Free NEET Chemistry multiple-choice questions on Carbohydrates. Attempt each question and reveal the answer with a full explanation.
The reaction of glucose with HI for a long time gives which of the following products? n -Hexane Gluconic acid Sorbitol Saccharic acid Acetylation of glucose with acetic anhydride gives glucose pentaacetate. What does this result prove? Presence of 5 -OH groups Presence of a ketone group Presence of an aldehyde group Presence of a straight chain of 6 carbon atoms Sugars are classified as reducing or non-reducing. A sugar is 'reducing' if it contains which of the following in its cyclic form? Hemiacetal or Hemiketal group Acetal or Ketal group Ether linkage only Ester linkage When D-Glucose is in equilibrium in aqueous solution, the percentage of the open-chain form is approximately: Less than 0.1 % 50 % 36 % 64 % Amylose, a component of starch, is a linear polymer of -D-glucose. The number of glucose units in amylose typically ranges from: 200 to 1000 10 to 50 2000 to 5000 Over 10,000 Raffinose is a trisaccharide found in many plants. Upon complete hydrolysis, it yields: Glucose, Fructose, and Galactose Two units of Glucose and one of Fructose Three units of Glucose Glucose, Galactose, and Maltose The Lobry de Bruyn-van Ekenstein transformation involves the interconversion of glucose, fructose, and mannose in the presence of dilute alkali. This occurs through the formation of which intermediate? Enediol Enediamine Hemiacetal Ozone In the Kiliani-Fischer synthesis, an aldopentose like D-arabinose is converted into a mixture of two aldohexoses. These two aldohexoses are related as: Epimers at C-2 Enantiomers Anomers Constitutional isomers The ring structure of D-Fructose is predominantly a furanose. In the -anomer of D-fructofuranose, the hydroxyl group at the anomeric carbon ( C-2 ) is oriented: To the right in the Fischer projection (down in Haworth) To the left in the Fischer projection (up in Haworth) Outside the ring entirely Opposite to the CH 2OH group at C-5 Which functional group in a glucose molecule is involved in the formation of an osazone with phenylhydrazine? Both Aldehyde and adjacent Secondary alcohol group Only the Aldehyde group Only the Primary alcohol group The Aldehyde and all Secondary alcohol groups Which of the following is NOT a property of glucose? It reacts with NaHSO 3 to form an addition product It reacts with HCN to form cyanohydrin It is an aldohexose It shows mutarotation The specific test used to distinguish between aldoses and ketoses is: Seliwanoff's test Fehling's test Tollen's test Iodine test Which of the following is the correct structural description of D-Fructose? It is a ketohexose It is an aldohexose It is a ketopentose It is an aldopentose What is the product formed when D-Glucose reacts with an excess of methanol in the presence of dry HCl gas? Methyl -D-glucoside and Methyl -D-glucoside α -D-glucopyranose Gluconic acid Sorbitol The reaction of Glucose with NH 2OH (hydroxylamine) yields an oxime. If the oxime is treated with acetic anhydride and then heated, it undergoes dehydration and loss of acetic acid to form a nitrile. This sequence is used in: Wohl degradation Kiliani-Fischer synthesis Ruff degradation Lobry de Bruyn transformation When D-Fructose is treated with HCN , followed by hydrolysis and subsequent reduction with an excess of HI and red phosphorus, the major organic product formed is: 2-methylhexanoic acid n-heptanoic acid n-hexane Hexanoic acid The specific rotation of a solution of sucrose is +66.5 . After complete hydrolysis (inversion), the resulting mixture of glucose ( [ ] D = +52.7 ) and fructose ( [ ] D = -92.4 ) has a net specific rotation of approximately: -19.8 +39.7 -39.7 +19.8 Gluconic acid, obtained by the mild oxidation of glucose, can easily form a cyclic lactone. The most stable lactone formed is usually a: γ -lactone or δ -lactone α -lactone β -lactone ε -lactone How many moles of Periodic acid ( HIO 4 ) are consumed during the complete oxidation of one mole of an open-chain D-Glucose molecule? 