F2 Worksheet 11.2 answers

F.2 Integrated Science                         11.2    How we see

i      Words to know:

	English term	Write the words again	Chinese term
1	Cornea	Cornea	角膜
2	Iris	Iris	虹膜
3	Pupil	Pupil	瞳孔
4	Lens	Lens	晶狀體
5	Retina	Retina	視網膜

i      Label the diagrams:

Eye lid

Eye lashes

Cornea

Pupil

Iris

White protective layer

                                                                                                    Retina

Cornea                                                                                        White protective coat

Iris                                                                                              Yellow spot

Pupil                                                                                           Blind spot

Lens                                                                                           Optic nerve

i      Fill in the table with the following parts of a human eye:

Retina                Optic nerve                  Lens                        Cornea           White protective coat                    Pupil                      Iris

          

Parts of our eye	Functions
Cornea	Protects the eye and allow light to pass through; helps to focus light onto the retina
Iris	Controls the size of the pupil and hence the amount of light entering the eye
Pupil	Allows light to enter the eye
Lens	Allows light to pass through and focuses light onto the retina
Retina	Contains light receptors that can detect light and produce signals
White protective coat	Protects the eyeball and give it shape
Optic nerve	Carries signal to the brain

i      Fill in the blanks:

1        Yellow spot is the part on the retina which gives the clearest vision.

2        The optic nerve leaves the eye at blind spot.
           At this point, there is no light receptor.

3        Iris controls the size of the pupil.

4        In bright light, pupil becomes smaller so that less light is allowed to enter the eyes.

5        In dim light, pupil becomes larger so that more light can enter the eyes.

6       When light from an object enters the eye, the cornea and the lens focus the light onto the retina, forming an sharp image.

7        Light stimulates the light receptors on the retina to produce signals
           which are then travel to the brain through the optic nerve.

8        The brain interprets the signals to give us the sense of sight.

F2 Worksheet 11.1 answers

F.2 Integrated Science                                       11.1    Senses and sense organs

i      Words to know:

	English term	Write the words again	Chinese term
1	Sense organ	Sense organ	感覺器官
2	Stimuli	Stimuli	刺激
3	Respond	Respond	反應
4	Receptor	Receptor	感受器
5	Brain	Brain	腦

i      Fill in the blanks:

1        We can use our sense organs to detect changes in the environment.

2        Other living things can also detect changes in the environment (          stimuli) and respond to them.

3        By responding to stimuli, living things can find food, shelters, mates, detect and escape from danger.

4        Humans have different sense organs which can detect different stimuli.

5        Sense organs contain special kinds of cells called receptors which are sensitive to particular kinds of stimuli.

6        When the receptors detect stimuli, they send signals to our brain through nerves, which are then interpreted to give us senses.

i      Fill in the table:

Sense organ	Stimuli	Senses produced
Eye	light	sight
Ear	Sounds	hearing
Nose	Chemicals in air	Smell
Tongue	Chemicals in food or drinks	taste
Touch	Things in contact with our skin	Heat/cold, touch, pain, pressure

F2 Worksheet 10.5 answers

10.2            Acid rain

I.    Words to know:

	English term	Write the words again	Chinese term
1	Acid rain	Acid rain	酸雨
2	Sulphur dioxide	Sulphur dioxide	二氧化硫
3	Nitrogen oxides	Nitrogen oxides	氮氧化物
4	Dissolve	Dissolve	溶解
5	Power station	Power station	發電廠
6	Sulphur	Sulphur	硫
7	Catalytic converter	Catalytic converter	催化反應器

II.   Fill in the blanks:

1.     Acid rain

Ø   Clean or unpolluted rainwater is slightly acidic and has a pH value of about 5.6.

Ø   When the pH value of rainwater drops below 5.6, it is regarded as (1) acid rain.

2.     Causes of acid rain

Ä  Acid rain is mainly caused by the acidic pollutant gases like (2) sulphur dioxide and (3) nitrogen oxides. A large amount of these pollutant gases are released from traditional power stations, factories and motor vehicles.

Ä  The acidic pollutant gases (4) dissolve in tiny water droplets in the air to form acids. The acidic water droplets in the air gather together to form clouds, and finally fall as acid rain.

(a)   Traditional power stations and factories

²  When coal and fuels obtained from petroleum are burnt in traditional (5) power station and factories, sulphur dioxide and nitrogen oxides are released.

(b)   Motor vehicles

²  When fuels are burnt in the engines of motor vehicles, sulphur dioxide and nitrogen oxides are released.

2.     Environmental effects of acid rain

(a)   Corroding buildings and structures

²  Acids have (6) corrosive effects on some metals and building materials.

²  Acid rain can gradually corrode buildings and structures made of metals, marble and limestone.

(b)   Killing water life

²  Acid rain makes the water in lakes and rivers so acidic that fish and plants cannot survive.

²  Many fish and plants (7) die if the pH value of water drops below 5.

(c)   Damaging plants

²  Acid rain makes soil too acidic and thus affects plant growth.

²  Acid rain may also damage leaves and make plants unable to carry out (8)

                photosynthesis.

3.     Preventive measures against acid rain

Ø   Some major ways of reducing the emission of sulphur dioxide and nitrogen oxides:

²  saving energy so that less coal and fuels obtained from petroleum are burnt;

²  using alternative energy sources like (9) solar / nuclear and wind power;

²  using high-grade fuels with a low (10) sulphur content;

²  reducing pollutants from the exhaust gas of motor vehicles, e.g. using (11) catalytic converter;

²  educating the public about the harmful effects of acid rain and the ways of reducing air pollution.

F2 Worksheet 10.4 answers

10.2            Acids and corrosion

I.    Words to know:

	English term	Write the words again	Chinese term
1	Hydrogen	Hydrogen	氫
2	Corrosive	Corrosive	腐蝕性
3	‘pop’ sound	‘pop’ sound	爆鳴聲
4	Marble	Marble	大理石
5	Limestone	Limestone	石灰石
6	Calcium carbonate	Calcium carbonate	碳酸鈣

II.   Fill in the blanks:

1.     Corrosive effects of acids on metals

Ø   Some metals (e.g. zinc and magnesium) react with dilute acids. During the reactions, (1) hydrogen gas and heat are produced. The metals decrease in size gradually. Thus acids have (2) corrosive effects on these metals.

²  Test for hydrogen:
Put a burning splint near the mouth of a test tube containing the gas. If the gas is hydrogen, it burns with a (3) “pop” sound.

2.     Corrosive effects of acids on building materials

Ø   Both (4) marble and (5) limestone are easily corroded by acids. This is because they contain (6) calcium carbonate, which reacts quickly with dilute acids to give off (7)carbon dioxide.