GRE Reading Comprehension
Many organisms are capable of altering their habitat significantly, sometimes limiting their own growth. The influence of the biological component of an ecosystem is often greater in fresh waters that in marine or terrestrial systems, because of the small size of many freshwater bodies. Many of the important effects of organisms are related to their physiology, especially growth and respiration. By their growth many species can deplete essential nutrients within the system, thus limiting their own growth or that of other species. Lund has demonstrated that in Lake Windermere the alga Asterionella is unable to grow in conditions that it itself has created. Once a year, in the spring, this plant starts to grow rapidly in the lake, using up so much silica from the water that by late spring there is no longer enough to maintain its own growth. The population decreases dramatically as a result.
Question List: 2
It can be inferred from the passage that which of the followings is true about Asterionella plants in Lake Windermere?
- A They are not present except in early spring.
- B They contribute silica to the waters as they grow.
- C They are food for other organisms.
- D They form a silica-rich layer on the lake bottom.
- E Their growth peaks in the spring.
Correct Answer: E