5 4 6 3 The Ruff degradation is used to decrease the carbon chain length of an aldose. What are the reagents used in the first step (oxidation) and the second step (decarboxylation) of this process? Bromine water and H 2O 2 in the presence of Fe 3+ salts Nitric acid and Sodium amalgam Tollen's reagent and LiAlH 4 Phenylhydrazine and Zinc/Acetic acid The preference of the substituents at the anomeric carbon to stay in the axial position rather than the equatorial position in certain pyranose rings (despite steric hindrance) is known as the: Anomeric effect Mutarotation effect Inductive effect Electromeric effect Which of the following is a non-reducing sugar? Sucrose Maltose Lactose Glucose -D-(+)-glucose and -D-(+)-glucose are examples of: Anomers Epimers Enantiomers Geometrical isomers In the reaction of glucose with HI , n-hexane is formed. What does this indicate? All six carbon atoms are linked in a straight chain Glucose has a cyclic structure Glucose has five -OH groups Glucose has a carbonyl group Which of the following is an example of an aldotetrose? Erythrose Ribose Glyceraldehyde Fructose The pyranose structure of glucose is a six-membered ring containing: 5 Carbon atoms and 1 Oxygen atom 6 Carbon atoms 4 Carbon atoms and 2 Oxygen atoms 5 Carbon atoms and 1 Nitrogen atom Which of the following tests is used as a general test for all carbohydrates? Molisch's Test Biuret Test Xanthoproteic Test Ninhydrin Test Which component of starch is water-soluble and makes up about 15-20 % of the total starch? Amylose Amylopectin Cellulose Glycogen Which of the following carbohydrates is the major component of the exoskeleton of arthropods and the cell walls of fungi? Chitin Cellulose Glycogen Starch Glycogen, a naturally occurring polymer stored in animals, is also known as: Animal starch Cellulose Amylopectin Inulin The enzyme used to convert sucrose into glucose and fructose during industrial fermentation is: Invertase Zymase Maltase Diastase Benedict's reagent, used to test for reducing sugars, contains which of the following metal ions? Cu 2+ Ag + Fe 3+ Zn 2+ The Molisch test for carbohydrates involves the addition of an alcoholic solution of -naphthol followed by the addition of concentrated H 2SO 4 . What is the characteristic observation of a positive test? A violet or purple ring at the junction of the two liquids A bright red precipitate A silver mirror on the walls of the test tube A canary yellow precipitate What is the product formed when glucose is treated with an excess of Phenylhydrazine? Glucosazone Glucaric acid Sorbitol Gluconic acid Which of the following carbohydrates cannot be digested by humans because we lack the enzyme cellulase? Cellulose Amylose Glycogen Lactose Agar-agar, widely used as a solidifying agent in culture media, is a polysaccharide obtained from: Red algae Brown algae Fungi Bacteria The two functional groups present in a typical carbohydrate molecule are: - OH and - CHO - OH and - COOH - CHO and - COOH - OH and - NH 2 The relationship between D-glyceraldehyde and L-glyceraldehyde is that they are: Enantiomers Diastereomers Epimers Anomers Which of the following is a non-sugar carbohydrate? Starch Glucose Fructose Lactose Which of the following is an example of a storage polysaccharide found specifically in the liver and muscles of animals? Glycogen Starch Cellulose Amylose Which of the following is NOT a property of starch? It is a reducing sugar It gives a blue color with iodine It is a polymer of -D-glucose It consists of amylose and amylopectin Which of the following is an example of an aldotriose? Glyceraldehyde Dihydroxyacetone Erythrose Ribose The primary site for the storage of glycogen in the human body is: Liver and muscles Adipose tissue Kidneys Spleen Starch is a polymer of: -D-Glucose -D-Glucose -D-Fructose -D-Fructose During the formation of a disaccharide from two monosaccharides, the