揽瓜阁阅读做题小分队 第156天 天蓝色蛔虫

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Until recently, Ascaris azure, known as the Diaz blueworm, and Ascaris tropica, known as the Costa Rican heatworm, were thought to be different species of roundworm. The heatworm is about 0.5 centimeters long, and lives within the bark of huge cecropia trees in Southeast Asian rain forests. The blueworm, barely visible with the naked eye, is found in frigid seafloors. Despite these apparent differences, the Institute of Helminthological Studies has officially stated that “both” species are actually Diaz blueworms.

Dr. Ginny Bolton, examining roundworm samples collected in Borneo, noticed that the heatworm’s tiny cilia (hairlike organelles) appeared to beat in a single direction, aiding in the expulsion of food. Dr. Bolton later determined that the cilia also made it much easier for the heatworm to live in the stifling confines of tree bark. The cilia project from a cuticle that is made of keratin, a protein that protects the worm’s epidermis from drying out and overheating. The cilia help regulate the proliferation of the keratin, and the force of the cilia’s movements varies as the external temperature changes, allowing for a highly responsive thermostatic system, constantly adjusting the amount of keratin so that the worm would be neither overexposed nor stifled.

Knowing that the only other roundworm with directional cilia is the blueworm, Dr. Bolton consulted with several blueworm specialists. The thermostatic system that served the heatworm so well proved to be identical to the one used by oceangoing blueworm. However, the blueworm, which has been known to colonize methane ice mounds, uses the keratin to protect itself from frigid temperatures. The cilia sensed when the temperature was high enough to allow the production of keratin to slow down. Without the surrounding wall of keratin, the worm can more easily graze on bacteria.

Genetic testing showed that the blueworm and the heatworm were not merely structurally similar; to the scientists’ surprise, the worms were identical. This was startling, not only because of their vastly differing habitats, but also because of the difference in size. The answer again was to be found in the keratin, a tough substance that normally inhibits growth, keeping the hydrostatic pressure very high within the worm. The relatively large worm found in the rainforest molts as it grows, allowing the worm to increase its volume a very small amount each time it does, but the smaller worm cannot afford this much exposure. The freezing temperatures trigger the production of keratin so quickly that the worm has little chance to grow, thus keeping its volume approximately one-fourth that of the larger worm.

1. It can be inferred from the passage that, compared to blue worms found in the sea, heat worms found in rainforests ___________.
(A) do not graze on bacteria
(B) do not have high levels of hydrostatic pressure
(C) cannot survive in water
(D) have little chance to grow because of extreme temperature
(E) replace keratin more slowly

2. It can be inferred from the passage that if the cilia of a blue worm found on the seafloor were to become damaged, preventing the sensing of warmer temperatures, the worm ______________.
(A) could grow to a length of 0.5 centimeters
(B) would be in danger of freezing
(C) might not be able to gain access to enough nourishment to sustain life
(D) would be forced to find its way to warmer temperatures
(E) would experience a sudden drop of hydrostatic pressure

3. According to the passage, researchers were able to make the discovery of the unlikely relationship between the two worms because of which of the following?
(A) Both worms have mechanisms to produce keratin.
(B) Both worms exist in extreme temperatures.
(C) Both worms are researched by the Institute of Helminthological Studies.
(D) Both worms feature directional cilia.
(E) Both worms molt as they grow.

4.Which of the following is the primary purpose of the passage?
(A) To present an overview of the function of keratin in roundworms
(B) To give an example of the kind of discoveries that are still being made in the natural sciences
(C) To show the ways in which scientists who are highly specialized need to work together
(D) To provide some of the details of a surprising scientific discovery
(E) To show how genetic testing is an invaluable scientific tool

5. According to the passage, in what way do the blueworm’s cilia aid the worm in coping with extreme heat and cold?
(A) They help with the removal of food from the worm’s system.
(B) They provide a mechanism by which the production of keratin can be regulated.
(C) They collect the bacteria on which some blueworms graze.
(D) They keep the hydrostatic pressure within the worm high.
(E) They keep it securely attached to the bark of the cecropia tree.

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Second Q
Last two sentences in the third paragraph illustrates how cilia sense warmer environment, and restrain the production of keratin, allowing the blue warm to graze on bacteria. In light of this evidence, when cilia is damaged from sensing surrounding environment, keratin continues to be produced and the blue worm is restricted from absorbing nourishment

Tranquil.

总写旧观点，提出新观点：以前认为Diaz blueworm和Costa Rican heatworm不是一个东西，现在发现都是Diaz blueworms——keratin对heatworms的作用——keratin对blueworm的作用——这俩一样的物种为啥会这么不同（还是keratin的锅）
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