Concepts of Biochemistry practice exam quiz
Which of the following macromolecules are primarily responsible for catalyzing biochemical reactions?
A) Carbohydrates
B) Lipids
C) Proteins
D) Nucleic Acids
What is the primary function of ribonucleic acid (RNA) in cells?
A) Store genetic information
B) Catalyze metabolic reactions
C) Carry genetic instructions from DNA to the ribosome
D) Provide structural support in the cell
Which of the following is the most basic unit of a protein?
A) Nucleotide
B) Amino acid
C) Fatty acid
D) Sugar
Which of the following interactions is the primary force stabilizing the tertiary structure of a protein?
A) Hydrogen bonds
B) Peptide bonds
C) Hydrophobic interactions
D) Ionic bonds
Which of the following elements is not commonly found in proteins?
A) Carbon
B) Nitrogen
C) Oxygen
D) Phosphorus
What term describes the collection of reactions through which cells extract energy from food and store it in high-energy bonds like ATP?
A) Photosynthesis
B) Glycolysis
C) Metabolism
D) Replication
Which of the following molecules are primarily involved in the storage and transfer of energy in cells?
A) Carbohydrates
B) Proteins
C) Lipids
D) Nucleotides
Which type of bond is responsible for holding the two strands of a DNA molecule together?
A) Hydrogen bond
B) Ionic bond
C) Covalent bond
D) Disulfide bond
Which of the following is the correct monomer for nucleic acids?
A) Nucleotide
B) Amino acid
C) Monosaccharide
D) Fatty acid
Which of the following statements about enzymes is false?
A) Enzymes increase the rate of a reaction.
B) Enzymes are used up in reactions.
C) Enzymes lower the activation energy of a reaction.
D) Enzymes are specific to their substrates.
In a biochemical reaction, what does the term “activation energy” refer to?
A) The energy required to break down substrates
B) The energy required to start a reaction
C) The energy released by the reaction
D) The energy stored in products
Which molecule is the primary energy carrier in most living organisms?
A) NADH
B) ATP
C) GTP
D) FADH2
Which of the following is the most important carbohydrate used by living organisms for energy production?
A) Sucrose
B) Glucose
C) Lactose
D) Fructose
Which of the following is a major component of biological membranes?
A) Proteins
B) Nucleic acids
C) Lipids
D) Carbohydrates
What type of bond holds the two strands of DNA together in the double helix structure?
A) Hydrogen bond
B) Covalent bond
C) Ionic bond
D) Disulfide bond
Which of the following is the main function of triglycerides in organisms?
A) Catalyzing biochemical reactions
B) Acting as a source of stored energy
C) Providing structure to cell membranes
D) Transporting oxygen in the blood
Which molecule is the primary product of glycolysis?
A) Lactic acid
B) Pyruvate
C) Acetyl-CoA
D) Glucose
Which of the following is not a role of lipids in cells?
A) Energy storage
B) Structural component of cell membranes
C) Catalysis of biochemical reactions
D) Insulation and protection
Which of the following best describes the relationship between structure and function in proteins?
A) Protein function is independent of structure.
B) A protein’s function is determined by its primary structure.
C) A protein’s function is determined by its secondary structure.
D) A protein’s function is determined by its three-dimensional structure.
What type of bond forms between amino acids to form a polypeptide chain?
A) Ionic bond
B) Hydrogen bond
C) Peptide bond
D) Disulfide bond
Which metabolic pathway occurs in the cytoplasm and does not require oxygen?
A) Citric acid cycle
B) Electron transport chain
C) Glycolysis
D) Beta-oxidation
Which molecule is produced during the citric acid cycle and is used to generate ATP?
A) NADH
B) Pyruvate
C) Acetyl-CoA
D) GTP
In what form is most of the energy generated by aerobic respiration stored?
A) NADH
B) FADH2
C) ATP
D) GTP
Which of the following is a characteristic feature of enzymes?
A) They increase the activation energy of reactions.
B) They are consumed in the reaction they catalyze.
C) They have a specific active site for binding substrates.
D) They are not affected by temperature changes.
Which of the following is true about the structure of carbohydrates?
A) They consist of long chains of nucleotides.
B) They are composed of amino acid residues.
C) They are composed of simple sugars or polysaccharides.
D) They are made up of fatty acid chains.
What process involves the breakdown of glucose to produce energy in the absence of oxygen?
A) Fermentation
B) Glycolysis
C) Oxidative phosphorylation
D) Photosynthesis
Which of the following biomolecules contains a phosphate group?
A) Carbohydrates
B) Proteins
C) Nucleic acids
D) Lipids
Which of the following is a feature of phospholipids?
A) They are hydrophobic molecules that do not interact with water.
B) They form the structural basis of cell membranes.
C) They are soluble in non-polar solvents.
D) They are the primary energy source in cells.
What is the role of ATP in cellular metabolism?
A) ATP stores genetic information.
B) ATP is a coenzyme in metabolic reactions.
C) ATP provides energy for cellular processes.
D) ATP is a structural component of proteins.
Which of the following biochemical pathways produces the most ATP per molecule of glucose?
A) Glycolysis
B) Citric acid cycle
C) Oxidative phosphorylation
D) Fermentation
31. Which of the following processes directly produces the most ATP during cellular respiration?
A) Glycolysis
B) Citric acid cycle
C) Oxidative phosphorylation
D) Fermentation
32. Which type of reaction breaks down large molecules into smaller ones, releasing energy?
A) Anabolic
B) Catabolic
C) Endergonic
D) Exergonic
33. Which of the following molecules is not typically a lipid?
A) Triglyceride
B) Phospholipid
C) Glycogen
D) Steroid
34. Which of the following is true regarding the role of NAD+ in cellular metabolism?
A) It is a coenzyme involved in the reduction of glucose.
B) It carries electrons during redox reactions in metabolism.
C) It is used to transport fatty acids into the mitochondria.
D) It is used to synthesize ATP.
35. What is the primary role of carbohydrates in living organisms?
A) Catalyzing biochemical reactions
B) Providing long-term energy storage
C) Facilitating cellular communication
D) Serving as the primary energy source
36. Which part of the cell is primarily responsible for protein synthesis?
A) Nucleus
B) Golgi apparatus
C) Ribosome
D) Mitochondrion
37. In which form is energy most commonly stored in animals?
A) Glycogen
B) Glucose
C) Phospholipids
D) Proteins
38. Which of the following is the primary function of enzymes?
A) To provide structure to cells
B) To act as carriers of genetic information
C) To lower the activation energy of biochemical reactions
D) To store energy for future use
39. Which of the following molecules are produced during the Calvin cycle in photosynthesis?
A) Oxygen and glucose
B) NADH and ATP
C) Glucose and carbon dioxide
D) Glucose and NADP+
40. Which of the following best describes a lipid bilayer in a membrane?
A) A layer of proteins surrounding a water-soluble core
B) A double layer of hydrophobic proteins
C) A double layer of hydrophilic phospholipids
D) A double layer of hydrophobic phospholipids
41. What is the primary structural feature of all proteins?
A) They are made up of fatty acids.
B) They are composed of a sequence of nucleotides.
C) They consist of amino acid residues linked by peptide bonds.
D) They consist of monosaccharide units.
42. Which of the following statements about the fluid mosaic model of membrane structure is correct?
A) It states that membranes are rigid and impermeable.
B) It indicates that proteins are randomly dispersed in the lipid bilayer.
C) It explains that phospholipids are free to move within the membrane.
D) It suggests that membranes have no protein components.
43. Which of the following is a characteristic of a saturated fatty acid?
A) Contains one or more double bonds between carbon atoms
B) Has a lower melting point than unsaturated fatty acids
C) Contains only single bonds between carbon atoms
D) Is liquid at room temperature
44. Which of the following structures is involved in energy production through cellular respiration?
A) Chloroplast
B) Nucleus
C) Mitochondrion
D) Ribosome
45. Which of the following is the major difference between DNA and RNA?
A) DNA is single-stranded, while RNA is double-stranded.
B) RNA contains thymine, whereas DNA contains uracil.
C) DNA is used for energy storage, whereas RNA is used for protein synthesis.
D) DNA contains deoxyribose, while RNA contains ribose.
46. Which of the following is an example of a polysaccharide?
A) Glucose
B) Sucrose
C) Starch
D) Lactose
47. Which of the following molecules is an electron carrier in cellular respiration?
A) Oxygen
B) NAD+
C) Glucose
D) ATP
48. Which of the following biomolecules contains a nitrogenous base, a sugar, and a phosphate group?
A) Protein
B) Carbohydrate
C) Nucleic acid
D) Lipid
49. Which of the following is involved in protein translation in cells?
A) Ribosome
B) Chloroplast
C) Nucleolus
D) Lysosome
50. Which of the following best describes the structure of an amino acid?
A) A central carbon bonded to an amino group, carboxyl group, hydrogen atom, and R group
B) A sugar bonded to a phosphate group
C) A fatty acid with a glycerol backbone
D) A nitrogenous base bonded to a sugar
51. Which of the following statements about phospholipids is true?
A) Phospholipids are composed of a hydrophilic tail and a hydrophobic head.
