Rucete ✏ AP Biology In a Nutshell
2. Macromolecules — Practice Questions 2
This chapter explores the diversity and function of biological macromolecules and how their structure determines their role in cellular processes.
(Multiple Choice — Click to Reveal Answer)
1. Which of the following is a monomer used to build proteins?
(A) Nucleotide
(B) Monosaccharide
(C) Fatty acid
(D) Amino acid
Answer
(D) — Amino acids are the monomers that form polypeptide chains in proteins.
2. Which structural feature is unique to DNA and not found in RNA?
(A) Uracil
(B) Ribose sugar
(C) Deoxyribose sugar
(D) Single-stranded helix
Answer
(C) — DNA contains deoxyribose, while RNA contains ribose.
3. Which macromolecule contains instructions for building proteins?
(A) Lipid
(B) Carbohydrate
(C) DNA
(D) Protein
Answer
(C) — DNA holds the genetic blueprint for protein synthesis.
4. What type of macromolecule are enzymes classified as?
(A) Protein
(B) Carbohydrate
(C) Nucleic acid
(D) Lipid
Answer
(A) — Enzymes are functional proteins that speed up chemical reactions.
5. Which element is found in nucleic acids but not in carbohydrates or lipids?
(A) Oxygen
(B) Phosphorus
(C) Carbon
(D) Hydrogen
Answer
(B) — Nucleic acids contain phosphorus in their phosphate groups, unlike carbohydrates and lipids.
6. What kind of bond links nucleotides together in a DNA strand?
(A) Peptide bond
(B) Glycosidic linkage
(C) Phosphodiester bond
(D) Disulfide bond
Answer
(C) — Phosphodiester bonds form between the sugar and phosphate groups of nucleotides in DNA and RNA.
7. Which macromolecule group is most involved in long-term energy storage?
(A) Proteins
(B) Lipids
(C) Carbohydrates
(D) Nucleic acids
Answer
(B) — Lipids, such as triglycerides, store more energy per gram than carbohydrates.
8. Which nitrogenous base is found in RNA but not DNA?
(A) Thymine
(B) Cytosine
(C) Uracil
(D) Adenine
Answer
(C) — Uracil replaces thymine in RNA.
9. What do carbohydrates, lipids, and proteins have in common?
(A) All are composed only of carbon and hydrogen
(B) All are polymers of nucleotides
(C) All contain carbon, hydrogen, and oxygen
(D) All are soluble in water
Answer
(C) — While their structures vary, all three macromolecules contain carbon, hydrogen, and oxygen atoms.
10. Which term best describes cellulose?
(A) Monosaccharide
(B) Disaccharide
(C) Structural polysaccharide
(D) Storage lipid
Answer
(C) — Cellulose is a structural carbohydrate found in plant cell walls.
11. Which part of a phospholipid is hydrophilic?
(A) Glycerol
(B) Fatty acid tails
(C) Phosphate head
(D) Cholesterol ring
Answer
(C) — The phosphate group on a phospholipid interacts well with water.
12. Which macromolecule is most responsible for regulating chemical reactions in a cell?
(A) Carbohydrates
(B) Proteins
(C) Lipids
(D) Nucleic acids
Answer
(B) — Enzymes, which regulate reactions, are proteins.
13. Which of the following is a disaccharide?
(A) Glucose
(B) Sucrose
(C) Starch
(D) Cellulose
Answer
(B) — Sucrose is composed of one glucose and one fructose molecule.
14. What is the primary function of RNA in cells?
(A) Store genetic information permanently
(B) Transport amino acids
(C) Facilitate protein synthesis
(D) Create phospholipid bilayers
Answer
(C) — RNA assists in reading and translating DNA’s genetic code into proteins.
15. What term describes the sequence of amino acids in a polypeptide chain?
(A) Primary structure
(B) Secondary structure
(C) Tertiary structure
(D) Quaternary structure
Answer
(A) — The primary structure is the linear sequence of amino acids.
16. What feature distinguishes one amino acid from another?
(A) Carboxyl group
(B) Amino group
(C) Central carbon
(D) R-group (side chain)
Answer
(D) — The R-group gives each amino acid its unique chemical properties.
