Biodiversity(生物多样性), or biological diversity, is a wide-ranging concept that covers all the different kinds of plant and animal species present on earth. Environmentalists believe that many millions of species exist. As all these living organisms are dependent on each other in some way, biodiversity is desirable. Any loss to the planet is actually a loss for mankind as well, and it is our responsibility to try and save Earth’s biodiversity.
Biodiversity has a vital role to play in the evolution（演变）of species. Species become extinct, but new species evolve, and this is how a balance is maintained. This may sound pretty simple, but it takes millions of years for changes to take place.
Biodiversity is also very important to the stability of food webs. Damage to them can mean disaster for an entire ecosystem. The extinction of a single animal species can put huge pressure on the numerous other species dependent on it.
Biodiversity also has an important role to play in human society. Apart from being the most intelligent species on earth, human beings are also the most dependent. We depend on nature to meet our basic needs. When we change the balance of nature to create our cities and bring about our technical advances, we knowing or unknowing cause great damage to the ecosystem. This must be understood, and the damages must be reversed（颠倒）in any way they can to ensure that the balance of the ecosystem is maintained.
小题1:We learn from the first paragraph that_________.
A biodiversity can be seen
B all living species are found on earth.
C people everywhere are aware of the importance of biodiversity
D the loss of any species can affect humans
小题2:Why can change in food webs lead to disaster?
A Because it can make people suffer from disease
B Because it can put huge pressure on some species
C Because it takes a long time for such changes to take place
D Because it will damage ninety-nine percent of species
小题3:What does the underlined word probably mean?
A 画线 B Peace C Strength D Variety
小题4:We learn from the last paragraph that __________.
A humans are as independent as they are intelligent
B the balance of the ecosystem is easily maintained
C nature has given us a lot
D nature is taking revenge on us
小题5:Which of the following may be the best title for this passage?
A Food Webs are Closely Related to Biodiversity.
B Biodiversity Plays a Very Important Role in Evolution
C How Biodiversity Affects Human Society.
D Understanding Biodiversity and Its Importance.