Biochemistry Quiz On Carbohydrates

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Stephen Reinbold has a PhD in Biological Sciences and a strong passion for teaching. He taught various subjects including General Biology, Environmental Science, Zoology, Genetics, and Anatomy & Physiology at Metropolitan Community College in Kansas City, Missouri, for nearly thirty years. He focused on scientific methodology and student research projects. Now retired, he works part-time as an editor and engages in online activities.
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  • 1/25 Questions

    Which of these elements is NOT a constituent of Carbohydrates?

    • Carbon
    • Hydrogen
    • Oxygen
    • Nitrogen
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About This Quiz

Carbohydrates are essential biomolecules that provide energy and play crucial roles in biological processes. This Carbohydrates Quiz is designed to test your knowledge of their structure, function, classification, and biochemical significance. If you're a student studying biochemistry or want to refresh your understanding, this quiz will help you assess your grasp of monosaccharides, disaccharides, polysaccharides, and their metabolic pathways.

In this biochemistry carbohydrates quiz, you will answer carefully designed questions covering carbohydrate digestion, enzymatic breakdown, and the role of carbohydrates in cellular respiration. Understanding carbohydrates is fundamental in biochemistry, as they serve as a primary energy source and contribute to various metabolic functions.

Biochemistry Quiz On Carbohydrates - Quiz

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  • 2. 

    What is the main sugar found in milk?

    • Sucrose

    • Glucose

    • Fructose

    • Lactose

    Correct Answer
    A. Lactose
    Explanation
    Lactose is the main sugar found in milk. It is a disaccharide composed of glucose and galactose. Lactose is digested in the small intestine by the enzyme lactase, which breaks it down into its monosaccharide components for absorption. Lactose is an important source of energy for infants and young mammals. Some people have lactose intolerance, which means they lack sufficient lactase to digest lactose properly, leading to digestive discomfort.

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  • 3. 

    What carbohydrate is stored in the liver and muscles for energy?

    • Starch

    • Cellulose

    • Sucrose

    • Glycogen

    Correct Answer
    A. Glycogen
    Explanation
    Glycogen is the carbohydrate stored in the liver and muscles for energy. It is a polysaccharide composed of glucose units linked together in a highly branched structure. When the body needs energy, glycogen is broken down into glucose, which is then used in cellular respiration to produce ATP. Glycogen storage allows for quick release of glucose during physical activity or between meals, maintaining blood sugar levels and energy supply.

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  • 4. 

    What is the most common monosaccharide found in the human body?

    • Fructose

    • Galactos

    • Ribose

    • Glucose

    Correct Answer
    A. Glucose
    Explanation
    Glucose is the most common monosaccharide found in the human body. It is a primary source of energy for cells and is essential for metabolic processes. Glucose is transported through the bloodstream to provide energy to all body tissues. It is also a building block for more complex carbohydrates like starch and glycogen. Monitoring glucose levels is crucial in managing conditions like diabetes, highlighting its importance in biochemistry and health.

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  • 5. 

    What is another word that might describe complex carbohydrates?

    • Monosaccharide

    • Disaccharide

    • Polysaccharide

    • None of the above

    Correct Answer
    A. Polysaccharide
    Explanation
    Complex carbohydrates are often referred to as polysaccharides. These are large molecules composed of many sugar units (monosaccharides) bonded together. Unlike simple carbohydrates (monosaccharides and disaccharides), which are quickly digested and absorbed into the bloodstream, complex carbohydrates take longer to break down due to their complex structure. They provide a sustained release of energy and are found in foods such as whole grains, vegetables, and legumes. Polysaccharides play a crucial role in providing energy storage and structural support in plants and animals, contributing to overall dietary fiber and digestive health.

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  • 6. 

    Which category of carbohydrates do the sugars lactose, maltose, and sucrose belong to?

