1978-11-03 — Page 31

TIL DE NO 莫三第張八第日三初月十年牛皮层夏

1979

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生物

BIOLOGY (4)

Unit Two: Respiration

(四)

4. Four test-tubes containing

bicarbonate indicator so- lution are set up as shown in the following diagran. They are placed in bright light

Snail

B

D Air-

tight

Hydrilla

Test-tube B and D contain a snail of same weight Test- tube C and D contain an equal amount of green plant material (Hydrilla). The bicarbonate. indicator solution changes colour in accordance with the carbon dioxide concentration in the solution as shown in the table below.

Colour of

indicator

solution

Red

Orange Yellow

CO2

002

concentration

by volume):

<<0.03%

= 0.03% 0.03%

At the beginning of the ex- periment the colour of the bicarbonate indicator solu-: tion is orange in all the test-tubes. Two hours later, the results are observed.

(a) What is the importance of

testotube A in this ex- periment?

(b) What colour change of the solution would you expect to see in test-tube B? Give reasons for the change.

(c) What colour change of the solution would you expect to see in test-tube C. Give reasons for the change.

(d) Suggest a possible reason

to explain why there is no colour change of the solution in test-tube D.

(e) In which tube do organ-

iams die first? Give reasons.

(f) In which tube do organ-

iems die first if all the tubes are kept in total darkness? Give reasons.

5. The diagram below shows

the apparatus used to demonstrate yeast respi- ration.

B

Gas X

yeast-

glucose solution

A mixture of 10 ml. 10%.

glucose solution and 0.6g of dried yeast was put in a flask. The volume of the gas produced was. · measured at 10-minute inter- vals. The results are shown in the following table:

glucose solution.

WAH KIU YAT PO

(b) What is the function of

(1) the structure A.

(2) the structure B.

(*) Name' the gao X.

(d) What other substance was

formed during the experi- ment?

(e) Using the above data, plot

a graph to show the pro-. duction of gas X in rela- tion with time.

(f) From the graph calculate the initial rate of res- piration of the yeast cells.

(g) Give a reason to explain

why the volume of gas X

released remained conɛ-

tant 70 minutes after.

the beginning of the experiment..

(h) Suggest an improvement

on the apparatus so that a more satis factory result would be obtained.

Answers:

4(a) Test tube A is taken as a control for comparing the colour of the carbonate indicator solution in test-tubes B, C and D.

(b) The colour of the solu- tion in test-tube B becomes yellow.

The increased carbón dioxide concentration in. water, due to the respi- ration of the snail, causes the solution to become yellow.

(c) The colour of the, solu- tion in test-tube. C becomes red.

Under the bright light. the activity of photo- synthesis occurs to a greater extent than that of respiration. The decreased carbon dioxide concentration in water causes the solution. to become red. (d) Since carbon dioxide

released by both orga- nisms during respiration compensates the amount consumed by the activity. of photosynthesis, there is no change in the carbon dioxide concen tration and therefore no colour change.

(e) Tube B.

No additional oxygen supply for the respira- tion of the snail.

(f) Tube D.

Both the snail and the plant use oxygen for respiration. That oxygen is consumed faster than that in other tubes makes the organisms to die first.

5. Boiling the glucose (a)solution would

(1) drive away all the dissolved oxygen in order to provide an anaerobic condition.

(2) kill the bacteria to ensure that the gas is: produced by the respira- tion of the yeast cells only.

(b)(1) A was used to regu-

late the pressure inside the flask so that the syringe can be set at zero mark at the begin ning of the experiment. (2) B was used to mea- sure the volume of the gas produced during the experiment.

(c) Carbon dioxide. (d) Ethyl alcohol.

(e) 4r

Time (min) (cm3)

Gas

60 34

70

36

10%

80

36

20

12

90

36

30

17

100

36

40

50

28

62730

28

(a) The glucose solution was

firstly boiled and then cooled before it was mixed with dried yeast cells. Give two possible reasons for boiling the

gas vol.(cm3).

10

40752 % 140

Time (minute) (f) The initial rate of

respiration of the yeast cells is

3

報日僑華

(g) The yeast uses up all

glucose in respiration. When no more respiratory substrate is present, respiration ceases; the curve remains at constant level subsquently.

(h)

The apparatus can be placed in an environment with constant tempera- ture (e.g, a water bath) so that the respiratory. activity of the yeast and the volume of gaɛ

cannot be affected by any fluctuation in the

surrounding temperature.

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(四)

地理

GEOGRAPHY (4)

Suggested answers i

The Seasonal Distribution

of

Finfall in Hong

the clinatio graph, we can see that the rainfall in Hong Kong, with an annual total of about 2,000 - 2,600 me,, does not distribütə svenly. About 80% of the rain oòcurs in the summer. months - from May to Septem- ber. A monthly total of over 250 mm. in the summer rainy season is not uncommon." While in winter, it is rela- tively dry.

The summer maximum of· rainfall in Hong Kong can partly be explained by the influence of mensoOME.: Hong Kong lies in the Asian mons sonnal wind belt, in summer, a low pressure belt is formed over Mongolin, while a high pressure belt is found over the sea. As a result, the winds blow inland from the som. They are therefore moist and they bring heavy rain to Hong Kong. the winds blew offshore bacaune the low pressure over Mongolia is by now replaced by a high pressure system. Thus the winds that influence

· Hong Kong are quite dry (Fig. A).

