Passage Four
Questions 16 to 20 are based on the following passage.
English people are less genetically diverse today than they were in the days of the Vikings, possibly due to two deadly diseases that swept their country centuries ago, a new study says.

The study compared DNA from ancient and modem Englanders and found that the country has a smaller gene pool than it did a thousand years ago.

The findings come in contrast to modem England’s reputation as a cultural melting pot, where in many major cities you are as likely to hear Urdu from India or Yoruba from Nigeria being spoken on the streets as English. 

Rus Hoelzel, a geneticist from the Britain’s University of Durham, and his colleagues obtained DNA samples from the skeletal remains of 48 ancient Britons who lived between A. D. 300 and 1000. The researchers studied the DNA, which was passed down from mothers to their children. By comparing the DNA with that of thousands of people from various ethnic backgrounds living in England today, they found that genetic diversity was greater in the ancient population. The team also compared the ancient DNA with samples from people living in continental Europe and the Middle East, and found a similar lack of genetic variety.

One possible explanation for this narrowing of diversity might be two major outbreaks of plague that swept England and much of Europe — the Black Death (1347 — 1351) and the Great Plague (1665 — 1666).

The Black Death epidemic is estimated to have killed as much as 50 percent of the population of Europe. Three centuries later, a fifth of the population of London died in the Great Plague. However, these diseases didn’t kill randomly, Hoelzel explained. “The plague killed some people while others remained resistant,” he said.

Eske Willerslev, a specialist in ancient DNA from the University of Copenhagen, said he is surprised by the findings but agrees that the historic epidemics may explain the loss in diversity.

Since the diseases, it appears that England hasn’t been able to make up the loss to the gene pool, despite the high rate of immigration into the country over the past 200 years.

16. The modem England’s reputation as “a cultural melting pot” (Para. 3) most probably means ______.

A. English people speak many different languages

B. England has a population of many different cultural origins

C. England is famous for exporting melting pot

D. England has a close diplomatic relationship with India and Nigeria

17. The DNA comparison between modern and ancient English people reveals ______.

A. great changes have taken place in the genetic contents in the DNA

B. DNA differs among different people from different ethnic backgrounds

C. there is less DNA diversity in modern Englishmen than in their ancestors

D. modern Englishmen has the same DNA diversity as their ancestors

18. According to the passage, which of the following statements is NOT true?

A. The ancient DNA used in this study was gathered from the bones of the ancient British people.

B. The genetic information carried by DNA is passed to children from fathers.

C. Although modern England has high immigration rate, it still suffers from poor genetic variety.

D. England, European continent and Middle East all suffer from lack of genetic variety.

19. The two deadly diseases, namely the Black Death and the Great Plague ______.

A. affected England more than any other countries in Europe

B. broke out between the thirteenth century and the sixteenth century

C. took less than half of the population away in England

D. left some people alive with resistance for the diseases

20. It can be inferred from the passage that ______.

A. Willerslev was not prepared to see the lack of genetic variety in modern England

B. many immigrants moved to England to seek a new life after the two diseases

C. the gene bank will need to introduce more new genes to make up for its losses

D. England will need to immigrate more people to make up its gene loss