| Perhaps the most familiar plant
movement belongs to one species of mimosa called the sensitive plant. Within
seconds, it can lower its leaves and make its tiny leaflets close up like
folding chairs. This movement is thought to be initiated by electrical impulses
remarkably similar to nerve signals in animals. But without the animals’
sophisticated motion machinery, the mimosa has had to be creative in devising a
way to move. For motion, the plant depends on tiny, bulb-shaped organs located at the base of each leaf stalk and leaflet. Called pulvini, these organs hold the plant parts in place. When the mimosa is stimulated--say, by a crawling insect or a sudden change in temperature--an electrical impulse sweeps through the plant. This causes potassium and then water to be shifted from certain cells in the pulvini to others, quickly turning one side of the A. geographical distribution of plant and animal species B. location and purpose of the pulvini C. appearance of the mimosa D. process that causes movement in the mimosa [单项选择]The Internet, perhaps the most important technological development of the past 30 years, succeeded unexpectedly. It started out in an experimental backwater, nurtured far from the mainstream. It was spawned with no business plan and with no CEO leading the charge. Instead, a group of researchers—nerds, really—had the very unentrepreneurial idea to develop a set of free and open technical protocols to move data from one place to another. The PC, which I think of as a companion technology to the Internet, likewise groomed as the hobbyhorse of passionate nerds who (at least initially) shared their designs. Both the Internet and the PC were released unfinished, and because they were open technologies, businesses and inventors could use them as a springboard for innovation. New applications were deployed to use them without needing the permission of their vendors.
This kind of openness isn’t found in cars, fridges, Video or any other major technology. It’s what helped the Internet and A. It was born as a result of a business plan. B. It was initially developed by enterpreneurs to make profits. C. It was born by accident as an open and free technique. D. It was born as a finishing product at first. [单项选择]
|
