雅思阅读测试题

Reading

READING PASSAGE 1

You should spend about 20 minutes on Questions 1-14 which are based on Reading Passage 1 on pages 9 and 10.

Spider silk cuts weight of bridges

A strong, light bio- material made by genes from spiders could transform construction and

industry

A

Scientists have succeeded in copying the silk-producing genes of the Golden Orb Weaver spider and using

them

to

create

a

synthetic

material

which

they

believe

is

the

model

for

a

new

generation

of

advanced

bio- materials. The new material, biosilk, which has been spun for the first time by researchers at DuPont,

has an enormous range of potential uses in construction and manufacturing.

B

The attraction of the silk spun by the spider is a combination of great strength and enormous elasticity,

which man-made fibres have been unable to replicate. On an equal- weight basis, spider silk is far stronger

than steel and it is estimated that if a single strand could be made about 10m in diameter, it

would be

strong enough to stop a jumbo jet in flight.

A third important factor is

that it

is

extremely light.

Army

scientists

are

already

looking

at

the

possibilities

of

using

it

for

lightweight,

bullet-proof

vests

and

parachutes.

C

For some time, biochemists have been trying to synthesize the drag-line silk of the Golden Orb Weaver.

The drag-line silk, which forms the radial arms of the web, is stronger than the other parts of the web and

some biochemists believe a synthetic version could prove to be as important a material as nylon, which

has been around for 50 years, since the discoveries of Wallace Carothers and his team ushered in the age

of polymers.

D

To

recreate

the

material,

scientists,

including

Randolph

Lewis

at

the

University

of

Wyoming,

first

examined the silk-producing gland of the spider.

“

We took out the glands that produce the silk and looked

at

the

coding

for

the

protein

material

they

make,

which

is

spun

into

a

web.

We

then

went

looking

for

clones with the right DNA,

”

he says.

E

At DuPont, researchers have used both yeast and bacteria as hosts to grow the raw material, which they

have spun into fibres. Robert Dorsch, Dupont

?

s director of biochemical development, says the globules of

protein, comparable with marbles in an egg, are harvested and processed.

“

We break open the bacteria,

separate out the globules of protein and use them as the row starting material. With yeast, the gene system

can be designed so that the material excretes the protein outside the yeast for better access,

”

he says.

F

“

The bacteria and the yeast produce the same protein, equivalent to that which the spider uses in the drag

lines of the web. The spider mixes the protein into a water-based solution and then spins it into a solid

fibre

in

one

go.

Since

we

are

not

as

clever

as

the

spider

and

we

are

not

using

such

sophisticated

organisms, we substituted

man-made approaches and dissolved the protein in chemical solvents, which

are then spun to push the material through small holes to form the solid fibre.

”

G

Researchers at DuPont say they envisage many possible uses for a new biosilk material.

They say

that

earthquake-resistant

suspension

bridges

hung

from

cables

of

synthetic

spider

silk

fibres

may

become

a

reality. Stronger ropes, safer seat belts, shoe soles that do not wear out so quickly and tough new clothing

are among the other applications. Biochemists such as Lewis see the potential range of uses of biosilk as

almost limitless.

“

It is very strong and retains elasticity, there are no man-made materials that can mimic

both these properties. It is also a biological material with all the advantages that has over petrochemicals,

”

he says.

H

At DuPont

?

s laboratories, Dorsch is excited by the prospect of new super- strong materials but he warns

they are many years away.

“

We are at an early stage but theoretical predictions are that we will wind up

with a very strong, tough material, with an ability to absorb shock, which is stronger and tougher than the

man-made materials that are conventionally available to us,

”

he says.

I

The

spider

is

not

the

only

creature

that

has

aroused

the

interest

of

material

scientists.

They

have

also

become

envious

of

the

natural

adhesive

secreted

by

the

sea

mussel.

It

produces

a

protein

adhesive

to

attach

itself

to

rocks.

It

is

tedious

and expensive

to

extract

the

protein

from

the

mussel,

so

researchers

have already produced a synthetic gene for use in surrogate bacteria.

Questions 1-5

The passage has nine paragraphs A-I

Which paragraph contains the following information?

Write the correct letter A-I in boxes 1-5 on your answer sheet.

1

2

3

4

5

a comparison of the ways two materials are used to replace silk-producing glands

predictions regarding the availability of the synthetic silk

on- going research into other synthetic materials

the research into the part of the spider that manufactures silk

the possible application of the silk in civil engineering

Questions 6-11

Complete the flow chart below.

Choose

NO MORE THAN THREE WORDS

from the passage for each answer.

Write your answers in boxes 6-11 on your answer sheet.

Synthetic gene growth in

6

………………

..or

7

………………

globules of

8

……………….

passed through

10

……………

dissolved in

9

………………

Questions 12-14

In boxes 12-14 on your answer sheet write

TRUE

FALSE

NOT GIVEN

to produce

11

………………

Do the following statements agree with the information given in Reading Passage 1?

if the statement agrees with the information

if the statement contradicts the information

if there is no information on this

12

Biosilk has already replaced nylon in parachute manufacture.

13

The spider produces silk of varying strengths.

14

Lewis and Dorsch co-operated in the synthetic production of silk.