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人教版小学自然第九册第十一课的内容是观察植物茎内有输送水分和养料的细管。教科书上的方法是用刀切割植物的茎,观察到茎上渗出水滴,将植物浸在红水里,过一段时间,把植物水面上部的茎横切、纵切后,观察到植物的表皮内呈红色,这是因为植物吸收被红水染红的水分后,沿茎往上输送水分的缘故。此现象说明植物的茎内有
The content of the eleventh lesson of the Natural Pedagogic Element of the People’s Education Press Primary School is to observe the thin tubes carrying moisture and nutrients in the stems of plants. The textbook method is to cut the stem of the plant with a knife, observe the water droplets oozing from the stem, and soak the plant in the red water. After a period of time, the stem of the upper part of the plant is cut transversely and cut, and then the epidermis of the plant is observed. The inside is red, because the plant absorbs the water that has been reddish by the red water and then transports water along the stem. This phenomenon shows that there are