MDCAT Biological Molecules (Biomolecules) MCQs

This comprehensive set of MCQs on Biological Molecules (Biomolecules) is designed to cover all essential topics required for success in the Medical and Dental College Admission Test (MDCAT). Focused on key subjects such as the structure and function of carbohydrates, proteins, lipids, and nucleic acids, these MCQs are crafted to help aspiring medical and dental students build a strong foundation in the chemistry of life and the role of biomolecules in biological processes.

Who should practice Biological Molecules MCQs?

Students preparing for the MDCAT who wish to deepen their understanding of the various types of biomolecules and their significance in cellular functions and human health.
Individuals seeking to enhance their knowledge of biochemical interactions, metabolic pathways, and the molecular basis of diseases.
University students targeting high-yield topics like enzyme function, molecular genetics, and the biochemical properties of macromolecules.
Anyone aiming to strengthen their foundational understanding of biomolecules and their implications for health, nutrition, and disease prevention.
Candidates focused on developing critical thinking and analytical skills related to the molecular aspects of biological systems and their impact on human health.

1. Which of the following is considered a biological molecule?

A) Water
B) Carbohydrates
C) Proteins
D) All of the above

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2. Water is considered a polar molecule because:

A) It has a neutral charge
B) It has a symmetrical shape
C) It has partial positive and negative charges
D) It is a gas at room temperature

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3. The main function of carbohydrates in living organisms is to:

A) Store genetic information
B) Provide energy
C) Catalyze biochemical reactions
D) Store lipids

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4. Which of the following is a monosaccharide?

A) Glucose
B) Sucrose
C) Lactose
D) Starch

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5. The general formula for carbohydrates is:

A) Cn(H2O)n
B) CnH2nOn
C) Cn(H2O)n-2
D) CnH2n+2

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6. Which of the following is a polysaccharide?

A) Fructose
B) Cellulose
C) Galactose
D) Ribose

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7. The process by which glucose is broken down to release energy is called:

A) Photosynthesis
B) Glycolysis
C) Fermentation
D) Respiration

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8. Which type of bond links amino acids together to form proteins?

A) Hydrogen bonds
B) Ionic bonds
C) Peptide bonds
D) Covalent bonds

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9. The primary structure of a protein refers to:

A) The sequence of amino acids
B) The three-dimensional shape
C) The folding of the protein
D) The arrangement of subunits

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10. Lipids are primarily composed of:

A) Amino acids
B) Nucleotides
C) Glycerol and fatty acids
D) Monosaccharides

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11. Which of the following is a function of lipids?

A) Energy storage
B) Hormone production
C) Insulation
D) All of the above

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12. A common type of lipid found in cell membranes is:

A) Triglycerides
B) Phospholipids
C) Steroids
D) Waxes

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13. Glycolipids are formed by:

A) Lipids and nucleotides
B) Lipids and proteins
C) Lipids and carbohydrates
D) Carbohydrates and proteins

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14. Which of the following molecules serves as the primary energy currency in cells?

A) DNA
B) RNA
C) ATP
D) NADPH

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15. Which functional group is commonly found in carbohydrates?

A) Hydroxyl group (-OH)
B) Carboxyl group (-COOH)
C) Amino group (-NH2)
D) Phosphate group (-PO4)

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16. The term “conjugated molecules” refers to molecules that:

A) Are composed of only one type of monomer
B) Contain both protein and carbohydrate components
C) Are only found in plant cells
D) Are used for energy storage only

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17. The structural component of plant cell walls is:

A) Starch
B) Glycogen
C) Cellulose
D) Chitin

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18. The primary storage form of glucose in animals is:

A) Starch
B) Glycogen
C) Cellulose
D) Fructose

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19. Proteins that act as biological catalysts are called:

A) Hormones
B) Enzymes
C) Antibodies
D) Receptors

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20. The secondary structure of a protein is stabilized by:

A) Peptide bonds
B) Hydrogen bonds
C) Ionic bonds
D) Disulfide bridges

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21. Which of the following is NOT a characteristic of lipids?

