1978-02-22 — Page 29

日二十月二年八七九一服公年七十六國民華中

育教僑華 頁一第張八第日六十月正年午戊夏

WAH KIU YAT PO

報日僑

三期星

13 Sodium (or potassium) hyro-

xide: to absorb CO2.

Black-box.

cap

present time. It faces: the

Light

育教僑華

14 Vaseline; for air-tightness.

A

B

C.

problem of rural overpopulation) because there is a very high proportion of the population engaged in agriculture, From the shown figures, there is 75% of the btal working papu- lation engaged in agriculture but

1978

【中學會考試題預習專欄

生物 廿一 梁永華

BIOLOGY (21)

Tnit 11

About Experiments.

I THE DETERMINATION OF SOME

SUBSTANCES

1 OXYGEN

a. Relights a glowing splint b. Absorbed by pyrogallol

solution

2 CARBON DIOXIDE.

a. Turns lime water milky b. Turns bicarbonate indi-

cater solution yellow:

e. Abosrbed by sodium hydro-

xide or potassium hydro- xide

3 CONCENTRATION OF CARBON

DIOXIDE IN WATEX

Add several drops of bicarbonate indicator solution to the solution sol.colour

co_conc. >0.035

Yellow

Orange

Red.

4 WATER

a.

0.03 <0.03

Turns white anhydrous copper (31) sulphate blue

b Turns blue anhydrous

cobalt chloride paper pale pink

c. Absorbed by calcium-

chloride

S REDUCING SUGARS e.g. glucose

a. A brick-red precipitate

is formed on boiling with Fehling's solution (Fehling's Test)

b-An orange precipitate is

formed on boiling with Benedict solution (Benedict's Test)

6 NON-REDUCING SUGARS eg.

sticrose

Boil the solution with a few drops of conc. hydro- chloric acid and ther⠀ neutralize it with sodium hydroxide solution, An orange precipitate is

formed on Eailing with the Benedict's solution

7 STARCH

Forms a blue-black colora-. tion with iodine solution:

8 FATS AND OILS

Drop then on a filter paper a translucent mark which can be removed by ether appears ('Grease-spot 'Test

9. PROTEIN

A brick-red precipitate is formed on heating with Millon's reagent (Millon's. Test)

II THE USE OF SOME CHEMICALS IN

BIOLOGICAL EXPERIMENTS

1 Agar: for the culture of bacteria and fungi; to. demonstrate the effect of auxins.

2 Alcohol: for aterilization;

to extract the chlorophyll out of the leaf.

3 Anhydrous cobalt chloride

to test water vapour

4 Anhydrous copper sulphate:

to test water

Calcium chloride: to absorb

moisture.

5 Ether: to dissolve lipids;

to etherise animals.

7. 10% formalin solution: to kill cells; to preserve biological specimens.

8 Methylene blue: to stain.

cells.

9 15 milton solution; for

sterilization.

10 Lime water ( Ca(OH)2solution);

to test and to absorb 002.

11 Pyrogallol solution: to

absorb oxygen.

12 0.9% saline: an isotonic

solution.

15 Watery iodine solution: to

test starch.

III SOME REMARKS

These a

are some points which may be asked in questions about experiments.

1. The concept of CONTROL

A CONTROL or CONTROL EXPERI-

MENT is an experiment with its set-up similar to that of the

test experiment except that

all conditions are kept normal.

It is used as a standard of

comparison for results of the test experiment.

Examples:

a.hy is a control essential

in this experiment? (73нKCEE):

b.How would you prepare a con-

trol for this experiment? (72HKCEE).

2 The CHOICE OF MATERIALS

Both the quantity and quality of the experimental materials should be noticed." Examples:

a What would be the advantages:

or disadvantages of using two or one hundred bean seeds in each set? (73HKCEE) : b.What complication would occur

in this experiment if the germinating seeds had begun to show green leaves?(72HKCEE). c.Explain why fruit-fly is a good choice of material in studying genetics?

3 The SET-UP

The purpose and the correct- né sa of the

up may be asked mental set-

Examples:

a.Why the wire gauze place in

a slanting position?(76HKCEE). b.What is the hypothesis that

this experimental set-up is endeavouring to verify? (721KCEE)

C.The apparatus was not set

up properly. Suggest, with reason's, two corrections you would wake to improve the experiment? (76HKUEE) 4 Describe and explain the

CHANGE OF the RESULT

Describe and explain step by step. Give complete answer. Do not write things. that are not needed.

Questions may be asked in this way.

What colour change of the solution would you expect. to see in test tube C. ? Give reasons for the change.

(75HKCEE) - P.

b. What would be the difference

in the development of the fruits above and below the ning after several days? Explain why there is such a difference: (76HKCEE).

5 To draw CONCLUSIONS

Draw conclusions directly from the experiment. Do no write things that cannot be drawn from it although they are true.

TV EXCERCISE

4 A student tried to investi-

gate whether fermentation- can take place in a boiled yeast-sugar solution, Naving cotton-pluged the flask and boiled the solution, he left it (fig 1) on the table and observed the change several days later..

fig.1

Cotton-plug

flask

"Yeast-sugar

solution (boiled)

Which of the following is

a suitable control for this experiment ?

A.

B.

C

yeast- sugar solution

yeast in

sugar water... solution

(not (not (not boiled) boiled) boiled)

E

D.

sugar solution

(boiled)

yeast-sugar solution

(boiled)

2 The following experimental

set-up shows the responses

of treated seedlings to unilateral light.

