101. Which feature is generally associated with polysaccharides rather than monosaccharides?
ⓐ. High molar mass due to many linked sugar units
ⓑ. Single sugar unit with no glycosidic linkage
ⓒ. Mandatory ketone group as the only functional group
ⓓ. Complete absence of carbon and oxygen atoms
Correct Answer: High molar mass due to many linked sugar units
Explanation: Polysaccharides are large carbohydrates formed from many monosaccharide units. Because of this repeated linking, they have high molar masses. Their structures contain glycosidic linkages between sugar units. Monosaccharides are single units and do not have this polymeric character.
102. Which description best fits polysaccharides in general?
ⓐ. They are always sweet and highly volatile.
ⓑ. They are high-molar-mass carbohydrates.
ⓒ. They are single sugar units only.
ⓓ. They are nitrogen bases in DNA.
Correct Answer: They are high-molar-mass carbohydrates.
Explanation: Polysaccharides are carbohydrates made by linking a large number of monosaccharide units. Their high molar mass gives them properties different from simple sugars. They are generally not sweet and are often less soluble than monosaccharides. DNA bases and single sugar units belong to different categories of biomolecule chemistry.
103. Which role is commonly associated with polysaccharides?
ⓐ. Storage or structural support
ⓑ. Direct coding of genetic bases
ⓒ. Formation of peptide hormones only
ⓓ. Transport of metallic electrons
Correct Answer: Storage or structural support
Explanation: Polysaccharides commonly serve storage or structural roles in living systems. Starch and glycogen are storage polysaccharides, while cellulose has a structural role in plants. Their functions depend on the way glucose units are linked and arranged. Genetic coding is mainly associated with nucleic acids, not polysaccharides.
104. Which property generally separates polysaccharides from many monosaccharides?
ⓐ. Polysaccharides are usually sweeter and more volatile.
ⓑ. Polysaccharides are always gases at room temperature.
ⓒ. Polysaccharides are less sweet and less soluble.
ⓓ. Polysaccharides contain no covalent bonds.
Correct Answer: Polysaccharides are less sweet and less soluble.
Explanation: Many monosaccharides are sweet and water-soluble because they are small molecules with several hydroxyl groups. Polysaccharides are much larger and their chains interact differently with water. They are generally non-sweet and less soluble than simple sugars. This broad physical contrast helps distinguish large carbohydrate polymers from simple carbohydrate units.
105. A carbohydrate gives a very large number of monosaccharide units after complete hydrolysis. Which class is indicated?
ⓐ. Disaccharide
ⓑ. Monosaccharide
ⓒ. Polysaccharide
ⓓ. Nucleoside
Correct Answer: Polysaccharide
Explanation: The phrase “very large number of monosaccharide units” points to a polysaccharide. Polysaccharides are polymeric carbohydrates made from many repeating sugar units. Complete hydrolysis breaks their glycosidic linkages and releases many monosaccharides. A disaccharide would give only two monosaccharide units.
106. Which pair correctly matches a polysaccharide with a broad biological function?
ⓐ. Insulin — plant cell wall fibre
ⓑ. DNA — animal starch storage
ⓒ. Vitamin \(C\) — glucose polymer
ⓓ. Starch — plant energy storage
Correct Answer: Starch — plant energy storage
Explanation: Starch is a storage polysaccharide in plants. It is made of glucose units and serves as a reserve carbohydrate. DNA is a nucleic acid, vitamin \(C\) is a vitamin, and insulin is a peptide hormone. These do not fit the broad classification of starch as a plant storage polysaccharide.
107. Which statement best compares disaccharides and polysaccharides?
ⓐ. Disaccharides contain two sugar units, while polysaccharides contain many.
ⓑ. Disaccharides contain many units, while polysaccharides contain two.
ⓒ. Disaccharides are amino-acid chains, while polysaccharides are nucleotides.
ⓓ. Disaccharides have no oxygen, while polysaccharides contain no carbon.
Correct Answer: Disaccharides contain two sugar units, while polysaccharides contain many.
Explanation: Disaccharides are carbohydrates formed from two monosaccharide units. Polysaccharides are carbohydrates formed from a large number of monosaccharide units. Both contain sugar units joined by glycosidic linkages, but the number of units differs greatly. This difference strongly affects their properties and biological roles.
108. Which assertion-reason pair is correctly evaluated?
Assertion: Polysaccharides usually do not taste sweet like many simple sugars.
Reason: Polysaccharides are large carbohydrate molecules made from many monosaccharide units.
ⓐ. Assertion is true, but Reason is false.
ⓑ. Both are true, but Reason is unrelated to Assertion.
ⓒ. Assertion is false, but Reason is true.