B) Phospholipids form bilayers in aqueous environments due to their amphipathic nature.
C) Phospholipids are exclusively found in prokaryotic cells.
D) Phospholipids are primarily used for energy storage.
52. What is the primary role of cholesterol in the cell membrane?
A) To store genetic information
B) To provide rigidity and stability to the membrane
C) To act as an energy source
D) To facilitate enzyme activity
53. Which of the following pathways is involved in the synthesis of glucose from non-carbohydrate precursors?
A) Glycolysis
B) Gluconeogenesis
C) Citric acid cycle
D) Fermentation
54. Which of the following is the end product of the electron transport chain in cellular respiration?
A) Carbon dioxide
B) Oxygen
C) ATP
D) Water
55. Which of the following statements is true about enzymes?
A) Enzymes are consumed in the reactions they catalyze.
B) Enzymes function by increasing the activation energy of biochemical reactions.
C) Enzymes speed up chemical reactions without being consumed.
D) Enzymes are not specific to their substrates.
56. Which of the following is a characteristic of a double-stranded DNA molecule?
A) It forms a helix with complementary base pairing between adenine and thymine, and cytosine and guanine.
B) It contains ribose as the sugar.
C) It has a single strand of nucleotides.
D) It is found exclusively in prokaryotic cells.
57. Which of the following is a key difference between prokaryotic and eukaryotic cells?
A) Eukaryotic cells lack mitochondria.
B) Prokaryotic cells have a nucleus.
C) Eukaryotic cells have membrane-bound organelles.
D) Prokaryotic cells are much larger than eukaryotic cells.
58. Which of the following is the main function of the endoplasmic reticulum?
A) Synthesize proteins and lipids
B) Package and transport proteins
C) Produce ATP
D) Provide structural support to the cell
59. Which of the following is true about DNA replication?
A) It is a process that occurs only during cell division.
B) It results in the synthesis of a new RNA strand.
C) It is catalyzed by RNA polymerase.
D) It occurs in the cytoplasm.
60. What is the main function of the Golgi apparatus in cells?
A) Synthesizing proteins
B) Modifying, sorting, and packaging proteins
C) Synthesizing lipids
D) Storing genetic information
61. Which of the following is the main function of ATP in cells?
A) Storing genetic information
B) Serving as a long-term energy storage molecule
C) Providing the energy needed for cellular processes
D) Acting as a coenzyme in metabolic reactions
62. Which of the following biomolecules can be used as a source of energy during cellular respiration?
A) Proteins
B) Carbohydrates
C) Lipids
D) All of the above
63. Which of the following processes occurs in the mitochondria?
A) Glycolysis
B) Citric acid cycle
C) Protein synthesis
D) DNA replication
64. Which of the following is the primary function of nucleic acids in cells?
A) Providing structural support to the cell
B) Storing and transmitting genetic information
C) Acting as catalysts for biochemical reactions
D) Providing short-term energy storage
65. Which of the following structures is responsible for synthesizing lipids in a cell?
A) Ribosomes
B) Golgi apparatus
C) Smooth endoplasmic reticulum
D) Mitochondrion
66. Which of the following amino acids contains a sulfur atom in its side chain?
A) Glycine
B) Leucine
C) Cysteine
D) Arginine
67. Which of the following is true regarding the structure of a triglyceride?
A) It contains three fatty acid molecules attached to a glycerol backbone.
B) It consists of a phosphate group, glycerol, and two fatty acids.
C) It is a type of nucleic acid used for energy storage.
D) It contains only hydrophilic components.
68. Which of the following enzymes is responsible for unwinding the DNA helix during replication?
A) RNA polymerase
B) DNA helicase
C) DNA ligase
D) DNA polymerase
69. Which of the following terms refers to the energy required to start a biochemical reaction?
A) Activation energy
B) Free energy
C) Equilibrium constant
D) Enzyme specificity
70. Which of the following is a characteristic of glycolysis?
A) It occurs in the mitochondria.
B) It requires oxygen to proceed.
C) It results in the production of pyruvate from glucose.
D) It generates large amounts of ATP.
71. Which of the following best describes a competitive inhibitor of an enzyme?
A) It binds to the enzyme’s active site, preventing the substrate from binding.
B) It binds to the enzyme’s allosteric site and increases the enzyme’s activity.
C) It prevents the enzyme from binding to its substrate by binding to a non-active site.
D) It speeds up the reaction rate by stabilizing the transition state.
72. Which of the following is a characteristic of RNA that differentiates it from DNA?
A) RNA is double-stranded, while DNA is single-stranded.
B) RNA contains uracil instead of thymine as one of its nitrogenous bases.
C) RNA contains deoxyribose as the sugar.
D) RNA is found exclusively in the nucleus.
73. Which of the following is a characteristic of an anabolic reaction?
A) It breaks down molecules and releases energy.
B) It synthesizes molecules and requires energy.
C) It involves the conversion of glucose to pyruvate.
D) It results in the production of ATP.
74. Which of the following structures in the cell is responsible for sorting and packaging proteins for transport?
A) Nucleolus
B) Endoplasmic reticulum
C) Golgi apparatus
D) Mitochondrion
75. Which of the following is the main function of ribosomal RNA (rRNA)?
A) Synthesizing proteins
B) Transmitting genetic information
C) Catalyzing protein synthesis in ribosomes
D) Transcribing DNA into RNA
76. Which of the following is an example of a nonpolar molecule?
A) Water
B) Glucose
C) Oxygen
D) Sodium chloride
77. Which of the following pathways is involved in the conversion of pyruvate into acetyl-CoA?
A) Glycolysis
B) Citric acid cycle
C) Fermentation
D) Pyruvate decarboxylation
78. Which of the following describes the quaternary structure of a protein?
A) The sequence of amino acids in the polypeptide chain.
B) The coiling or folding of the polypeptide chain into an alpha helix or beta sheet.
C) The three-dimensional shape of a single polypeptide chain.
D) The association of multiple polypeptide chains into a functional protein complex.
79. Which of the following molecules is used by the cell to temporarily store energy during metabolism?
A) DNA
B) ATP
C) Protein
D) Glycogen
80. Which of the following is a key feature of the secondary structure of proteins?
A) The folding of the polypeptide chain into a specific three-dimensional shape.
B) The formation of beta-pleated sheets and alpha helices.
C) The sequence of amino acids in the protein.
D) The interactions between different protein subunits.
81. Which of the following molecules are responsible for the transport of oxygen in the blood?
A) Platelets
B) Red blood cells
C) White blood cells
D) Plasma proteins
82. Which of the following is true about the citric acid cycle?
A) It produces glucose.
B) It takes place in the cytoplasm.
C) It generates ATP, NADH, and FADH2.
D) It requires oxygen to occur.
83. Which of the following best describes an enzyme’s active site?
A) The region where substrates are bound and catalysis occurs.
B) The part of the enzyme responsible for its folding.
C) The site where cofactors bind to the enzyme.
D) The portion of the enzyme that stabilizes the product.
84. Which of the following is a product of the light reactions of photosynthesis?
A) Oxygen
B) Glucose
C) Carbon dioxide
D) ATP
85. Which of the following molecules is involved in energy storage in plants?
A) Starch
B) Glycogen
C) Cellulose
D) Chitin
86. Which of the following is the primary role of the mitochondrion?
A) Synthesizing proteins
B) Packaging and shipping cellular products
C) Generating ATP through cellular respiration
D) Producing lipids
87. Which of the following describes the role of transfer RNA (tRNA) in protein synthesis?
A) It carries the genetic code from DNA to the ribosome.
B) It links amino acids together in a polypeptide chain.
C) It helps form the ribosome.
D) It carries amino acids to the ribosome for protein synthesis.
88. Which of the following compounds is a coenzyme involved in many biochemical reactions?
A) ATP
B) NAD+
C) DNA
D) Glycogen
89. Which of the following is the final electron acceptor in the electron transport chain?
A) Oxygen
B) NADH
C) ATP
D) Water
90. Which of the following is a function of cholesterol in the cell membrane?
A) Stabilizing the membrane’s fluidity
B) Catalyzing metabolic reactions
C) Transporting molecules across the membrane
D) Providing energy for the cell
91. Which of the following best describes a nonpolar covalent bond?
A) Electrons are shared equally between atoms.
B) Electrons are transferred from one atom to another.
C) One atom attracts the electrons more strongly than the other.
D) Electrons are shared unequally but with some balance.
92. Which of the following is the role of ribosomal RNA (rRNA)?
A) It serves as a template for protein synthesis.
B) It carries genetic information from the nucleus to the cytoplasm.
C) It catalyzes the formation of peptide bonds during protein synthesis.
D) It stores genetic information in cells.
