Lab1 - Carbohydrates Identification
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Questions and Answers

What color indicates a positive result in the Anthrone test for carbohydrates?

  • Blue-green (correct)
  • Red
  • Purple ring
  • Brown

    • Which test is specifically used to identify pentoses?

  • Bi al's test (correct)
  • Benedict's test
  • Seliwanoff test
  • Barfoed's test

    • Which of the following is the main reducing agent used in Fehling's test?

  • Coppersulfate
  • Sodium citrate
  • Cupric ion (correct)
  • Tartrate ion

    • How long does it typically take for ketohexoses to react in the Seliwanoff test?

    <p>2 minutes (D)</p> Signup and view all the answers

    What type of product is formed from the oxidation of galactose in the Mucic Acid test?

    <p>Insoluble mucic acid (A)</p> Signup and view all the answers

    Which test differentiates between aldohexoses and ketohexoses based on time of reaction?

    <p>Seliwanoff test (A)</p> Signup and view all the answers

    What indicates a positive result in the Barfoed's test?

    <p>Formation of a red precipitate (B)</p> Signup and view all the answers

    Which of the following carbohydrate types does the Molisch test identify?

    <p>All carbohydrates (D)</p> Signup and view all the answers

    What is the primary reagent used in the Benedict's test?

    <p>Copper(II) sulfate (B)</p> Signup and view all the answers

    Which of the following sugars is specifically identified by the Mucic Acid test?

    <p>Galactose (B)</p> Signup and view all the answers

    Which disaccharide is formed by the combination of glucose and galactose?

    <p>Lactose (B)</p> Signup and view all the answers

    What type of bond is characteristic of sugars like ribose and glucose?

    <p>Covalent bond (D)</p> Signup and view all the answers

    Which of the following reagents is used in the Fehling's test to identify reducing sugars?

    <p>Copper(II) sulfate (C)</p> Signup and view all the answers

    Which sugar is characterized as a ketone?

    <p>Fructose (A)</p> Signup and view all the answers

    During the Seliwanoff's test, which color indicates the presence of a ketose sugar?

    <p>Purple (A)</p> Signup and view all the answers

    What byproduct is formed during the mucic acid test when lactose is present?

    <p>Galactose (B)</p> Signup and view all the answers

    Which method can be used to identify pentoses in a sugar solution?

    <p>Bial's test (B)</p> Signup and view all the answers

    What characteristic change occurs in a reducing sugar during the Benedict's test?

    <p>Color change to red (D)</p> Signup and view all the answers

    What type of sugars are ribose and deoxyribose classified as?

    <p>Monosaccharides (C)</p> Signup and view all the answers

    Which sugar contains a double bond in its molecular structure?

    <p>Fructose (D)</p> Signup and view all the answers

    Which term correctly classifies gum based on its carbohydrate structure?

    <p>Heteropolysaccharide (D)</p> Signup and view all the answers

    Which of the following substances is classified as a polysaccharide?

    <p>Inulin (B)</p> Signup and view all the answers

    What reagent is known to oxidize reducing sugars?

    <p>Tollen’s reagent (A)</p> Signup and view all the answers

    Which test is predominantly employed to identify pentoses?

    <p>Bial’s test (B)</p> Signup and view all the answers

    What is the role of copper ions in the Benedict’s test?

    <p>They reduce the sugars (A)</p> Signup and view all the answers

    Which carbohydrate is an example of a monosaccharide?

    <p>Galactose (D)</p> Signup and view all the answers

    Which of the following compounds is considered a heteropolysaccharide?

    <p>Xyloglucan (D)</p> Signup and view all the answers

    What type of carbohydrate is maltose classified as?

    <p>Disaccharide (B)</p> Signup and view all the answers

    Which test can be used to identify reducing sugars aside from the Benedict's test?

    <p>Fehling's solution (D)</p> Signup and view all the answers

    Which of the following is NOT a reducing sugar?

    <p>Sucrose (A)</p> Signup and view all the answers

    Flashcards

    Disaccharide

    A carbohydrate formed by the combination of two monosaccharides.

    Covalent Bond

    A chemical bond formed by sharing electrons between atoms.

    Monosaccharide

    A simple sugar that cannot be broken down into smaller sugars.

    Tollen's test

    A chemical test used to identify aldehydes.

