Programme 21: Food and Digestion

Activity Sheet 1

Programme Questions

Food Tests

1. Staple foods make up the bulk of a meal. Staple foods like bread contain a lot of starch. Which other foods would you expect to contain starch?
2. How could you use the Benedict’s test to decide which fruits contain the most sugar? Would the test be reliable?

The Digestive System

1. It is possible to drink a glass of water whilst standing on your head! Can you explain this using the idea of peristalsis? Why doesn’t the water run back out of your stomach?
2. If you eat a very large meal you may feel a burning at the back of your throat. This is called heartburn, but is has nothing to do with your heart! Can you explain how we get heartburn using information about secretions in the stomach?
3. The surface area of the small intestine is 9m2. How is such a large area achieved?
4. How does the structure of the small intestine help it to absorb food?
5. Can you list the organs that food passes through from the mouth to the anus?

Digestive Enzymes

1. During digestion larger nutrient molecules are broken down into smaller ones. Complete the table to show how certain enzymes help to break down nutrients into smaller molecules.

Nutrient	Enzyme	Product of digestion
Starch
Protein	protease
Fat		fatty acids and glycerol

2. Bile salts neutralise acids made in the stomach. Can you explain how this helps amylase to break down starch?

3. When investigating the digestion of fat we use a phenolphthalein indicator. Why is a dilute base added to the mixture before the start of the investigation?