A) Insoluble in water
B) High energy content
C) Polymers of amino acids
D) Important for cell membrane structure

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22. Phospholipids have a hydrophilic head and:

A) A hydrophobic tail
B) A hydrophilic tail
C) A polar head
D) A charged tail

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23. The primary function of nucleic acids is to:

A) Provide energy
B) Store and transmit genetic information
C) Serve as enzymes
D) Act as structural components

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24. Glycoproteins are formed by:

A) Proteins and nucleotides
B) Proteins and lipids
C) Proteins and carbohydrates
D) Nucleotides and carbohydrates

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25. The most abundant organic molecule on Earth is:

A) Lipids
B) Proteins
C) Cellulose
D) Starch

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26. Which of the following is a characteristic of enzymes?

A) They are consumed in the reaction.
B) They increase the activation energy of reactions.
C) They can be reused multiple times.
D) They only function at high temperatures.

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27. The term “saturated fat” refers to:

A) Fatty acids with double bonds
B) Fatty acids with no double bonds
C) A type of carbohydrate
D) A type of protein

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28. The backbone of a DNA molecule is composed of:

A) Ribose and phosphate
B) Deoxyribose and phosphate
C) Glucose and ribose
D) Amino acids and sugars

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29. Which type of carbohydrate is known as “blood sugar”?

A) Sucrose
B) Fructose
C) Glucose
D) Galactose

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30. The primary structure of proteins is determined by:

A) Hydrogen bonds
B) Peptide bonds
C) The sequence of amino acids
D) Disulfide bridges

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31. Lipids can serve as:

A) Hormones
B) Insulators
C) Energy sources
D) All of the above

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32. The major function of carbohydrates in plants is to:

A) Store energy
B) Provide structure
C) Provide insulation
D) Both A and B

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33. The primary components of nucleotides are:

A) Sugars, amino acids, and bases
B) Sugars, phosphates, and nitrogenous bases
C) Fatty acids and glycerol
D) Amino acids and carboxyl groups

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34. Which of the following is a function of proteins?

A) Transport molecules
B) Serve as enzymes
C) Provide structural support
D) All of the above

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35. The storage form of carbohydrates in plants is:

A) Glycogen
B) Cellulose
C) Starch
D) Glucose

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36. The tertiary structure of a protein is primarily determined by:

A) The sequence of amino acids
B) Hydrogen bonds
C) Ionic interactions and hydrophobic interactions
D) Peptide bonds

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37. A hydrophilic molecule:

A) Is soluble in water
B) Is insoluble in water
C) Repels water
D) Is a lipid

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38. The function of ATP in the cell is to:

A) Store genetic information
B) Provide energy for cellular processes
C) Serve as a structural component
D) Catalyze biochemical reactions

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39. Which type of lipid is used to make hormones?

A) Phospholipids
B) Triglycerides
C) Steroids
D) Waxes

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40. Which of the following is NOT a monosaccharide?

A) Glucose
B) Ribose
C) Maltose
D) Fructose

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41. The term “amphipathic” refers to molecules that:

A) Are hydrophobic
B) Are hydrophilic
C) Have both hydrophilic and hydrophobic regions
D) Are only polar

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42. The main structural component of bacterial cell walls is:

A) Chitin
B) Peptidoglycan
C) Cellulose
D) Starch

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43. The main type of lipid in biological membranes is:

A) Triglycerides
B) Phospholipids
C) Glycolipids
D) Steroids

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44. The sugar component of RNA is:

A) Deoxyribose
B) Ribose
C) Glucose
D) Fructose

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45. Which of the following is true about unsaturated fatty acids?

A) They are solid at room temperature.
B) They contain one or more double bonds.
C) They are found in animal fats.
D) They contain no double bonds.

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46. The nitrogenous bases in DNA include:

A) Adenine, uracil, cytosine, and guanine
B) Adenine, thymine, cytosine, and guanine
C) Adenine, thymine, cytosine, and uracil
D) Adenine, guanine, cytosine, and uracil

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47. Which of the following is a characteristic of all amino acids?

A) They contain a carboxyl group and an amino group.
B) They are all nonpolar.
C) They are all essential.
D) They all have the same side chain.