    • Monosaccharides

    • Disaccharides

    • Polysaccharides

    • None of the above

    Correct Answer
    A. Disaccharides
    Explanation
    Lactose, maltose, and sucrose are all examples of disaccharides, which are carbohydrates composed of two monosaccharide units bonded together. Specifically:Lactose is composed of glucose and galactose.Maltose is composed of two glucose molecules.Sucrose is composed of glucose and fructose.Disaccharides are formed through a condensation reaction (dehydration synthesis) where a molecule of water is removed to bond two monosaccharides together. They are commonly found in foods such as milk (lactose), grains (maltose), and table sugar (sucrose). Disaccharides are broken down into their monosaccharide components during digestion to be absorbed and used for energy by the body.

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  • 7. 

    Which of these functional groups are you not going to find in a carbohydrate?

    • Carbonyl -C=O

    • Sulfhydryl -SH

    • Hydroxyl -OH

    • Ether -C-O-C-

    Correct Answer
    A. Sulfhydryl -SH
    Explanation
    Carbohydrates primarily contain carbonyl (-C=O) and hydroxyl (-OH) groups, which contribute to their solubility and reactivity. The ether (-C-O-C-) group is also found in some carbohydrate structures, especially in polysaccharides. However, the sulfhydryl (-SH) group is characteristic of proteins rather than carbohydrates. It plays a key role in forming disulfide bonds in proteins, particularly in stabilizing protein structures. Since sulfur is not a standard component of carbohydrates, the sulfhydryl group is not commonly found in their molecular structure.

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  • 8. 

    What enzyme is responsible for breaking down starch into simpler sugars?

    • Lactase

    • Amylase

    • Maltase

    • Sucrase

    Correct Answer
    A. Amylase
    Explanation
    Amylase is the enzyme responsible for breaking down starch into simpler sugars like maltose and glucose. Amylase is produced in the salivary glands and the pancreas. When we eat starchy foods, amylase in saliva begins the digestion process in the mouth, and pancreatic amylase continues the process in the small intestine. This enzyme plays a crucial role in carbohydrate digestion, ensuring that complex carbohydrates can be converted into a form that the body can use for energy.

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  • 9. 

    Which category of carbohydrates do the sugars glucose, fructose, and galactose belong to?

    • Monosaccharides

    • Disaccharides

    • Polysaccharides

    Correct Answer
    A. Monosaccharides
    Explanation
    Glucose, fructose, and galactose are all examples of monosaccharides, which are simple sugars. Monosaccharides are the most basic units of carbohydrates and cannot be broken down into smaller sugars by hydrolysis. They consist of a single sugar molecule and are easily absorbed by the body for quick energy. Glucose is a primary source of energy for cells, fructose is commonly found in fruits and honey, and galactose is typically found in dairy products. These monosaccharides serve as building blocks for more complex carbohydrates like disaccharides and polysaccharides, which consist of two or more monosaccharide units bonded together.

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  • 10. 
    Which of the following carbohydrates does this structural diagram represent? - ProProfs

    Which of the following carbohydrates does this structural diagram represent?

    • Glucose

    • Fructose

    • Maltose

    • Sucrose

    Correct Answer
    A. Sucrose
    Explanation
    The diagram represents sucrose, a disaccharide composed of one glucose molecule and one fructose molecule. Sucrose is the common table sugar found in plants, fruits, and processed foods. It is broken down by the enzyme sucrase in the digestive system, releasing glucose and fructose for metabolism. Unlike maltose (which consists of two glucose units), sucrose has a unique glycosidic bond linking its monosaccharides. This difference in structure gives sucrose distinct chemical and physiological properties.

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  • 11. 

    What type of carbohydrate serves as the primary energy source for the brain?