elimination of which molecule occurs? H 2O CO 2 NH 3 O 2 Artificial sweetener which is stable under cold conditions only is :- Saccharine Sucralose Aspartame Alitame Which one given below is a non-reducing sugar ? Maltose Lactose Glucose Sucrose The letter ‘D’ in D-glucose signifies : configuration at the penultimate Chiral Carbon configuration at all Chiral Carbons dextrorotatory that it is a monosaccharide Which of these artificial sweetener is unstable at cooking temperature? Saccharin Aspartame Alitame Sucralose The difference between amylose and amylopectin is Amylopectin have 1 ; ; 4 -linkage and 1 ; ; 6 -linkage Amylose have 1 ; ; 4 -linkage and 1 ; ; 6 -linkage Amylopectin have 1 ; ; 4 -linkage and 1 ; ; 6 -linkage Amylose is made up of glucose and galactose Sucrose on hydrolysis gives -D-Glucose + -D-Glucose -D-Glucose + -D-Fructose -D-Fructose + -D-Fructose -D-Glucose + -D-Fructose How many ester linkages are formed when one molecule of glucose is completely acetylated with acetic anhydride? 5 4 6 1 Sugar ‘X’ A. is found in honey B. is a keto sugar C. exists in α and β – anomeric forms. D. Is laevorotatory. ‘X’ is : Sucrose D-Glucose D-Fructose Maltose Which linkage is present between glucose units in cellulose? -1,4-glycosidic linkage -1,4-glycosidic linkage -1,6-glycosidic linkage -1,6-glycosidic linkage What is the product formed when glucose reacts with Br 2 water? Gluconic acid Saccharic acid Hexanoic acid Sorbitol Amylopectin is a polymer of -D-glucose with: C1-C4 and C1-C6 glycosidic linkages C1-C4 glycosidic linkage only C1-C6 glycosidic linkage only C1-C2 glycosidic linkage Number of chiral carbons in the open-chain structure of glucose is: 4 3 5 6 The oxidation of glucose with nitric acid ( HNO 3 ) yields which of the following compounds? Saccharic acid Gluconic acid Sorbitol Glutaric acid Sucrose is dextrorotatory, but after hydrolysis, the mixture becomes levorotatory. This phenomenon is known as: Inversion of sugar Mutarotation Epimerization Racemization In the structure of Maltose, the two -D-glucose units are linked by which type of glycosidic bond? C1 of one glucose and C4 of another C1 of one glucose and C6 of another C1 of one glucose and C2 of fructose C1 of one glucose and C1 of another Mutarotation is a property exhibited by which of the following? Glucose Sucrose Starch Glycine Glucose and Galactose are: Epimers Anomers Functional isomers Enantiomers Which of the following is the structural sugar found in the exoskeleton of insects? Chitin Cellulose Glycogen Amylopectin Starch consists of two components: Amylose and Amylopectin. Which statement is correct? Amylose is water soluble and unbranched Amylopectin is water soluble and unbranched Amylose is water insoluble and branched Amylopectin is water soluble and branched D-Glucose and D-Mannose are related to each other as: Epimers at C-2 Anomers at C-1 Epimers at C-4 Enantiomers How many chiral carbon atoms are present in the cyclic structure of -D-(+)-glucopyranose? 5 4 3 6 Which of the following compounds will form the same osazone when reacted with excess phenylhydrazine? Glucose, Fructose, and Mannose Glucose, Galactose, and Fructose Glucose and Galactose Glucose and Sucrose Inulin is a naturally occurring polymer of which monosaccharide? Fructose Glucose Galactose Arabinose Sucrose is composed of -D-glucose and -D-fructose. The glycosidic linkage is formed between which carbon atoms? C1 of glucose and C2 of fructose C1 of glucose and C4 of fructose C1 of glucose and C1 of fructose C1 of glucose and C6 of fructose When -D-glucose is dissolved in water, its specific rotation changes from +112 to an equilibrium value of +52.7 . This process is called: Mutarotation Inversion Epimerization Racemization A glycosidic linkage is essentially which type of functional group linkage? Ether Ester Amide Acetal While glucose reacts with Br 2 water to form gluconic acid, fructose remains unreacted. This is because Br 2 water is a: Mild oxidizing