All plant cells are capable of taking up（吸收）water. Even dead ones do to a certai

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All plant cells are capable of taking up（吸收）water. Even dead ones do to a certain degree. Absorption（吸收）of water by dead cell walls makes wood become larger.
In common land plants, the living cells of roots take upmost of the water. Land plants without roots do exist, however. Those greenish-yellow lichens（苔藓）you see on rocks in the high mountains have no roots. Half a billion years ago, when water plants started to enter the land, the first land plants did not have roots.
Even among the flowering plants, one finds rootless forms. These flowering plants are “the higher plants” because they evolved（进化）recently and are thus considered higher on the evolutionary scale（进化度）.
In the Peruvian desert, there grows one of these rootless higher plants, a bromeliad. It is a relative of the pineapple. Even if this plant had roots, they would be of no use, because where the plant grows, it never rains. The plant gets its water only from the dew（露水）it collects at night, when its leaves cool off. Such rootless plants, of course, can be moved with ease, but they will only grow when they are placed out in the open. If they are placed too near a house, the radiation from the heat of the house prevents the leaves from cooling and so prevents dew from forming, and the plant dies.
In the southern United States and in Puerto Rico, one sees bromeliads growing high above the streets on the insulation（绝缘物）of electric wires. These plants get their water from rain, and the only soil they ever come in contact with is the dust that may blow on their leaves.
小题1:Wood becomes larger because of       .

A．dead cell walls	B．water entering dead cells
C．the growth of cells	D．the death of cells

小题2:From the passage we know that the evolutionary scale is graded according to      .

A．evolutionary cycles	B．heights and depths
C．time	D．kinds

小题3:The “bromeliad” is a plant that     .

A．has no roots	B．is a pineapple
C．can grow anywhere	D．takes up water through its leaves

小题4:The most suitable title for this passage is “      ”.

A．Absorption of water by plants	B．Rootless plants in America
C．Plants in the desert	D．Higher plants

答案

小题1:B
小题2:C
小题3:D
小题4:A

解析

小题1:B  根据短文第一段中的“Absorption（吸收）of water by dead cell walls makes wood become larger.”可知，树木变大是因为水分进入了细胞。选项A意为“死细胞壁”；选项B意为“水分进入死细胞”；选项C意为“细胞的生长”；选项D意为“细胞的死亡”。所以选项B正确。
小题2:C  根据短文中的“Even among the flowering plants, one finds rootless forms. These flowering plants are “the higher plants” because they evolved（进化）recently and are thus considered higher on the evolutionary scale（进化度）.”以及下文可知，进化度是依据时间逐渐发生变化的。选项A意为“进化周期”；选选项B意为“高度和深度”；选项C意为“时间”；选项D意为“种类”。所以选项C正确。
小题3:D  此题为词义猜测题。根据此段中的“These plants get their water from rain, and the only soil they ever come in contact with is the dust that may blow on their leaves.”可知正确答案为D (通过其叶子补给水分的植物).
小题4:A  选项A意为“植物对水分的吸收”；选项B意为“美洲的无根植物”；选项C意为“沙漠中的植物”；选项D意为“高等植物”。根据短文第一段及全文可知，正确答案为A.