93. Which of the following amino acids contains a basic group in its side chain?
A) Alanine
B) Lysine
C) Glycine
D) Serine
94. What is the major purpose of the Calvin cycle in photosynthesis?
A) To produce glucose from carbon dioxide
B) To generate oxygen from water
C) To produce ATP for cellular energy
D) To break down glucose into pyruvate
95. Which of the following molecules is required for the initiation of DNA replication?
A) Ribosomal RNA (rRNA)
B) DNA polymerase
C) Helicase
D) RNA primer
96. Which of the following describes the primary structure of a protein?
A) The sequence of amino acids in the polypeptide chain
B) The coiling or folding of the polypeptide chain into alpha helices or beta sheets
C) The overall three-dimensional shape of the protein
D) The interaction between different protein subunits
97. Which of the following molecules is used in cellular respiration to generate ATP?
A) Glucose
B) Water
C) Oxygen
D) Nitrogen
98. Which of the following best describes the function of an enzyme in a biochemical reaction?
A) It decreases the activation energy of the reaction.
B) It increases the activation energy of the reaction.
C) It serves as a reactant in the reaction.
D) It is consumed during the reaction.
99. Which of the following is the final product of the citric acid cycle (Krebs cycle)?
A) Glucose
B) Oxygen
C) Carbon dioxide
D) Water
100. Which of the following is a primary function of lipids in the body?
A) Storing genetic information
B) Providing energy storage and insulation
C) Serving as enzymes for biochemical reactions
D) Synthesizing proteins
101. Which of the following molecules contains ribose sugar?
A) DNA
B) RNA
C) Protein
D) Fatty acids
102. Which of the following is a function of glycogen in animals?
A) It stores genetic information.
B) It stores energy for short-term use.
C) It provides structural support for the cell.
D) It is used for long-term energy storage.
103. Which of the following is involved in the synthesis of proteins in the cell?
A) Ribosome
B) Lysosome
C) Nucleolus
D) Mitochondrion
104. Which of the following molecules is required to initiate the process of transcription?
A) ATP
B) RNA polymerase
C) Ribosomal RNA
D) DNA polymerase
105. Which of the following is the main component of the plasma membrane of cells?
A) Carbohydrates
B) Phospholipids
C) Proteins
D) Nucleic acids
106. Which of the following processes takes place in the cytoplasm?
A) Glycolysis
B) Citric acid cycle
C) Electron transport chain
D) Photosynthesis
107. Which of the following is a characteristic of a competitive enzyme inhibitor?
A) It binds to an enzyme’s active site and prevents substrate binding.
B) It binds to the allosteric site and increases enzyme activity.
C) It binds to the enzyme irreversibly.
D) It decreases the enzyme’s reaction rate by altering its structure.
108. Which of the following is true about ATP synthesis?
A) ATP synthesis occurs only in the presence of oxygen.
B) ATP is synthesized through oxidative phosphorylation in the mitochondria.
C) ATP is synthesized only during photosynthesis.
D) ATP is synthesized through fermentation in the cytoplasm.
109. Which of the following molecules serves as the genetic material in most organisms?
A) Proteins
B) Carbohydrates
C) DNA
D) Lipids
110. Which of the following is the main function of the Golgi apparatus?
A) Synthesizing proteins
B) Modifying and packaging proteins for secretion
C) Storing genetic material
D) Generating ATP
111. Which of the following processes is responsible for the production of lactate in muscle cells under anaerobic conditions?
A) Glycolysis
B) Citric acid cycle
C) Fermentation
D) Electron transport chain
112. Which of the following is true about the structure of a lipid bilayer?
A) Hydrophilic heads face inward, and hydrophobic tails face outward.
B) Hydrophilic heads face outward, and hydrophobic tails face inward.
C) Both heads and tails are hydrophobic.
D) Both heads and tails are hydrophilic.
113. Which of the following molecules is a product of the process of photosynthesis?
A) Oxygen
B) Glucose
C) Carbon dioxide
D) Both A and B
114. Which of the following best describes a hydrogen bond?
A) A strong bond that involves the sharing of electrons between atoms.
B) A bond that involves the attraction between a hydrogen atom and a highly electronegative atom.
C) A bond that forms when two atoms share a pair of electrons.
D) A bond between two nonpolar atoms.
115. Which of the following is a component of the extracellular matrix?
A) Nucleic acids
B) Glycoproteins
C) Ribosomal RNA
D) Lysosomal enzymes
116. Which of the following enzymes is involved in the synthesis of DNA?
A) DNA polymerase
B) RNA polymerase
C) Ligase
D) Helicase
117. Which of the following structures is responsible for the packaging of newly synthesized proteins?
A) Ribosome
B) Golgi apparatus
C) Mitochondrion
D) Nucleolus
118. Which of the following is a major role of phospholipids in the cell membrane?
A) To act as catalysts for biochemical reactions
B) To store genetic information
C) To form the structural framework of the membrane
D) To store energy for the cell
119. Which of the following is true about the process of oxidative phosphorylation?
A) It occurs in the cytoplasm and generates glucose.
B) It generates ATP using the energy of electrons transferred through the electron transport chain.
C) It produces carbon dioxide and water in the absence of oxygen.
D) It occurs in the ribosomes and synthesizes proteins.
120. Which of the following is a function of the smooth endoplasmic reticulum?
A) Synthesizing proteins
B) Synthesizing lipids and detoxifying chemicals
C) Packaging proteins for transport
D) Synthesizing ribosomal RNA
121. Which of the following is a characteristic of an enzyme’s active site?
A) It is a region that can only bind to nonpolar substrates.
B) It has a shape that allows it to specifically bind to its substrate.
C) It is a rigid structure that does not change shape.
D) It is responsible for producing the final product of the reaction.
122. Which of the following is a major role of cholesterol in the cell membrane?
A) It provides a structural framework for protein synthesis.
B) It stabilizes the membrane’s fluidity.
C) It acts as a receptor for signal transduction.
D) It assists in the transport of ions across the membrane.
123. Which of the following is the function of transfer RNA (tRNA)?
A) It carries amino acids to the ribosome during protein synthesis.
B) It stores genetic information in the nucleus.
C) It catalyzes the formation of peptide bonds during translation.
D) It synthesizes messenger RNA (mRNA) from DNA.
124. Which of the following is the primary energy carrier in the cell?
A) Glucose
B) NADH
C) ATP
D) Oxygen
125. Which of the following best describes the process of feedback inhibition in enzyme regulation?
A) The product of a metabolic pathway inhibits the activity of an enzyme involved early in the pathway.
B) The enzyme catalyzes a reaction at a faster rate to increase product formation.
C) The substrate concentration is increased to stimulate enzyme activity.
D) The enzyme becomes more efficient at higher temperatures.
126. Which of the following processes occurs in the mitochondria?
A) Glycolysis
B) Citric acid cycle (Krebs cycle)
C) Fermentation
D) Photosynthesis
127. Which of the following molecules is a major component of the extracellular matrix?
A) Lipids
B) Nucleotides
C) Collagen
D) Ribosomal RNA
128. Which of the following best describes the role of coenzymes in enzyme catalysis?
A) They are consumed in the reaction.
B) They serve as structural components of enzymes.
C) They donate or accept electrons or functional groups during the reaction.
D) They bind to the enzyme’s active site, preventing the substrate from binding.
129. Which of the following processes directly produces the most ATP?
A) Glycolysis
B) Citric acid cycle
C) Electron transport chain and oxidative phosphorylation
D) Fermentation
130. Which of the following is the primary function of nucleotides in cells?
A) To provide a structural component of cell membranes
B) To serve as the building blocks for proteins
C) To store and transmit genetic information
D) To provide energy for metabolic reactions
131. Which of the following is the function of the electron transport chain in cellular respiration?
A) To produce glucose from carbon dioxide and water
B) To create a proton gradient across the mitochondrial membrane
C) To synthesize ribosomal RNA
D) To convert pyruvate into lactic acid
132. Which of the following molecules directly provides the energy required for muscle contraction?
A) ATP
B) Glucose
C) Oxygen
D) Phosphocreatine
133. Which of the following structures is responsible for synthesizing proteins?
A) Mitochondrion
B) Ribosome
C) Golgi apparatus
D) Endoplasmic reticulum
134. Which of the following is true about the structure of RNA?
A) RNA contains thymine instead of uracil.
B) RNA is a double-stranded molecule.
C) RNA contains ribose sugar.
D) RNA has no role in protein synthesis.
135. Which of the following is a product of glycolysis?
A) NADH
B) Acetyl-CoA
C) Oxygen
D) Carbon dioxide
136. Which of the following molecules is essential for the process of photosynthesis?
A) Oxygen
B) ATP
C) Lactic acid
D) Glucose
137. Which of the following amino acids contains a sulfur atom in its side chain?
A) Methionine
B) Lysine
C) Glutamate
D) Alanine
138. Which of the following is the final electron acceptor in the electron transport chain?
A) NADH
B) Oxygen
C) Carbon dioxide
D) Water
139. Which of the following best describes a peptide bond?
A) It is a bond between two sugar molecules.
B) It is a covalent bond between two amino acids.
C) It is a bond between a protein and a carbohydrate.
