Test No-42
What if everything had a barcode?
A vast new database will let us catalogue every plant and animal on the planet,
and identify them in seconds. Sanjida O’Connell reports
1. Imagine going for a walk and spotting a wild flower. Its beauty and fragrance
delight you, but the name eludes you. No problem. You whip out a hand-held
scanner, about the size of a mobile phone, and pop a fragment of a leaf into the
device. A few seconds, and the read-out tells you that you’re looking at a
pyramidal orchid. Satisfied, you continue on your way.
2. Sound far-fetched? Not at all. Scientists are currently creating a DNA barcode
for every species of plant and animal on the planet. It won’t be long before
everyone, from experts to amateurs, will be able to scan the world’s flora and
fauna as if they were checking out groceries at a supermarket, to look up or
confirm their identities.
3. There are numerous practical uses too. Such a device would let you scan fish
at the fishmonger’s to check if it’s been labelled properly, work out exactly what is
in your mixed vegetable soup, and confirm whether a piece of furniture really has
come from a renewable forest, as the retailer claims. It would also assist forensic
science teams, who could quickly identify the pollen on a suspect, to link him to a
particular location; customs officials, in their efforts to prevent disease-carrying
pests being taken across national borders; and environmental inspectors
assessing water quality, who need to work out what microbes, are lurking in a
particular sample.
4 It was Professor Paul Hebert, a biologist from the University of Guelph in
Canada, who came up with the idea of DNA bar coding the natural world. The
inspiration came while he was walking up and down the aisles of a supermarket,
marveling at the ability of the store to keep track of all the lines stocked and sold
using the thick and thin lines that make up a barcode. Could scientists, he
wondered, exploit a barcode system to record the millions of species on earth via
their DNA?
5 The compilation of a planetary inventory began more than 250 years ago, with
the Swedish life classifier Carl Linnaeus. In 1758, he founded the science of
taxonomy – a method of classifying living things – based on physical and
behavioral characteristics. To date, scientists have classified about 1.7 million
organisms, a small fraction of the total number of species, which has been
estimated at anywhere between 5 and 30 million. But taxonomy is difficult and
time-consuming. Many species, such as the different kinds of flies, look
remarkably similar. Only an expert who has spent years examining a particular
group can distinguish one from another. Even the experts may be stumped,
however, when presented with an egg, an embryo, a seedling or a root. The next
problem is that we are running out of time in which to complete the inventory.
The International Union for the Conservation of Nature estimates that a quarter of
the world’s population of mammals is threatened with extinction.
6 So, Hebert’s idea centered on finding a fragment of DNA that would disclose
the identity of a species without having to decode its entire genetic code. He
envisaged a ‘DNA barcode reader’, similar to the scanners at retail checkouts.
Outlining his idea in Scientific American, Hebert writes: ‘An inspector at a busy
seaport, a hiker on a mountain trail, or a scientist in a lab could insert a sample
containing DNA – a snippet of whisker, say, or the leg of an insect – into the
device, which would detect the sequence of nucleic acids in the barcode
segment. This information would be instantly relayed to a reference database, a
public library of DNA barcodes. Anyone, anywhere, could identify species.’
7 To create the barcode, Hebert proposed the use of a section of DNA, from the
energy-producing units found in all cells. He selected a gene that gives rise to an
enzyme known as CO1. This gene is small enough to be quickly and easily
deciphered, but has sufficient variation for us to be able to tell most animal
species apart. You and I, for instance, will have different versions of CO1, but
they will be similar enough to show that we’re both humans and not
chimpanzees.
8 In 2003, Hebert and his team published their first results. They showed that the
barcode system could identify the group an animal came from (for example,
whether it was a vertebrate, a worm or an insect) and even the species when it
was stored in the barcode library. After five more years of work, results indicate
that animals can now be identified by their barcodes in 98 per cent of cases.
Early results have confirmed the additional benefits of the new system: for
example, caterpillars of the tropical butterfly Astraptes fulgerator, which was first,
recognized as a species in 1775, all look very similar, and were assumed to
belong to a single species. Bar coding has shown there are 10 different kinds.
9 Of course, the value of the system depends on a comprehensive reference
library of the DNA (CO1) barcodes of established species. The Barcode of Life
Data (Bold) system is an enormous international collaboration supported by 150
institutions in 45 countries. To date, it has compiled more than 500,000 records
from 50,000 species. The consortium is hoping that the world’s birds will be
barcoded by 2011. ‘People have watched birds for so long that they might think
every different tweet has been heard, every different colour observed, but
barcoding may prove otherwise,’ says Professor Mark Stoeckle, professor of the
human environment at Rockefeller University, New York, who works with Hebert.
He estimates that out of the world’s 10,000 bird species, DNA barcoding will
distinguish at least 1,000 new ones.
Questions 1 to 3
Choose NO MORE THAN ONE WORD AND/OR A NUMBER from the passage
for each answer.
Write your answers in boxes 1-4 on your answer sheet.
Problems with taxonomy

only 1.......species have been classified so far

Difficult to distinguish between species of certain creatures, for example
2.......

possibility of a large number of species of 3.......dying out soon
Questions 4 - 8
Complete the flow-chart below.
Choose NO MORE THAN THREE WORDS AND/OR A NUMBER from the
passage for each answer. Write your answers in boxes 4-8 on your answer
sheet.
Hebert's system
decided to create a device called a 4......., like ones used in shops
↓
chose a 5....... that produces a substance called CO1
↓
samples of CO1 read by the device and matched with those kept in the 6.......
↓
current results show that 7....... of animal species can be identified in this way
↓
results show different species being identified, eg of 8.......
Questions 9 - 13
Do the following statements agree with the information given in Reading Passage
1?
TRUE -
if the statement agrees with the information
FALSE -
if the statement contradicts the information
NOT GIVEN -
if there is no information on this
9 The writer believes that the barcode system will be widely used by the general
public.
10 It is likely that the barcode device will show that many foods and goods have
not been correctly described.
11 Hebert got the idea for DNA barcoding from someone who worked at a
supermarket.
12 The number of organisations supporting Hebert’s barcoding project is growing
all the time.
13 A large number of new bird species have already been identified by the DNA
barcode system.