5′ end and a 3′ end in a nucleotide strand.
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The 5′ end has a free phosphate group; the 3′ end has a free hydroxyl group on the sugar. Polymerases add to the 3′ end only.
49. What role do ribosomes play in gene expression?
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Ribosomes read the mRNA sequence and assemble amino acids into polypeptides using instructions encoded in the mRNA.
50. Why is the sequence of nitrogenous bases critical to heredity?
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The base sequence forms the genetic code, determining the sequence of amino acids in proteins, which controls traits and inheritance.