1980-10-09 — Page 24

頁四第張六第日一初月九年申庚歷夏

1981

中學會考試題預習專欄

生

物

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BIOLOGY (1)

W、 W. Leung

MILL & DALE PRESS LTD.

Unit 1: NUTRITION.

1. The table below shows the minimum daily requirement

of a number đó nutrients, together with a list of some of the things present in cow's milk.

Food' energy

Proteia

Iron

Daily

Tax an

réquirement.

Present

in 100.

11500: KJ

cowi Ik

276 KJ

3.38

WAH KIU YAT PO

(b) Cow's milk is deficient

in iron and vitamin B

(c) Deficiency in iron and

vitamin B would cause anemia and beri-berif dermatitis respectively.

Vitamin D..

It is because vitamin D. can be produced by the skin under the action. of the ultraviolet light.

(e) Roughage.

2.(a) Enzyme A breaks down

insoluble egg-white protein into soluble products.

(b) (1)

20

Enzyme activity

(x-y) m

30 min

10

Calefu

Vitamin A

Vitamin B

Vitamin C

Vitamin D

80.2 12:0 g

08

5000 iu 13.7 mg.

20

0,03 g

0

4

9. 10

0.128

150-in

0.27.og

2 g

2.iu

(a) If a man puts himself on

a diet of cow's milk, calaulate the weight of milk required to provide enough energy for him per day.

(b) Why would a diet of cow's milk be inadequate for man?

(c) Name two deficiency

diseases as a result of (b).

(d) Which of the vitamins

would not necessarily be

present in our food? Why?

(e) Give an important

component of mammal's

food, which is absent in cow's milk..

The following diagram

shows the method to

investigate the activity

of enzyme A.

37°C | 30 mín

boiled egg white

buffer solution

enzyme aÅ

glass tube

The effect of pH on enzyme activity can be investigated by using buffer solutions of different pH values. The results are recorde As shown in the followin table.

pil of the

X

Y

buffer solution (mm) (1)

35

1.0

37

36

35

33

(a) Describe the function of

enzyme A.

(b) (1) Using the above data

plot a graph with

enzyme activity' a the vertical axis and

pH as the

horizontal axis.

(2) What is the optimum pH for the activity of enzyme A?

(3) Give a possible

activation for the activity of enzyme1⁄4À at pil 10;

(c) Suggest an enzyme in our

alimentary canel, which has properties similar to enzyme A. Give reasons for your suggestion.

ANSWERS

1.(a) 11500 X 100

276

@

(2) The optimum pH

determined in this experiment is pH 2 (3) Enzyme A does not

-function at pH 10, perhaps the enzyme protein is t

inactivated or

denatured in such alkaline solution:

Pepsin.

Pepsin is a gastric enzyme which digests

protein and acts best at pll 2.

1981

中學會考試題預習專欄

地理

明德出版社李婉儀提供資料

GEOGRAPHY (1).

1. Y. Lee

MILL & DALE PRESS LTD.

series of exercises is to

help you to get aā

much better

result in the Geography Paper

of the School Certificate Examination. Two essay type questions are each time, with suggestive model answers. They aim at supplying supplementary information as well as providing revision for you. To acquire the optimum bebefit, students are advised to think of the points carefully by themselves first bofore reading the model answers, The questions are 90 carefully set that they covering almost every item of

Jon Syllabus, not only give

you ample

also help you evaluate your ability to observe accurately, interpret systematically and present your ideas logically.

Revisional Questions:

1. If you were given the task

of setting up a school weather station to measure * relative air temperatures". humidity and rainfall amounts, what would you buy?. How would you set them out? Draw well1-Tabelled diagram to illustrate your answer

Suggested Answers: 1.8.

Air temperatures. To measure air.

temperatures, the following instruments should

be bought:

1) An ordinary mercury

thermometer to measure current air temperature or the temperature at a

particular time,

Maximum thermometer to nca sure maximum temp Minimum thermometer to measure minimum temp. DIAGRAMS TO SHOW THE THREE TYPES OF THERMOMETERS Mercury thermometer

Bulk

Mercury in

Maximum thermometer with constriction

Constriction Mer

4167 (c)

・Break in mer

tirend

報日僑華

Maximum thermometers with ・metal index

•Max. T":

Merc

Métal index

Minimum thermometer

Alcohei

Metal inder

Procedure of Setting Up

四期星

1) All the above instruments

should be housed

horizontally in a Stevenson Screen.

2) This is done since shaded

temperatures are required. 3) The Stevenson Screen is a

wooden box whose roof is

air double boarded with an space between so that the heating effect of the sun can be minimized.

The louvred sides allow the air to move freely so that the air inside the acreen has the same characteristics as the air

outside.

5) The screen is painted white

to improve insolation.

6) The screen is mounted on a

stand to avoid heat

reflecting from the ground. from influencing the thermometers directly. ·

7) It should be positioned in

the most open and exposed place with its door opening to the north to prevent the sun from

shining into the screen whilst readings are being

taken.

The readings should be recorded daily at a fixed time, preferrable in the morning. After recording, the maximum thermometer should be reset by using a magnet (for the one with a metal index) or by shaking

vigorously (for that with

a constriction) and the minimum thermometer should. be reset by tilting it gently,

b. Relative humidity

To measure relative.

humidity, a wet-bulb "and dry-bulb thermometer should. be bought.

