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A Level Biology 1 > 2.2 Food Tests > Flashcards

2.2 Food Tests Flashcards

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1
Q

What are the two types of sugar?

A

Reducing and non reducing

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2
Q

What is the process of the test for reducing sugars?

A
  • Add Benedicts reagent

- heat in water bath that has been brought to boil

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3
Q

What colour is Benedicts reagent?

A

Blue

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4
Q

If the test is positive what will happen?

A

A coloured precipitate will form

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5
Q

What is the colour change of the precipitate?

A

Blue > green > yellow > orange > brick red

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6
Q

What happens the higher the concentration of the precipitate?

A

The further the colour change

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7
Q

What does the colour change indicate?

A

The presence of a reducing sugar

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8
Q

How can you compare the amount of reducing sugar in different solutions?

A

Compare the colour changes in both

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9
Q

What is a more accurate way of comparing the amount of reducing sugar in solutions?

A

Weighing the precipitate

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10
Q

If the test for reducing sugars is negative what could there still be?

A

A non reducing sugar present

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11
Q

What do you have to do to test for non reducing sugars?

A

Break them down to monosaccharides

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12
Q

How do you break them down to monosaccharides?

A

By getting a new sample of solution
Adding dilute hydrochloric acid
Heat in water bath

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13
Q

What do you neutralise the solution with?

A

Sodium hydrogen carbonate

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14
Q

What is the test for sugars?

A

Benedicts test

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15
Q

What do you do after neutralising in the test for non reducing sugars?

A

Carry out the Benedicts test again

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16
Q

If the test is positive why will happen?

A

A colours precipitate will form

17
Q

If the test is negative what will happen?

A

The solution will stay blue meaning it doesn’t contain any sugar

18
Q

What do you use to test for glucose?

A

Test strips dipped in reagent

19
Q

What happens to the colour strips?

A

They change colour of glucose is present

20
Q

What is the test for starch?

A

Iodine test

21
Q

What does the iodine test involve?

A

Adding dissolved potassium iodide solution to the test sample

22
Q

If starch is present what happens to the sample?

A

It changes from browny orange to blue black

23
Q

What does the biruet test test for?

A

Proteins

24
Q

What is the first stage of the biuret test?

A

Add a few drops of sodium hydroxide to make the solution alkaline

25
Q

What is the second stage of the biuret test?

A

Add some copper sulfate solution

26
Q

If a protein is present what will happen?

A

Solution turns purple

27
Q

What does emulsion test test for?

A

Lipids

28
Q

What do you do in the emulsion test?

A

Shake the test substance with ethanol for a minute then pour the solution in water

29
Q

If a lipid is present-

A

Solution turns milky

A Level Biology 1 (102 decks)

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