ⓓ. Both are true, and Reason explains Assertion.
Correct Answer: Both are true, and Reason explains Assertion.
Explanation: Many simple sugars are sweet because they are small molecules that interact readily with taste receptors. Polysaccharides are much larger molecules and generally do not show the same sweet taste. Their polymeric nature also affects solubility and physical behaviour. Thus the large size and many linked monosaccharide units help explain the stated property.
109. Which molecular formula is associated with glucose?
ⓐ. \(C_5H_{10}O_5\)
ⓑ. \(C_6H_{12}O_6\)
ⓒ. \(C_{12}H_{22}O_{11}\)
ⓓ. \(C_6H_{14}O_6\)
Correct Answer: \(C_6H_{12}O_6\)
Explanation: Glucose is a hexose sugar, so it contains six carbon atoms. Its molecular formula is \(C_6H_{12}O_6\), which is also shared by some other hexoses such as fructose. The formula gives the number of atoms but does not alone show whether the sugar is an aldose or a ketose. Structural information is needed to classify glucose more specifically as an aldohexose.
110. Glucose is described as an aldohexose. Which statement best explains this name?
ⓐ. It contains six carbon atoms and an aldehyde group.
ⓑ. It contains five carbon atoms and a ketone group.
ⓒ. It contains two sugar units joined by a glycosidic bond.
ⓓ. It contains a phosphate group and a nitrogenous base.
Correct Answer: It contains six carbon atoms and an aldehyde group.
Explanation: The word “aldohexose” has two parts. “Aldo” indicates an aldehyde group in the open-chain form of the sugar. “Hexose” indicates a six-carbon monosaccharide. Glucose fits both conditions, so it is classified as an aldohexose.
111. Which name is commonly associated with glucose?
ⓐ. Cane sugar
ⓑ. Fruit sugar
ⓒ. Dextrose
ⓓ. Milk sugar
Correct Answer: Dextrose
Explanation: Glucose is also known as dextrose. Cane sugar refers to sucrose, fruit sugar is commonly associated with fructose, and milk sugar refers to lactose. Such common names can be useful, but chemical classification gives a deeper understanding. Glucose is chemically a six-carbon aldose sugar.
112. Which statement best identifies glucose and fructose as molecular formula isomers?
ⓐ. Both have the formula \(C_6H_{12}O_6\), but glucose is an aldose.
ⓑ. Both have the formula \(C_5H_{10}O_5\), but glucose is a ketose.
ⓒ. Both are disaccharides, but glucose contains an aldehyde group.
ⓓ. Both are polysaccharides, but fructose contains a ketone group.
Correct Answer: Both have the formula \(C_6H_{12}O_6\), but glucose is an aldose.
Explanation: Glucose and fructose are molecular formula isomers because both have the formula \(C_6H_{12}O_6\). Their difference lies in the arrangement of atoms and the type of carbonyl group. Glucose is an aldose, while fructose is a ketose. This shows why molecular formula alone cannot fully describe sugar structure.
113. What is the molar mass of glucose, \(C_6H_{12}O_6\), using \(C=12\), \(H=1\), and \(O=16\)?
ⓐ. \(150\,\text{g mol}^{-1}\)
ⓑ. \(168\,\text{g mol}^{-1}\)
ⓒ. \(180\,\text{g mol}^{-1}\)
ⓓ. \(192\,\text{g mol}^{-1}\)
Correct Answer: \(180\,\text{g mol}^{-1}\)
Explanation: \( \textbf{Given:} \)
Molecular formula of glucose \(= C_6H_{12}O_6\)
Atomic masses: \(C=12\), \(H=1\), \(O=16\)
\( \textbf{Required:} \)
Molar mass of glucose
\( \textbf{Useful relation:} \)
Molar mass \(=\) sum of atomic masses of all atoms in the formula
\( \textbf{Carbon contribution:} \)
\(6 \times 12 = 72\,\text{g mol}^{-1}\)
\( \textbf{Hydrogen contribution:} \)
\(12 \times 1 = 12\,\text{g mol}^{-1}\)
\( \textbf{Oxygen contribution:} \)
\(6 \times 16 = 96\,\text{g mol}^{-1}\)
\( \textbf{Final calculation:} \)
\(72+12+96=180\,\text{g mol}^{-1}\)
\( \textbf{Unit check:} \)
Molar mass is expressed in \(\text{g mol}^{-1}\)
\( \textbf{Final Answer:} \)
\(180\,\text{g mol}^{-1}\)
114. Which option best identifies glucose by both formula and carbohydrate type?
ⓐ. \(C_{12}H_{22}O_{11}\), disaccharide
ⓑ. \(C_6H_{12}O_6\), monosaccharide
ⓒ. \(C_5H_{10}O_5\), polysaccharide
ⓓ. \(C_6H_{14}O_6\), sugar alcohol
Correct Answer: \(C_6H_{12}O_6\), monosaccharide
Explanation: Glucose has the molecular formula \(C_6H_{12}O_6\). It is a monosaccharide, meaning it is a single sugar unit and cannot be hydrolysed into simpler carbohydrates. \(C_{12}H_{22}O_{11}\) is commonly associated with disaccharides such as sucrose, maltose, and lactose. \(C_6H_{14}O_6\) corresponds to sorbitol, the reduction product of glucose.
