Suggested answer for Chapter 7 exercises

 

Page 1

Breathed air: the air we breathe out.

Burning: The chemical reaction in which substances react with oxygen and release heat energy.

Destarching: removal of starch stored in the leaves.

Food Chain: the way of showing the feeding relationship between living things.

Gaseous exchange: the process taking useful gases into the body of a living cell and getting rid of waste gases.

Greenhouse effect: the warming effect produced when heat energy is trapped in the earth’s atmosphere by gases, such as carbon dioxide.

Passive smoking: breathing in the smoke from cigarette smokers.

Photosynthesis: the process in which plants use light energy to make food from carbon dioxide and water.

Respiration: the breakdown of food to release energy in living cells.

 

Page 5

1 carbon dioxide, water, light, light, chlorophyll;

2 They make my house more fresh air and it can make my house more beautiful.

3 Cut down fewer trees and plant more trees; reduce paper consumption; enacting laws to protect the natural forests.

4 carbon dioxide + water ---light and chlorophyll---> oxygen + food

 

Page 8

A)         B>E>A>C>D

B)         YELLOW

C)         It is because the alcohol was removed from the leaf.

D)         Soften the leaf;

E)          Iodine solution

F)          The uncovered part of the leaf turns into blue-black/dark blue colour.

 

Page 9

1 C

2 B

3 C

4 B

5 A

6 C (only options i and iv are correct)

 

Page 11

1.

A)    a=lung, b=diaphragm, c=ribs

B)     b is relaxing;

C)    The man breathing in air in diagram A.

D)    The men breathing out air in diagram B.

 

2.

A)    If smokers smoked more cigarettes a day, he would has higher chance to develop lung cancer.

B)     28 times

C)    tar

 

3

A)    A purple, B red, C yellow, D yellow;

B)     Carbon dioxide, photosynthesis;

C)    Carbon dioxide, pond weeds;

D)    Tube C would turn colour first;

E)     Given out, respiration;