【雅思閱讀分享篇】說(shuō)說(shuō)葉子那些事兒

做過(guò)劍橋真題10的同學(xué)會(huì)知道在雅思閱讀test3中有篇文章講樹葉的事情，標(biāo)題就是Autumn Leaves。里面有些貌似比較專業(yè)的詞匯實(shí)際我們?cè)谥袑W(xué)的生物課上學(xué)植物相關(guān)內(nèi)容的時(shí)候都有所涉獵，比如葉綠素(chlorophyl)、花青素(anthocyanin)、針葉樹(conifer)等。此外很多同學(xué)覺(jué)得內(nèi)容非常的專業(yè)，其實(shí)這是篇很平常的科普文章。

那么在雅思閱讀中為什么這篇文章很多同學(xué)覺(jué)得內(nèi)容難理解呢？一般會(huì)有以下幾個(gè)原因：1.平時(shí)對(duì)科普文章涉獵太少，注意力被生詞吸引，覺(jué)得高不可攀；2.相關(guān)的比較基本的背景知識(shí)不足，增加了理解的難度。

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如果你覺(jué)得雅思閱讀中這些科普文章虐了你，那只能說(shuō)明你還是被他們虐得不夠。那么今天就讓我們?cè)偻谝煌谌~子的那些事吧。先讓我們來(lái)看看什么是葉子，英文版哦~

A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot. Foliage is a mass noun that refers to leaves collectively.
Typically a leaf is a thin, dorsiventrally flattened organ, borne above ground and specialized for photosynthesis. In most leaves, the primary photosynthetic tissue, the (palisade mesophyll), is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves have distinctive upper (adaxial) and lower (abaxial) surfaces that differ in colour, hairiness, the number of stomata (pores that intake and output gases), epicuticular wax amount and structure and other features.

那葉子又是如何進(jìn)化的呢？讓我們來(lái)看看Leaf Adaptations： 【在線咨詢】

Poinsettia bracts are leaves which have evolved red pigmentation in order to attract insects and birds to the central flowers, an adaptive function normally served by petals (which are themselves leaves highly modified by evolution).
In the course of evolution, leaves have adapted to different environments in the following ways:
·A certain surface structure avoids moistening by rain and contamination (See Lotus effect).
·Sliced leaves reduce wind resistance.
·Hairs on the leaf surface trap humidity in dry climates and create a boundary layer reducing water loss.
·Waxy leaf surfaces reduce water loss.
·Large surface area provides large area for sunlight and shade for plant to minimize heating and reduce water loss.
·In harmful levels of sunlight, specialised leaves, opaque or partly buried, admit light through a translucent leaf window for photosynthesis at inner leaf surfaces (e.g. Fenestraria).
·Succulent leaves store water and organic acids for use in CAM photosynthesis.
·Aromatic oils, poisons or pheromones produced by leaf borne glands deter herbivores (e.g. eucalypts).
·Inclusions of crystalline minerals deter herbivores (e.g. silica phytoliths in grasses, raphides in Araceae).
·Petals attract pollinators.
·Spines protect the plants (e.g. cacti).
·Special leaves on carnivorous plants are adapted to trapping food, mainly invertebrate prey, though some species trap small vertebrates as well (see carnivorous plants).
·Bulbs store food and water (e.g. onions).
·Tendrils allow the plant to climb (e.g. peas).
·Bracts and pseudanthia (false flowers) replace normal flower structures when the true flowers are greatly reduced (e.g. Spurges).
·Spathe.

雅思閱讀高分詞匯Vocabulary:  【在線咨詢更多詞匯】

apex （n.）葉子的尖端
midvein (Primary vein) （n.）中脈
secondary vein （n.）副脈
lamina （n.） 葉片
leaf margin（n.） 葉緣
petiole（n.） 葉柄
bud（n.）芽
stem（n.）莖
palisade（n.）細(xì)胞層
mesophyll（n.）葉肉
isobilateral（adj.）等面的
stomata（n.）氣孔
epicuticular wax（n.）表面蠟質(zhì)
poinsettia bract   n. 一品紅苞片
fenestraria  n.棒葉花屬
succulent  adj. 多汁的；多水分的；多汁性的, n. 肉質(zhì)植物；多汁植物
photosynthesis n. 光合作用
aromatic adj. 芳香的，芬芳的；芳香族的 ,n. 芳香植物；芳香劑
pheromone n. 信息素（用于生化領(lǐng)域）；費(fèi)洛蒙（昆蟲分泌以刺激同種昆蟲之化合物質(zhì)）
herbivores n. [動(dòng)] 食草動(dòng)物，植食動(dòng)物；食草者（herbivore的復(fù)數(shù)形式）
crystalline adj. 透明的；水晶般的；水晶制的
petal n. 花瓣
carnivorous adj. 食肉的；肉食性的
tendrils n. [植] 卷須；卷須狀物（tendril的復(fù)數(shù)形式）
pseudanthia n. [植] 偽花（pseudanthium的復(fù)數(shù)形式）
spathe n. [植] 佛焰苞

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