F2 1st Term IS WS 06 Answers

1st Term WS 06 Submission date：_____________ Name：______________________ Class & no.：2 _________(     )

7.3       How does our body obtain energy?

i      Words to know:

	English term	Write the words again	Chinese term
1	Chemical energy	Chemical energy	化學能
2	Respiration	Respiration	呼吸作用
3	Energy content	Energy content	能量值
4	Kilojoules	Kilojoules	千焦耳
5	Kilocalories	Kilocalories	千卡路里
6	Overweight	Overweight	過重

i      Matching:

Chemical energy	•	is a form of energy stored in food
Respiration	•	is a complex chemical process in living cells from which energy stored in food is released
Energy content	•	is the amount of energy provided by a particular amount of food
Kilojoules	•	is usually used to express the energy content of food
Kilocalories	•	the short form of which is kcal
Overweight	•	is caused by eating too much high-energy foods

i      Fill in the blanks:

1             We need energy to carry out various activities. Energy is also needed for maintaining

our body temperature, heartbeat and breathing. Such energy comes from the food we eat.

2        In our body, the chemical energy stored in food is released by a complex chemical process called

respiration. It takes place in our living cells.

3        In respiration, food reacts with oxygen to form carbon dioxide and water. The energy released is used to support our body activities.

4        Write down the word equation of respiration.

                                        living cells

           food + oxygen --------------------à energy + carbon dioxide + water

5        In both burning and respiration, oxygen is consumed and carbon dioxide and water are produced. Energy is released faster in burning than in respiration.

6        The amounts of energy that the foods can provide are called the energy content.

It is measured in kilojoules (kJ) or kilocalories (kcal).

7       The table below shows the differences差異 between respiration and burning:

	Respiration	Burning
Does a flame exist?	no	Yes
The process is…	much more complicated複雜	Less complicated / simpler
Takes place in…	Living cells	Air
Energy release is…	slower	much faster

8        Eating too much of high-energy food can make us become overweight.