Download PART FIVE: QUESTIONS 21-25

PART FOUR: QUESTIONS 16-20
Read the following article on flu and circle the best answer for each
question.
(0) has been done for you as an example
Scientists believe they have uncovered a key reason why flu viruses tend to
strike in cold weather. They found the viruses coat themselves in fatty
material that hardens to a gel, protecting them from exterior influences. This
coating melts in the higher temperatures of the respiratory tract, allowing the
virus to infect cells.
The US National Institutes of Health Team hope their study, which features in
the journal Nature Chemical Biology, could lead to new treatments. However,
a UK expert said the discovery did not explain why some flu viruses also
thrived in tropical climates.
The hard rubbery coating around the virus, which forms in colder
temperatures, gives it the protection it needs to pass from person to person.
The coating is so robust it can even resist to certain detergents. However,
once inside a host the virus can only infect a target cell once the coating has
melted. But this liquid phase is not tough enough to protect the virus against
the elements, and so if the protective coating melts when the virus is outside
the host, it dies.
Dr Duane Alexander, director of the National Institute of Child Health and
Human Development, said: "The study results open new avenues of research
for preventing winter flu outbreaks. Now that we understand how the flu virus
protects itself so that it can spread from person to person, we can work on
ways to interfere with that protective mechanism."
The researchers used a sophisticated magnetic resonance technique to
create a detailed fingerprint of how the flu virus's outer membranes responded
to variations in temperature. The virus's outer membrane is composed chiefly
of molecules known as lipids, such as oils, fats and cholesterol. The
researchers found that at temperatures slightly above freezing, this lipid
covering turned into a gel. However, as temperatures approached 15.6C
(60F), the covering gradually melted. The researchers concluded that
temperatures in the spring and summer were too high to allow the viral
membrane to enter its gel state. As a result, at these temperatures the
individual flu viruses would dry out and weaken - accounting for the end of the
flu season.
Professor John Oxford, an expert in virology at Queen Mary College School of
Medicine, London, said the paper was interesting, but it might be premature to
draw firm conclusions. He said: "If this is the case why do we get flu in tropical
areas, where the temperature is 35C (95F) all the time?" Professor Oxford
said researchers had tried to link flu infection definitively to cold weather since
the great Russian outbreak of 1890, but had failed to come up with conclusive
proof of a link. "I don't think this study provides anything like a definitive
answer on the spread of the virus - there must be some other factors that
come into play," he said.
(0) According to the author, viruses resist:
a) high temperatures
b) low temperatures
c) temperature changes
d) doesn’t say
(16) The American scientists:
a) want to get their work published soon
b) hope new therapies will be developed
c) need to do some further researches
d) need more help from other experts
(17) The virus’s protective layer:
a) can only be destroyed by immune system
b) does not react to any chemical substances
c) hardens when it gets inside human body
d) melts before the virus attacks host’s cells
(18) When Dr Alexander talks about this discovery he is:
a) pessimistic
b) uncertain
c) optimistic
d) worried
(19) The researchers, the virus’s protective coat weakens when:
e) it is exposed to magnetic field
f) It contacts the lipid molecules
g) winter ends and spring begins
d) outside temperature goes up
(20) Professor Oxford states that this study:
a) isn’t relevant for flu prevention
b) ignores some important facts
c) has not been finished yet
d) focuses on climate changes
Key:
16. b
17. d
18. c
19. d
20. b