balanced diet year 7

1. Week 3:
Year 7 : Biology
Lessons: Balanced diet

2. Learning objectives:
Understand that carbohydrates and fats can be used as a store of energy
in animals, and animals consume food to obtain energy and nutrients.
Balanced diet
Keywords:
• Calorie
• Joule
• Carbohydrate.
• fat.
• nutrient.
• Energy.
• store

3. Which food groups provide us with energy?

4. What if you take in more energy (carbohydrates/ fats) than you need?
You will gain weight as your body stores it as fat for
future use.

5. What if you eat less than your body needs?
You will lose weight because the body will use energy from
its store of fat.

6. what happens if the fat store is all used up?
The body starts to use protein stores.
That’s why starving people have reduced muscle mass as
protein is used to form and maintain muscles.

7. The energy in the food someone eats should be
equal to the energy they need for the activities that
they do.

8. Unit for measuring energy is

9. =
=

10. How the Body Uses Calories
Your body needs calories just to operate — to keep your heart beating
and your lungs breathing. As a kid, your body also needs calories and
nutrients from a variety of foods to grow and develop. And you burn off
some calories without even thinking about it — by walking your dog or
making your bed.

11. 1 Gram of carbohydrates
=
4 Calories
1 Gram of fats
=
9 Calories

14. How many grams of
proteins are in 100 g of
food?
10.3 g
How large is one serving?
45 g
How many grams of fat are
in one serving?
0.9 g

15. Give the name of one
mineral in the food.
Sodium
How much energy is in 100
grams of the food?
375 Kcal / 1570 KJ

16. How many grams of fats in
50 g?
1 g
What process does your
body use to release energy
from food?
Respiration

17. Investigating energy in food
How do we compare the energy released by different
food?
This figure shows how to heat
cold water using burning
food. The more energy
releases, the more the water
temperature rises.

18. Investigating energy in food
1- Add 20 cm3 of cold water to a boiling tube.
2- Measure the temperature
of water.
3- Use a balance to find the mass
of the food.
4- Heat the food until it starts
to burn.
5- Heat the water using the burning
food until it stops burning.

19. Investigating energy in food
6- Measure the temperature of the water again.
7- Calculate the change in
temperature using this
equation:
Change in temperature= Temperature at end – Temperature at start

20. Investigating energy in food
Food Temperature
of water at
start (∘ C)
Temperature
of water at
end (∘ C)
Rise in
emperature
(∘ C)
Bread 17.2 22.6
Cookies 18.5 28.5
Popcorn 17.9 25.8
5.4
10
7.9

21. Investigating energy in food
Which food contained the most energy?
Cookies
What was used to measure the water temperature?
Thermometer

22. Investigating energy in food
1- Independent variable
(The variable we will change in the experiment)
The type of food
2- Dependent variable
(The variable we will measure in the experiment)
Rise in temperature
3- Contolled variables
(The variable we have to keep the same)
Water volume
Mass of food
Same distance between the burnt food and the water

23. Investigating energy in food
Why do we need to control the variables?
To have a fair test
Why do we need to repeat the test?
To have reliable and accurate results.