Testing for biological molecules

Question 1

How can you test for fat(lipids)?

Answer 1

Fats can be tested for using an emulsion test or a filter paper test

Question 2

How does the emulsion test work?

Answer 2

1. Add ethanol to the sample
2. Shake it
3. Add water to the sample
4. Look for a colour change, if it goes cloudy then lipids are present

Question 3

How does the filter paper test work?

Answer 3

1. Rub the sample on filter paper

2. The filter paper will become see-through is the sample contains lipids

Question 4

How can you test for starch?

Answer 4

You can test for starch using an iodine test

Question 5

How does an iodine test work?

Answer 5

1. Add iodine to the sample

2. If starch is present the sample will turn black/dark blue

Question 6

How can you test for sugar?

Answer 6

You can test for sugar using a Benedict solution test

Question 7

How does a Benedict solution test work?

Answer 7

1. Add Benedict’s solution to the sample
2. Heat it for 2 minutes
3. The solution will turn red if there is lots of sugar and pale green/yellow if there’s a little bit of sugar

Question 8

How can you test for protein?

Answer 8

You can test for protein using the Biurets test.

Question 9

How does the Biurtes test work?

Answer 9

1. Add biurets solution to the sample

2. The solution will turn purple if protein is present.