A: imbalances in ecosystems
B: develop new dominant pest species
C: lose keystone species.
D: Beneficial organisms and even natural enemies of the pests may be among the species eliminated by pesticides
举一反三
- The first species to live on new land, such as that formed from volcanic lava, are called A: clomax community. B: keystone species. C: foundation species. D: pioneer species. E: parasite.
- The amino acid sequence of cytochrome c is used to reveal the organisms that are most closely related. Which of the following organisms are most closely related? A: Species R and S B: Species S and T C: Species T and W D: Species S and W
- None of these species may feel entirely “at home"in the new place — but together, they may make a(n) _______ species list. A: progressive B: aggressive C: impressive D: excessive
- The most effective way to prevent extinctions for the long term would be A: protecting the endangered species habitat B: capture breeding programs C: paying poachers to refrain from poaching D: removing the predators of endangered species E: instigating feeding programs for endangered species
- The conclusion seems to be that we ______. A: could make use of more natural species B: don't cultivate the right kind of food C: produce more food than we need D: cultivate too many different species
内容
- 0
The representative strain that can represent the typical characteristics of a strain is called ( ). A: Model species B: Typical species C: Representative species D: Reference species
- 1
How many_______known altogether A: species of fishes are B: species of fish is C: specieses of fish are D: species of fish are
- 2
What is the keystone species for the Pacific northwest? A: kelp B: sea urchin C: fish D: sea otter
- 3
Questions 22 to 25 are based on the following passage. What has happened since the end of the Ice Age A: Many species have moved further north. B: Many new species have come into existence. C: Many species have developed a habit of migration. D: Many species have become less sensitive to climate.
- 4
_____ is the existence of a wide variety of plant and animal species living in their natural environment.