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48. Which of the following best describes a peptide bond?

A) A bond between two nucleotides
B) A bond between two monosaccharides
C) A bond between amino acids
D) A bond between glycerol and fatty acids

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49. The functional group -COOH is characteristic of:

A) Amines
B) Alcohols
C) Carboxylic acids
D) Ketones

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50. Which type of lipid serves as a protective coating for plants and animals?

A) Phospholipids
B) Steroids
C) Waxes
D) Triglycerides

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51. The simplest form of carbohydrates is:

A) Polysaccharides
B) Disaccharides
C) Monosaccharides
D) Oligosaccharides

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52. Glycogen is primarily stored in:

A) Muscles and liver
B) Brain and heart
C) Skin and bones
D) Kidneys and lungs

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53. The backbone of RNA is formed by:

A) Sugars and phosphates
B) Amino acids and sugars
C) Nucleotides and lipids
D) Proteins and nucleotides

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54. The secondary structure of proteins can be described as:

A) Linear sequence of amino acids
B) Alpha helices and beta sheets
C) Folding into a three-dimensional shape
D) Combination of multiple polypeptides

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55. Which of the following is a characteristic of triglycerides?

A) They are made of one glycerol and three fatty acids.
B) They are soluble in water.
C) They contain phosphates.
D) They are found in DNA.

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56. Which of the following molecules is NOT a biological macromolecule?

A) Carbohydrates
B) Proteins
C) Lipids
D) Vitamins

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57. Which of the following is an example of a conjugated molecule?

A) Glycogen
B) Hemoglobin
C) Glucose
D) Fructose

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58. The function of enzymes in biochemical reactions is to:

A) Slow down reactions
B) Increase the activation energy
C) Lower the activation energy
D) Change the products of the reaction

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59. The primary role of water in biological systems is:

A) Providing energy
B) Acting as a solvent
C) Serving as a structural component
D) Catalyzing reactions

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60. The most common type of lipid found in the body is:

A) Triglycerides
B) Phospholipids
C) Steroids
D) Waxes

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61. The storage of energy in the form of starch occurs in:

A) Animals
B) Plants
C) Bacteria
D) Fungi

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62. Which of the following best describes the function of hemoglobin?

A) Energy storage
B) Oxygen transport
C) Catalyzing reactions
D) Structural support

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63. Which of the following is a disaccharide?

A) Glucose
B) Fructose
C) Sucrose
D) Cellulose

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64. Which component of a nucleotide varies between different nucleotides?

A) Sugar
B) Phosphate group
C) Nitrogenous base
D) All of the above

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65. Which type of bond is formed between the glycerol and fatty acids in triglycerides?

A) Hydrogen bond
B) Ionic bond
C) Ester bond
D) Peptide bond

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66. The primary role of the lipoproteins in the body is to:

A) Store glucose
B) Transport lipids
C) Provide structural support
D) Generate ATP

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67. The sugar component of DNA is:

A) Ribose
B) Deoxyribose
C) Glucose
D) Fructose

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68. The term “denaturation” refers to:

A) The process of protein synthesis
B) The unfolding of a protein’s structure
C) The breaking of peptide bonds
D) The formation of disulfide bridges

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69. Which of the following is a component of the cell membrane?

A) Phospholipids
B) Glycoproteins
C) Cholesterol
D) All of the above

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70. The primary component of the plant cell wall is:

A) Chitin
B) Cellulose
C) Peptidoglycan
D) Starch

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71. The term “oligosaccharide” refers to carbohydrates that are composed of:

A) One to two sugar units
B) Two to ten sugar units
C) More than ten sugar units
D) None of the above

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72. Which of the following biomolecules can function as both structural and functional components of cells?

A) Carbohydrates
B) Proteins
C) Lipids
D) Nucleic acids

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73. Which functional group is associated with amino acids?

A) Hydroxyl group
B) Amino group
C) Carboxyl group
D) Both B and C

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74. The main storage carbohydrate in animals is:

A) Starch
B) Glycogen
C) Cellulose
D) Fructose

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75. The molecule that serves as a genetic blueprint for the organism is:

A) RNA
B) DNA
C) Protein
D) Carbohydrate

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76. Which of the following best describes a lipid’s solubility in water?

