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Unit 2
When was the last time you saw a frog? Chances are, if you
live in a city, you have not seen con
for some time. Even in wet areas once teeming with frogs and toads,
it is becoming less and less
easy to find those slimy, hopping and sometimes poisonous members of
the animal kingdom. All
over the world, and even in remote parts of Australia, frogs are
losing the ecological battle for
survival, and biologists are at a loss to explain their demise. Are
amphibians simply over-sensitive
to changes in the ecosystem? Could it be that their rapid decline in
numbers is signaling some
coming environmental disaster for us all?
This frightening scenario is in part the consequence of a
dramatic increase over the last quarter
century in the development of once natural areas of wet marshland;
home not only to frogs but to
all manner of wildlife. However, as yet, there are no obvious
reasons why certain frog species are
disappearing from rainforests in Australia that have barely been
touched by human band. The
mystery is unsettling to say the least, for it is known that
amphibian species are extremely
sensitive to environmental variations in temperature and moisture
levels. The danger is that planet
Earth might not only lose a vital link in the ecological food chain
(frogs keep populations of
otherwise pestilent insects at manageable levels), but we might be
increasing our output of
air pollutants to levels that may have already become irreversible.
Frogs could be inadvertently
warning us of a catastrophe.
An example of a species of frog that, as far as is known, has
become extinct, is the platypus frog.
Like the well-known Australian mammal it was named after, it
exhibited some very strange
behaviour; instead of giving birth to tadpoles in the water, it
raised its young within its stomach.
The baby frogs were actually born from out of their mother's mouth.
Discovered in 1981, less than
ten years later the frog had completely vanished from the crystal
clear waters of Booloumba Creek
near Queensland's Sunshine Coast. Unfortunately, this freak of
nature is not the only frog species
to have been lost in Australia. Since the 1970's, no less than eight
others have suffered the same
fate.
One theory that seems to fit the facts concerns the depletion
of the ozone layer, a
well-documented phenomenon which has led to a sharp increase in
ultraviolet radiation levels.
The ozone layer is meant to shield the Earth from UV rays, but
increased radiation may be having
a greater effect upon frog populations than previously believed.
Another theory is that worldwide
temperature increases are upsetting the breeding cycles of frogs.
a. Frogs are disappearing only from city areas.
b. Frogs and toads are usually poisonous.
c. Biologists are unable to explain why frogs are dying.
d. The frogs 'natural habitat is becoming more and more developed.
e. Attempts are being made to halt the development of wet marshland.
f. Frogs are important in the ecosystem because they control pests.
g. The platypus frog became extinct by 1991.
h. Frogs usually give birth to their young in an underwater nest.
i. Eight frog species have become extinct so far in Australia.
j. There is convincing evidence that the ozone layer is being
depleted.
k. It is a fact that frogs' breeding cycles are upset by worldwide
increases in temperature.
answer:
a.F b. F c.T d..T e. NG f.T g.T h.NG i.F j.T k.F
Unit 3
Almost everyone with or without a computer is aware of the
latest technological revolution
destined to change forever the way in which humans communicate,
namely, the Information
Superhighway, best exemplified by the ubiquitous Internet. Already,
millions of people around the
world are linked by computer simply by having a modem and an address
on the 'Net', in much the
same way that owning a telephone links us to almost anyone who pays
a phone bill. In fact, since
the computer connections are made via the phone line, the Internet
can be envisaged as a network
of visual telephone links. It remains to be seen in which direction
the Information Superhighway is
headed, but many believe it is the educational hope of the future.
The World Wide Web, an enormous collection of Internet
addresses or sites, all of which can
be accessed for information, has been mainly responsible for the
increase in interest in the Internet
in the 1990s. Before the World Wide Web, the 'Net' was comparable to
an integrated collection of
computerized typewriters, but the introduction of the 'Web' in 1990
allowed not only text links to
be made but also graphs, images and even video. A Web site consists
of a 'home page', the first
screen of a particular site on the computer to which you are
connected, from where access can be
had to other subject related 'pages' (or screens) at the site and on
thousands of other computers all
over the world. This is achieved by a process called 'hypertext'. By
clicking with a mouse device on various
parts of the screen, a per son connected to the 'Net' can go
traveling, or 'surfing'
through a web of pages to locate whatever information is required.
Anyone can set up a site; promoting your club, your
institution, your company's products or
simply yourself, is what the Web and the Internet is all about. And
what is more, information on
the Internet is not owned or controlled by any one organization. It
is, perhaps, true to say that
no-one and there fore everyone owns the 'Net'. Because of the
relative freedom of access to
information, the Internet has often been criticized by the media as
a potentially hazardous tool in
the hands of young computer users. This perception has proved to be
largely false however, and
the dual purposes for which it was intended-discovery and delight.
a. Everyone is aware of the Information Superhighway.
b. Using the Internet costs the owner of a telephone extra money.
c. Internet computer connections are made by using telephone lines.
d. The World Wide Web is a network of computerized typewriters.
e. According to the author, the Information Superhighway may be the
future hope of education.
f. The process called 'hypertext' requires the use of a mouse
device.
g. The Internet was created in the 1990s.
h. The 'home page' is the first screen of a 'Web' site on the 'Net'.
i. The media has often criticized the Internet because it is
dangerous.
j. The latest technological revolution will change the way humans
communicate.
Answer:
F NG T F T T F T F T
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