Biology Experiments

Question 1

To test for the presence of starch

Answer 1

1. Fill two test tubes with equal amounts of starch + water
2. Put 2-3 drops of iodine in each
3. Gently shake + note colour changes

iodine = blue when starch is present, brown/yellow when it isn’t

Question 2

To test for the presence of a reducing sugar (glucose)

Answer 2

1. Fill two test-tubes with equal amounts of glucose solution + water
2. Put 2-3 drops of Benedict’s Solution in each
3. Stand them in a boiling water bath for around 3 mins, note changes

tube with glucose –> brick-red, tube with water –> stays blue

Question 3

To test for the presence of protein

Answer 3

1. Set up two test-tubes, one containing milk + sodium hydroxide solution, and the other water + sodium hydroxide solution
2. Add 3-4 drops of copper sulfate solution to each, swirl gently

mixture with milk –> purple/violet, water –> remains blue

Question 4

To test for the presence of fats

Answer 4

1. Two pieces of brown paper, butter on one + water on other
2. Allow to dry, hold up to light

where butter was rubbed will allow light to pass through –> translucent spot

Question 5

Conversion of chemical energy in food into heat energy

Answer 5

1. 20cm^3 of water in test tube on retort stand + clamp

2. Burn cracker under it, take temperature before and after