All living organisms, regardless of their uniqueidentity, have certain logical, chemical,
A. as a result of
B. considering
C. on purpose
D. whatever
A. as a result of
B. considering
C. on purpose
D. whatever
第1题
A.as a result of
B.considering
C.on purpose
D.whatever
第2题
A.as result of
B.considering
C.on purpose
D.whatever
第3题
第4题
A、Society is the sum of the relationships formed by living things and the environment
B、Human production, consumption, entertainment, politics, education, etc, all belong to the scope of social activities
C、Society refers to the organisms living together in a specific environment, which can be maintained for a long time and cannot be separated from each other. It is a kind of structure that cannot be easily changed
D、Society is a collection of individuals who live together united through a variety of relationships
第5题
阅读材料,回答题。
How does Organisms Ward off Invaders
The livelihood of each species in the vast and intricate assemblage of living things depends on the existence of other organisms.This interdependence is sometimes subtle,some times obvious.Perhaps the most straightforward dependence of one species on another occurs with parasites,organisms that live on or in other living things and derive nutrients directly from them.The parasitic way of life is widespread.A multitude of microorganisms(including viruses and bacteria,and an army of invertebrates or creatures lacking a spinal column(including crustaceans,insects,and many different types of worms)make their livings directly at the expense of other creatures.In the face of this onslaught,living things have evolved a variety of defense mechanisms for protecting their bodies from invasion by other organisms.
Certain fungi and even some kinds of bacteria create substances known as antibiotics into their external environment.These substances are capable of killing or inhibiting the growth of various kinds of bacteria that also occupy the area,thereby eliminating or reducing the competition for nutrients.The same principle is used in defense against invaders in other groups of organisms.For example,when attacked by disease--causing fungi or bacteria,many kinds of plants produce chemicals that help to ward off the invaders.
Members of the animal kingdom have developed a variety of defense mechanisms for dealing with parasites.Although these mechanisms vary considerably,all major groups of animals are capable of detecting and reacting to the presence of“foreign”cells.In fact,throughout the animal kingdom from sponges to certain types of wornls shellfish,and all vertebrates(creatures possessing spinal column)
there is evidence that transplants of cells or fragments of tissues into an animal are accepted only if they come from genetically compatible or closely related individuals.
The ability to distinguish between“self”and“non-self”,while present in all animals,is most efficient among vertebrates,which have developed an immune system as their defense mechanism.The immune system recognizes and takes action against foreign invaders and transplanted tissues that are treated as foreign cells.
What does the passage mainly discuss? 查看材料
A.How parasites reproduce
B.How organisms react to invaders
C.How antibiotics work to cure disease
D.How the immune system of vertebrates developed
第6题
第7题
Why do oil-eating microbes threaten the organisms living in the water within the plumes?
A.They pollute the waters seriously.
B.They cause infectious diseases.
C.They consume too much oxygen.
D.Their number increases dramatically.
第8题
Text 2
Bacteria are microscopic organisms which live on the surface of objects. They are one of the most ancient living things,which exist on this planet for nearly 4,000 million years. Do you know the size of bacteria? It can only be measured in microns. Maybe you have not a standard in your mind how long a micron is. One micron is a thousandth of a millimeter, which equals about the diameter of a pinhead. Therefore, even if we enlarged the rounded bacter:ium a thousand times, it would only be the size of a pinhead. We barely see bacteria by a magnification an ordinary microscope of 100 times, even if we try, we cannot make out anything of their structure. There are normally millions of them together, for they can multiply really fast.
Scientists have found that some bacteria have attached to wavy-looking "hairs" called flagella.The flagella rotate, pushing the bacteria through the water. Others can glide along over surfaces by some little-understood mechanism. Bacteria are so small that they are influenced by the movements of the chemical molecules around them. They are active all the time. Even the bacteria without flagella often bound about in the water. They are pushed here and there, colliding with the watery molecules.
Bacteria cannot be detected because they don't produce bad odor or change the color or texture of the food. Therefore, when people eat the food with many bacteria, they are likely to get hepatitis A, acute gastroenteritis and a host of other illnesses. Many households have refrigerators to prevent from bacteria. Of course, freezing food slows or stops the growth of bacteria, however, when food is thawed, the bacteria will become reactivated. Bacteria can not be totally destroyed before the food is thoroughly cooked. We need to know that not all bacteria are in connection with illness.Just some bacteria can cause disease. They are called pathogenic bacteria. Fortunately our immune system can protect us from them.
