Directions:In this part, you will have 15 minutes to go over the passage quickly
For questions 1-7, mark
Y (for YES)if the statement agrees with the information given in the passage;
N (for NO)if he statement contradicts the information given in the passage;
NG (for NOT GIVEN)if the information is not given in the passage；
For questions 8-10, complete the sentences with the information given in the passage.
8. Animals on the Move
It looked like a scene from “Jaws”but without the dramatic music. A huge shark was lowly swimming through the water, its tail swinging back and forth like the pendulum of a clock.
Suddenly sensitive nerve ending in the sharks skin picked up vibrations of a struggling fish. The shark was immediately transformed into a deadly, efficient machine of death. With muscles taut, the shark knifed through the water at a rapid speed. In a flash the shark caught its victim, a large fish, in its powerful jaws. Then, jerking its head back and forth, the shark tore huge chunks of flesh from its victim and swallowed them. Soon the action was over.
Moving to Survive
In pursuing its prey, the shark demonstrated in a dramatic way the important role of movement, or locomotion, in animals.
Like the shark, most animals use movement to find food. They also use locomotion to escape enemies, find a mate, and explore now territories. The methods of locomotion include crawling, hopping, slithering, flying, swimming, or walking.
Humans have the added advantage of using their various inventions to move about in just about any kind of environment. Automobiles, rockets, and submarines transport humans from deep oceans to as far away as the moon. However, for other animals movement came about naturally through millions of years of evolution. One of the most successful examples of animal locomotion is that of the shark. Its ability to quickly zero in on its prey has always impressed scientists. But it took a detailed study by Duke University marine biologists S. A. Wainwright, F. Vosburgh, and J. H. Hebrank to find out how the sharks did it. In their study the scientists observed sharks swimming in a tank at Marine land in Saint Augustine, Fla. Movies were taken of the sharks’ movements and analyzed. Studies were also made of shark skin and muscle.
Skin Is the Key
The biologists discovered that the skin of the shark is the key to the animal’s high efficiency in swimming through the water. The skin contains many fibers that crisscross like the inside of a belted radial tire. The fibers are called collagen fibers. These fibers can either store or release large amounts of energy depending on whether the fibers are relaxed or taut. When the fibers are stretched, energy is stored in them the way energy is stored in the string of a bow when pulled tight. When the energy is released, the fibers become relaxed.
The Duke University biologists have found that the greatest stretching occurs where the shark bends its body while swimming. During the body’s back and forth motion, fibers along the outside part of the bending body stretch greatly. Much potential energy is stored in the fibers. This energy is released when the sharks body snaps back the other way.
As energy is alternately stored and released on both sides of the animal’s body, the tail whips strongly back and forth. This whiplike action propels the animal through the water like a living bullet.
Source of Energy
What causes the fibers to store so much energy? In finding the answer the Duke University scientists learned that the shark’s similarity to a belted radial tire doesn’t stop with the skin. Just as a radial tire is inflated by pressure, so, too, is the area just under the shark’s collagen “radials”. Instead of air pressure, however, the pressure in the shark may be due to the force of the blood pressing on the collagen fibers.
When the shark swims slowly, the pressure on the fibers is relatively low. The fibers are more relaxed, and the shark is able to bend its body at sharp angles. The animal swims this way when looking around for food or just swimming. However, when the shark detects an important food source, some fantastic involuntary changes take place.
The pressure inside the animal may increase by 10 times. This pressure change greatly stretches the fibers, enabling much energy to be stored.
This energy is then transferred to the tail, and the shark is off. The rest of the story is predictable.
Dolphin Has Speed Record
Another fast marine animal is the dolphin. This seagoing mammal has been clocked at speeds of 32 kilometers (20 miles) an hour. Biologists studying the dolphin have discovered that, like the shark, the animal’s efficient locomotion can be traced to its skin. A dolphin’s skin is made up in such a way that it offers very little resistance to the water flowing over it. Normally when a fish or other object moves slowly through the water, the water flows smoothly past the body. This smooth flow is known as laminar flow. However, at faster speeds the water becomes more turbulent along the moving fish. This turbulence muses friction and slows the fish down.
In a dolphin the skin is so flexible that it bends and yields to the waviness of the water.
The waves, in effect, become tucked into the skins folds. This allows the rest of the water to move smoothly by in a laminar flow. Where other animals would be slowed by turbulent water at rapid speeds, the dolphin can race through the water at record breaking speeds.
Other Animals Less Efficient
Not all animals move as efficiently as sharks and dolphins. Perhaps the greatest loser in locomotion efficiency is the slug. The slug, which looks like a snail without a shell, lays down a slimy trail over which it crawls. It uses so much energy producing the slimy mucus and crawling over it that a mouse traveling the same distance uses only one twelfth as much energy.
Scientists say that because of the slug’s inefficient use of energy, its lifestyle must be restricted. That is, the animals are forced to confine themselves to small areas for obtaining food and finding proper living conditions. Have humans ever been faced with this kind of problem?
1.Automobiles, rockets, and submarines are all examples given to support the idea that human inventions enable us to travel in almost any kind of environment.
2.The tail of the shark contributes to its swift locomotion.
3.The greatest stretching of the collagen fibers occurs when a shark tears huge chunks of flesh from its prey.
4.The area just under the shark’s collagen fibers is similar to a belted radial tire because it is also inflated by pressure.
5.A laminar flow is formed when a fish swims against the current.
6.Consuming the equal amount of energy as a slug does, a mouse can travel 12 times as long as a slug.
7.Most species of sharks, including very small ones, can endanger man’s life.
8.A shark finds its prey by.
9.According to the passage,can be compared to the string of a bow for both of them store energy when stretched.
10.When the shark detects an important food source,take place.
【答案与解析】
8. Animals on the Move
1. Y根据第五段第一、二句判断。
2. N在Skin Is the Key中，第一句话，The biologists discovered that the skin of the shark is the key to the animal’s high efficiency in swimming through the water.很明显的可以看出是skin 起了重要的作用。
3. N在Skin Is the Key中，第二段第一句话，The Duke University biologists have found that the greatest stretching occurs where the shark bends its body while swimming.我们可以看出是The greatest stretching of the collagen fibers occurs when a shark bends its body while swimming.
4. Y题目与Source of Energy 中第一段的最后一句相吻合。
5. N在Dolphin Has Speed Record中，第一段倒数第四句话，Normally when a fish or other object moves slowly through the water, the water flows smoothly past the body. 所以应该是A laminar flow is formed when a fish swims slowly through the water.
6. Y题目与Other Animals Less Efficient 中第一段的最后一句相符合。
7. NG文章中并没有提到shark 能威胁到人的生命安全的事实。
8.feeling the vibrations of a struggling prey鲨鱼靠感受猎物游动的震动来发现猎物。
9.collagen fibers 根据Skin Is the Key标题下面一段中，第三句，The fibers are called collagen fibers.
10.some fantastic involuntary changes在Source of Energy中，第二段倒数第一句话就是答案。
