32天
115. OG10 (Botany)+ s4 a3 a( k( _5 ~7 s
开始听写在:2008-6-1 下午 09:15:25
Y! f/ Y9 n7 W( T8 sListen to part of (a) talk in a botany class, okay, so we’ve talk (about) some types of root systems of plants, and I’ve shown you some pretty cool slides, but now I want to talk about the extent (of) the root system, the overall size of the root system, the depth, I want to tell you about one particular experiment, I think you’re going to find this pretty amazing, okay, so, there was this scientist, this very (meticulous{n.一丝不苟的})scientist decided that the best (place) to see the whole root system, to actually see how big the entire system got, the best place to be to grow it, where, um, water, in water, so he took (rye{n.裸麦,黑麦}) plants, it was rye plants, and he started growing them in water, now, you’ve all heard (of) growing (staff) in water (before), right? It’s done commercially, like to grow vegetables and flowers, right, they grow all (kind of) commercial crops in water, so, if you’re growing things in water, you can add the fertilizer, what do you need to do to that water besides to put fertilizer in it, anyone (ever) actually tried to grow plants in water, you must bubble water through it, bubble gas through it, I’m sorry, you must bubble gas through it, so, gas, you have to bubble through, think about the soil we talked about last week, about growing plants in soil, think about some of you who have killed your favorite plant because you loved them to much, if you over water, why do your favorite houseplants die, oh, no oxygen, not enough oxygen for the roots, which do what twenty-four hours a day in all seasons, respiration, respire, respiration, they breathe, if you just (stick rye) plants in water, it doesn’t make difference how much fertilizer you add, you also need to bubble gas through the water, so they have access to that oxygen, if they don’t have that, they’re in big trouble, okay, so this (guy), this scientist grew a rye plant in water so he could see the root system how big (it) got, its surface area, I read about this and the book said one thousand kilometers of roots, I kept thinking, this has to be a mistake, it just doesn’t make any sense, to me, that, that could be right, but that’s (what) all the books have, and no one’s ever corrected it, so, let me explain to you about this rye plant, if you take a little seed of many grasses, and remember rye is a grass, and if you take a tiny little seed and you (germinate{v.使发芽}), actually, take one of my least favorite grasses that’s starts growing about may, what’s my least favorite grass that growing about may, crabgrass, remember how I show you in the lab, one little seed starts (out producing) one little shoot, then at a week so later you’ve got about six shoots, and then, three weeks later you’ve got about fifteen shoots coming out all directions like this, all those little shoots up there, well, that’s what they did (with the rye), and (the) little seedling started and pretty soon there were several shoots, and then more shoots, in the end, that one signal seed produced eighty shoots, with an average of fifty centimeters of height, from one seed, eighty shoots coming out, average fifty centimeters high, when they looked at the shoot (versus{prep.对;与...相对}) the root surface, they found (that) the shoot surface, with all of its leaves, had a total surface area of about five square meters, now, here is the (biggie{n.大的东西}), when they looked at the root surface area, you would except (that) the root and the shoot would be in balance, right, so, they should be pretty close in (terms of) surface area, right, um, what’s that, does somebody say no, well, you’re absolutely correct, instead of five square meters, the root system was found to have more than two hundred square meters of surface area, where did all of that extra surface area come from, who did it, who was responsible for those extra square meters of surface area, what did roots do to increase their surface area, root hairs, root hairs, that’s exactly it, so those root hairs were responsible for incredible chunk of surface area, they constantly have to be spread out in the water so they can absorb minerals from the fertilizer, and of course they need oxygen access as well.
& t' B8 O; d$ O以上听写编辑在:2008-6-1 下午 10:15:57
9 ?4 V' T& D# c! j7 |听写结束。共录入 1句, 737英文单词。
9 r5 n% Z$ ^) G. E- B3 O开始时间为:2008-6-1 下午 09:15:25,结束时间为: 2008-6-1 下午 10:15:58,共用时
+ _7 \2 d; v/ p' n60分钟。平均 12.2833333333333词每分钟。116. 0310 (Plant react pest)" `5 }6 l9 O3 @5 @# l! z# o& X; M! {4 B
开始听写在:2008-6-1 下午 11:25:08
' ^& V* t/ ~# X8 I4 B5 J' ?Listen to part of
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in biology class, today, we’re going to talk about special way some plants respond to the invaded by pests, the plants react by (emitting) a chemical signal, which (acts) like (a) call for help, let’s take corn plants for example, sometimes, caterpillars chew on the corn leaves, when the caterpillar (saliva{n.唾液}) mixes with the chew potion of (a) leaf, the plant releases a chemical cream that attracts wasps, the wasps respond (to) the signal by flying to the chewed on leaf, and laying their eggs on the caterpillars, the caterpillar die in the next few days (as) the swaps offspring nourish themselves by feeding of them, thus the corn plant prevents all (its) leaves from being eaten by the caterpillars, this chemical cream is specific, it’s only (released after) the plant has detected the caterpillar (saliva), a plant that (is cut) by the other means doesn’t give off the same signal, nor doesn’t undamaged plant, this also explains how wasp can find caterpillar in (a) huge (field) of corn, soybean, cotton (and) probably many other plants use the similar type of defense against pests, by enhancing this natural response (in) plants, researchers might reduce, some day even eliminate the (need) for chemical pesticide, which can cause ecological damage, for example, scientist might (breed) plants for this (creaming trait), or they might transplant specific genes to increase the release of (the) chemical signals.
R! b2 i6 f+ B& H以上听写编辑在:2008-6-1 下午 11:58:18
9 Z# n' m- T0 _" ~% n听写结束。共录入 1句, 228英文单词。3 u9 l5 o; z1 o
开始时间为:2008-6-1 下午 11:25:08,结束时间为: 2008-6-1 下午 11:58:18,共用时
5 Z. J( w+ b- f$ s4 K7 K: k* e4 l33分钟。平均 6.90909090909091词每分钟。
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[ 本帖最后由 eagledoudou 于 2008-6-2 20:00 编辑 ]