Workbook Answers 7.3

A

1.     True

2.     False

3.     True

4.     False

5.     False

B

1.     (a)    chemical

        (b)    respiration

        (c)    living cells

        (d)   oxygen

        (e)    carbon dioxide

        (f)    water

2.     energy content

C

1.     (a)    (i)     A: oxygen; B: water / carbon dioxide; C: carbon dioxide / water

                (ii)    Support body functions / support movement / maintain body temperature.

(any two or other reasonable answers)

        (b)    (i)     X: oxygen; Y: water / carbon dioxide; Z: carbon dioxide / water

(ii)    In both respiration and burning, oxygen is consumed and carbon dioxide and water are produced.

        (c)    Respiration occurs in living cells while burning takes place in air. /

A flame exists in burning but not in respiration. /

Respiration is a much more complicated process than burning. /

The energy is released much slower in respiration than burning.

(any two or other reasonable answer)

2.     (a)    Increase in temperature per gram of food

(b)    60℃

        (c)    The highest water temperature reached  =    Water temperature at the beginning +

                                                                                      (change in water temperature for 4g of

                                                                                      food Z used / 2)

                                                                                =    20℃ + 60℃ / 2

                                                                             =    50℃

(d)       Food Z

(e)        Food Y

                  Overweight / coronary heart disease / diabetes (any two or other reasonable answers)