D) It is a non-covalent bond between two protein subunits.
140. Which of the following is true about the structure of a nucleotide?
A) A nucleotide consists of a phosphate group, a sugar, and a fatty acid.
B) A nucleotide consists of a phosphate group, a sugar, and an amino acid.
C) A nucleotide consists of a phosphate group, a sugar, and a nitrogenous base.
D) A nucleotide consists of a protein, a sugar, and a nitrogenous base.
141. Which of the following types of RNA is directly involved in translation?
A) Messenger RNA (mRNA)
B) Transfer RNA (tRNA)
C) Ribosomal RNA (rRNA)
D) All of the above
142. Which of the following is true about the citric acid cycle (Krebs cycle)?
A) It occurs in the cytoplasm of eukaryotic cells.
B) It generates ATP through substrate-level phosphorylation.
C) It requires oxygen as a direct reactant.
D) It directly produces glucose.
143. Which of the following molecules is NOT involved in the electron transport chain?
A) NADH
B) Oxygen
C) Glucose
D) FADH2
144. Which of the following is true about the process of fermentation?
A) It requires oxygen to proceed.
B) It produces more ATP than aerobic respiration.
C) It regenerates NAD+ for glycolysis to continue in the absence of oxygen.
D) It directly produces ATP via oxidative phosphorylation.
145. Which of the following is an example of a disaccharide?
A) Glucose
B) Fructose
C) Sucrose
D) Starch
146. Which of the following is a component of the prokaryotic cell membrane?
A) Phospholipids
B) Ribosomes
C) Mitochondria
D) Chloroplasts
147. Which of the following molecules is produced during the light reactions of photosynthesis?
A) Glucose
B) Oxygen
C) NADPH
D) Both B and C
148. Which of the following is a function of the lysosome?
A) Synthesizing proteins
B) Breaking down waste materials and cellular debris
C) Storing genetic information
D) Packaging proteins for secretion
149. Which of the following is true about the structure of a fatty acid?
A) It contains both a hydrophilic head and a hydrophobic tail.
B) It is composed of amino acids linked by peptide bonds.
C) It contains nitrogen as part of its structure.
D) It has a hydrophilic tail and a hydrophobic head.
150. Which of the following best describes the role of NADH in cellular respiration?
A) It acts as an electron donor in the electron transport chain.
B) It is produced in the citric acid cycle and used in glycolysis.
C) It stores energy in the form of glucose.
D) It is directly converted into ATP.
151. Which of the following describes the role of the Golgi apparatus in the cell?
A) It synthesizes proteins and lipids.
B) It modifies, sorts, and packages proteins for secretion.
C) It stores genetic information.
D) It synthesizes ATP.
152. Which of the following describes a characteristic of lipids in biological membranes?
A) They are hydrophilic and dissolve easily in water.
B) They contain a hydrophobic tail and a hydrophilic head.
C) They form stable hydrogen bonds with water molecules.
D) They are typically composed of nucleotides.
153. Which of the following statements about enzymes is true?
A) Enzymes increase the activation energy of a reaction.
B) Enzymes are consumed in the reactions they catalyze.
C) Enzymes can be used multiple times to catalyze reactions.
D) Enzymes only catalyze exergonic reactions.
154. Which of the following best describes an anabolic pathway?
A) It breaks down large molecules into smaller ones.
B) It generates energy by breaking down glucose.
C) It consumes energy to build complex molecules from simpler ones.
D) It transfers electrons to the electron transport chain.
155. Which of the following molecules is involved in the synthesis of ATP through oxidative phosphorylation?
A) Glucose
B) Oxygen
C) FADH2
D) NADPH
156. Which of the following is a function of the smooth endoplasmic reticulum (ER)?
A) Protein synthesis
B) Lipid synthesis
C) DNA replication
D) Protein folding
157. Which of the following is a characteristic feature of a phospholipid?
A) It is hydrophilic and forms the interior of the lipid bilayer.
B) It has two hydrophobic tails and one hydrophilic head.
C) It is a simple carbohydrate.
D) It is a steroid with a four-ring structure.
158. Which of the following structures in the mitochondrion is responsible for producing ATP?
A) Matrix
B) Inner mitochondrial membrane
C) Outer mitochondrial membrane
D) Cristae
159. Which of the following is NOT part of the cell theory?
A) All living organisms are composed of cells.
B) The cell is the basic unit of life.
C) All cells arise from pre-existing cells.
D) Cells have no influence on an organism’s function.
160. Which of the following statements about ATP is true?
A) ATP is a protein that catalyzes reactions in cells.
B) ATP contains three phosphate groups and releases energy when hydrolyzed.
C) ATP is produced only in the mitochondria and is never consumed.
D) ATP is the building block for DNA and RNA.
161. Which of the following structures is a key component of the cytoskeleton in eukaryotic cells?
A) Mitochondria
B) Microtubules
C) Lysosomes
D) Golgi apparatus
162. Which of the following is a primary structure in the formation of proteins?
A) Hydrogen bonds between amino acids
B) The sequence of amino acids in a polypeptide chain
C) The folding of the protein into a three-dimensional shape
D) Interactions between protein subunits
163. Which of the following is a major product of the citric acid cycle (Krebs cycle)?
A) Glucose
B) Pyruvate
C) NADH and FADH2
D) Oxygen
164. Which of the following describes the function of a ribosome?
A) It assembles proteins based on the information encoded in mRNA.
B) It synthesizes lipids.
C) It transports proteins across the cell membrane.
D) It modifies proteins after they are synthesized.
165. Which of the following is true about enzymes’ mechanism of action?
A) Enzymes raise the activation energy of the reaction.
B) Enzymes change the equilibrium constant of the reaction.
C) Enzymes lower the activation energy of the reaction.
D) Enzymes are consumed in the reaction.
166. Which of the following best describes a catabolic pathway?
A) It breaks down larger molecules to release energy.
B) It builds complex molecules from simple ones.
C) It produces glucose during photosynthesis.
D) It stores energy in the form of ATP.
167. Which of the following compounds is NOT an example of a lipid?
A) Triglycerides
B) Phospholipids
C) Steroids
D) Amino acids
168. Which of the following statements about glucose is true?
A) Glucose is a monosaccharide used as a primary energy source.
B) Glucose is a disaccharide formed by two glucose units.
C) Glucose is the only carbohydrate used for energy.
D) Glucose is an amino acid.
169. Which of the following best describes the structure of a nucleic acid?
A) It consists of a sugar, phosphate group, and a nitrogenous base.
B) It consists of a chain of amino acids.
C) It is composed of fatty acids and glycerol.
D) It is composed of monosaccharides linked together.
170. Which of the following is the role of NAD+ in cellular respiration?
A) It acts as an electron donor.
B) It acts as an electron acceptor.
C) It generates ATP.
D) It serves as a coenzyme in protein synthesis.
171. Which of the following is true about the structure of carbohydrates?
A) Carbohydrates consist only of carbon, hydrogen, and nitrogen.
B) They contain a sugar backbone with nitrogenous bases.
C) They contain a sugar backbone that is usually linked to phospholipids.
D) They are made up of monosaccharides like glucose.
172. Which of the following types of bonds is responsible for holding two strands of DNA together?
A) Peptide bonds
B) Hydrogen bonds
C) Ionic bonds
D) Covalent bonds
173. Which of the following describes the function of the mitochondrion in the cell?
A) It synthesizes proteins.
B) It produces ribosomal RNA.
C) It generates energy through oxidative phosphorylation.
D) It packages proteins for secretion.
174. Which of the following describes the role of ribosomal RNA (rRNA)?
A) It carries the genetic code from DNA to the ribosome.
B) It catalyzes the synthesis of amino acids.
C) It forms the structure of the ribosome and aids in protein synthesis.
D) It acts as a transport molecule for amino acids.
175. Which of the following is true about the function of a catalyst?
A) It speeds up a chemical reaction without being consumed.
B) It is consumed in the reaction.
C) It increases the activation energy of the reaction.
D) It changes the equilibrium of the reaction.
176. Which of the following molecules is involved in the regulation of cell division?
A) Ribosomal RNA (rRNA)
B) Cyclins
C) ATP
D) Glucose
177. Which of the following statements is true about enzymes?
A) Enzymes are specific to the reactions they catalyze.
B) Enzymes change the equilibrium constant of reactions.
C) Enzymes are not affected by environmental factors such as temperature.
D) Enzymes always require coenzymes to function.
178. Which of the following processes occurs in the cytoplasm of a eukaryotic cell?
A) Glycolysis
B) Citric acid cycle
C) Oxidative phosphorylation
D) DNA replication
179. Which of the following is true about the process of DNA replication?
A) It occurs during the G1 phase of the cell cycle.
B) It is catalyzed by DNA polymerase.
C) It requires oxygen as a substrate.
D) It only occurs in prokaryotic cells.
180. Which of the following is a feature of a prokaryotic cell?
A) It contains a nucleus.
B) It has membrane-bound organelles.
C) It has a single circular DNA molecule.
