'09.

Nutrition and gas exchange

in plant

Q&A

What are the raw materials of photosynthesis?

光合作⽤⽤什麼作原料？
carbon dioxide and water

⼆氧化碳和⽔
State the products of Photosynthesis.
說出光合作⽤的產品。
glucose/glucose and oxygen

葡萄糖/葡萄糖和氧氣
What is the by-product of photosynthesis?
光合作⽤的副產品是什麼？
oxygen

氧氣
What happens to the product after its formation?
產品形成後會變成什麼？
Glucose converted to starch for storage.

'09. Nutrition and gas exchange in plant 1

 葡萄糖隨即轉化為可儲藏的澱粉
What is the source of oxygen?
說出氧氣的來源。
water⽔

What is the function of light in light reaction?

光在光反應中有什麼⽤？
Water is split by light energy to give hydrogen atom and oxygen gas.

葉綠素吸收光能把⽔光解成氫原⼦和氧氣，氧釋放到植物體外。
What happens in dark reaction?
暗反應有什麼事發⽣？
Carbon dioxide is reduced by hydrogen to form carbohydrates.

⼆氧化碳被氫原⼦還原為碳⽔化合物。
Can dark reaction take place in light?
暗反應可否在光中進⾏？
可以 yes
Write the word equation of photosynthesis.
寫出光合作⽤的⽂字⽅程式。
⼆氧化碳 + ⽔ 葉綠素
光
葡萄糖 + 氧氣
carbon dioxide + water chlorophyll

light

glucose + oxygen

What is the fate of carbohydrate produced in the plant?

植物所製造的碳⽔化合物的最終命運為何？
for energy release, for storage and conversion into other products for
growth.

提供能量，儲起或轉化成⽤作⽣⻑的物質。
State the two importance of photosynthesis?
說出光合作⽤的兩個重要性。

'09. Nutrition and gas exchange in plant 2

 Ultimate food source for all living organisms

⽣物的最終極⾷物來源
Produce oxygen and remove carbon dioxide.

產⽣氧氣並排除⼆氧化碳
State the factors that affect the rate of photosynthesis?
說出影響光合作⽤的因素。
light, carbon dioxide, water supply, temperature

光、⼆氧化碳、⽔的供應、溫度
How does light intensity affect the rate of photosynthesis?
光度如何影響光合作⽤？
Photosynthetic rate increase with light intensity.

光合作⽤速率隨光度增加⽽增加
What happens to chlorophyll when the light intensity is too high?
光度過強對葉綠素有何影響？
destruction of chlorophyll

葉綠素被破壞
Which light colours are most effective in photosynthesis?
何種光⾊最為有效？
red and blue light

最有效的光是紅光和藍光
Which light colour is ineffective in photosynthesis?
何種光⾊最為無效？
green light

綠光
17 What happens to the chlorophyll in the absence of light?
缺少陽光對葉綠素有何影響？
chlorophyll degenerate and the leaves turn yellow

葉綠素會退化樹葉便變成⿈⾊

'09. Nutrition and gas exchange in plant 3

 How does CO2 concentration affect the rate of photosynthesis?
⼆氧化碳的濃度如何影響光合作⽤的速率？
Photosynthetic rate increase with concentration of carbon dioxide up to
1%

光合作⽤速率隨⼆氧化碳濃度增加⽽增加直⾄1%
How to increase CO2 concentration in water?
如何在⽔中增加⼆氧化碳的濃度？
It can be increased by adding sodium hydrogen carbonate into water.
(aquatic plants only)

⼆氧化碳濃度可以透過在⽔中加⼊碳酸氫鈉來增加
How does water supply affect photosynthetic rate?
⽔的供應如何影響光合作⽤的速率？
In short of water, stomata close, carbon dioxide supply reduces, and the
photosynthetic rate drops.

⽔源短缺，氣孔關閉，⼆氧化碳供應減少引致光合作⽤速率下降
How does temperature affect photosynthesis?
溫度如何影響光合作⽤的速率？
Photosynthetic rate increase with temperature up to 40oC.

光合作⽤速率隨溫度增加⽽增加直⾄40oC
Explain why does the photosynthetic rate drop when temperature is over
40oC.
解釋超過 40oC 時為什麼光合作⽤的速率會下降？
Over 40oC, enzymes is denatured

超過40oC酵素會變質
Describe the process of photosynthesis in detail
詳細解釋光合作⽤怎樣進⾏ ?

Photosynthesis occurs inside chloroplasts. There are 2 stages namely

light and dark reaction.Light

reaction : chlorophyll absorb light, water is split by light energy to give

hydrogen atom and oxygen gas. Oxygen gas is released.

'09. Nutrition and gas exchange in plant 4

 Dark reaction : Carbon dioxide is reduced by hydrogen atom to form
carbohydrates.

