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The bacteria depend on worms for hydrogen sulfide in the symbiotic relationship.
A．Y
B．N
C．NG
答案
更多“The bacteria depend on worms for hydrogen sulfide in the symbiotic relationship.A．YB．NC．NG”相关的问题
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第3题
听力原文：M: So, what is your biology project about？
W: It is about microorganisms that live by chemosynthesis.
M: Err...what's chemosynthesis？
W: Well, it's pretty complicated. You know how most life on Earth depends either directly or indirectly on sunlight？
M: You mean like plants get energy directly from sunlight, and animals eat plants, so they depend indirectly on sunlight？
W: Right. But down on the ocean floor, there is no sunlight. In some places though, there are hydrothermal vents, which are small cracks on the ocean floor. And these vents release heat and minerals from the inside of the Earth into the seawater. And all along the vents there are these unusual microorganisms. They are called archaean. And these archaean use chemical reactions to get their energy from the minerals. The minerals that are released by the vents. So their energy comes from chemical reactions, not sunlight.
M: So chemosynthesis is getting their energy from chemicals？
W: That's right.
M: That makes archaean very different from other forms of life.
W: And their genetic makeup is very different, too. They are one sort of organisms just like bacteria are, but genetically they are as different from bacteria as we humans are.
M: Wah, that's a really interesting project.
(23)
A．How hydrothermal vents are formed.
B．How living things get energy from sunlight.
C．The harmful effects of certain chemicals in the ocean.
D．Microorganisms that get energy from chemical reactions.
第4题
Food which is kept too long decays because it is attacked by yeasts (酵母菌), moulds (霉) and bacteria (细菌). The canning process, however, seals the product in a container so that no infection can reach it, and then it is sterilized (消毒) by heat. Heat sterilization destroys all infectious present in food inside the can. No chemical preservatives are necessary, and properly canned food does not deteriorate during storage.
Today vegetables, fish, fruit, meat and beer are canned in enormous quantifies. Foods that were previously seasonal may now be eaten at any time, and strange foods are available far from the countries where they are grown. The profitable crops many farmers now produce often depend on the proximity (邻近) of a canning factory.
The first stage in the canning process is the preparation of the raw food. Diseased and waste portions are thrown away; meat and fish are cleaned and trimmed; fruit and vegetables washed and graded for size. The jobs are principally done by machine
The next stage, for vegetables only, is blanching. This is immersion (浸洗) in very hot or boiling water for a short time to remove air and soften the vegetable. This makes it easier to pack into cans for sterilization. Some packing machines fill up to 400 cans a minute. Fruit, fish and meat are packed mw and cold into cans, and then all the air is removed. When the cans are sealed, the pressure inside each can is only about half the pressure of the outside air. This is "vacuum" packing.
During the sterilization process which follows, the cans are subjected to steam or boiling water, with the temperature and duration varying according to the type of food. Cans of fruit, for example, take only 5-10 minutes in boiling water, while meat and fish are cooked at higher temperature for longer periods. After sterilization, the cans are cooled quickly to 32℃, to prevent the contents from becoming too soft.
The final stage before dispatch to the wholesale or retail grocer is labeling, and packing the tins into boxes. Nowadays, however, labeling is often printed on in advance by the can maker and no paper labels are then required.
Food deteriorates during storage because ______.
A．necessary chemical preservatives are totally absent from it
B．it is infected with yeasts, moulds and bacteria
C．heat sterilization destroys infections present in it
D．it isn't fit for storage
第5题
Aliens
Are there other forms of life in the universe'？ The scientific search for extraterrestrial (ET) life forms has been bolstered by two recent discoveries. First, the discovery of life forms in exotic environments on Earth indicates that life is very hearty and can adapt to the strangest and most hostile environments. Second, astronomers found planets orbiting stars besides our sun—over 50 extrasolar planets have been discovered as of 2001. Are there alien life forms on any of these planets？
If alien life does exist, what might it be like？ Would it be simple forms of life such as bacteria, viruses or algae, or more advanced, multi-cellular creatures, perhaps even intelligent beings？ Would aliens be animals, plants or have characteristics of both？ Would they have arms and legs and walk upright as we do？ Would they depend upon vision as their primary sense or use another way to gather information about their surroundings？ Would they "breathe" oxygen or some other gas？
Greetings, Carbon-based Bipeds(两足动物)!
Most of us picture alien life the way it's portrayed in movies, where aliens are commonly depicted as human-like forms because they use actors either to play the roles directly in make up or to be models for computer-generated animation. Also, audiences relate to human-like aliens better than to more exotic, monster like. However, the human body plan bilateral symmetry with one
head, two legs and two arms—stems from when early animals such as lizard, crocodile, or dinosaur colonized the Earth's land masses, and it seems unlikely that such a shape would evolve on an alien world. So, let's forget Hollywood for the moment and look closely at the real science of astrobiology.
Astrobiology is the scientific study of life in the universe. Astrobiologists seek to understand (among other things) how life arose and evolved on Earth, what governs the way life is organized and what makes a planet habitable.
Astrobiology combines the disciplines of biology, chemistry, physics, geology and astronomy. Often, astrobiologists must use the information learned about life on Earth as a guide for studying life elsewhere. Let's examine some of the unusual things that we have learned from life on Earth:
Life in the Extreme
Up until about 30 years ago, it was believed that all life on Earth was dependent upon energy from the sun. Furthermore, it was thought that you would probably not find life where temperatures were extremely hot, like in geysers or hot springs, or extremely cold,' like in the Antarctic desert.
These ideas changed when oceanographers explored hydrothermal vents, openings in the ocean floor where extremely hot, mineral-rich water erupts from the crust. Hydrothermal vents are located several miles below the surface, on the ocean floor, where the surrounding water is at or near freezing, it is absolutely dark and the pressure is high. In organized communities around the bases of these vents, called black smokers, scientists found clams, crabs and exotic, giant tubeworms measuring 6 feet (2 meters) long. The water coming out of these vents is 230 to 662 degrees Fahrenheit (110 to 350 degrees Celsius).
How can these animals survive so far from the sunlight, under these extreme conditions？ In the water, scientists found species of bacteria that split hydrogen sulfide(硫化物)from the water to get energy to make organic compounds. The tubeworms have bacteria in their tissues that help them derive energy from the water. The clams feed on the bacteria, and the crabs feed on the tubeworms.
The discovery of hydrothermal-vent communities showed that it is possible for life to evolve in places without light from the sun, and in other worlds without sufficient light from the parent star. In view of the discovery of hydrothermal vents, it may be possible that life exists on Europa, an icy moon of Ju
A．Y
B．N
C．NG
第6题
A．The bacteria would be killed by the human immune system.
B．The bacteria would die if brought to the surface.
C．Many antidotes and remedies are available.
D．Drilling operations are always closely monitored.
第7题
It can be inferred from the last paragraph that ______.
A．researchers are quite clear about what attracts bacteria into microcapsules
B．the negative-charged layer of polymers attracted the positive charged bacteria
C．a larger "mousetrap" may be helpful in fighting against infection
D．polymers and bacteria may be pushed together by water's attraction
第8题
If the food with bacteria are cooked under 75℃, food poisoning can be prevented.
A．Y
B．N
C．NG
第9题
A.used
B.to use
C.using
D.use
第10题
