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Sunday Science: Plant water loss 植物水份流失
Welcome to Sunday Science! Every Sunday, we're going to guide you through some cool experiments that you can do at home. It's a good idea for you to keep a record of what you do in a Science Journal. That way you can record what you learn, compare results and maybe use them to design new experiments! Have a look at the Science Journal box for some ideas to get you started. Remember to always ask a grown-up's permission before trying out an experiment.
歡迎閱讀《週日科學版》！我們每週日都要為你介紹可以在家中進行的有趣科學實驗。你可以在《科學日誌》中記錄自己做了哪些活動，這樣就可以將所學的紀錄下來，比較這些結果，也許還可以利用它們來設計新的實驗！先看一下《科學日誌》的點子再開始吧。展開實驗之前，記得要獲得大人許可喔！
Sunday, Jan 06, 2008,Page 14
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照片: MICHAEL KEARNEY
PHOTO: MICHAEL KEARNEY, TAIPEI TIMES
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Have you ever wondered if plants lose water from their leaves? This week we're going to do an experiment to find out.
What you will need:
Various kinds of leafy plants
Small plastic bags or ziplock bags
Tape (optional)
▲ Before you start, note that this works best on plants exposed to the sun.
▲ Put a plastic bag around one leaf on each plant. Close the bag in such a way that water won't be able to easily escape. Be careful not to crush the stem of the leaf.
▲ Close another bag and leave it to one side. This is your control.
▲ Periodically take a look at the bags. Note how much moisture appears in each of the bags.
▲ After a couple hours, take the bags off the plants and record your observations.
(MICHAEL KEARNEY, STAFF WRITER)
你是否曾想過植物內的水分會不會從它們的葉子流失呢？這個星期，我們將要做實驗來驗證。
所需材料︰
各類多葉植物
小塑膠袋或是封口袋
膠帶（可有可無）
▲實驗以前，請注意：如果將植物暴露在陽光下，實驗效果會最好。
▲將塑膠袋套在每一株植物的其中一片葉子上，然後將袋口封好，讓水氣不容易跑掉。請小心不要把葉柄給壓壞了。
▲將另一個塑膠袋也封好，然後放置一旁，作為對照組。
▲定期觀察這些塑膠袋，注意每一個袋子有多少水氣出現。
▲數小時後，將塑膠袋從植物上拿下來，並記錄所觀察到的現象。
（翻譯︰楊鴻泰）
| WHAT'S THE SCIENCE? 科學原理 |
| Plants take up water through their roots. The water travels up the plants' stems and exits through the leaves. This cycle helps to keep water continuously traveling through plants. The water loss also helps to cool the plants down.
Water exits plants through their stomata. Stomata are located on the undersides of plant leaves. Transpiration is the loss of water from plants through their stomata. Water exits the stomata by evaporation.
Oxygen and carbon dioxide also pass through the stomata. The stomata include two guard cells that open and close depending on whether the plants need to hold on to or lose water.
植物藉由它們的根部來吸收水分。水分通過植物的莖然後從葉子散發出去。這樣的循環有助於水分持續在植物內輸送。水分流失也可以幫助降低植物本身的溫度。
水分透過位於植物葉子下側的氣孔散發出去。「散發」意指水分經由植物的氣孔流失，而水分透過蒸發的方式來散發。
氧氣和二氧化碳也會經由氣孔出入。氣孔包含兩個保衛細胞，會視植物需要留住或排放水分而打開或閉合。 |
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| VOCABULARY 今日單字 |
| 1. expose v.t.
暴露 (pu4 lu4)
2. control n.
對照組 (dui4 zhao4 zu3)
3. periodically adv.
定期地 (ding4 qi2 de5)
4. moisture n.
濕氣 (shi1 qi4)
5. broad adj.
寬闊的 (kuan1 kuo4 de5)
6. stomata n.
氣孔 (qi4 kong3)
7. transpiration n.
散發 (san4 fa1)
8. evaporation n.
蒸發 (zheng1 fa1)
9. guard cell n.
保衛細胞 (bao3 wei4 xi4 bao1)
10. waxy adj.
蠟的 (la4 de5)
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| SCIENCE JOURNAL 科學日誌 |
| Look up some information about plants on the Internet or in a biology book. Where do plants take water in? How does water travel to different parts of plants? Where do plants lose water? Why do plants in the desert usually have small leaves (or no leaves at all)? Where do plants tend to have broad leaves?
上網或是參考生物學書籍，查詢有關植物的資訊。植物是從哪裡吸收水分的？水分是如何輸送到植物的各個部位？植物的水分從哪裡流失？為什麼沙漠裡的植物葉子通常很小（或根本沒有葉子）呢？生長在哪裡的植物比較會有寬大的葉子呢？ |
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