agent Strong oxidizing agent Mild reducing agent Dehydrating agent Seliwanoff's test is used to distinguish between: Aldoses and Ketoses Monosaccharides and Disaccharides Reducing and Non-reducing sugars Glucose and Galactose In the reaction: Glucose Tollen's Reagent Product , the product formed is: Gluconic acid Saccharic acid Sorbitol n-Hexane The specific rotation of a freshly prepared solution of fructose changes from -133 to an equilibrium value of -92 . This change is an example of: Mutarotation Inversion Epimerization Racemization Which of the following describes the 'Inversion of Cane Sugar'? Change in specific rotation from dextrorotatory to levorotatory upon hydrolysis Change in the configuration of C-2 of glucose Conversion of glucose into fructose using an enzyme Formation of an equimolar mixture of galactose and glucose Cellobiose is a disaccharide obtained by the partial hydrolysis of cellulose. It consists of two glucose units linked by which bond? -1,4-glycosidic linkage -1,4-glycosidic linkage -1,6-glycosidic linkage -1,2-glycosidic linkage Sucrose is a non-reducing sugar. This is because: The reducing groups of both glucose and fructose are involved in glycosidic bond formation It does not contain any hydroxyl groups It is a very large molecule It is a polymer of many glucose units Upon treatment with HNO 3 , both glucose and gluconic acid yield the same dicarboxylic acid. Name the acid. Saccharic acid Oxalic acid Malonic acid Succinic acid What is the relation between D-Glucose and L-Glucose? Enantiomers Diastereomers Epimers Anomers The reaction of Glucose with Tollen's reagent produces a silver mirror. This indicates the presence of: Free or hemiacetal aldehyde group Ketone group Alcoholic group Carboxylic acid group The configuration of the anomeric carbon in -D-glucose and -D-glucose is determined at which carbon position? C-1 C-2 C-5 C-6 A positive Fehling's test is indicated by the formation of a red precipitate of: Cu 2O CuO Cu(OH) 2 Cu In the nomenclature of sugars, the 'D' and 'L' designations are based on the configuration of the hydroxyl group on the: Highest numbered chiral carbon Lowest numbered chiral carbon Anomeric carbon Carbon attached to the - CH 2 OH group In the process of protein synthesis, the 'energy currency' ATP provides the energy required for the activation of amino acids. The sugar moiety present in the structure of ATP is: D-ribose 2-deoxy-D-ribose D-fructose D-glucose Which type of linkage is responsible for the branching in amylopectin? -1,6-glycosidic linkage -1,4-glycosidic linkage -1,4-glycosidic linkage -1,6-glycosidic linkage Despite having an aldehyde group, glucose does not give which of the following tests? Schiff's test Tollen's test Fehling's test Oxime formation with NH 2OH The linkage between the C-1 of one glucose unit and C-4 of the next glucose unit in cellulose is: β-1,4- glycosidic linkage α-1,4- glycosidic linkage α-1,6- glycosidic linkage β-1,6- glycosidic linkage The 'inversion of sugar' refers to the hydrolysis of sucrose. The resulting mixture of glucose and fructose is: Levorotatory Dextrorotatory Optically inactive Racemic Which of the following describes the relationship between D-Glucose and D-Galactose? C-4 epimers C-2 epimers Anomers Enantiomers A positive Iodine test resulting in a blue-black color is characteristic of: Amylose Amylopectin Cellulose Sucrose The sugar found in milk is lactose. It is a disaccharide composed of: β -D-galactose and β -D-glucose α -D-glucose and β -D-fructose Two units of α -D-glucose α -D-galactose and α -D-glucose What is the relation between α -D-glucose and β -D-glucose? Anomers Epimers Enantiomers Chain isomers The glycosidic linkage in Maltose is formed between: C-1 of one α -glucose and C-4 of another α -glucose C-1 of one β -glucose and C-4 of another β -glucose C-1 of α -glucose and C-2 of β -fructose C-1 of β -galactose and C-4 of β -glucose Which of the following statements regarding 'Invert Sugar' is