Testing for biological molecules

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  • Created by: Meklit.G
  • Created on: 10-06-17 19:47
How can you test for sugar and how can you tell if sugar is present?
You can test for sugar with benedict's raegant (which is blue) and you can tell if it is present if it turns brick red
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How can you test for starch and how can you tell if starch is present?
You can test for starch with iodine (which is browny-orange) and if starch is present then it would turn blue-black
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How can you test for lipids and how can you tell if lipids are present?
You use the emulsion test to test for lipids, you shakr s test substane in ethanol, put it in water and if there are any lipids present then a milky liquid/emulsion will appear. The more lipid, the more noticeable the milky colour will be
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What is an emulsion?
An emulsion is when one liquid doesn't dissolve in another - it just forms little droplets
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How can you test for proteins and how can you tell if proteins are present?
The Biuret test is used to test for proteins, first you add a few drops of potassium hydroxide to make the solution alkaline, then you add some copper sulfate solution (which is bright blue). If protein is present, the solution would turn purple
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How can you test for energy in food?
You can test for energy in food by doing a simple experiment where you set a piece of dry food alight and you hold it under a tube with water and a themometer. You record the temperature at the beginning and end and see how much energy's there is
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How can you work out how many joules (J) of energy the food contains?
Energy in food(in J)= mass of water (in g) x temperature change of water (in °C) x 4.2
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How can you work out how much energy there is per gram of food (in J/g)
Energy per gram of food (in J/g)= energy in food (in J)/mass of food (in g)
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Other cards in this set

Card 2

Front

How can you test for starch and how can you tell if starch is present?

Back

You can test for starch with iodine (which is browny-orange) and if starch is present then it would turn blue-black

Card 3

Front

How can you test for lipids and how can you tell if lipids are present?

Back

Preview of the front of card 3

Card 4

Front

What is an emulsion?

Back

Preview of the front of card 4

Card 5

Front

How can you test for proteins and how can you tell if proteins are present?

Back

Preview of the front of card 5
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