1.3- Carbohydrates - disaccharides and polysaccharides

  • Created by: Megan2413
  • Created on: 15-07-17 10:49
What two monosaccharides form maltose?
alpha glucose + alpha glucose
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What two monosaccharides form sucrose?
alpha glucose + fructose
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What disaccharide is formed from glucose + galactose?
Lactose
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What reaction forms a disaccharide?
Condensation reaction
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What bond is formed during a condensation reaction?
Glycosidic bond
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What reaction breaks the glycosidic bond?
Hydrolysis recation
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Some disaccharides are non-reducing sugars, how is this test carried out?
- After having found a negative result in a reducing sugars test, another 2cm3 food sample is added to a test tube - Add dilute HCl - Add to gently boiling water bath for 5 mins - Slowly add sodium hydrogencarbonate to the test tube until the HCl -->
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-->
is neutralised (test with pH paper) - Add benedict's reagent to the test tube - gently boil in water bath for 5 mins
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What is a positive result of the non-reducing sugars test?
The solution turns orange-brown
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Why is HCl added to the test tube?
To hydrolyse any disaccharides into monosaccharides
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Why is sodium hydrogencarbonate added?
Benedict's reagent doesn't work in acidic conditions- this neutralises the solution
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What type of saccharide is starch?
Polysaccharide
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What is the test for starch?
Detecting a colour change in the presence of iodide solution
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How is the test for starch carried out?
- Add 2cm3 of the sample to the test tube - Add a few drops of potassium iodide - Shake or stir
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What is a positive result for the starch test?
Blue-black colour change
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Other cards in this set

Card 2

Front

What two monosaccharides form sucrose?

Back

alpha glucose + fructose

Card 3

Front

What disaccharide is formed from glucose + galactose?

Back

Preview of the front of card 3

Card 4

Front

What reaction forms a disaccharide?

Back

Preview of the front of card 4

Card 5

Front

What bond is formed during a condensation reaction?

Back

Preview of the front of card 5
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