1981-01-24

頁二第張六第日九十月二十年申庚歷

1981

WAH KIU YAT PO

association between the

nitrogen-fixing bacteria and leguminous plants.

Þau (a) State the importance of

生物

(十六)

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Leung

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Unit 13: Environment

The following diagram is a food web in a habitat.

Sun

(1) the nitrogen-fixing

bacteria to the

leguminous plants.

(2) the leguminous plants to

the nitrogen-fixing bacteria.

(e) Give two uses of nitrates.

to plants.

(f) (1) Name the processes A,

B and C.

(2) Describe and explain the effects on plants and.. animals if process A is inhibited,

(g) Give two ways by which

nitrogen in animals returns

to the soil,

ANSWERS:

Green: plants

Cater

pillar

[Mouse

Snake

Hawk

Sparrow

(a)(1) What is the importance of

the sun in this food web? (2) What does the arrow

denote in this food web? (3) By what processes that energy is lost from one level to another.

(b)(1) Construct is a pyramid of

numbers using some of these organisms.

(2) Account for the difference.

in number of the organisms.

to the community if

(1) insecticides are used in

this habitat.

(2) Hawks are killed in this

habitat.

The following diagram is a simplified nitrogen cycle.

Animals

Ammonium compounds

| Plants ||Nitrites:

Nitrates

(a) What should X be?

Nitrogen fixing bacteria in

the root nodules of leguminous plants

(b) Which form of nitrogen is

the greatest nitrogen

reservoir of the system?

(a)(1) The sun is the ultimate

energy source of the food web.

(2) The arrow denotes the flow of energy or the passage of materials from one level to another.

(3) Energy is lost from one

level to another because some of the energy is utilized by the organisms to do work and some of the energy is lost as heat.

(b)(1)

Hawk

Sparrow

Hawk

Cater- pillar

Green plants

Snake

Mouse

Green plants

(2) When energy flows through

a food chain, only a small proportion of the energy taken up by each link is transferred to the next

step because some of the

energy is lost as heat and for utilized by the

organisms to do work. On

the other hand, the

organisms become progressively bigger than the organisms being consumed, therefore number of organisms in each step progressively decrease towards the top of the food chain as the amount of available energy progressively decreases. (c)(1) If insecticides are used in

this habitat, the number

六期星

of caterpillar decreases. As a result, the number of green plants will increase since less green plants are consumed by caterpillar, but the number of sparrow will decrease due to inadaquacy of food (caterpillar).

(2) If hawks are killed in this habitat, the number of sparrow and snake will increase, 'since less predator eats them. As a result, the number of caterpillar and mouse will decrease since they are the foods of sparrow and snake respectively.

(a) Atmospheric nitrogen. (b) Atmospheric nitrogen. (c) Symbiosis.

(d)(1) Nitrogen-fixing bacteria

provide, the leguminous plants with nitrogenous compounds.

(2) The leguminous plants

provide the nitrogen-fixing bacteria with water, nutrients and shelter. (e)(1) Synthesis of protein.

(2) Synthesis of chlorophyll. (f) (1) A: absorption

B: nitrification

C: denitrification. (2) Since plants use nitrates

to form proteins and chlorophyll, the inhibition of process A would cause a reduction of growth and eventually death of the plants. Since animals feed on plants, they would also result in death for the lack of food.

(g) Excretion and decomposition

of their death remains.

理

地

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GEOGRAPHY (16)

Y. Y. Lee

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31.

(a) Mushroom-shaped rook

blocks are common in desert areas. Explain in brief their formation.

(b) Compare and contrast. zeugen and yardang in their places of origin, outward appearances and

formations.

日四廿月一年一八九一股公年十七國民華中目播育教

Suggested Answers:

(a) In desert areas, wind is

the most powerful agent of erosion. Winds, armed with loads, may abrade or wear down the rock surfaces with which it comes into contact. As most of the coarse materials are transported only half a metre above the ground, the power of abrasion is most effective at that level. The winds. uplifting these materials as a tool undercut the base of a boulder, which is gradually transformed into a mushroom-shaped blocks can be of gour. The blocks can be of uniform structure, i.e. it is not necessary to have a resistant layer overlying a soft one,

(b) 1) Places or Origin

Both of them are common features found in desert area or areas: which experienced arid climate for a long time. 3) Outward Appearances

Both of them are ridge and furrow landscapes, consisting of depressions or furrows separated by long block-like ridges. The ridges of zeugen may be as high as 30 metres. The ridges of yardang may stand up as high as 15

metres..

Formation

Both of them are formed mainly by wind erosion.

For the zeugen, the presence of joints are erosion. Joints are numerous important in controlling wind

in the rocks in arid regions as produced by physical weathering induced by marked diurnal temperature changes. If it so happens that parallel vertical Joints are found in rocks which have a horizontal resistant layer overlies the weaker ones, wind. abrasion will concentrate along the joints. As abrasion proceeds, these joints are further enlarged into long depressions separated by block-like ridges. The ridges have a wide top because the resistant layer forms a capping rock protecting the weaker rocks

Different from the zeugens,

below.

yardangs are mainly found in

areas where layers of

resistant and soft rocks lie

parallel to the direction of

prevailing wind. Abrasive action will be most effectively along the softer, less-resistant layers, turning them into t furrows. In between the furrows, the resistant bands or may stand up as ridges.

rocks

32. Name the type of coast

shown in the sketch map below. Describe and account for the characteristics of this. type of coast.

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