Investigation 5, Part 1

1. Investigation 5, Part 1 Energy in Food

2. Warm up • What is a food chain? • What is a food web? • The path that food takes from one to another organism in called a food chain. • A diagram that shows all the feeding relationships is called a food web.

3. Question… • How does your body get the energy to to do what you want to do? • Write down your ideas in your journal. • Class discussion.

4. Energy • What do you do when you are “out of energy?” • Rest • Sleep • Food • Coal, wood and gas are all energy sources. What kind of energy do we get from these energy sources? • They are burned to release energy. • The heat released is a form of energy. • People get energy by “burning” food. It does not go up in flames, but it gives us energy.

5. Burn Food? • I have some cheese balls. • Do you think they will burn? • What did you observe? • It burned. • What does this tell us? • The food does have energy that was released in the form of heat and light. • How can we measure this? • Heat something and measure the temperature change. • We can use the cheese ball to heat water and measure the temperature change.

6. Heat Water • Use the information that we obtained to fill in lab sheet 23. • Heat is measured in units called calories. • One calorie is the amount of heat needed to raise the temp of 1 mL of water 1 degree C. • How many calories of heat did we transfer from our burning cheese balls to our water? • Complete the math on your lab sheet to figure this out.

7. Does Food Have Energy? • Based on our experiment, do we have evidence that food has energy? • Food can burn, it gave off heat, it has energy. • What evidence is this? • It produces heat when it burns. • Why do people eat food? • To get the energy needed for life. • What do energy bars and drinks contain that provide energy? • Food. Usually in the form of SUGAR.

8. Does Food Have Energy? • Is water food? • No, it has no calories and it will not burn. • Where do people get energy besides food? • Nowhere. All organisms only get energy from food. • What units do we use to measure the energy in food? • Calories. • How many calories does a cheese ball have? • 500-700

9. How Many Calories? • The suggested intake of calories for middle school students is 2000 calories. • How many cheese balls would we have to eat to get that? • Two to four would equal about 2000 calories. • Does that make sense? • Um. No. • One serving of cheese balls is about 34 and 160 calories. • Calories in one cheese ball is about 4.7

10. Why the Difference? • The calories that we have been using is the scientific or “small calorie.” • Because it takes so many calories to keep the human body going, health and nutrition scientists describe the energy in food in “food calories” or kilocalories. • One food calorie is equal to is equal to 1000 small calories. • The symbol for food calories is a capital C and the small calorie is a lower case c.

11. Experimental Error? • The label on the cheese balls says 4.7 C or 4700 c. • Our experiment got 500-700 c or 0.5 to 0.7 C. • Why the difference? • Burning the cheese balls is not the most efficient way to measure the calories. • There is a lot of lost energy in the form of heat in the air and carbon (black marks on the foil). • This activity is designed to show there is energy in food.