correct? It is a mixture of equal parts of D-glucose and D-fructose It is more dextrorotatory than sucrose It is a pure form of glucose It is obtained by the oxidation of sucrose Which of the following is the most abundant organic compound on earth? Cellulose Starch Glucose Protein The sugar found in the coenzyme NAD + and FAD is: Ribose Deoxyribose Glucose Galactose The number of chiral centers in the open-chain and cyclic (glucopyranose) forms of D-glucose are respectively: 4 and 5 4 and 4 5 and 5 3 and 4 In the Haworth projection of -D-glucopyranose, the OH group at the anomeric carbon is placed: Below the plane of the ring Above the plane of the ring In the plane of the ring At the end of the chain Which of the following contains an -1,6-glycosidic bond? Amylopectin Amylose Cellulose Maltose How many moles of phenylhydrazine are consumed per mole of D-glucose during the formation of an osazone? 3 2 1 4 How does Glycogen differ structurally from Amylopectin? Glycogen is more highly branched than Amylopectin Glycogen has only -1,4 linkages, while Amylopectin has both Glycogen is a linear polymer, while Amylopectin is branched Glycogen consists of -D-glucose units Amylose, a linear component of starch, forms a secondary structure that is best described as a: Left-handed helix Right-handed helix Triple helix Beta-pleated sheet When D-Fructose is reduced with sodium amalgam ( Na/Hg ) and water, it yields a mixture of two epimeric alcohols. These are: Sorbitol and Mannitol Sorbitol and Dulcitol Mannitol and Iditol Glucitol and Galactitol The number of possible optical isomers for an aldohexose in its open-chain form is 16. How many optical isomers are possible for an aldopentose in its open-chain form? 8 4 16 32 Starch forms a blue-black complex with Iodine. This color is due to: Physical entrapment of I 5 - ions within the amylose helix Chemical covalent bonding between Iodine and Glucose units Formation of a charge-transfer complex between Amylopectin and I 2 Oxidation of Glucose by Iodine Glucose reacts with hydroxylamine to form an oxime. This reaction confirms the presence of which functional group? Carbonyl group Primary alcoholic group Secondary alcoholic group Aldehydic group only The hemiacetal linkage in the α -anomer of D-Glucopyranose is formed between the hydroxyl group at which carbon and the aldehyde group at C-1 ? C-5 C-4 C-6 C-2 Which of the following carbohydrates does NOT show mutarotation when dissolved in water? Sucrose Lactose Maltose Glucose The ABO blood group antigens are examples of which type of biomolecule attached to the surface of red blood cells? Glycoproteins and Glycolipids Pure Polysaccharides Phosphoproteins Nucleoproteins When D-Glucose is treated with semicarbazide, it forms a semicarbazone. This reaction involves the functional group at which carbon? C-1 C-2 C-6 All carbons simultaneously D (+) glucose reacts with hydroxylamine and yields an oxime. The structure of the oxime would be : The reagents with which glucose does not react to give the corresponding tests/products are A. Tollen’s reagent B. Schiff’s reagent C. HCN D. NH2OH E. NaHSO3 Choose the correct options from the given below: B and C A and D B and E E and D Hydrolysis of sucrose with dilute HCl yields: Equimolar mixture of D-(+)-glucose and D-(-)-fructose Two moles of D-(+)-glucose Two moles of D-(-)-fructose Equimolar mixture of D-(+)-glucose and D-(+)-galactose The linkage between the two monosaccharide units in lactose is: -C1 of galactose and -C4 of glucose -C1 of glucose and -C2 of fructose -C1 of glucose and -C4 of glucose -C1 of glucose and -C4 of glucose Reaction of glucose with HCN followed by hydrolysis and heating with HI yields: Heptanoic acid n-Hexane Gluconic acid Saccharic acid Fructose is a ketohexose, yet it reduces Tollen's reagent. This is due to: Enolization and rearrangement in alkaline medium Presence of a terminal aldehyde group Presence of multiple hydroxyl groups Its cyclic furanose structure