光合作⽤在葉綠體進⾏，分為光反應和暗反應兩個階段。在光反應中，葉
綠素吸收光能把⽔
光解成氫原⼦和氧，氧釋放到植物體外。在暗反應中，氫原⼦與⼆氧化碳
結合成碳⽔化合物。
Name a chemical that is used to absorb carbon dioxide.
說出⼀種可吸收⼆氧化碳的藥物。
Potassium (or sodium ) hydroxide

氫氧化鉀(或鈉)
Name a chemical that is used to supply carbon dioxide to water plants.
說出⼀種可供應⽔⽣植物⼆氧化碳的藥物。
Sodium hydrogen carbonate (sodium bicarbonate)

碳酸氫鈉
What happen to lime water when CO2 is added to it?
當⼆氧化碳加進⽯灰⽔時有何轉變？
Carbon dioxide turns lime water milky

⼆氧化碳可將⽯灰⽔變為奶⽩⾊
What is the purpose of using lime water in the experiment?
在實驗中使⽤⽯灰⽔的⽬的為何？
It is used to check whether all carbon dioxide has been removed).

⽤來測試⼆氧化碳是否⼰除盡
State the colour changes of bicarbonate indicator when
(1) a little of CO2 (2) CO2 is 0.03% (3) a lot of CO2

說出碳酸氫鹽指⽰劑顏⾊上的轉變當
(1) 很少 CO2 (2) CO2 是 0.03% (3) 很多 CO2

(1) purple紫⾊， (2) red紅⾊， (3) yellow⿈⾊

State the function of epidermis and cuticle.

說出表⽪和⾓質層的功能。
Epidermis: protect the inner layers of leaf cells.

'09. Nutrition and gas exchange in plant 5

 Cuticle: prevents water loss and bacterial (or fungal) infection on leaf
surface.

表⽪:保護樹葉內層的細胞，
⾓質層: 在葉的表⾯保護⽔份的散失和免受細菌(或真菌)感染
State the function of stoma and guard cell.
說出氣孔和保衛細胞的功能。
stoma :for gases exchange and water loss by transpiration.

氣孔:⽤作氣體交換和蒸騰作⽤時的⽔份流失
guard cell : control the size of stomatal opening.

保衛細胞: 控制氣孔開關的⼤⼩
State the features of palisade mesophyll.
說出柵狀葉⾁的特徵。
It is on the upper side of leaf, closely packed, contains many
chloroplasts.

在葉的上層，緊密排列，含有許多葉綠體
State the features of spongy mesophyll.
說出海綿葉⾁的特徵。
It is loosely packed with large air spaces, allow rapid diffusion of gases
to promote photosynthesis, contains less chloroplasts.

鬆散排列和有⼤氣室，容許氣體快速擴散以促進光合作⽤，含有較少葉綠
體
What will be the advantages of having closely packed palisade mesophyll at
the upper side
and a lot of chloroplasts within it?

柵狀葉⾁在上層緊密排列並含有許多葉綠體有什麼好處?
This arrangement can speed up the rate of photosynthesis. For the
chlorplast are much more

concentrated in the paliside mesophyll and it is on the upper side of the

leaf. Both features can help

it to obtain more light when compare with spongy mesophyll.

'09. Nutrition and gas exchange in plant 6

 這種分佈模式使葉⽚能較快速地進⾏合作⽤。由為柵狀葉⾁的葉綠體密度
較⾼，再加上柵狀
葉⾁是位於葉⽚的上層，所以可以⽐海綿葉⾁吸收更多光。
State the function of xylem and phloem.
說出⽊質部和韌⽪部的功能。
xylem : It contains vessels for carrying water and mineral salts, provide
mechanical support.

⽊質部: 含有⽤來運輸⽔份和礦物鹽的導管，提供機械性⽀持
phloem : It contains sieve tubes for carrying food away from the leaf.

韌⽪部: 含有運輸⾷物遠離樹葉的篩管
Before the photosynthesis experiment, what will be the treatment on the
plant? explain.
在光合作⽤實驗開始前，應如何處理植物 試加以解釋。 ?

Destarch the plant by keeping it in dark for two days.

將植物置於⿊房中⼆天以作去澱粉
Explain why do the plants can destarch after putting a dark environment for
2 days.
解釋為什麼植物置於⿊暗處⼆天後，便可以脫澱粉。
In darkness, the starch in leaf will be converted to sugar and transported
to other part of the plant.

⿊暗中，葉⽚內的澱粉會被轉化為糖，並運到植物的其他部份。
What is the general effect of deficiency of different elements?
缺少不同元素的⼀般性病狀是什麼 ?

The general effect of deficiency of different elements are Stunted growth

and chlorosis.

缺少各元素的⼀般性病狀是⽣⻑減慢及萎⿈病(⿈化綠葉病)。
Where does gases exchange occur in terrestrial plant?
陸⽣植物的氣體交換在什麼地⽅發⽣ ?

Plants exchange gases by diffusion. For terrestrial plants, gas exchange

takes place through leaves, stems and roots.

植物藉擴散進⾏氣體交換，在陸⽣植物中，氣體交換發⽣於葉、莖和根。

'09. Nutrition and gas exchange in plant 7

 Explain the meaning of compensation point.
解釋補償點的含意。
At low light intensity, photosynthetic rate equals to respiration rate. No
net exchange of gases occurs

在低光強度，光合作⽤速率等如呼吸作⽤速率，沒有淨氣體交換。

'09. Nutrition and gas exchange in plant 8