    • Starch

    • Glucose

    • Sucrose

    • Cellulose

    Correct Answer
    A. Glucose
    Explanation
    Glucose serves as the primary energy source for the brain because it is the most readily available monosaccharide in the bloodstream. The brain consumes about 120 grams of glucose per day, accounting for nearly 20% of the body's total energy use. Unlike other organs, the brain lacks significant energy storage and depends on a continuous glucose supply. During fasting or low carbohydrate intake, the liver converts stored glycogen into glucose. If glucose levels drop, the body shifts to ketone production, but glucose remains the brain’s preferred fuel due to its efficiency in ATP production via glycolysis and oxidative phosphorylation.

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  • 12. 

    What carbohydrate is the main structural component of plant cell walls?

    • Starch

    • Glycogen

    • Cellulose

    • Chitin

    Correct Answer
    A. Cellulose
    Explanation
    Cellulose is the main structural component of plant cell walls. It is a polysaccharide made up of long chains of glucose molecules linked together. These chains are arranged in a way that provides strength and rigidity to plant cells, helping to maintain their shape and structural integrity. Cellulose is indigestible by humans due to our lack of enzymes capable of breaking its bonds, but it serves as an important dietary fiber that aids in digestion. Unlike starch and glycogen, which are used for energy storage in plants and animals respectively, cellulose primarily functions as a structural support in plant tissues.

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  • 13. 

    What structural carbohydrate makes up the exoskeleton of insects and crustaceans?

    • Chitin

    • Cellulose

    • Glycogen

    • Pectin

    Correct Answer
    A. Chitin
    Explanation
    Chitin is a structural carbohydrate found in the exoskeleton of insects, crustaceans, and the cell walls of fungi. It is a polysaccharide composed of N-acetylglucosamine units linked by β-1,4-glycosidic bonds. Chitin provides mechanical strength and protection due to its rigid, fibrous nature. It has a high tensile strength comparable to collagen in vertebrates. When combined with proteins and calcium carbonate in crustaceans, it forms a hardened exoskeleton. Unlike cellulose, chitin is modified with nitrogen-containing groups, making it less digestible. Its applications extend to medical, agricultural, and industrial uses, including biodegradable plastics, wound dressings, and water purification materials.

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  • 14. 

    Which of the following is not a monosaccharide?

    • Glucose

    • Fructose

    • Galactose

    • Sucrose

    Correct Answer
    A. Sucrose
    Explanation
    Sucrose is not a monosaccharide because it is a disaccharide composed of two monosaccharides, glucose and fructose, joined together by a glycosidic bond. Monosaccharides, on the other hand, are single sugar molecules that cannot be broken down into smaller sugar units. Glucose, fructose, and galactose are all monosaccharides because they consist of a single sugar unit.

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  • 15. 
    Which of the following carbohydrates does this structural diagram represent? - ProProfs

    Which of the following carbohydrates does this structural diagram represent?

    • Glucose

    • Fructose

    • Maltose

    • Sucrose

    Correct Answer
    A. Glucose
    Explanation
    The structural diagram represents glucose, a simple sugar and monosaccharide. Glucose is an important carbohydrate in the body and is used as a source of energy. It is a hexose sugar, meaning it has six carbon atoms. The diagram shows the arrangement of the carbon, hydrogen, and oxygen atoms in glucose, with a ring structure formed by five carbon atoms and an oxygen atom.

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  • 16. 
    Which of the following carbohydrates does this structural diagram represent? - ProProfs

    Which of the following carbohydrates does this structural diagram represent?

    • Glucose

    • Fructose

    • Maltose

    • Sucrose

    Correct Answer
    A. Fructose
    Explanation
    The diagram represents fructose, a monosaccharide with a five-membered ring structure. Unlike glucose, which forms a six-membered ring, fructose has a different atomic arrangement but still follows the formula C₆H₁₂O₆. Fructose is found in fruits, honey, and high-fructose corn syrup. It is metabolized differently than glucose, primarily in the liver, and has a higher sweetness level. Maltose and sucrose contain more than one sugar unit, making them disaccharides, unlike fructose, which is a single sugar molecule.

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  • 17. 

    What type of bond links monosaccharides together in polysaccharides?