D) It uses a mitochondrion for energy production.
181. Which of the following is the primary function of the rough endoplasmic reticulum (ER)?
A) Synthesizes lipids
B) Transports proteins and modifies them
C) Synthesizes DNA
D) Synthesizes and stores carbohydrates
182. Which of the following is the most common type of bond that stabilizes the tertiary structure of proteins?
A) Hydrogen bonds
B) Covalent bonds
C) Ionic bonds
D) Van der Waals interactions
183. Which of the following is true about the structure of triglycerides?
A) Triglycerides are composed of two fatty acids and a glycerol molecule.
B) Triglycerides are composed of three fatty acids and a glycerol molecule.
C) Triglycerides are composed of one fatty acid and two glycerol molecules.
D) Triglycerides are composed of a nitrogenous base and a sugar molecule.
184. Which of the following molecules is required for the synthesis of RNA?
A) Deoxyribonucleic acid (DNA)
B) Ribose
C) Thymine
D) Uracil
185. Which of the following molecules acts as an allosteric inhibitor of phosphofructokinase in glycolysis?
A) ADP
B) ATP
C) NADH
D) AMP
186. Which of the following describes the role of coenzymes in enzyme-catalyzed reactions?
A) Coenzymes increase the enzyme’s substrate specificity.
B) Coenzymes stabilize the enzyme-substrate complex.
C) Coenzymes act as electron donors or acceptors.
D) Coenzymes lower the activation energy of reactions.
187. Which of the following best describes an example of feedback inhibition?
A) The presence of ATP decreases the activity of an enzyme in glycolysis.
B) An enzyme increases its activity in response to substrate accumulation.
C) A reaction proceeds spontaneously without regulation.
D) The concentration of a product directly increases the rate of its own production.
188. Which of the following statements about the citric acid cycle is correct?
A) The citric acid cycle occurs in the cytoplasm.
B) The citric acid cycle generates ATP through substrate-level phosphorylation.
C) The citric acid cycle directly produces glucose.
D) The citric acid cycle is involved in the synthesis of proteins.
189. Which of the following molecules is involved in the process of photosynthesis?
A) NADH
B) ATP
C) FADH2
D) Pyruvate
190. Which of the following is true about the structure of DNA?
A) DNA consists of a single strand of nucleotides.
B) DNA is double-stranded, with strands held together by hydrogen bonds between complementary bases.
C) DNA contains uracil instead of thymine.
D) DNA is composed of ribose sugars.
191. Which of the following processes is responsible for the majority of ATP production in cellular respiration?
A) Glycolysis
B) Citric acid cycle
C) Oxidative phosphorylation
D) Fermentation
192. Which of the following is a characteristic feature of saturated fatty acids?
A) They have one or more double bonds between carbon atoms.
B) They are typically liquid at room temperature.
C) They are typically solid at room temperature.
D) They contain at least one nitrogen atom.
193. Which of the following types of RNA carries the genetic code from the DNA to the ribosome for protein synthesis?
A) Ribosomal RNA (rRNA)
B) Messenger RNA (mRNA)
C) Transfer RNA (tRNA)
D) Small nuclear RNA (snRNA)
194. Which of the following is the correct order of the processes involved in cellular respiration?
A) Glycolysis → Citric acid cycle → Electron transport chain
B) Citric acid cycle → Glycolysis → Electron transport chain
C) Glycolysis → Electron transport chain → Citric acid cycle
D) Electron transport chain → Glycolysis → Citric acid cycle
195. Which of the following is the main purpose of the electron transport chain?
A) To generate glucose
B) To produce NADH and FADH2
C) To produce ATP through oxidative phosphorylation
D) To break down fatty acids
196. Which of the following is true about the structure of hemoglobin?
A) Hemoglobin contains a single polypeptide chain.
B) Hemoglobin binds to oxygen through ionic bonds.
C) Hemoglobin is a tetramer with four subunits.
D) Hemoglobin contains only non-polar amino acids.
197. Which of the following is the primary purpose of the Calvin cycle?
A) To produce ATP
B) To fix carbon dioxide into organic molecules
C) To produce oxygen
D) To break down glucose
198. Which of the following is an example of a non-competitive enzyme inhibitor?
A) A molecule that binds to the enzyme’s active site
B) A molecule that binds to a site other than the active site and reduces the enzyme’s activity
C) A molecule that increases the enzyme’s affinity for its substrate
D) A molecule that forms a covalent bond with the enzyme
199. Which of the following is NOT a part of the process of translation?
A) mRNA is transcribed from DNA.
B) mRNA is translated into a protein at the ribosome.
C) tRNA brings amino acids to the ribosome.
D) rRNA catalyzes the formation of peptide bonds.
200. Which of the following describes the role of the Golgi apparatus in protein processing?
A) It synthesizes proteins.
B) It packages and ships proteins to their final destination.
C) It breaks down proteins into amino acids.
D) It stores proteins for later use.
201. Which of the following is a characteristic of an enzyme-substrate complex?
A) It is a stable, long-lasting structure.
B) It temporarily lowers the activation energy of the reaction.
C) It remains unchanged after the reaction.
D) It binds only to one specific type of substrate in all conditions.
202. Which of the following is true regarding the structure of RNA compared to DNA?
A) RNA contains thymine, while DNA contains uracil.
B) RNA is double-stranded, while DNA is single-stranded.
C) RNA contains ribose sugar, while DNA contains deoxyribose.
D) RNA is composed of amino acids, while DNA is composed of nucleotides.
203. Which of the following enzymes is involved in the process of DNA replication?
A) RNA polymerase
B) DNA ligase
C) Reverse transcriptase
D) Hexokinase
204. Which of the following describes the role of NADH in the electron transport chain?
A) It donates electrons to the complex, which powers ATP synthesis.
B) It synthesizes ATP.
C) It pumps protons across the mitochondrial membrane.
D) It generates glucose.
205. Which of the following is true about glycolysis?
A) It occurs in the mitochondria.
B) It requires oxygen.
C) It produces ATP and NADH from glucose.
D) It produces acetyl-CoA.
206. Which of the following is a feature of facilitated diffusion?
A) It requires ATP for movement across the membrane.
B) It is a passive process that does not require energy.
C) It involves the movement of molecules against their concentration gradient.
D) It requires the use of transport proteins.
207. Which of the following statements about fatty acid oxidation is true?
A) Fatty acid oxidation occurs in the cytoplasm.
B) Fatty acids are broken down into glucose molecules during this process.
C) Fatty acid oxidation generates acetyl-CoA, NADH, and FADH2.
D) Fatty acid oxidation produces ATP without requiring oxygen.
208. Which of the following molecules contains the highest energy content?
A) ATP
B) Glucose
C) NADH
D) Fatty acids
209. Which of the following is true about the process of fermentation?
A) Fermentation produces ATP in the presence of oxygen.
B) Fermentation does not require oxygen and produces less ATP than aerobic respiration.
C) Fermentation produces acetyl-CoA as a primary product.
D) Fermentation is a process that occurs only in plant cells.
210. Which of the following is the end product of glycolysis?
A) Acetyl-CoA
B) Pyruvate
C) Glucose
D) Oxygen
211. Which of the following is the primary structure of a protein determined by?
A) The sequence of amino acids
B) The arrangement of polypeptide chains
C) The folding into a 3D structure
D) The interactions between polypeptide chains
212. Which of the following is a product of the light-dependent reactions of photosynthesis?
A) NADPH and ATP
B) Oxygen and glucose
C) Oxygen and NADP+
D) Water and glucose
213. Which of the following is true about the structure of the plasma membrane?
A) It is composed primarily of nucleic acids.
B) It is composed of a bilayer of phospholipids with embedded proteins.
C) It is composed of a single layer of fatty acids.
D) It is composed of a single layer of ribonucleic acid.
214. Which of the following types of RNA carries the amino acid to the ribosome during protein synthesis?
A) Ribosomal RNA (rRNA)
B) Messenger RNA (mRNA)
C) Transfer RNA (tRNA)
D) Small nuclear RNA (snRNA)
215. Which of the following molecules is involved in the process of oxidative phosphorylation?
A) Ribosome
B) Glucose
C) NADH
D) Water
216. Which of the following compounds is a key intermediate in the citric acid cycle?
A) Acetyl-CoA
B) NADH
C) Glucose
D) Oxygen
217. Which of the following molecules acts as the final electron acceptor in the electron transport chain?
A) NADH
B) Oxygen
C) ATP
D) Carbon dioxide
218. Which of the following is a feature of prokaryotic cells?
A) They contain membrane-bound organelles.
B) They have a defined nucleus.
C) They have ribosomes but lack a membrane-bound nucleus.
D) They contain mitochondria.
219. Which of the following molecules is synthesized from acetyl-CoA during the citric acid cycle?
A) Glucose
B) NADH
C) Fatty acids
D) Oxaloacetate
220. Which of the following structures is responsible for protein synthesis in the cell?
A) Nucleus
B) Golgi apparatus
C) Ribosomes
D) Mitochondria
221. Which of the following is true about the structure of enzymes?
A) Enzymes are composed of nucleic acids.