17. What determines whether a lipid is saturated or unsaturated?
(A) The number of phosphate groups
(B) The type of sugar present
(C) The presence or absence of double bonds
(D) The number of nitrogen atoms
Answer
(C) — Saturated fats have no double bonds; unsaturated fats have one or more.
18. Which macromolecule is primarily responsible for genetic information transmission?
(A) Protein
(B) DNA
(C) Lipid
(D) Carbohydrate
Answer
(B) — DNA stores and transmits genetic information from generation to generation.
19. Which of the following elements is present in proteins but not in carbohydrates?
(A) Hydrogen
(B) Oxygen
(C) Nitrogen
(D) Carbon
Answer
(C) — Proteins contain nitrogen, while carbohydrates do not.
20. Which macromolecule includes both purines and pyrimidines?
(A) Carbohydrates
(B) Nucleic acids
(C) Lipids
(D) Proteins
Answer
(B) — DNA and RNA contain nitrogenous bases, which are either purines or pyrimidines.
21. Which macromolecule contains the most energy per gram?
(A) Carbohydrate
(B) Protein
(C) Lipid
(D) Nucleic acid
Answer
(C) — Lipids have a higher caloric content than carbohydrates or proteins.
22. What is formed when two monosaccharides are joined by dehydration synthesis?
(A) A disaccharide
(B) A polypeptide
(C) A fatty acid
(D) A phospholipid
Answer
(A) — Two monosaccharides linked by dehydration create a disaccharide.
23. Which level of protein structure includes alpha helices and beta sheets?
(A) Primary
(B) Secondary
(C) Tertiary
(D) Quaternary
Answer
(B) — These are characteristic patterns of the secondary protein structure, formed by hydrogen bonding.
24. What do all amino acids have in common structurally?
(A) Phosphate group
(B) Glycerol backbone
(C) Central carbon with amino, carboxyl, and R-group
(D) Long hydrocarbon tail
Answer
(C) — All amino acids share a basic structure with a central carbon bonded to an amino group, carboxyl group, and a variable R-group.
25. Which macromolecule’s monomers are joined by peptide bonds?
(A) Carbohydrates
(B) Nucleic acids
(C) Lipids
(D) Proteins
Answer
(D) — Peptide bonds connect amino acids in proteins.
26. Which structural feature of RNA allows it to fold into complex 3D shapes?
(A) Its deoxyribose sugar
(B) Its double-stranded helix
(C) Its ability to form internal base-pairing
(D) Its covalent phosphodiester bonds
Answer
(C) — RNA can base-pair within a single strand, forming hairpins and other complex 3D structures critical for its function.
27. A scientist hydrolyzes an unknown macromolecule and finds only glucose monomers. What is the molecule likely to be?
(A) Protein
(B) Glycogen
(C) DNA
(D) Triglyceride
Answer
(B) — Glycogen is a polysaccharide composed entirely of glucose monomers used for energy storage in animals.
28. Which interaction is responsible for holding together the quaternary structure of a protein like hemoglobin?
(A) Peptide bonds
(B) Hydrogen bonds only
(C) Interactions between multiple polypeptide chains
(D) Covalent bonding within a single polypeptide
Answer
(C) — Quaternary structure involves interactions between separate polypeptide subunits through various bonding types.
29. A single mutation replaces a hydrophobic amino acid with a hydrophilic one in a protein's core. What is a likely result?
(A) Enhanced enzyme function
(B) Increased membrane permeability
(C) Protein misfolding or instability
(D) Unaffected tertiary structure
Answer
(C) — Introducing a hydrophilic residue into a hydrophobic core may disrupt protein folding, leading to instability or loss of function.
30. Why does GC-rich DNA require more energy to separate than AT-rich DNA?
(A) GC pairs form ionic bonds
(B) GC pairs are larger molecules
(C) GC pairs have three hydrogen bonds, not two
(D) GC base pairing is covalent
Answer
(C) — Guanine and cytosine form three hydrogen bonds, requiring more energy to break than AT pairs, which form only two.