    • Peptide bond

    • Hydrogen bond

    • Glycosidic bond

    • Ionic bond

    Correct Answer
    A. Glycosidic bond
    Explanation
    A glycosidic bond links monosaccharides together in polysaccharides. This covalent bond forms between the hydroxyl group of one monosaccharide and the anomeric carbon of another, releasing a molecule of water. Glycosidic bonds can vary in their position and configuration, leading to different structures and properties of polysaccharides, such as starch, glycogen, and cellulose. Understanding glycosidic bonds is fundamental in biochemistry, as it explains how complex carbohydrates are built from simple sugars.

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  • 18. 

    Which carbohydrate is commonly used as a sweetener in processed foods?

    • Fructose

    • Lactose

    • Maltose

    • Ribose

    Correct Answer
    A. Fructose
    Explanation
    Fructose is commonly used as a sweetener in processed foods due to its high sweetness index and low glycemic response. It is about 1.2 to 1.8 times sweeter than sucrose (table sugar), making it an effective sweetener in lower quantities. High-fructose corn syrup (HFCS), a processed form of fructose, is widely used in beverages and snacks because it enhances flavor and shelf life. Unlike glucose, fructose is metabolized in the liver, where excessive intake can lead to fat accumulation, insulin resistance, and metabolic disorders, making its use in food products both beneficial and potentially harmful.

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  • 19. 
    The diagrams below show a complex carbohydrate in some of your body cells. Which complex carbohydrate is it? - ProProfs

    The diagrams below show a complex carbohydrate in some of your body cells. Which complex carbohydrate is it?

    • Cellulose

    • Chitin

    • Glucagon

    • Glycogen

    Correct Answer
    A. Glycogen
    Explanation
    The diagram represents glycogen, the primary storage polysaccharide in animals. Glycogen is composed of highly branched glucose units, allowing for rapid energy release when needed. It is stored mainly in the liver and skeletal muscles, where it can be quickly broken down into glucose during energy demands. Unlike cellulose and chitin, which serve structural roles, glycogen functions in energy storage. Glucagon, on the other hand, is a hormone that regulates glycogen breakdown rather than being a carbohydrate itself.

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  • 20. 

    As a component of Carbohydrates, Oxygen is very important, too. Which of the following statements is incorrect about the way Oxygen behaves as part of a molecule?

    • Oxygen has six outer valence electrons, and makes up to 2 bonds.

    • Oxygen is highly electronegative; it is an 'electron hog', sharing them unevenly.

    • The uneven sharing of electrons results in Oxygen forming polar covalent bonds.

    • The presence of oxygen in Carbohydrates makes them highly insoluble in water.

    Correct Answer
    A. The presence of oxygen in Carbohydrates makes them highly insoluble in water.
    Explanation
    Oxygen’s electronegativity makes carbohydrates polar and water-soluble, not insoluble. Oxygen forms polar covalent bonds with hydrogen, leading to partial charges that allow carbohydrates to dissolve in water. This property enables glucose and other simple sugars to travel in the bloodstream and participate in metabolic reactions. However, large polysaccharides like starch and cellulose have reduced solubility due to extensive hydrogen bonding and structural complexity. Despite this, oxygen’s presence in hydroxyl (-OH) and carbonyl (-C=O) groups contributes significantly to the hydrophilic nature of carbohydrates.

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  • 21. 

    What polysaccharide is used by plants to store energy?

    • Cellulose

    • Glycogen

    • Starch

    • Chitin

    Correct Answer
    A. Starch
    Explanation
    Starch is the polysaccharide used by plants to store energy. It is made up of glucose units linked together and is stored in plant cells as granules. When energy is needed, plants break down starch into glucose, which can then be used in cellular respiration to produce ATP, the energy currency of cells. Starch is also an important dietary carbohydrate for humans and animals, providing a significant source of energy.