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    Benedict's test

    A chemical test for reducing sugars.

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    Lactose

    A disaccharide composed of glucose and galactose.

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    Fructose

    A monosaccharide, a simple sugar.

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    Galactose

    A monosaccharide, a simple sugar.

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    Seliwanoff's test

    A test for the presence of fructose.

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    Bials test

    A test for pentoses and furfural.

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    Homopolysaccharide

    A polysaccharide composed of only one type of monosaccharide.

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    Heteropolysaccharide

    A polysaccharide composed of more than one type of monosaccharide.

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    Polysaccharide

    A large carbohydrate molecule made up of many monosaccharides.

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    Reducing sugar

    A sugar that can reduce other substances.

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    Benedict's reagent

    A chemical reagent used to test for reducing sugars.

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    Bial's test

    A chemical test used to identify pentoses (5-carbon sugars).

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    Mucic test

    A test used to identify glucuronic acid.

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    Inulin

    A polysaccharide used as a test for polysaccharides.

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    Monosaccharide

    The simplest form of carbohydrate.

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    Tollen's reagent

    A chemical reagent used to test for aldehydes and reducing sugars.

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    Molisch Test

    A test to identify carbohydrates (sugars). It detects the presence of a furfural derivative formed from the sugars with sulfuric acid.

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    Anthrone Test

    A test used for identifying carbohydrates. It produces a blue-green color.

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    Barfoed's Test

    A test that distinguishes monosaccharides, specifically checking for reducing properties. it specifically tests for MONOSACCHARIDES, taking less time than the test for disaccharides.

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    Seliwanoff's test

    Identifies ketohexoses. This test helps in detecting the presence of ketose sugars specifically. It's faster for ketohexoses than for aldohexoses, showing red.

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    Bial's Test

    Identifies pentoses (5-carbon sugars). It produces a specific color change, a hint.

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    Benedict's Test

    Identifies reducing sugars in a solution; it determines if there's a reducing sugar present.

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    Fehling's Test

    Another test for reducing sugars. It leverages copper ions to detect reducing sugars.

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    Mucic Acid Test

    A test specifically for galactose, using nitric acid as an oxidizing agent.

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    Reducing Sugar

    A carbohydrate that can donate electrons to an oxidizing agent (copper ion for example); thus, the oxidizing agent is reduced.

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    Carbohydrate Identification

    The process of using various tests (e.g., Molisch, Benedict's, Seliwanoff's) to determine the specific type of carbohydrate present in a sample.

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    Study Notes

    Carbohydrate Identification

    • Carbohydrates are primarily energy sources, composed of carbon, hydrogen, and oxygen.
    • Historically, they were considered hydrates of carbon (H₂O).
    • Classified as polyhydroxyaldehydes or polyhydroxyketones.
    • Three main classes studied: monosaccharides, oligosaccharides (disaccharides), and polysaccharides.

    Monosaccharides

    • Crystalline, water-soluble compounds.
    • Simple sugars; one carbonyl group and multiple hydroxyl groups.
    • Common hexoses include glucose, fructose, and galactose; pentoses include arabinose and xylose.
    • Aliphatic aldehydes or ketones.

    Oligosaccharides (Disaccharides)

    • Relatively low molecular weight polymers (2-20 monosaccharide units).
    • Covalently bonded through glycosidic linkages.
    • Examples include sucrose, lactose, and maltose.

    Polysaccharides

    • High molecular weight polymers (more than 20 monosaccharide units).
    • Examples include glycogen (animal storage), starch (plant storage), cellulose (fiber), and inulin (fructose storage).
    • Homopolysaccharides: Contain only one type of monosaccharide (e.g., starch, cellulose, glycogen).
    • Heteropolysaccharides: Contain more than one type of monosaccharide (e.g., pectin, hemicellulose, gums).

    Carbohydrate Nomenclature

    • Saccharide names end in -ose (e.g., glucose, fructose).
    • Names indicate the functional group (aldo- for aldehyde, keto- for ketone) and the number of carbons (e.g., aldohexose, ketohexose).

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    Related Documents

    Carbohydrates Practical Quiz 2018-2019 PDF

    Description

    Test your knowledge on carbohydrate classification and identification with this quiz! Explore the different types of carbohydrates, including monosaccharides, oligosaccharides, and polysaccharides, and learn about their structures and functions.

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