VET-BULB AND DRY-BULB THERMOMETER

Dry-bulb thermometer

Mercury.

Wet-bulb thermometer

Procedure of Setting Up 1) It should be housed in the

Stevenson Screen, too,

2) The bulb of the wet-bulb

thermometer should be kept moist all the time by covering it with muslin which dips into a container of water.

3) The difference between the

two readings is an indicator of the humidity of the air:

if there is no difference the air is saturated if the difference is large

humidity is low if the difference is small

humidity is high The actual value of relative humidity is obtained by checking the reading from a book of tables.

Amounts of Rainfall

"To measure the amount of rainfall, a rain gauge necessary.

A RAIN GAUGE

Funnel

~Copper cylinder.

Glass bottle

Outer capper case

Procedure of Setting Up

In setting up the rain gauge, the following points must be noted:

) It must be put on level

ground.

2) It must be placed in an

exposed position, far away from any objects which might affect the amount of rainfall collected. If the

日九月十年〇八九一圈公年九十六國民華中育教儁輩

buildings and trees are present, the gauge must be positioned away from them

at a distance of at least twice the height of these objects.

3) It must be sunk in the

ground to prevent it from being blown or knocked

over.

4) The top of the funnel must

be 30.8cm (12") above ground-level, to prevent rain nearby splashing inte the jar.

2. Below are diagrams showing

information of rainfall in Hong Kong. With the aid of

for the diagram, account seasonal and geographical distributions. of rainfall in Hong Kong.

Fig.I RAINFALL DISTRIBUTION

OF HONG KONG

Over 2500mm 1760-2000

7 2000-2250mm 69 below 1750mm

Fig. II TEMPERATURES &

RAINFALL OF HONG KONG

JÉMAMIJAS OND

Suggested Answers::

2. The Seasonal Distribution of Rainfall in Hong Kong

From the Climatic: graph,

ve can see that the rainfall annual in Hong Kong, with an total of about 200 – 2500. mm,

does not distribute evenly. About 80% of the rain occurs

from in the summer months - May to Sept. A monthly total of over 250 mm in the summer rainy season is not uncommon. While in winter, it is

relatively dry.

The summer maximum of rainfall in Hong Kong can Partly be explained by the influence of monsoons. Hong Kong lies in the Asian monsoonal wind belt, în summer, a low pressure belt is formed over Mongolia, while a high pressure belt is found over the sea. As a result, the wind blow inland from the sea. They are therefore moist and they bring heavy rain to Hong Kong In winter, the winds blow offshore because the low pressure over Mongolia is by now replaced a high pressure system. Thus the winds that influence Hong Kong are quite dry (Fig. Fig. A THE SUMMER MONSOON

OF ASIA

INTENSE

HORSE AT HIGH)

DOLORUM

Besides the monsoons, the seasonal distribution of rainfall in Hong Kong is also greatly affected by typhoons. The typhoons, which attack Hong Kong mostly from May to Sept, are always accompanied by torrential rain (Fig. B). Fig.B MAIN TYPHOON TRACKS IN THE WEST PACIFIC OCEAN

Whast of the

Arogical

formed to

the

Furthermore, the high summer temperatures in Hong Kong (with an average around 27 C) are likely to induce rainfall too. When the land surfaces are overheated, strong vertical air currents set up. As the air ascends, its temperature is reduced until condensation takes place and clouds are formed. The water droplets in

clouds will become bigger with further ascept, which meaus further cooling, In time the water droplets in clouds become too big and heavy to be saturated, rain

egins to fall, This type of rain is known as convectional rainfall. Hong Kong, being situated in the tropical latitudes, the convectional rainfall is especially characteristic in summer (Fig. C).

Fig.C FORMATION GE

CONVECTIONAL RAINFALL

DESCENDING

COOLER PENSER AIR

cloyd's

RAIN

GRISING WARM AIRL

the sun

and surface heated.

The Geographical

Distribution of Rainfall in Hong Kong

Fig II is the annual rainfall map of Hong Kong. The map shows that the areas with muximum rainfall (over 2200mm) coincide with highland areas, e.g. Tai Mo Shan region and Lantao Shan region.

The areas with the lowest amount of rainfall (below (1800mm) lies on the weat,

the northwest lowland around Deep Bay, the southwest of Lantao Island and the Tsing.. YI Island. Such a geographic distribution indicates an orographic effect. This is because, as mentioned above; most of the rain in Hong Kong is brought by onshore monsoons which blow mainly in an easterly direction from the

sea. As the moXAMS,

winds meet the

they will be forced to rise, They are then cooled, condensation thus, occurs and clouds are formed. Being subjected to much the same process as those in the rising air currents as heated, water droplets fall down at last, Thus the mountain regiona, especially the east-facing alopes in Hong Kong, have more rain because of this orographic effect. By the time the winds reach the lowlying western part, they are depleted of moisture. As they descent the leeward slopes, they are wormed by compression Consequently, there is little rain and these areas are referred to as rain shadow areas (Fig. D).

Fig.D THE FORMATION OF

OROGRPHIC (relief) RAIN

∙As air ascends, it becomes cooler.. ・and saturated:

R.H. rises

Wind ward slope

As air descends

1st compressed

and becomes

Warmer

B.H. falla

RAIN.

SHADOW

Leeward slope

Mountain

mass