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  • 22. 
    Which of the following carbohydrates does this structural diagram represent? - ProProfs

    Which of the following carbohydrates does this structural diagram represent?

    • Glucose

    • Fructose

    • Maltose

    • Sucrose

    Correct Answer
    A. Maltose
    Explanation
    The structural diagram represents maltose because it shows two glucose molecules linked together by a glycosidic bond. Maltose is a disaccharide composed of two glucose units, and the diagram accurately depicts this structure. Glucose is a monosaccharide, fructose is a different monosaccharide, and sucrose is a disaccharide composed of glucose and fructose. Therefore, the correct answer is maltose.

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  • 23. 
    The diagram below shows the most common reaction that helps more complex carbohydrates form. What is the name of the reaction? - ProProfs

    The diagram below shows the most common reaction that helps more complex carbohydrates form. What is the name of the reaction?

    • Hydrolysis

    • Dehydration synthesis

    • Dehydoxylation

    • Hydration

    Correct Answer
    A. Dehydration synthesis
    Explanation
    Dehydration synthesis is the process that joins two molecules by removing a water molecule (H₂O). This reaction links monosaccharides together to form disaccharides or polysaccharides. The removal of a hydroxyl group (OH) from one molecule and a hydrogen (H) from another creates water, leaving behind a bond between the molecules. This process is essential for building complex carbohydrates like starch and glycogen. In contrast, hydrolysis is the reverse reaction, where water is added to break down complex molecules into simpler ones. Dehydration synthesis is crucial for storing energy and forming structural components in living organisms.

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  • 24. 

    Which statement about carbon is incorrect regarding its role as the basic building block of life?

    • Carbon readily makes four stable bonds in single, double, or triple configurations.

    • Carbon is a very dense & heavy element, giving living things stability.

    • Carbon is the least electronegative non-metal

    • Carbon has a high affinity for Oxygen & Hydrogen, which make bonds easily with C.

    Correct Answer
    A. Carbon is a very dense & heavy element, giving living things stability.
    Explanation
    Carbon is a light and versatile element, not dense or heavy. Its stability in biomolecules comes from its ability to form four covalent bonds, allowing complex structures to exist. Carbon’s low electronegativity enables it to bond with many elements, including hydrogen, oxygen, nitrogen, and sulfur, which are essential for life. It forms single, double, and triple bonds, allowing for diverse molecular shapes. Carbon’s role as the foundation of life is due to its flexibility in forming stable yet reactive organic compounds, not because of its density or mass.

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  • 25. 

    Which of the following is NOT a role of Carbohydrates in a cell or organism?

    • Provide energy, either immediate or long-term (storage)

    • Provide structure, support, and strength in certain organisms.

    • Formation of muscle tissues & bone in vertebrate bodies

    • Osmoregulation - moderating fluid balance in living organisms

    Correct Answer
    A. Formation of muscle tissues & bone in vertebrate bodies
    Explanation
    Carbohydrates play various roles, including energy storage, structural support, and osmoregulation. Starch and glycogen store energy, cellulose provides structural support in plants, and chitin strengthens insect exoskeletons. Additionally, carbohydrates help regulate fluid balance by influencing osmosis in cells. However, muscle tissues and bones are primarily composed of proteins and minerals like collagen and calcium, not carbohydrates. Protein is responsible for muscle growth and repair, while bones rely on minerals for strength. This distinction highlights the diverse functions of macronutrients in living organisms.

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Stephen Reinbold |PhD (Biological Sciences) |
Biology Instructor
Stephen Reinbold has a PhD in Biological Sciences and a strong passion for teaching. He taught various subjects including General Biology, Environmental Science, Zoology, Genetics, and Anatomy & Physiology at Metropolitan Community College in Kansas City, Missouri, for nearly thirty years. He focused on scientific methodology and student research projects. Now retired, he works part-time as an editor and engages in online activities.

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  • Jun 13, 2025
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    Expert Reviewed by
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  • Feb 04, 2011
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