Like all animal species, plant species must spread their offspring to suitable areas where they can grow and pass on their parents’ genes. Young animals generally spread by walking or flying. Because plants don’t have that ability, they must somehow hitchhike(搭车). Some plant seeds scatter by blowing in the wind or floating on water. Many other plant species, though, trick an animal into carrying their seeds. How do they do this? They enclose the seeds within a tasty fruit and advertise the fruit’s ripeness by its colour or smell. The hungry animal collects and swallows the fruit, walks or flies off, and later spits out the seeds somewhere far from its parent tree. Seeds can thereby be carried for thousands of miles. It may surprise you to learn that plant seeds can resist digestion. In fact, some seeds actually require passage through an animal’s body before they can grow.
Wild strawberries offer a good example of hitchhiking tactics. When strawberry seeds are still young and not yet ready to be planted, the surrounding fruit is green, sour and hard. When the seeds finally mature, the berries turn red, sweet, and tender. The change in the berries’ colour serves as a signal to birds which then eat the strawberries, fly off, and eventually spit out the seeds.
Naturally, strawberry plants didn’t set out with a conscious intention of attracting birds only when their seeds were ready to be dispersed. Nor did birds set out with the intent of planting strawberries. Rather, strawberry plants evolved through natural selection. The sweeter and redder the final strawberry, the more birds spread its ripe seeds; the greener and more sour the young strawberry, the fewer birds destroyed the seeds by eating berries before the seeds were ready.
46．What does the underlined word “dispersed” in the third paragraph mean?
A．spread                               B．eaten        
C．born                                  D．planted
47．For plants, which of the following is NOT a way of spreading their offspring to suitable areas?
A．Hitchhiking.                           B．Blowing in the wind.  
C．Floating on water.                     D．Tracking an animal.
48．Which strategy does the example of wild strawberries describe?
A．The conscious intent of attracting birds.     B．Spreading by walking.
C．Spreading by flying.                   D．The strategy of taking a lift.
49．Why does the author describe how strawberry seeds are spread?
A．To show plants are good at adapting to the environment. .
B．To show strawberry’s special way.
C．To show the plant has different ways of spreading seeds.
D．To show the mystery of plant.
50．What’s the passage mainly about?
A．How animals disperse offspring.          B．How plants disperse their offspring.
C．Plant evolution.                       D．Plants’ hitchhiking on animals.

科目 英语   题型 阅读理解   难度 较易