In winter,

RIGA. THE SUMMER MONSOON OF ASLA

INTENSE

Low:

PRESSURE

*HONG KONG

HORSE LAT

HIGH

„DOLD RUMS

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 September, ‘are always, accomm panied by terrential rain (Fig. B)

FIG.B.

五期星

日三月一十年八七九一层公年七十六國民體中

set up.

As the air ascends, its temperature is reduced until condensation takes place and clouds are formed, The water droplets in the clouds will become bigger with further ascent, which means further cooling. In time the water droplets in clouds become too big and heavy to be saturated, rain begins to fall. This type of rain is known as convec➡ tional rainfall. Hong Kong being situated in the tropi- oal latitudes, the conves-- tional rainfall is especially characteristic in sTERMEZ (Pig. C). Fle. C. FORMATION #4 CONVECTIONAL

071

RAINFALL

Cumulo-Nimbus cloudsy

RAIN

level.

warm

Land surface heated by the sun

The Geographical Dis tribu- tion of Rainfall in H.K.

they

FIG. II is the annual rain- fall map of Hong Kong. The map shows that the areas with maximum rainfall (over 2,200 mm.) coincide with highland areas, t.g. Tai Mo Shan region -

The and Lantao Shan region. areas with the lowest amount of rainfall (below 1,800 mm, liss on the vest, e.z. 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 becacuse ,ns mentioned above,

most of the rain in H. K. is brought by onshore monsoons which blow mainly in an a terly direction from the men. As the moisture-laden winds meet the mountains, will be forced to rise. They are then cooled, condensation thus occurs and clouds are fromed. Being subjected to much

the same process, a

in the rising currants as heated; water dropleta fall down at last. Thus the mountain regions, especially the east-facing slopes in Hong Kong, have mover rain because of this orographie effect. By the time the winds reach the low- lying western part, they are depleted of mainture. As they descent the leeward

warned by slopes, they aED. compression. “onsequently, there is little rain and these areas are referred to as rain shadow areas (Fig. D),

MAIN TYPHOON TRACKS INTE

THE WEST PACIFIC OCEAN

da air accends,

·It becomes taster

+ Saburated- R.H. nie

HONG KONG

F16.0.

Plost of the Tropical cyclones gre formed to the

F. of the

I Milippines.

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,

(28/50)cm3/min.-0.24cm3/min. strong vertical air currents

0.

¿Asaredescents.

Leeward

MOUNTAIN

MASS

24 Compressed becomes

R.M. faits

[RAIN.

| WBIES --

THE FORMATION TE ORDURAPHIC (RELIEF) RAIN

The North China Plain and ́

of The Country with rich

natural resources' where agri onlture haa benefited a lot from its favourable natúral endowment. A comparison of the two regiona can be viswad from the following aspecte:

A) Method of Framing

The Szechwan Basin is. hilly in nature. Flat land is limited to only about 5% of the whole basin and secur only in patches. This moun-- tainous nature has direct effect on farming method. Terracing on slopes is out- standing. Fields are small and intensively cultivated,

Although intensive sub- sistence agriculture still exists in the North China Plain the transformation in the last twenty years cannot be overlooked. Due to the" flatness of the region, the Land Reform: Movement and the. rapid indus trialization since recent years, the subsistence intensive agriculture in the region has been gradually transforming into modernized agriculture. In recent years, Communes, are organised - small land holdings or poor possant are combined and cultivation is brought under joint effort, With this Land Reforem Hove- ment, farm ailes are increase and there is certain degree of mechanization,

B) Types of Crops

Szechwan, being situated to the south of Tsinling, has abundant rainfall and long growing season which enable the growth of double-cropped *paddi. kice in the most im-

portant food crop and its annual yield represents more than 80% of the total food production. Besides the pro- duction of food crop, Szechwan has long been famous of its wide range of cash orope produced, ..g. cotton, tang oil, milk, sugar-sane, tex, tobacco and fruits,

The cooler temperaturez of the North China Plain, the other hand, favours

growth of wheat, baT), ZER D

millet and kaoliang.

are important food crops in the region. Cash crops are important, too. Cotton, peanut, soya-bean and fruit are produced in large quantities.

C) Advantages benefited

Difficulties to be

Overcine.

Because of the warm temperatures, leng growing season and fertile soils, the productivity in the bas is very high. However, fur agricultural development depends on the importation of irrigation systems and trans» portation, and must ge hand in hand with industrial deve- lopment, too.

In spite of the fertile. alluvial soils and the flatness of the region, the agriculture in the North China Plain suf- fere a lot from the frequent flooding of rivera and drought cuased by the unreliability of rainfall. The operation of the Hwang-ho Multi-Purpose Water Soheme has provided sone checks against the nat- ural hazards, Just the same, the schone should go hand in. hand with industrialisation, urbanisation and improvements on transportation, thus North Chins can become China'n paradise.

+

Questions for Next Week:

7.

Using the following figures, describe the variations of Szechwan Basin are two imper-weather elemente on the day

tant agricultural regions in Chine. The North China Plain, Which is the largest plain is China, with over 60% of ita land under cultivation, has the largest peasant population. The memote inland basin of...“ Szechwan, on the other hand, being a hilly region, with about 60% of its land under cultivation, has long been known as 'Tien-fu-chih-kuo1

recorded.

Local

Time Cină

Temp

(°C) Aziative

Rainfall

{14}{2}04|82|48|19|12|14|16|18|20|22||

||25|24|23|22|24|34|7|34|33|29||37|23|