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Posted 2022-11-07 we1less

Orientation and Navigation
Paragraph 3: Early in his research, Kramer found that caged migratory birds became very restless at about the time they would normally have begun migration in the wild. Furthermore, he noticed that as they fluttered around in the cage, they often launched themselves in the direction of their normal migratory route. He then set up experiments with caged starlings and found that their orientation was, in fact, in the proper migratory direction except when the sky was overcast, at which times there was no clear direction to their restless movements. Kramer surmised, therefore, that they were orienting according to the position of the Sun. To test this idea, he blocked their view of the Sun and used mirrors to change its apparent position. He found that under these circumstances, the birds oriented with respect to the new "Sun." They seemed to be using the Sun as a compass to determine direction. At the time, this idea seemed preposterous. How could a bird navigate by the Sun when some of us lose our way with road maps? Obviously, more testing was in order.

6. According to paragraph 3, why did Kramer use mirrors to change the apparent position of the Sun? 

○ To test the effect of light on the birds' restlessness 

○ To test whether birds were using the Sun to navigate 

○To simulate the shifting of light the birds would encounter along their regular migratory route 

○ To cause the birds to migrate at a different time than they would in the wild

S：细节题 mirrors change Sun

D：原文

S：this 前句 orienting according Sun

G：orienting = navigate 

7. According to paragraph 3, when do caged starlings become restless? 

○ When the weather is overcast 

○ When they are unable to identify their normal migratory route

○ When their normal time for migration arrives 

○ When mirrors are used to change the apparent position of the Sun

S：细节题 when caged starlings become restless

D：原文

S：

G：

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Paragraph 5: In experimenting with artificial suns, Kramer made another interesting discovery. If the artificial Sun remained stationary, the birds would shift their direction with respect to it at a rate of about 15 degrees per hour, the Sun's rate of movement across the sky. Apparently, the birds were assuming that the "Sun" they saw was moving at that rate. When the real Sun was visible, however, the birds maintained a constant direction as it moved across the sky. In other words, they were able to compensate for the Sun's movement. This meant that some sort of biological clock was operating-and a very precise clock at that.

9. The experiment described in paragraph 5 caused Kramer to conclude that birds possess a biological clock because

○ when birds navigate they are able to compensate for the changing position of the Sun in the sky 

○ birds innate bearings keep them oriented in a direction that is within 15 degrees of the Suns direction 

○ birds' migration is triggered by natural environmental cues, such as the position of the Sun 

○ birds shift their direction at a rate of 15 degrees per hour whether the Sun is visible or not

S：细节题 陈述句文章最后 because biological clock

D：原文

S：this meant that = becaue 反向

G：Sun's movement = changing position of the Sun

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Symbiotic Relationships
Paragraph 2: Parasitism is a kind of predator-prey relationship in which one organism, the parasite, derives its food at the expense of its symbiotic associate, the host. Parasites are usually smaller than their hosts. An example of a parasite is a tapeworm that lives inside the intestines of a larger animal and absorbs nutrients from its host. Natural selection favors the parasites that are best able to find and feed on hosts. At the same time, defensive abilities of hosts are also selected for. As an example, plants make chemicals toxic to fungal and bacterial parasites, along with ones toxic to predatory animals (sometimes they are the same chemicals). In vertebrates, the immune system provides a multiple defense against internal parasites.

21. According to paragraph 2. which of the following is true of the action of natural selection on hosts and parasites? 

○Hosts benefit more from natural selection than parasites do.

○Both aggression in predators and defensive capacities in hosts are favored for species survival. 

○The ability to make toxic chemicals enables a parasite to find and isolate its host. 

○Larger size equips a parasite to prey on smaller host organisms.