31. Which experiment result would best confirm that a virus injects nucleic acid into host cells?
(A) Radiolabeled sulfur is detected inside cells
(B) Phosphorus, but not sulfur, is detected in infected cells
(C) The host produces viral proteins
(D) Lipid-based membrane changes are observed
Answer
(B) — Phosphorus is present in nucleic acids, not proteins. If only phosphorus enters the cell, it suggests the virus injected nucleic acid.
32. A researcher finds a molecule that includes phosphate, ribose, and nitrogenous bases. This is likely a:
(A) Steroid
(B) Triglyceride
(C) Nucleotide
(D) Disaccharide
Answer
(C) — A nucleotide is made of a phosphate group, a five-carbon sugar (like ribose), and a nitrogenous base.
33. Which of the following would most likely increase membrane fluidity?
(A) Higher levels of saturated fatty acids
(B) Adding more cholesterol at high temperatures
(C) Incorporation of unsaturated fatty acids
(D) Adding more phosphodiester bonds
Answer
(C) — Unsaturated fatty acids contain double bonds that prevent tight packing, making membranes more fluid.
34. Which describes a dehydration reaction between two amino acids?
(A) Formation of an ester bond
(B) Hydrolysis of a peptide bond
(C) Release of water and formation of a peptide bond
(D) Exchange of phosphate groups
Answer
(C) — A peptide bond forms between amino acids when water is removed in a dehydration synthesis reaction.
35. Which observation supports the hypothesis that RNA preceded DNA in evolution?
(A) DNA is more chemically stable
(B) RNA can catalyze reactions and store information
(C) DNA forms a double helix
(D) RNA contains uracil, not thymine
Answer
(B) — RNA has catalytic properties (ribozymes) and can carry genetic information, supporting the RNA world hypothesis.
36. What kind of reaction breaks down macromolecules into monomers, and what is required for it to occur?
Answer
Hydrolysis — It breaks covalent bonds between monomers by adding water.
37. Identify one function of carbohydrates in cells beyond energy storage.
Answer
Structural support — For example, cellulose in plant cell walls provides rigidity and strength.
38. What is the significance of an R-group in an amino acid?
Answer
The R-group determines the chemical properties (e.g., polarity, charge) of the amino acid and affects protein folding and function.
39. Which macromolecule is most directly involved in the formation of cellular membranes, and why?
Answer
Phospholipids — Their amphipathic nature (hydrophilic head and hydrophobic tails) allows them to form bilayers in aqueous environments.
40. What are two key structural differences between DNA and RNA?
Answer
DNA contains deoxyribose and thymine; RNA contains ribose and uracil.
41. How does a disulfide bridge influence protein structure?
Answer
Disulfide bridges create covalent bonds between sulfur atoms in cysteine residues, stabilizing tertiary or quaternary structure.
42. Why are lipids not considered true polymers?
Answer
Lipids are not formed by repeating identical monomers; they are made from glycerol and fatty acids in varying combinations.
43. How does the presence of double bonds in fatty acids affect the shape of lipids?
Answer
Double bonds create kinks or bends in the hydrocarbon chain, preventing tight packing and increasing fluidity.
44. What type of bond links the nitrogenous bases of DNA strands?
Answer
Hydrogen bonds — These non-covalent interactions hold complementary bases together across the double helix.
45. What is one reason proteins can have such diverse functions in organisms?
Answer
Variable R-groups and complex folding allow proteins to form diverse shapes and interact with a wide variety of molecules.
46. How does temperature affect enzyme activity?
Answer
Increasing temperature speeds up reactions until the enzyme denatures at high temperatures, losing its shape and function.
47. Name the three parts of a nucleotide.
Answer
Phosphate group, 5-carbon sugar (ribose or deoxyribose), nitrogenous base
48. What causes sickle cell anemia at the molecular level?
Answer
A mutation in the hemoglobin gene substitutes valine for glutamic acid, causing abnormal folding and aggregation of proteins.
49. How does the polarity of a macromolecule affect its function in the cell?
Answer
Polarity determines solubility and interactions with other molecules (e.g., water-soluble vs. membrane-bound).
50. Describe how dehydration synthesis creates a polymer.
Answer
Two monomers are joined by a covalent bond, and a water molecule is removed in the process.