Questions and Answers
Carbohydrates are made of?
Which of the following are monosaccharides? (Select all that apply)
What are the components of maltose?
Glucose + Glucose
What are the components of lactose?
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What are the components of sucrose?
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Which of the following are examples of polysaccharides? (Select all that apply)
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What is the role of starch in plants?
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Give examples of food containing starch.
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The Benedict's test detects sucrose.
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What are the indicators of a positive Benedict's test?
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What does a positive iodine test indicate?
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The Seliwanoff test can only detect reducing sugars.
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What is a chemical reaction used to break down polymers?
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Which carbohydrates are reducing sugars based on part A results?
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Which carbohydrates are ketoses according to part B results?
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Which carbohydrate gives a blue-black color in the iodine test?
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What carbohydrate produces a reddish-orange solid with Benedict's reagent?
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What carbohydrate produces no bubbles during fermentation?
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What carbohydrate turns blue-black with iodine reagent?
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How do the results of the iodine test indicate that hydrolysis of starch occurred?
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Study Notes
Carbohydrates Overview
- Composed of Carbon (C), Hydrogen (H), and Oxygen (O).
- Essential organic compounds that provide energy and structural functions.
Types of Carbohydrates
- Monosaccharides: Simple sugars like glucose, fructose, galactose, and ribose.
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Disaccharides: Formed by two monosaccharides:
- Maltose: Glucose + Glucose
- Lactose: Glucose + Galactose
- Sucrose: Glucose + Fructose
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Polysaccharides: Complex carbohydrates for storage and structure:
- Starch: Energy storage in plants
- Cellulose: Structural component of plant cell walls
- Glycogen: Energy storage in animals
Starch
- Primary function is to store glucose produced through photosynthesis.
- Found in foods such as potatoes and root vegetables.
Carbohydrate Tests
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Benedict's Test:
- Detects monosaccharides and disaccharides (not sucrose).
- Positive result: colored precipitate (yellow, green, orange, or red).
- Must be mixed with sample and heated; limitations include being qualitative.
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Seliwanoff Test:
- Identifies complex carbohydrates with fructose.
- Aldohexoses react but more slowly than ketoses like fructose.
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Iodine Test:
- Detects starch by mixing with iodine solution; positive: dark blue, negative: yellow.
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Fermentation Test:
- Detects monosaccharides and disaccharides (not lactose and galactose).
- Produces CO2 bubbles during fermentation.
Hydrolysis
- A reaction to break down polymers using water (H2O).
- Sucrose hydrolyzes faster than starch due to its simpler structure.
Reducing Sugars
- Reducing sugars include glucose, fructose, and lactose, identifiable by their reaction to specific tests.
Ketoses
- Fructose and sucrose are classified as ketoses based on test results.
Iodine Test Results
- Starch gives a blue-black color indicating its presence after hydrolysis.
Test Result Interpretations
- Fructose: Produces reddish-orange solid with Benedict's reagent, reacts quickly with Seliwanoff's reagent.
- Lactose: Shows color change with Benedict's reagent, slower with Seliwanoff's, produces no bubbles in fermentation.
- Amylose: No reaction with Benedict's or Seliwanoff's but turns blue-black with iodine.
Importance of Iodine Test in Hydrolysis
- Polysaccharides trap iodine, confirming the completion of starch hydrolysis.
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Description
Test your knowledge on carbohydrates with these flashcards covering key concepts, structures, and types of carbohydrates. Dive into monosaccharides, disaccharides, and polysaccharides to enhance your understanding of these essential biomolecules.
