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GCSE Science
Chapter 1
BIOLOGY 1
Adaptation and
Competition
Classifying Organisms
It’s likely that there are around 15 million living
organisms!
Only about 1.8 million of these have been named.
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Chapter 1
In order to make it easier to study organisms, scientists
sort them into groups – this is called classification
Why classify organisms?
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Scientists place similar organisms in the same
group.
You can usually see that these organisms have
similar characteristics. You can also have very
different looking organisms in the same group
because they share similar DNA.
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The grouping system
Kingdom
The first group that organisms are placed
in is a Kingdom. Examples are Animals
and Plants.
The animal kingdom has organisms as
diverse as an elephant and a fly!
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Classifying the
Tiger
Kingdom
Animal
Phylum
Class
Chordates
(vertebrates)
Mammal
Order
Carnivore
Family
Felidae
Genus
Panthera
Species
tigris
Scientific name
In order to give an organism its scientific name, you take
the name of its genus and its species e.g. with the tiger it
is Panthera tigris
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This is called the binomial system of naming organisms.
The name appears in italics with the first letter of the
genus written in a capital letter.
Why does an organism need
a scientific name?
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The binomial system of naming is used
worldwide. Scientists, no matter where they live,
would know that the Panthera tigris is a tiger
even though the local name for it is different. e.g.
in China , 老虎 is the name for the tiger.
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Why Latin?
The names of the groups come from the
Latin. This is because it was the scientist
Carl von Linne (1707 -1778) who started
the binomial system of classification. He
was so fond of the Latin language that he
even changed his own name to Carolus
Linnaeus! In those days, Latin was the
main language for teaching science. The
names have remained to this day.
Adaptation
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Every living organism has been adapted to
live in a particular environment.
Comparing two Foxes
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These two foxes are closely related, but
because they have adapted to live in very
different habitats, they look quite different :
Desert Fox
Arctic Fox
Differences between the foxes
Size of the ear – a large surface area to the outer
ear (pinna) allows heat to radiate from the body
and a smaller outer ear retains as much heat as
possible.
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Body fat and thick fur coat – this is more apparent
in arctic animals that want to insulate their bodies
as efficiently as possible.
Colour – having fur that’s the same colour as the
environment, allows animals to blend into their
background and become more difficult to see. This
is called camouflage.
Plant Adaptation
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Plants are also adapted to live in their
specific habitats. If a plant lives in a hot,
arid (dry) habitat, then it must be very
efficient at conserving water.
Plant Adaptation
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This is how a cactus survives the desert:
 Spines instead of leaves
 succulent stem
 thick cuticle (a wax-like
substance over the leaf
surface)
 No stomata (small holes)
in the leaf or stem
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These two adaptations help the organism to
survive, as producing a lot of offspring
increases the chances of survival.
Insects laying a large
number of eggs
Dandelion dispersing its
seeds
Competition
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If organisms share the same habitat and are
dependent on the same resources, then they
compete with each other. This can happen
between organisms of the same species or
between different species.
Fight!
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Why do you think that It could be over:
these two lions are
fighting?
 food
 territory
 a partner
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From small acorns ……
The acorn shown has
germinated and
grown into an oak
sapling). In the forest
it will be competing
for:
 sunlight
 water
 minerals from the soil
Predator and Prey
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A population’s size depends on the
number of predators and prey. The lynx is
the predator in the example below, and the
hare is the prey.
 if the population of hare increases, there will
be more food for the lynx, and their numbers
increase.
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 As more hares are eaten, their population
decreases.
 The pattern of a predator’s population
matches that of its prey, as can be seen in
the following graph:
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Predator-Prey Graph
Pollution Indicating Species
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A Pollution Indicator is anything that shows
us if pollution has happened.
Species vary significantly between clean and
polluted areas. The cleanliness of a river can
be monitored by looking at the species of
aquatic organisms that live in it.
Indicator Species in Freshwater
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A large population of tubeworms in a river
tells us that there are low oxygen levels. They
are red in colour because they contain
haemoglobin (the red pigment found in red
blood cells) to capture dissolved oxygen from
the water.
red tubeworms
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Oxygen levels can be a measure of
pollution. pH is also measured to
determine how clean water is. A data
logger can be used to measure these
factors.
Data logger
Trent Biotic Index
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This is a standard method of
measuring pollution. It is based on the
fact that different organisms can resist
different degrees of pollution. The next
slide shows an interpretation of Trent
Biotic Index results.
Trent Biotic Index Interpretation
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Index
State
Typical Animals
XI-X
VII-X
Very clean
Trout, salmon
Clean
Fish and various
arthropods
VI-VII
Clean
As above but fewer
species
V-VI
Fairly clean
A few fish, freshwater
fleas
III-IV
Dubious
As above but fewer
species
II-IV
I-III
Dubious
As above but only fish
Poor
Insect larvae and
tubeworms
Poor
Anaerobic organisms
only
0-I
Lichen
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Plants can also be good indicators of
pollution. Lichen are very sensitive to
sulphur dioxide in the air. They do not
grow well in areas with air pollution.
Lichen growing n a tree in a clean
air area.