B) Enzymes work by lowering the activation energy of a reaction.
C) Enzymes are permanent and do not change during reactions.
D) Enzymes only function at extremely high temperatures.
222. Which of the following occurs during the process of glycolysis?
A) Pyruvate is synthesized.
B) Glucose is synthesized from pyruvate.
C) Oxygen is required.
D) Glucose is broken down into two molecules of pyruvate.
223. Which of the following molecules can be used to produce ATP in the absence of oxygen?
A) NADH
B) Glucose
C) Pyruvate
D) Lactate
224. Which of the following statements about lipids is true?
A) Lipids are water-soluble molecules.
B) Lipids are the primary source of energy in the body.
C) Lipids are composed of amino acids.
D) Lipids do not contain fatty acids.
225. Which of the following is the correct order of steps in DNA replication?
A) Transcription → Replication → Translation
B) Replication → Transcription → Translation
C) Replication → Translation → Transcription
D) Translation → Replication → Transcription
226. Which of the following is an example of a hydrophilic molecule?
A) Oil
B) DNA
C) Oxygen
D) Phospholipid tail
227. Which of the following describes the structure of a nucleotide?
A) A nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
B) A nucleotide consists of amino acids and a sugar molecule.
C) A nucleotide consists of a sugar and a fatty acid.
D) A nucleotide consists of glucose and a nitrogenous base.
228. Which of the following is a characteristic of unsaturated fatty acids?
A) They have no double bonds between carbon atoms.
B) They are typically solid at room temperature.
C) They are typically liquid at room temperature.
D) They contain only saturated bonds.
229. Which of the following molecules is a byproduct of aerobic cellular respiration?
A) Oxygen
B) Glucose
C) Carbon dioxide
D) ATP
230. Which of the following processes requires oxygen?
A) Glycolysis
B) Fermentation
C) Citric acid cycle
D) Glycogenolysis
231. Which of the following molecules is the immediate energy source for muscle contraction?
A) Glucose
B) ATP
C) NADH
D) Phosphocreatine
232. Which of the following is the correct pairing of nitrogenous bases in DNA?
A) Adenine pairs with cytosine.
B) Cytosine pairs with thymine.
C) Guanine pairs with uracil.
D) Adenine pairs with thymine.
233. Which of the following is the function of the enzyme helicase in DNA replication?
A) To synthesize RNA primers
B) To unwind the DNA double helix
C) To join Okazaki fragments together
D) To correct errors during replication
234. Which of the following pathways is involved in the production of ATP in the absence of oxygen?
A) Glycolysis
B) Citric acid cycle
C) Electron transport chain
D) Calvin cycle
235. Which of the following molecules is involved in protein folding?
A) Chaperone proteins
B) Ribosomal RNA
C) Transfer RNA
D) Messenger RNA
236. Which of the following is true about the pentose phosphate pathway?
A) It generates ATP and NADH.
B) It is involved in the breakdown of fatty acids.
C) It produces ribose-5-phosphate for nucleotide synthesis.
D) It produces pyruvate from glucose.
237. Which of the following is true about enzymes?
A) Enzymes are consumed during the reaction they catalyze.
B) Enzymes increase the activation energy of a reaction.
C) Enzymes are highly specific to their substrates.
D) Enzymes are only active at very high temperatures.
238. Which of the following is a function of cholesterol in the plasma membrane?
A) To form a bilayer with phospholipids
B) To regulate membrane fluidity
C) To synthesize lipids
D) To assist in protein synthesis
239. Which of the following molecules is required for the citric acid cycle to proceed?
A) NADH
B) Glucose
C) Acetyl-CoA
D) Oxygen
240. Which of the following is the role of the ribosome in translation?
A) To synthesize DNA
B) To read the mRNA and assemble amino acids into a polypeptide chain
C) To transport amino acids to the nucleus
D) To splice the mRNA
241. Which of the following is the major role of carbohydrates in cells?
A) Provide structural support
B) Store genetic information
C) Serve as a source of energy
D) Serve as hormones
242. Which of the following enzymes is involved in the process of transcription?
A) RNA polymerase
B) DNA polymerase
C) Ligase
D) Helicase
243. Which of the following processes occurs in the cytoplasm of eukaryotic cells?
A) Glycolysis
B) Citric acid cycle
C) Electron transport chain
D) DNA replication
244. Which of the following is a key feature of enzyme catalysis?
A) Enzymes lower the activation energy of a reaction.
B) Enzymes increase the activation energy of a reaction.
C) Enzymes increase the equilibrium constant of a reaction.
D) Enzymes alter the products of a reaction.
245. Which of the following molecules is directly responsible for the formation of the proton gradient in the electron transport chain?
A) NADH
B) Oxygen
C) ATP synthase
D) Electron carriers like cytochrome
246. Which of the following describes the secondary structure of proteins?
A) The sequence of amino acids in a polypeptide chain.
B) The three-dimensional arrangement of a polypeptide chain.
C) The specific shape formed by hydrogen bonding between amino acids.
D) The interaction between two or more polypeptide chains.
247. Which of the following is NOT a function of lipids?
A) Energy storage
B) Insulation
C) Protein synthesis
D) Formation of cell membranes
248. Which of the following best describes the structure of a phospholipid?
A) A glycerol backbone with two fatty acids and a phosphate group.
B) A glycerol backbone with three fatty acids and a nitrogenous base.
C) A glucose molecule with phosphate groups.
D) A protein with hydrophobic and hydrophilic regions.
249. Which of the following is NOT a product of glycolysis?
A) Pyruvate
B) NADH
C) ATP
D) Glucose
250. Which of the following describes the function of ribosomal RNA (rRNA)?
A) Carries genetic information from DNA to the ribosome.
B) Catalyzes the formation of peptide bonds during translation.
C) Provides the template for protein synthesis.
D) Modifies and processes other types of RNA.
251. Which of the following is a major function of the citric acid cycle?
A) Production of ATP
B) Conversion of glucose into pyruvate
C) Production of NADH and FADH2 for the electron transport chain
D) Synthesis of glucose
252. Which of the following is involved in the process of oxidative phosphorylation?
A) Production of glucose from pyruvate
B) Reduction of NADH to NAD+
C) Transfer of electrons through the electron transport chain
D) Conversion of ADP to ATP by glycolysis
253. Which of the following is the function of the Golgi apparatus?
A) Synthesizes proteins
B) Synthesizes lipids
C) Modifies, sorts, and packages proteins and lipids for transport
D) Provides structural support to the cell
254. Which of the following is a characteristic of saturated fatty acids?
A) They contain one or more double bonds between carbon atoms.
B) They are liquid at room temperature.
C) They have no double bonds between carbon atoms.
D) They are found exclusively in plant oils.
255. Which of the following is the main energy currency of the cell?
A) Glucose
B) NADH
C) ATP
D) Phosphocreatine
256. Which of the following statements about the structure of DNA is true?
A) DNA consists of a single strand of nucleotides.
B) DNA strands are held together by hydrogen bonds between nitrogenous bases.
C) DNA contains uracil instead of thymine.
D) DNA is composed of ribose sugars.
257. Which of the following enzymes is responsible for adding nucleotides during DNA replication?
A) DNA polymerase
B) RNA polymerase
C) Ligase
D) Helicase
258. Which of the following is the primary function of the rough endoplasmic reticulum (ER)?
A) Detoxification of harmful substances
B) Synthesis of lipids
C) Synthesis of proteins and modification of proteins
D) Packaging proteins for transport
259. Which of the following best describes the function of mitochondria?
A) Produce ribosomes
B) Synthesize lipids
C) Generate ATP through oxidative phosphorylation
D) Modifies proteins for secretion
260. Which of the following occurs in the process of transcription?
A) The mRNA is translated into a protein.
B) RNA polymerase synthesizes RNA from a DNA template.
C) The ribosome synthesizes mRNA.
D) RNA is converted into DNA.
261. Which of the following is true about glycolysis?
A) It occurs in the mitochondria.
B) It requires oxygen to proceed.
C) It produces ATP by substrate-level phosphorylation.
D) It generates glucose from pyruvate.
262. Which of the following molecules is produced during fermentation in the absence of oxygen?
A) Pyruvate
B) NADH
C) Lactic acid or ethanol
D) ATP
263. Which of the following molecules is involved in the process of cellular respiration by transferring electrons to the electron transport chain?
A) NADH and FADH2
B) Glucose and ATP
C) Oxygen and NADPH
D) Acetyl-CoA and ATP
264. Which of the following statements about enzymes is true?
A) Enzymes can change the equilibrium of a reaction.
B) Enzymes increase the activation energy required for a reaction.
C) Enzymes are consumed in the reactions they catalyze.
D) Enzymes lower the activation energy required for a reaction.
265. Which of the following is true about the citric acid cycle?
A) It occurs in the cytoplasm of the cell.
B) It generates NADH, FADH2, and ATP.
