更多"How many kinds of nerve cells are d"的相关试题:
[单项选择]Of 100 billion nerve cells in the human brain, how many form after birth For years, the official answer was "zero". Scientists thought people were born with all the neurons they’d ever have. But from 1980s, biologists overturned that doctrine, finding a reservoir of stem cells that became fresh neurons in two parts of the brains of adult birds, monkeys and humans. Those discoveries were stunning, but the next seemed to top them all. In 1999, psychologist Elizabeth Gould reported large numbers of new nerve cells in a third of the monkey brain, hinting that the same part in humans—the neocortex, which lets us reason and remember—was regenerating, too. If she was right, scientists would have to revise almost all their ideas about human memory, and doctors might someday find a way to treat Alzheimer’s patients by simply turning on the neural-construction equipment.
The birth of new nerve cells, or "neurogenesis", is now confirmed in the original two parts of human brain, the hippocamp
A. The human brain contains 100 billion nerve cells.
B. The nerve cells can be generated after birth.
C. The nerve cells can’t be generated after birth.
D. The human brain has a reservoir of stem cells.
[单项选择]Why do nerve cells have fibres
A. To reproduce themselves.
B. To stretch and grow.
C. To attach themselves to muscle.
D. To carry messages.
[单项选择]What is one function of sensory nerve cells
A. To move the muscles.
B. To detect light.
C. To protect the nerves.
D. To soothe the brain.
[单项选择]Many Americans breathed a sigh of relief about this week’s ruling by the Supreme Court on "affirmative action". In a 5-4 ruling, the court decided that universities (and by extension companies and the armed forces) can use race as a criterion when they choose which people they let in. Citing the importance of racial diversity, the court argued that giving preference to "disadvantaged minorities" was in the national interest. On the other hand, in a 6-3 decision, the justices struck down a specific points-scoring system used by the University of Michigan because it made race "a decisive factor". The compromise has been welcomed by George Bush, various Democratic presidential candidates, the Pentagon and several large companies,
Alas, a popular decision is not necessarily a correct one. In this case the decision seems doubly incorrect—wrong in principle and wrong in execution This is not the pragmatic solution that takes race out of the equation.
The principle part of the arg
A. separate students on the basis of their skin color
B. admit students of different races to universities
C. make sure students of all races have an equal chance for higher education
D. replace points-scoring system used by the University of Michigan
[单项选择]According to the speaker, how does a nerve fibre look
A. Elongated and stringy.
B. Round and compact.
C. Flat and transparent.
D. Flexible and chainlike.
[填空题]Zinc can help reproduce many new brain cells.
