托福聽力涉及話題多樣，尤其是偏向于學(xué)術(shù)課堂場景的講座類，經(jīng)常考到一些我們并不熟悉的學(xué)科，適當(dāng)?shù)恼莆找恍┍尘爸R(shí)和常考考點(diǎn)有助于我們更迅速精準(zhǔn)地聽懂聽力內(nèi)容。光學(xué)是托福聽力常考學(xué)科話題領(lǐng)域之一，無論是機(jī)經(jīng)真題還是托福TPO都能見到它的身影，下面我們就結(jié)合TPO28的Lecture3涉及的“紅光與遠(yuǎn)紅光”,了解一下托福聽力會(huì)如何考察相關(guān)內(nèi)容吧。

Introduction：

Red and Far-red

光環(huán)境是植物生長發(fā)育不可缺少的重要物理環(huán)境因素之一,通過光質(zhì)調(diào)節(jié),控制植株形態(tài)建成是設(shè)施栽培領(lǐng)域的一項(xiàng)重要技術(shù)。紅光和遠(yuǎn)紅光的吸收比率對(duì)植物的生長有重要影響。

Background information：

Light isan important environmental factor in most ecosystems. Photosynthetic organismsin particular must sense and respond to light cues to optimize their growth andmetabolism. The quantity, direction and spectral make-up (the color or'quality') of the light sensed by an organism conveys information regarding theabiotic and biotic environment and can be used to control adaptive responses.One superfamily of photosensory receptors comprises the phytochromes ('plantcolor'), which absorb in the red/far-red part of the spectrum. These receptorswere first discovered in plants in the 1950s, but have more recently beenidentified in a broad spectrum of eukaryotic and prokaryotic phyla.

Far-redlight is light at the extreme red end of the visible spectrum, between red andinfra- red light. Usually regarded as the region between 710 and 850 nmwavelength, it is dimly visible to some eyes. It is largely reflected ortransmitted byplantsbecause of the absorbance spectrum of chlorophyll, and itis perceived by the plant photoreceptor phytochrome. However, some organismscan use it as a source of energy in photosynthesis. Far-red light also is usedfor vision by certain organisms such as some species of deep-sea fishes.

Knowledge points：

1. 生態(tài)系統(tǒng)中光是十分重要的一個(gè)元素。特別是光合生物必須感知和響應(yīng)光來優(yōu)化它們的生長和代謝。

2. 光感接收器中間的一部分由光敏色素組成,它吸收光譜中的紅光和遠(yuǎn)紅光。

3. 遠(yuǎn)紅光大部分都被植物反射掉了。然而,有些植物在光合作用中用遠(yuǎn)紅光作為能量來源。一些深海魚類用遠(yuǎn)紅光來辨別視野。

Vocabulary prediction：

Infrared 紅外線

Photoreceptor 感光器

Ratio 比率

Simulate 模擬

Test Point – TPO28L3

Plants are also able to distinguish betweenspecific wavelengths of light that the human eye cannot even see! Specificallythere’s a wavelength called far-red. Although why they call it far- red ... Imean, it is not red at all. It lies in the infrared range of the spectrum. Wecan’t see it, but plants can sense it as a different wavelength.

OK. Now I need to mention another thingabout photosynthesis. I didn’t explain how different wavelengths of light affectphotosynthesis. When a plant absorbs light for performing photosynthesis, itonly absorbs some wavelengths of light and reflects others.

Plants absorb most of the red light thathits them, but plants only absorb some of the far-red light that hits them.They reflect the rest. Remember this, because it’s going to be relevant in anexperiment I want to discuss.

This fascinating experiment showed thatplants not only detect and react to specific wavelengths of light, plants canalso detect and react to changes in the ratio of one wavelength to another.This experiment was called the Pampas experiment.

Knowledge points

1.遠(yuǎn)紅外線并不是紅色的。只是它位于光譜中紅外線的頻譜。人類不能看見,但是植物能夠感知它。

2.當(dāng)植物吸收光線用作光合作用,植物僅僅吸收一些特定波長的光線,反射另一些。

3.植物吸收大部分的投射到的紅光,但是植物只吸收一部分遠(yuǎn)紅光。

4.植物也可以就不同波長的比率做反應(yīng)。