Biochemistry Quiz On Carbohydrates
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 Read morevarious metabolic functions.
Carbohydrates Questions and Answers
- 1.
Which of these elements is NOT a constituent of Carbohydrates?
- A.
Carbon
- B.
Hydrogen
- C.
Oxygen
- D.
Nitrogen
Correct Answer
D. NitrogenExplanation
Carbohydrates are composed of three primary elements: carbon (C), hydrogen (H), and oxygen (O). These elements follow the general formula (CH₂O)ₙ, which reflects their composition of carbon and water (hydrogen and oxygen in a 2:1 ratio). Nitrogen (N) is not a structural component of carbohydrates but is essential in proteins and nucleic acids. While some complex biomolecules contain both nitrogen and carbohydrate units, pure carbohydrates, such as glucose and starch, do not include nitrogen in their molecular structure. Thus, nitrogen is not a fundamental component of carbohydrates.Rate this question:
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- 2.
What is another word that might describe complex carbohydrates?
- A.
Monosaccharide
- B.
Disaccharide
- C.
Polysaccharide
- D.
None of the above
Correct Answer
C. PolysaccharideExplanation
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.Rate this question:
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- 3.
Which statement about carbon is incorrect regarding its role as the basic building block of life?
- A.
Carbon readily makes four stable bonds in single, double, or triple configurations.
- B.
Carbon is a very dense & heavy element, giving living things stability.
- C.
Carbon is the least electronegative non-metal
- D.
Carbon has a high affinity for Oxygen & Hydrogen, which make bonds easily with C.
Correct Answer
B. 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.Rate this question:
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- 4.
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?
- A.
Oxygen has six outer valence electrons, and makes up to 2 bonds.
- B.
Oxygen is highly electronegative; it is an 'electron hog', sharing them unevenly.
- C.
The uneven sharing of electrons results in Oxygen forming polar covalent bonds.
- D.
The presence of oxygen in Carbohydrates makes them highly insoluble in water.
Correct Answer
D. 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.Rate this question:
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- 5.
Which of these functional groups are you not going to find in a carbohydrate?
- A.
Carbonyl -C=O
- B.
Sulfhydryl -SH
- C.
Hydroxyl -OH
- D.
Ether -C-O-C-
Correct Answer
B. Sulfhydryl -SHExplanation
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.Rate this question:
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- 6.
Which of the following carbohydrates does this structural diagram represent?
- A.
Glucose
- B.
Fructose
- C.
Maltose
- D.
Sucrose
Correct Answer
A. GlucoseExplanation
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.Rate this question:
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- 7.
Which of the following carbohydrates does this structural diagram represent?
- A.
Glucose
- B.
Fructose
- C.
Maltose
- D.
Sucrose
Correct Answer
C. MaltoseExplanation
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.Rate this question:
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- 8.
Which of the following carbohydrates does this structural diagram represent?
- A.
Glucose
- B.
Fructose
- C.
Maltose
- D.
Sucrose
Correct Answer
B. FructoseExplanation
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.Rate this question:
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- 9.
Which of the following carbohydrates does this structural diagram represent?
- A.
Glucose
- B.
Fructose
- C.
Maltose
- D.
Sucrose
Correct Answer
D. SucroseExplanation
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.Rate this question:
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- 10.
The diagrams below show a complex carbohydrate in some of your body cells. Which complex carbohydrate is it?
- A.
Cellulose
- B.
Chitin
- C.
Glucagon
- D.
Glycogen
Correct Answer
D. GlycogenExplanation
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.Rate this question:
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- 11.
Which category of carbohydrates do the sugars glucose, fructose, and galactose belong to?
- A.
Monosaccharides
- B.
Disaccharides
- C.
Polysaccharides
Correct Answer
A. MonosaccharidesExplanation
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.Rate this question:
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- 12.
Which category of carbohydrates do the sugars lactose, maltose, and sucrose belong to?
- A.
Monosaccharides
- B.
Disaccharides
- C.
Polysaccharides
- D.
None of the above
Correct Answer
B. DisaccharidesExplanation
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.Rate this question:
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- 13.
The diagram below shows the most common reaction that helps more complex carbohydrates form. What is the name of the reaction?
- A.
Hydrolysis
- B.
Dehydration synthesis
- C.
Dehydoxylation
- D.
Hydration
Correct Answer
B. Dehydration synthesisExplanation
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.Rate this question:
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- 14.
Which of the following is NOT a role of Carbohydrates in a cell or organism?
- A.
Provide energy, either immediate or long-term (storage)
- B.
Provide structure, support, and strength in certain organisms.
- C.
Formation of muscle tissues & bone in vertebrate bodies
- D.
Osmoregulation - moderating fluid balance in living organisms
Correct Answer
C. Formation of muscle tissues & bone in vertebrate bodiesExplanation
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.Rate this question:
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- 15.
Which of the following is not a monosaccharide?
- A.
Glucose
- B.
Fructose
- C.
Galactose
- D.
Sucrose
Correct Answer
D. SucroseExplanation
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.Rate this question:
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- 16.
What is the most common monosaccharide found in the human body?
- A.
Fructose
- B.
Galactos
- C.
Ribose
- D.
Glucose
Correct Answer
D. GlucoseExplanation
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.Rate this question:
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- 17.
What polysaccharide is used by plants to store energy?
- A.
Cellulose
- B.
Glycogen
- C.
Starch
- D.
Chitin
Correct Answer
C. StarchExplanation
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.Rate this question:
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- 18.
What enzyme is responsible for breaking down starch into simpler sugars?
- A.
Lactase
- B.
Amylase
- C.
Maltase
- D.
Sucrase
Correct Answer
B. AmylaseExplanation
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.Rate this question:
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- 19.
What carbohydrate is the main structural component of plant cell walls?
- A.
Starch
- B.
Glycogen
- C.
Cellulose
- D.
Chitin
Correct Answer
C. CelluloseExplanation
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.Rate this question:
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- 20.
What carbohydrate is stored in the liver and muscles for energy?
- A.
Starch
- B.
Cellulose
- C.
Sucrose
- D.
Glycogen
Correct Answer
D. GlycogenExplanation
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.Rate this question:
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- 21.
What is the main sugar found in milk?
- A.
Sucrose
- B.
Glucose
- C.
Fructose
- D.
Lactose
Correct Answer
D. LactoseExplanation
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.Rate this question:
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- 22.
What type of bond links monosaccharides together in polysaccharides?
- A.
Peptide bond
- B.
Hydrogen bond
- C.
Glycosidic bond
- D.
Ionic bond
Correct Answer
C. Glycosidic bondExplanation
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.Rate this question:
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- 23.
What type of carbohydrate serves as the primary energy source for the brain?
- A.
Starch
- B.
Glucose
- C.
Sucrose
- D.
Cellulose
Correct Answer
B. GlucoseExplanation
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.Rate this question:
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- 24.
Which carbohydrate is commonly used as a sweetener in processed foods?
- A.
Fructose
- B.
Lactose
- C.
Maltose
- D.
Ribose
Correct Answer
A. FructoseExplanation
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.Rate this question:
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- 25.
What structural carbohydrate makes up the exoskeleton of insects and crustaceans?
- A.
Chitin
- B.
Cellulose
- C.
Glycogen
- D.
Pectin
Correct Answer
A. ChitinExplanation
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.Rate this question:
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