How do you feel after you've stayed up late to finish schoolwork? Or the day aft

     How do you feel after you've stayed up late to finish schoolwork? Orthe day after a slumber party? Scientists now say that your answers to thesequestions may depend on your genes.

     Genes arestretches of DNA that work like an instruction manual for our cells. Genes tellour bodies and brains what to do. People have about 40,000 genes, and each genecan have different forms. So, for example, certain forms of some genes makeyour eyes blue. Other versions of those genes make your eyes brown.

In a similarway, new research suggests that a gene called period3 affects how wellyou function without sleep. The discovery adds to older evidence that period3helps determine whether you like to stay up late or get up early.

The period3gene comes in two forms: short and long. Everyone has two copies of the gene.So, you may have two longs, two shorts, or one of each. Your particularcombination depends on what your parents passed on to you.

Scientists fromthe University of Surrey in England studied 24 people who had either two shortor two long copies of period3. Study participants had to stay awakefor 40 hours straight. Then, they took tests that measured how quickly theypushed a button when numbers flashed on a screen and how well they couldremember lists of numbers.

Results showedthat the people with the short form of period3 performed much betteron these tests than the people with the long form did. In both groups, peopleperformed worst in the early morning. That's the time when truck drivers andother night-shift workers say they have the most trouble concentrating.

After the firstround of experiments, participants were finally allowed to sleep. People in thegroup that performed well on the tests took about 18 minutes to nod off.

People with thelong period3 gene, by contrast, fell asleep in just 8 minutes. Theyalso spent more time in deep sleep. That suggests that people with the longform of the gene need more and deeper sleep to keep their brains working at topform.

1.We can know from the passage that genes can not ________.

 A. tellour bodies and brains what to do

 B. make oureyes blue or brown

 C. decidehow well you work without sleep

 D. ensurewhether you’re good at driving

2.Which of the following statements about the period3 is wrong?

 A. It affects whether you like to stay up lateor get up early.

 B. It comes in two forms: short and long.

 C. One has either two longs or two shorts ofit.

 D. Your parents determine what particularcombination you have.

3.People with the short form of period3__________.

 A. need to go to bed early and get up early

 B. can work better than the people with longform of period3 without sleep

 C. takeless time to fall asleep after they stay up late

 D. needmore and deeper sleep to keep their brains working at top form

4.What’s the best title of the passage?

A. The Period3Gene                            B.The Function of Genes

 C. Wakeup, Sleepy Gene                             D.Stay up Late or Get up Early?

试题答案

【答案】

1.D

2.C

3.B

4.C