High-Q | חטיף 4

חטיף מס '4

אנגלית

Reading Comprehension This part consists of two passages, each followed by several related questions. For each question, choose the most appropriate answer based on the text .

Text I (Questions 13-17)

Southern California residents, having weathered fire, floods, riots, and a 6.7 earthquake in recent years, are now enduring - what else? - pestilence. The culprit is linepithema humile , a tiny ant that hitchhiked to New Orleans aboard ships from Argentina sometime around the turn of the century and has since spread over much of the United States. Last August, researchers reported that linepithema , besides being a tenacious 5 household pest - "They don't sting or bite humans, but once inside your house they're a pain to get rid of," says researcher Andrew Suarez - is also wreaking agricultural and ecological havoc in California. The Argentine ants, as they're called, are prolific and mobile. Each colony contains multiple queens, each queen produces thousands of eggs a day, and the same ant family 10 may found colonies that are miles apart. Too much rain, or too much heat, and the ants flee their shallow nests to colonize the cooler, sheltered habitats of humans - in droves. The threat they pose to agriculture is more indirect but involves perhaps more serious consequences. "The ants love honeydew, the sweet excrement of aphids," says Suarez. "They'll actually cultivate aphids and protect them from other predators." Aphids, of 15 course, are the bane of farmers and backyard gardeners alike, destroying tomatoes, citrus fruits, and other crops by sucking juices from leaves and stems. While pampering aphids, the Argentine invaders are savaging California's native harvester ants, ecologically useful insects that consume, and thus help spread, plant seeds. Argentine ants don't eat seeds, but in battles for territory they mob and dismember the 20 larger harvester ants. The impact of those battles reverberates up the food chain - to horned lizards, for example, which feed on harvester ants. By strapping tiny radio transmitters to lizards' backs, researchers found that as soon as linepithema drives the native ants out of an area, the lizards invariably leave, too, and change their diet from ants to beetles. What effect that has on the lizards' ability to grow and reproduce or on their own predators - such 25 as birds and snakes - is still unknown.

Questions

13. The primary subject of the passage above is -

(1) how some ant species use aphids to provide food (2) the natural life cycle of linepithema (3) an ecological problem caused by ants (4) different ant species of southern California

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