Solar ponds are bodies of water in which circulation is incomplete and there is a very high salt concentration that
An artificial pond of this type has been constructed on the western shore of the Dead Sea in Israel in order to test its suitability as a source of low-grade heat for conversion into electricity. An immediate threat to the success of the venture was the growth of algae. Water in solar ponds must be kept maximally transparent to allow penetration of light to the deep storage area. Therefore, any particles of matter in the water, such as algae cells, that scatter or absorb light will interfere with the collection of heat.
One proposed method of controlling the algae was the application of an algicide. However, the Dead Sea is a closed body of water without any outlet and as such is very easily contaminated. Extensive use of chemicals in numerous future full-scale solar ponds would lead to such contamination of the Dead Sea, which now enjoys a lucrative tourist trade.
A recent experiment has supplied a more promising method for controlling the algae. To repress the algae cells' capacity for accommodating themselves to environmental changes, the water in the solar pond was first made more saline through evaporation and then diluted by a rapid inflow of fresh water. This shock reduced the cells' ability to regulate the movement of water through their membranes. They rapidly absorbed water, resulting in distortions of shape, increase in volume, and impairment to motility. Their buoyancy adversely affected, the cells sank to the bottom of the pond, where they encountered the hot waters of the storage layer and were destroyed. This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use.
Which of the following, if true, would seriously undermine the
(A) The algae cells that sank to the bottom of the pond were destroyed only after a time lag of twenty-four hours.
(B) The lateral motility of the algae cells that sank to the bottom of the pond was not impaired.
(C) The water with which the artificial solar pond was diluted contained microorganisms that kill algae.
(D) The algae cells that sank to the bottom of the pond were actually killed by the rapid change in pressure.
(E) The higher salinity brought about through evaporation increased the transparency of the upper levels of water in the pond.
- 【OG18-P680-668题】In a review of 2,000 studies of human behavior that date back to the 1940s, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could be taken seriously.
- Following several years of declining advertising sales, the Greenville Times reorganized its advertising sales force two years ago. Before the reorganization, the sales force was organized geographically, with some sales representatives concentrating on city-center businesses and others concentrating on different outlying regions. The reorganization attempted to increase the sales representatives’ knowledge of clients’ businesses by having each sales representative deal with only one type of industry or of retailing. After the reorganization, advertising sales increased.In assessing whether the improvement in advertising sales can properly be attributed to the reorganization, it would be helpful to find out each of the following EXCEPT:
- The author of the passage would most likely agree with which of the following statements about the link between increased solar activity and certain seasonal weather changes on the Earth?
- The passage provides information to support which of the following statement about La Nina?
- X: In order to reduce the amount of plastic in landfills, legislatures should impose a ban on the use of plastics for packaging goods.Y: Impossible! Plastic packaging is necessary for public safety. Consumers will lose all of the safety features that plastic offers, chiefly tamper-resistant closures and shatterproof bottles.Which of the following best describes the weak point in Y's response to X's proposal?