115. How many oxygen atoms are present in one molecule of glucose, \(C_6H_{12}O_6\)?
ⓐ. \(5\)
ⓑ. \(6\)
ⓒ. \(10\)
ⓓ. \(12\)
Correct Answer: \(6\)
Explanation: \( \textbf{Given:} \)
Formula of glucose \(= C_6H_{12}O_6\)
\( \textbf{Required:} \)
Number of oxygen atoms in one molecule
\( \textbf{Reading the formula:} \)
The subscript after \(O\) shows the number of oxygen atoms.
\( \textbf{Apply to glucose:} \)
In \(C_6H_{12}O_6\), the subscript of \(O\) is \(6\).
\( \textbf{Final Answer:} \)
One molecule of glucose contains \(6\) oxygen atoms.
116. Which statement correctly explains why glucose is a central carbohydrate in living systems?
ⓐ. It is a common biological energy source.
ⓑ. It is the main nitrogenous base of DNA.
ⓒ. It is a peptide hormone secreted by glands.
ⓓ. It is a vitamin required only in trace amounts.
Correct Answer: It is a common biological energy source.
Explanation: Glucose is one of the most important simple sugars in living systems. It is commonly used as an immediate source of energy in cellular processes. Larger storage carbohydrates can also be related to glucose units. It should not be confused with nitrogenous bases, peptide hormones, or vitamins.
117. Which glucose classification pair is correctly matched?
ⓐ. Glucose — ketohexose
ⓑ. Glucose — aldohexose
ⓒ. Glucose — disaccharide
ⓓ. Glucose — nucleotide
Correct Answer: Glucose — aldohexose
Explanation: Glucose is a six-carbon sugar, so it is a hexose. Its open-chain form contains an aldehyde group, so it is an aldose. Combining these two features gives aldohexose. It is not a disaccharide or nucleotide because it is a single carbohydrate unit, not a linked sugar pair or nucleic-acid monomer.
118. A sugar has formula \(C_6H_{12}O_6\) and gives evidence for an aldehyde group in its open-chain form. Which identification is most suitable?
ⓐ. Ribose
ⓑ. Sucrose
ⓒ. Glucose
ⓓ. Cellulose
Correct Answer: Glucose
Explanation: A six-carbon sugar with aldehydic character fits glucose in standard carbohydrate classification. Ribose is a pentose with formula \(C_5H_{10}O_5\). Sucrose is a disaccharide with formula \(C_{12}H_{22}O_{11}\), and cellulose is a polysaccharide. The aldehyde-bearing hexose identity points toward glucose.
119. Which statement is least appropriate for glucose?
ⓐ. It is a monosaccharide.
ⓑ. It has formula \(C_6H_{12}O_6\).
ⓒ. It is commonly called dextrose.
ⓓ. It is a two-unit sugar.
Correct Answer: It is a two-unit sugar.
Explanation: Glucose is a monosaccharide, so it is a single sugar unit. It has the formula \(C_6H_{12}O_6\) and is commonly called dextrose. A compound formed from two sugar units is a disaccharide, not glucose itself. This distinction is important when comparing glucose with sucrose, maltose, or lactose.
120. What is the total number of atoms in one molecule of glucose, \(C_6H_{12}O_6\)?
ⓐ. \(18\)
ⓑ. \(20\)
ⓒ. \(22\)
ⓓ. \(24\)
Correct Answer: \(24\)
Explanation: \( \textbf{Given:} \)
Molecular formula of glucose \(= C_6H_{12}O_6\)
\( \textbf{Required:} \)
Total number of atoms in one molecule
\( \textbf{Count carbon atoms:} \)
\(C_6\) gives \(6\) carbon atoms.
\( \textbf{Count hydrogen atoms:} \)
\(H_{12}\) gives \(12\) hydrogen atoms.
\( \textbf{Count oxygen atoms:} \)
\(O_6\) gives \(6\) oxygen atoms.
\( \textbf{Add all atoms:} \)
\(6+12+6=24\)
\( \textbf{Final Answer:} \)
One molecule of glucose contains \(24\) atoms in total.
