Lesson 3 - Food Tests

Question 1

What is the test for starch, and what indicates a positive result?

Answer 1

The test for starch is the iodine test. Add iodine solution to the food sample.

Positive result: The solution changes from orange-brown to blue-black.

Question 2

What is the test for sugar (glucose), and what indicates a positive result?

Answer 2

The test for sugar is the Benedict’s test. Add Benedict’s solution to the food sample and heat it in a water bath.

Positive result: The solution changes from blue to green, yellow, or brick-red, depending on the sugar concentration.

Question 3

How do you test for fats using filter paper?

Answer 3

Rub a small amount of the food onto a piece of filter paper.

Positive result: A translucent (greasy) spot appears on the paper, indicating the presence of fats.

Question 4

What is the test for protein, and what indicates a positive result?

Answer 4

The test for protein is the Biuret test. Add Biuret solution (a mix of sodium hydroxide and copper sulfate) to the food sample.

Positive result: The solution changes from blue to purple.

Question 5

Why are food tests important in biology?

Answer 5

Food tests help identify the nutrients in different foods, allowing scientists to study diets and their effects on health.