不隨禮柯多新彩無報請速 另報拜式采頴色任販就 :收附出印多雜華歡訂近關 費送版刷姿誌儒 ̊迎閱向戸

Which of the following conclusions can be drawn from the results of the above experiment.

a) Haked seedlings bend towards the light b) Auxing accumulated at

the shaded side of the seedlings...

c) The tip of the seedlings is sensitive to light

d) Growth occurs at the

tip of seedlings

A. a

B. ac C. abc D. acd E. abcd

AME: 1A 23.

地理

GEOGRAPHY (21)

李婉儀。

Suggested answers tu. ¿uestions, 36 & 37:

River capture had taken place in that area.

Before capture occurred, there were two main streams. flowing in the area, they ran parallel to each other, from NE to SW. One of them (stream S), with a tributary flowing. NW - SE (St), discharged into the sea near Sham Tseng, ether (T), flew slowly and discharged into the sea near Tsing Lung Tan (Fig. 1).

The

As shown by map 'evidence, stream St is a more powerful river because of its steeper gradient, more serione head- ward erssion took place at ita source, and in this way, St extends headvards, It came nearer and megrer to Stream T. Finally, 16 broke through the watershed and the two streams. met together. River

capture did take place. Due to the the steeper gradient of st, upper water of stream T was diverted into the valley of St.

Since the upper water of

T had been diverted to 5t, its -lower-course now has little- water. It becañas small for the existing valley and is therefore known as a misfit stream. There is a sharp bend. where a trean T is captured and is known as the elbow of cap- ture.

e. Beside the elbow of cpature, there is a wind gap or a dry valley (Fig. 11). RIVER CAPTURE NEAR TAI LAM CHUNG

FIG.I.

·BEFORE CAPTURE

•Tring Lung

Tol

FIG. II.

AFTER CAPTURE

Elbow of

Capture

Wind Gap

Misfit stream

37.

Sham Tseng

Viting

Pirate.

Steep sided valley

resulted from downculling

PROBLEMS DERIVED FROM OVER- POPULATION

Low living standard and wal sutrition

The mentioned country has a tremendous population of about 40 millions. It has a high birth rate of 47/1000. The natural increase rate is about 32/1000, qui te a high rate in population growth, We can see that this country has more people than the resourses can support at his

t only 1/5 of the tal area is used for cultivation, Obviously, the agricultural lands, which have been inten- sively cultivated for years, decressed in their yields.

A constant, fear of famine and low living standard accompany the high population in this

People suffer from undernourishment and malnutri-

area.

tion.

Low productivity

The farming methods which engaged in this country are so sutdated that there almost 1/5 of the total area is me fallowed er abandoned. Since toe much land is useless (including 40% of the stal area is woodland and 20% is uban- doned land), the production from both the primary and secondary economic activities canxet catch up with the growing size of population.

Lack of capital

The development of in- dustry is quite slow. It has only 5% of total werking pop- ulation engaged in industry with merely 1% of the total area used as industrial land. The under-development of the secondary porduction in- plies that the national income of this country is mest probably net high enough to support its large population. It has no surplus of colome- ditites for export. It can hardly reach capital Tation. ithout enough capital, it canmet require a higher level of economic development. Diversification of its economy is impossible for lacking of cupital.

Unemployment

10% of the total werking populatisa is enemployed. The burden of the country is heavier in case te support this unemployed werkers. Lack of Bacial welfare services

The medical services in this country are as matter⠀ underdeveloped for the death rate is about 15/1000, qui to -high, în comparison with those

advanced countries. Young people lack sound education. Most people live in simple, unhygienic conditions,

SOLUTIONS

Develop sparsely populated areas (migration}

Out-migration te sparsely populated areas should be encouraged, in order to re- lease the burden of those densely populated countries,

Internal-migration can

The. alas be encouraged. country which has large area can urge its people to Beve to the potentially rich marginal districts.

2. Land Reform

Land should be redistri- buted into larger and more economic units in order to euble mechanization and implementation of irrigation. schemes and water conservation. Diversification of agri culture should also be encouraged ss that soil fertility can be. conserved and productivity raised.

3. Increase of agricultural

products

A higher yield in agri- culture is possible by

a) wider application of chen- ical fertilizers to improve. soil fertility..

b) introduction of better seeds, new strains or new breeds of animal.

c) Opening up or reclaiming more arable land by terracing of the mountain sides or

· making use of the marginal. land to create new fields.

d) Implementation of water. conservation, drainage and irrigation schemes,

e) Educating the farmers. the basic knowledge of soil science and plants.

f} Increased use of insecti– cides and other agenta to control the pests and diseases.

4. Increase of marine products

Marine products cam be increased by better fishing methods. Fish breeding in local lakes, ponds and rivers alse supply additional food for people..

5. Reduction

rate of repu-

lation increase

Encourage the young late marriage and introduce family planning to the married couple in order to reduce the family members. These can give the children better opportunity to receive sound education. The practice of birth control may also provide more leisure time and money for the married couple.

6. Foreigh aids-

If the overpopulated area! can receive aids from rich advanced countries, ita econozy can be promoted in a greater stride.

7. Industrialization

The overpopulated cou) – tries should employ new/ industrial methods to produce

core manufactured praducta. for experts which will obtain more money to buy food for feeding their people. After industrialization, capital will easily accumulated and help indirectly further pre- duction.

Questions for revisions

38.

The diagram above shows the characteristic features on a fload plain, name the Features marked A – D and for each, explain its formation.

39.

Describe the industries of Shanghai and New Castle-Part

Kembla Region,and show how they are dependent on local natural resources.

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