C) It produces glucose from pyruvate.
D) It requires oxygen directly for the reactions to proceed.
266. Which of the following is the main purpose of the electron transport chain?
A) To generate glucose from fatty acids
B) To produce ATP through oxidative phosphorylation
C) To break down fatty acids
D) To synthesize amino acids
267. Which of the following is true about ribosomes?
A) Ribosomes are found only in eukaryotic cells.
B) Ribosomes consist of RNA and protein.
C) Ribosomes are involved in transcription.
D) Ribosomes are responsible for protein degradation.
268. Which of the following is NOT involved in the process of protein synthesis?
A) mRNA
B) tRNA
C) Ribosomes
D) Ligase
269. Which of the following is the main difference between RNA and DNA?
A) RNA contains thymine, whereas DNA contains uracil.
B) RNA is a double-stranded molecule, whereas DNA is single-stranded.
C) RNA contains ribose, whereas DNA contains deoxyribose.
D) RNA is involved in protein synthesis, while DNA stores genetic information.
270. Which of the following is a feature of active transport?
A) It requires energy input from ATP.
B) It moves molecules from high concentration to low concentration.
C) It does not require proteins to facilitate movement.
D) It occurs along a concentration gradient.
271. Which of the following best describes a disaccharide?
A) A sugar molecule consisting of a single sugar unit
B) A sugar molecule composed of two monosaccharide units
C) A sugar molecule composed of three monosaccharide units
D) A sugar molecule that contains a nitrogenous base
272. Which of the following enzymes is responsible for the breakdown of lactose into glucose and galactose?
A) Lactase
B) Amylase
C) Lipase
D) Peptidase
273. Which of the following molecules are involved in the regulation of gene expression?
A) DNA polymerase
B) Ribosomes
C) Transcription factors
D) ATP synthase
274. Which of the following is a characteristic of unsaturated fatty acids?
A) They contain no double bonds between carbon atoms.
B) They are typically solid at room temperature.
C) They contain one or more double bonds between carbon atoms.
D) They have a straight chain structure.
275. Which of the following amino acids is classified as nonpolar?
A) Glutamine
B) Alanine
C) Aspartate
D) Serine
276. Which of the following is a function of the sodium-potassium pump?
A) Synthesize ATP
B) Move sodium and potassium ions across the membrane against their concentration gradients
C) Facilitate the diffusion of glucose
D) Maintain the pH of the cell
277. Which of the following is a result of phosphorylation in cellular metabolism?
A) Decrease in the energy of the molecule
B) Increase in the molecule’s charge, making it more reactive
C) Stabilization of the molecule for storage
D) Removal of a phosphate group to release energy
278. Which of the following is true regarding the structure of an enzyme active site?
A) The active site only binds the substrate through hydrogen bonds.
B) The active site may undergo conformational changes to accommodate the substrate.
C) The active site is always rigid and does not change shape.
D) The active site binds to the product of the reaction.
279. Which of the following molecules is NOT directly involved in the process of cellular respiration?
A) Oxygen
B) Glucose
C) Acetyl-CoA
D) Chlorophyll
280. Which of the following is a function of the plasma membrane in a cell?
A) Synthesize proteins
B) Store genetic material
C) Provide structural support and regulate transport of materials
D) Control the release of energy from glucose
281. Which of the following is the role of tRNA in translation?
A) It carries amino acids to the ribosome for protein synthesis.
B) It transcribes the genetic code into mRNA.
C) It catalyzes the formation of peptide bonds.
D) It provides energy for translation.
282. Which of the following is a key component of the electron transport chain?
A) ATP
B) Ribose
C) NADH
D) Glucose
283. Which of the following is an example of a hydrophilic amino acid?
A) Leucine
B) Phenylalanine
C) Serine
D) Alanine
284. Which of the following processes occurs in the mitochondria?
A) Glycolysis
B) DNA replication
C) Citric acid cycle
D) Protein synthesis
285. Which of the following is a byproduct of the citric acid cycle?
A) ATP
B) Oxygen
C) Water
D) Glucose
286. Which of the following molecules serves as the final electron acceptor in the electron transport chain?
A) NADH
B) ATP
C) Oxygen
D) Carbon dioxide
287. Which of the following describes the structure of a triglyceride?
A) A glycerol backbone attached to three fatty acid chains
B) A sugar molecule attached to three phosphate groups
C) A nitrogenous base attached to three sugar units
D) A fatty acid backbone with three glucose molecules
288. Which of the following is an example of a protein’s quaternary structure?
A) The specific amino acid sequence of a polypeptide
B) The arrangement of multiple polypeptide chains in a multi-subunit protein
C) The three-dimensional folding of a single polypeptide chain
D) The formation of alpha-helices and beta-sheets
289. Which of the following is true regarding the ATP synthase enzyme?
A) It is involved in the breakdown of glucose during glycolysis.
B) It converts ADP and inorganic phosphate into ATP.
C) It uses oxygen to produce ATP.
D) It is involved in the process of DNA replication.
290. Which of the following molecules is involved in the process of DNA replication?
A) RNA polymerase
B) DNA helicase
C) Ribosome
D) tRNA
291. Which of the following describes a saturated fatty acid?
A) Contains one or more double bonds
B) Contains no double bonds
C) Is liquid at room temperature
D) Contains three phosphate groups
292. Which of the following molecules can cross the cell membrane most easily?
A) Large polar molecules
B) Ions
C) Small nonpolar molecules
D) Charged macromolecules
293. Which of the following is a feature of the rough endoplasmic reticulum (ER)?
A) It synthesizes lipids and steroids.
B) It is studded with ribosomes and synthesizes proteins.
C) It stores genetic material.
D) It synthesizes RNA from DNA.
294. Which of the following statements about enzymes is correct?
A) Enzymes are consumed in the reactions they catalyze.
B) Enzymes increase the activation energy of a reaction.
C) Enzymes only function in the presence of oxygen.
D) Enzymes lower the activation energy of a reaction.
295. Which of the following is the role of NAD+ in cellular metabolism?
A) It stores energy as ATP.
B) It acts as an electron carrier in redox reactions.
C) It catalyzes the breakdown of glucose.
D) It transports oxygen to mitochondria.
296. Which of the following is NOT part of the structure of a nucleic acid?
A) Nitrogenous base
B) Sugar molecule
C) Fatty acid chain
D) Phosphate group
297. Which of the following processes is a type of passive transport?
A) Endocytosis
B) Active transport
C) Facilitated diffusion
D) Sodium-potassium pump
298. Which of the following enzymes is involved in the breakdown of proteins?
A) Amylase
B) Lipase
C) Protease
D) Lactase
299. Which of the following is true about the structure of RNA?
A) RNA is double-stranded, like DNA.
B) RNA contains the sugar deoxyribose.
C) RNA contains uracil instead of thymine.
D) RNA is not involved in protein synthesis.
300. Which of the following pathways produces the most ATP?
A) Glycolysis
B) Citric acid cycle
C) Oxidative phosphorylation
D) Fermentation
301. Which of the following is a major function of proteins in the cell?
A) Store genetic information
B) Catalyze biochemical reactions
C) Store energy
D) Act as structural components of lipids
302. Which of the following is a key characteristic of enzymes?
A) They are consumed in the reaction they catalyze.
B) They increase the activation energy of a reaction.
C) They lower the activation energy of a reaction.
D) They are permanently altered during the reaction.
303. Which of the following is NOT a type of lipid?
A) Phospholipid
B) Steroid
C) Nucleic acid
D) Triglyceride
304. Which of the following is the primary energy carrier in the cell?
A) NADH
B) ATP
C) Glucose
D) Oxygen
305. Which of the following macromolecules is made up of amino acids?
A) Carbohydrates
B) Proteins
C) Nucleic acids
D) Lipids
306. Which of the following is NOT a function of carbohydrates?
A) Provide energy for cellular processes
B) Store genetic information
C) Serve as structural components in cell walls
D) Act as receptors for cell signaling
307. Which of the following molecules is NOT involved in the process of transcription?
A) DNA
B) RNA polymerase
C) tRNA
D) mRNA
308. Which of the following structures is involved in the synthesis of proteins?
A) Nucleus
B) Mitochondrion
C) Ribosome
D) Golgi apparatus
309. Which of the following is a key feature of the phospholipid bilayer?
A) It is impermeable to all molecules.
B) It contains embedded proteins that regulate the passage of substances.
C) It is made solely of cholesterol molecules.
D) It is a rigid structure with no flexibility.
310. Which of the following is the main source of energy for cellular respiration?
A) Oxygen
B) Glucose
C) ATP
D) Fatty acids
311. Which of the following amino acids contains a sulfur atom in its side chain?
A) Serine
B) Cysteine
C) Glutamine
D) Tyrosine
312. Which of the following is the main function of nucleotides in the cell?
A) Catalyze biochemical reactions
B) Provide structural support to the cell
C) Store and transfer genetic information
D) Form cell membranes
313. Which of the following is NOT a component of an amino acid?
A) Amino group
B) Carboxyl group
C) Phosphate group
D) R group
314. Which of the following is true about glycolysis?
A) It occurs in the mitochondria.