A) Highly soluble
B) Partially soluble
C) Insoluble
D) Fully soluble

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77. The primary purpose of glycolipids in cell membranes is to:

A) Provide energy
B) Assist in cell recognition
C) Act as enzymes
D) Store genetic information

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78. Which of the following statements is TRUE regarding enzymes?

A) They are consumed in reactions.
B) They lower the activation energy of reactions.
C) They change the equilibrium of the reaction.
D) They only work at extreme temperatures.

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79. The structure of a triglyceride consists of:

A) Two fatty acids and one glycerol
B) Three fatty acids and one glycerol
C) One fatty acid and two glycerols
D) Four fatty acids and one glycerol

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80. The carbohydrate component of nucleotides in RNA is:

A) Ribose
B) Deoxyribose
C) Glucose
D) Fructose

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81. Which type of protein function involves the immune response?

A) Enzymatic
B) Structural
C) Transport
D) Defensive

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82. Which of the following is NOT a lipid?

A) Cholesterol
B) Triglyceride
C) Phospholipid
D) Glycogen

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83. The sugar that is commonly used in cellular respiration is:

A) Fructose
B) Sucrose
C) Glucose
D) Lactose

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84. Which of the following structures is NOT part of an amino acid?

A) Central carbon
B) Amino group
C) Carboxyl group
D) Phosphate group

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85. The lipid bilayer is primarily composed of:

A) Proteins
B) Carbohydrates
C) Phospholipids
D) Nucleic acids

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86. Which of the following is a characteristic of enzymes?

A) They can function at any temperature.
B) They are specific to substrates.
C) They can only catalyze one reaction.
D) They do not require a pH range to function.

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87. The energy stored in triglycerides is used primarily for:

A) Short-term energy needs
B) Long-term energy needs
C) Protein synthesis
D) Nucleic acid formation

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88. The hydrophobic nature of lipids is due to:

A) Their high carbon content
B) Their low molecular weight
C) Their polar functional groups
D) Their nonpolar fatty acid chains

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89. The process of converting glucose into glycogen for storage is called:

A) Glycolysis
B) Glycogenesis
C) Glycogenolysis
D) Gluconeogenesis

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90. Which of the following is true about saturated fats?

A) They contain double bonds.
B) They are usually liquid at room temperature.
C) They can increase cholesterol levels.
D) They are found primarily in plants.

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91. The component of lipids that provides energy is:

A) Glycerol
B) Fatty acids
C) Phosphate
D) Cholesterol

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92. The main function of carbohydrates in animals is:

A) Energy storage
B) Insulation
C) Cellular structure
D) Genetic information storage

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93. The primary role of cholesterol in the cell membrane is to:

A) Provide rigidity and fluidity
B) Serve as a structural carbohydrate
C) Store energy
D) Transport proteins

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94. Which of the following is a characteristic of an enzyme’s active site?

A) It is a rigid structure.
B) It can accommodate many different substrates.
C) It is where the substrate binds.
D) It is not involved in the chemical reaction.

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95. Which of the following is NOT a role of proteins?

A) Energy storage
B) Enzymatic activity
C) Structural support
D) Genetic information storage

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96. The basic building blocks of proteins are called:

A) Nucleotides
B) Amino acids
C) Fatty acids
D) Monosaccharides

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97. Which molecule is produced as a result of the breakdown of glucose during cellular respiration?

A) Lipids
B) Proteins
C) ATP
D) Nucleic acids

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98. Which of the following best describes the structure of a phospholipid?

A) Glycerol + two fatty acids + phosphate group
B) Glycerol + three fatty acids
C) One fatty acid + one amino acid
D) One nucleotide + one sugar

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99. The main function of RNA is to:

A) Store genetic information
B) Transfer genetic information to proteins
C) Provide structural support
D) Store energy

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100. The energy released during cellular respiration is primarily stored in:

A) Glucose
B) DNA
C) ATP
D) Lipids

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