Bacteria are prokaryotes (single cells that do not contain a nucleus). It may seem weird to classify organisms according to such details, but with or without a nucleus is not trivial at all. The division between prokaryotes and eukaryotes (all organisms with a nucleus inside their cells) is of extreme importance in biology, and is the result of a major evolutionary breakthrough. Visit our program tomorrow if you want to know more, thank you.
46. Which of the following is true according to the first paragraph?
[A] Bacteria are as big as a pinhead.
[B] Bacteria can not be seen by an ordinary microscope.
[C] Bacteria are hard to see because they often live together.
[ D] Bacteria are very small so they can only be measured in microns.
第9题
Scientists have found that some bacteria have attached to wavy-looking "hairs" called flagella. The flagella rotate, pushing the bacteria through the water. Others can glide along over surfaces by some little-understood mechanism. Bacteria are so small that they are influenced by the movements of the chemical molecules around them. They are active all the time. Even the bacteria without flagella often bound about in the water. They are pushed here and there, colliding with the watery molecules.
Bacteria cannot be detected because they don't produce bad odor or change the color or texture of the food. Therefore, when people eat the food with many bacteria, they are likely to get hepatitis A, acute gastroenteritis and a host of other illnesses. Many households have refrigerators to prevent from bacteria. Of course, freezing food slows or stops-the growth of bacteria, however, when food is thawed, the bacteria will become reactivated. Bacteria can not be totally destroyed before the food is thoroughly cooked. We need to know that not all bacteria are in connection with illness. Just some bacteria can cause disease. They are called pathogenic bacteria. Fortunately our immune system can protect us from them.
Bacteria are prokaryotes (single cells that do not contain a nucleus). It may seem weird to classify organisms according to such details, but with or without a nucleus is not trivial at all. The division between prokaryotes and eukaryotes (all organisms with a nucleus inside their cells) is of extreme importance in biology, and is the result of a major evolutionary breakthrough. Visit our program tomorrow if you want to know more, thank you.
Which of the following is true according to the first paragraph?
A.Bacteria are as big as a pinhead.
B.Bacteria can not be seen by an ordinary microscope.
C.Bacteria are hard to see because they often live together.
D.Bacteria are very small so they can only be measured in microns.
第10题
Certainly no creature in the sea is odder than the common sea cucumber(海参). All living creatures, especially human beings, have their peculiarities, but everything about the little sea cucumber seems unusual. What else can be said about an odd animal that, among other eccentricities, eats mud, feeds almost continuously day and night but can live without eating for long periods, and can be poisonous hut is considered supremely edible by gourmets(美食家) ?
For some fifty million years, despite all its eccentricities, the sea cucumber has subsisted on its diet of mud. It is adaptable enough to live attached to rocks by its tube feet, under rocks in shallow water, or on the surface of mud fiats. Common in cool water on both Atlantic and Pacific shores, it has the ability to suck up .mud or sand and digest whatever nutrients are present.
Sea cucumbers come in a variety of colors, ranging from black to reddish-brown to sandcolor and nearly white. One form. even had vivid purple tentacles. Usually the creatures are cucumbers-shaped——hence their name——and because they are typically rock inhabitants, this shape, combined with flexibility, enables them to squeeze into narrow cracks where they are safe from predators and ocean currents.
Although they have voracious appetites, eating day and night, sea cucumbers have the capacity to become inactive and live at a low metabolic rate feeding sparingly or not at all for long periods, so that the marine organisms that provide their food have a chance to multiply. If it were not for this faculty, they would devour all the food available in a short time and would probably starve themselves out' of existence.
But the most spectacular thing about the sea cucumber is the way it defends itself. Its major enemies are fish and crabs, when attacked, it squirts all its internal organs into the water. It also casts off attached structures such as tentacles. The sea cucumber will eviscerate排除内脏) and regenerate itself if it is attacked or even touched; it will do the same if the surrounding water temperature is too high or if the water becomes too polluted.
The passage is mainly about______.
A.the reason for the sea cucumber's name
B.ways to identify the sea cucumber
C.places where the sea cucumber can be found
D.the peculiarities that make the sea cucumber unusual