Environment

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Environment
(EdExcel)
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Food chains
A food chain shows where the energy goes in a
food chain (in other words, what gets eaten by
what)
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Match these words

• Tertiary
• consumer
• Herbivore
• Top carnivore
• Producer
• Secondary
• consumer
• Consumer
• Omnivore
• Carnivore
• Primary
• consumer

Usually plants. Starts off a food chain Animals
that only eat plants An animal that eats
producers An animal that eats primary
consumers An animal that eats secondary
consumers A general word for an eater Eats only
animals Not eaten by anything else Eats both
animals and plants
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Predators and Prey
A PREDATOR is an animal that hunts and eats
another animal The PREY is the animal it eats,
for example
Yum
Prey
Predator
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Pyramids of biomass
In this food chain we can see that the mass of
organisms in each stage is less than in the
previous stage
We can draw a Pyramid of Biomass to show this
pattern
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Energy flow in a food chain
Consider the energy flow in this food chain
100
10
1
0.1
Words 10, move, sun, waste, cabbage
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Improving the efficiency of a food chain
Clearly, food chains arent very efficient. How
could the efficiency of a food chain be improved?
1) Reduce the number of stages in the chain
2) Limit an animals movement or keep it warm
3) Use plant hormones to regulate the ripening
of fruit
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Competition
Any living species competes with each other.
They may compete for
Get off my land
- Living space - Food - Water
In addition to this competition, the population
of a species can be affected by predators,
disease, migration etc
Yum!
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Predators and Prey
A PREDATOR is an animal that hunts and eats
another animal The PREY is the animal it eats,
for example
Hey! I ordered a steak
Prey
Predator
Consider the populations of these two animals
over time
Rabbit
Fox
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Pollution
Humans pollute the Earth in a number of ways
Water with sewage, fertiliser or toxic
chemicals Air with smoke or gases such as
sulphur dioxide Land with toxic chemicals,
pesticides and waste
NO, NO2 and CO
These gases produce acid rain (which affects
tress and buildings) and worsens the greenhouse
effect
Power stations produce CO2, SO2 and NO2
Cars produce NO, NO2 and CO
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Pollution Indicators
Lichens can be used as air pollution indicators
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Pollution Indicators
The quality of water can be monitored by looking
at the species of insect in the water
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Farming Methods
There are basically two types of farming method
intensive and organic
Intensive
Organic
Cost
Produce
Fertilisers
Space
Labour done by...
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Selective breeding
I raise cows. Each type of cow is good at a
certain job. The Friesian cow produces large
quantities of milk, the Jersey cow produces very
nice milk and the Hereford cow produces lot of
beef.
If, for example, I want lots of milk I would only
breed Friesian cows with each other this is
SELECTIVE BREEDING.
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Genetic Modification
Possible uses of genetic modification of
organisms

• Improving crop yield
• Improving resistance to pesticides
• Extend shelf-life
• Manufacture a certain chemical (e.g. insulin)
• Convenience

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Genetic engineering an example
Insulin is a hormone produced by the pancreas to
help control blood sugar levels. Diabetics cant
produce enough insulin and often need to inject
it. Insulin can be made by genetic engineering
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Genetic engineering - Insulin
Step 1 Using RESTRICTION ENZYMES cut out the
part of the human chromosome that is responsible
for producing insulin.
Step 2 Using another restriction enzyme cut open
a ring of bacterial DNA (a plasmid). Other
enzymes are then used to insert the piece of
human DNA into the plasmid.
Step 3 Place the plasmid into a bacterium which
will start to divide rapidly. As it divides it
will replicate the plasmid and make millions of
them, each with the instruction to produce
insulin. Commercial quantities of insulin can
then be produced.
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Evolution
Charles Darwin (1809-1882)
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Evolution
Evolution is the slow, continual change of
organisms over a very long time. All living
things on the Earth have developed from the first
simple life forms that arrived 3,000,000,000
years ago.

• One of the effects of evolution is that species
  will become better adapted to their environment.
  If these species dont adapt they may become
  extinct due to being unable to deal with any of
  these factors
• Increased competition
• Changes in the environment
• New diseases
• New predators

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The Evolution Tree
Family Hominidae (Great Apes)
Family Hylobatidae (Lesser Apes)
Subfamily Hominidae
Subfamily Ponginae
Tribe Homini
Tribe Panini
Tribe Gorillini
Humans
Chimpanzees
Gorillas
Orangutans
Gibbons
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Evidence for Evolution
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Evolution

• My key observations
• All living things produce more offspring than
  survive to adulthood
• In spite of this, population sizes remain roughly
  constant
• Variation exists among species
• Characteristics can be passed on from one
  generation to the next.
• These observations led me to the conclusion that
  species evolve over a along period of time by a
  mechanism called Natural Selection. The main
  evidence for this is from fossil records.

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Natural Selection
1) Each species shows variation

• There is competition within each species for
  food, living space, water, mates etc

Get off my land
Gutted!

• The better adapted members of these species are
  more likely to survive Survival of the Fittest

Yum

• These survivors will pass on their better genes
  to their offspring who will also show this
  beneficial variation.

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A smaller example
Consider the four steps of natural selection in
the example of some bacteria that has become
resistant to penicillin

• Variation some strains of bacteria are
  resistant and some arent.
• Competition The non-resistant bacteria are
  killed by the penicillin.
• Survival of the fittest the resistant bacteria
  survive.
• Passing on of genes the resistant bacteria
  reproduce and pass on their adaptations to their
  offspring.

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Darwin vs Lamarck
Darwin wasnt the first to come up with evolution
he was simply the one credited with explaining
how it worked (i.e. Natural Selection). An
earlier scientist called Lamarck explained
evolution by different means
The giraffe has a long neck because it
stretches its neck to reach the food, and these
long necks are passed on to their offspring.
Organs which arent used will eventually
disappear.
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Changing Species summary
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Classification
The world is populated by millions of different
species of animals and plants
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Classifying organisms
All organisms are classified into groups. For
example
Organism
Plants
Animals
Vertebrates
Invertebrates
Reptiles
Fish
Birds
Mammals
Amphibians