B) It requires oxygen to proceed.
C) It results in the production of pyruvate.
D) It is a type of oxidative phosphorylation.
315. Which of the following describes the structure of a triglyceride molecule?
A) One glycerol molecule and two fatty acid chains
B) One glycerol molecule and three fatty acid chains
C) One sugar molecule and three phosphate groups
D) One amino acid and two peptide bonds
316. Which of the following enzymes is involved in DNA replication?
A) RNA polymerase
B) Ligase
C) DNA polymerase
D) Peptidase
317. Which of the following is a product of the Calvin cycle?
A) Oxygen
B) Glucose
C) NADPH
D) Acetyl-CoA
318. Which of the following molecules is directly responsible for carrying electrons during oxidative phosphorylation?
A) NADH
B) ATP
C) Acetyl-CoA
D) Glucose
319. Which of the following is NOT a role of lipids in the body?
A) Providing long-term energy storage
B) Acting as hormones
C) Serving as structural components of cell membranes
D) Serving as a direct energy source for cells
320. Which of the following is an example of a polysaccharide?
A) Glucose
B) Fructose
C) Starch
D) Lactose
321. Which of the following molecules can easily pass through a phospholipid bilayer?
A) Small nonpolar molecules
B) Large charged molecules
C) Large polar molecules
D) Ions
322. Which of the following best describes the function of ribosomes in a cell?
A) They store genetic information.
B) They facilitate protein synthesis.
C) They break down toxic substances.
D) They regulate the flow of ions across the membrane.
323. Which of the following describes the structure of DNA?
A) Single-stranded with a helical shape
B) Double-stranded with a double helix shape
C) Triple-stranded with a flat shape
D) Single-stranded with a linear shape
324. Which of the following is a product of the light-dependent reactions of photosynthesis?
A) Glucose
B) Oxygen
C) Carbon dioxide
D) NADH
325. Which of the following is a characteristic of a competitive inhibitor?
A) It binds to an enzyme’s active site and competes with the substrate.
B) It binds to a site other than the enzyme’s active site.
C) It increases the rate of the reaction.
D) It is permanently bound to the enzyme.
326. Which of the following structures is involved in cellular communication?
A) Nucleus
B) Plasma membrane
C) Mitochondrion
D) Ribosome
327. Which of the following is a function of the Golgi apparatus?
A) Synthesizing proteins
B) Modifying and packaging proteins for transport
C) Synthesizing lipids
D) Producing ATP
328. Which of the following best describes the structure of a phospholipid?
A) A hydrophilic head and two hydrophobic tails
B) A hydrophobic head and two hydrophilic tails
C) A hydrophilic head and three hydrophobic tails
D) A hydrophilic head with no tails
329. Which of the following molecules serves as the final electron acceptor in the electron transport chain?
A) NADH
B) Oxygen
C) Water
D) ATP
330. Which of the following describes the role of mitochondria in the cell?
A) They are involved in protein synthesis.
B) They store genetic information.
C) They are the site of ATP production via cellular respiration.
D) They are involved in cell division.
331. Which of the following molecules is responsible for the structure of the plasma membrane?
A) Proteins
B) Lipids
C) Carbohydrates
D) Nucleic acids
332. What is the main product of the citric acid cycle (Krebs cycle)?
A) Glucose
B) NADH and FADH2
C) Oxygen
D) ATP
333. Which of the following is true about the structure of enzymes?
A) Enzymes have a rigid structure and do not change.
B) Enzymes can undergo conformational changes that are crucial for their function.
C) Enzymes are composed entirely of nucleic acids.
D) Enzymes are always specific to one substrate but cannot be regulated.
334. Which of the following is the precursor molecule for the synthesis of cholesterol?
A) Acetyl-CoA
B) Pyruvate
C) Glucose
D) Fatty acids
335. Which of the following amino acids is essential for humans?
A) Glycine
B) Serine
C) Leucine
D) Alanine
336. Which of the following is a characteristic of an allosteric enzyme?
A) It has multiple active sites.
B) It can be regulated by binding to a site other than the active site.
C) It is not affected by temperature.
D) It has only one active site.
337. Which of the following processes occurs in the cytoplasm of the cell?
A) Glycolysis
B) Citric acid cycle
C) Electron transport chain
D) Protein synthesis
338. Which of the following describes the function of ribonucleic acid (RNA)?
A) Storing genetic information
B) Transmitting genetic information to offspring
C) Facilitating protein synthesis
D) Controlling metabolic pathways
339. Which of the following is the main energy source used in the process of cellular respiration?
A) ATP
B) Glucose
C) Oxygen
D) NADH
340. Which of the following describes the role of ATP in cellular processes?
A) It acts as a storage molecule for genetic information.
B) It provides energy for biochemical reactions.
C) It acts as an enzyme in chemical reactions.
D) It carries oxygen in the bloodstream.
341. Which of the following is true about nucleic acids?
A) They consist of sugar, phosphate, and nitrogenous base.
B) They contain fatty acid chains.
C) They store energy for cellular functions.
D) They are composed of amino acids.
342. Which of the following molecules is involved in the process of translation?
A) DNA
B) mRNA
C) Ribosome
D) All of the above
343. Which of the following molecules is a coenzyme that carries electrons in cellular respiration?
A) NADH
B) Glucose
C) Oxygen
D) Pyruvate
344. Which of the following best describes the structure of a nucleotide?
A) A sugar, phosphate group, and a fatty acid
B) A sugar, phosphate group, and a nitrogenous base
C) A glycerol, two fatty acids, and a phosphate group
D) A peptide chain and a ribose sugar
345. Which of the following processes involves the use of light to synthesize carbohydrates?
A) Glycolysis
B) Photosynthesis
C) Citric acid cycle
D) Oxidative phosphorylation
346. Which of the following types of RNA carries the genetic information from the DNA to the ribosome?
A) tRNA
B) mRNA
C) rRNA
D) snRNA
347. Which of the following is true about the electron transport chain?
A) It generates a proton gradient across the inner mitochondrial membrane.
B) It takes place in the cytoplasm.
C) It directly produces ATP.
D) It does not require oxygen.
348. Which of the following is a characteristic of saturated fatty acids?
A) They contain one or more double bonds between carbon atoms.
B) They are liquid at room temperature.
C) They are composed of short chains of carbon atoms.
D) They contain no double bonds between carbon atoms.
349. Which of the following is true about the role of oxygen in cellular respiration?
A) Oxygen is used in glycolysis.
B) Oxygen is the final electron acceptor in the electron transport chain.
C) Oxygen is not required for cellular respiration.
D) Oxygen is produced during glycolysis.
350. Which of the following is the main role of chlorophyll in photosynthesis?
A) It converts light energy into chemical energy.
B) It carries electrons through the electron transport chain.
C) It generates ATP.
D) It splits water molecules.
351. Which of the following is true about the structure of a phospholipid?
A) It has a hydrophilic head and hydrophobic tails.
B) It is composed only of fatty acids.
C) It is hydrophobic and repels water.
D) It is a major component of starch.
352. Which of the following is a key feature of enzyme kinetics?
A) Enzyme activity increases as substrate concentration decreases.
B) Enzymes work equally well under all environmental conditions.
C) The reaction rate of an enzyme-catalyzed reaction increases with increasing substrate concentration, up to a point.
D) Enzymes can only catalyze reactions that break down molecules.
353. Which of the following molecules is produced during anaerobic respiration?
A) Oxygen
B) Water
C) Lactic acid or ethanol
D) Glucose
354. Which of the following is the primary function of cholesterol in the body?
A) To serve as a building block for DNA
B) To act as a precursor for the synthesis of hormones
C) To carry oxygen in the blood
D) To store energy for long-term use
355. Which of the following is a common feature of all cells?
A) They all contain a nucleus.
B) They all have a plasma membrane.
C) They all have a cell wall.
D) They all contain chlorophyll.
356. Which of the following is true about the process of oxidative phosphorylation?
A) It occurs in the cytoplasm.
B) It produces most of the ATP in cellular respiration.
C) It does not require oxygen.
D) It occurs in the chloroplasts.
357. Which of the following best describes the function of tRNA in translation?
A) It carries amino acids to the ribosome.
B) It synthesizes proteins.
C) It carries the genetic code from DNA.
D) It catalyzes the formation of peptide bonds.
358. Which of the following is true about RNA polymerase?
A) It is responsible for DNA replication.
B) It is involved in protein synthesis.
C) It synthesizes RNA from a DNA template.
D) It forms the structure of ribosomes.
359. Which of the following is a role of glycerol in metabolism?
A) It is a building block of nucleic acids.
B) It is used to form ATP during glycolysis.
C) It is a precursor for the synthesis of lipids.
D) It is involved in the synthesis of proteins.
360. Which of the following processes occurs in the mitochondria?
A) Glycolysis
B) Citric acid cycle
C) Photosynthesis
D) Protein synthesis