Download Evolution and the Environment

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Evolution and the
Environment
(AQA)
New Bridge Academy Science Dept.
Adaptation
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Organisms are ADAPTED to the habitat they live in. In
other words, they have special features that help them to
survive. Some examples:
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Competition
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Any living species competes with each other. They may
compete for:
- Living space
- Food
Get off my
land
- Water
In addition to this competition, the population of a species can
be affected by predators, disease, migration etc
Yum!
Predators and Prey
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A PREDATOR is an animal that hunts and eats another animal
The PREY is the animal it eats, for example…
Prey
Hey! I
ordered a
steak
Predator
Consider the populations of these two animals over time:
Population
of animal
Rabbit
Fox
Time
Variation
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“Variation” is the name given to differences between
individuals of the SAME species.
Variation is due to GENETIC or ENVIRONMENTAL causes.
For example, consider dogs:
1) Ways in which they are the
same:
2) Ways in which they are
different:
Where is this information stored?
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Section of a chromosome:
Genes for
blood group:
Genes for
eye colour
Genes for
hair colour
Different species have different numbers
of chromosomes. Humans have 46 (23
pairs) in every cell.
Sexual Reproduction
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We have similar characteristics to our parents due to genetic
information being passed down in genes through gametes:
The human egg
and sperm cell
(“GAMETES”)
contain 23
chromosomes
each.
When fertilisation happens the
gametes fuse together to make
a single cell called a ZYGOTE.
The zygote has 46 chromosomes
(23 pairs) and contains
information from each parent.
Sexual vs. Asexual reproduction
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Sexual reproduction:
•2 parents are needed
•Offspring will have “pairs” of chromosomes
•This will cause genetic variation
Asexual reproduction:
•Only 1 parent needed
•Offspring are GENETICALLY IDENTICAL to
parent (“clones”)
“Snuppy” – the
first cloned dog
(Aug 05)
Cloning Plants
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Plants can reproduce ASEXUALLY. The offspring are
genetically ________ to the parent plant and are called
_________. Two examples:
1) This spider plant has grown a rooting
side branch (“stolon”) which will
eventually become __________.
2) A gardener has taken cuttings of
this plant (which probably has good
characteristics) and is growing them
in a ____ atmosphere until the
____ develop.
Words – clones, damp, independent, roots, identical
Cloning Animals
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Method 1 – “Embryo transplants”
A developing embryo is “split” before the cells specialise and
the identical embryos are implanted into host mothers.
Cloning Animals
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Method 2 - Fusion
Host mother
Clone
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.
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Friesian
Jersey
If, for example, I want lots of
milk I would only breed
Friesian cows with each other
– this is SELECTIVE
BREEDING.
Hereford
Selective breeding vs. Cloning
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Advantages
Cloning
Selective
breeding
Disadvantages
Selective breeding vs. Cloning
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Cloning
Selective
breeding
Advantages
Disadvantages
1) Allows large
numbers of
organisms with good
characteristics to
be produced
2) Very efficient
1) Causes reduced
numbers of alleles
2) Loss of variation
could harm survival
chances if the
environment changes
1) Produced organisms
with favoured
characteristics
2) Very efficient and
economically viable
1) Causes reduced
numbers of alleles
2) Loss of variation
could harm survival
chances if the
environment changes
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
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Insulin is a hormone produced by the pancreas to help control
blood sugar levels. Diabetics can’t produce enough insulin and
often need to inject it.
Insulin can be made by genetic engineering:
Genetic engineering - Insulin
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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.
Evolution
Charles Darwin (1809-1882)
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Evolution
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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
don’t adapt they may become extinct due to being unable to
deal with any of these factors…
1) Increased competition
2) Changes in the environment
3) New diseases
4) New predators
The “Evolution Tree”
Family Hylobatidae
(Lesser Apes)
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Family Hominidae
(Great Apes)
Subfamily
Ponginae
Subfamily
Hominidae
Tribe Panini
Tribe Homini
Tribe Gorillini
Gibbons
Orangutans
Chimpanzees
Gorillas
Humans
Evidence for Evolution
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The Grand Canyon
Humans with tails
Fossil records
“Missing links”
Evolution
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My key observations:
1) All living things produce more
offspring than survive to adulthood
2) In spite of this, population sizes
remain roughly constant
3) Variation exists among species
4) 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.
Natural Selection
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1) Each species shows variation:
Get off
my land
2) There is competition within each
species for food, living space,
water, mates etc
3) The “better adapted” members of
these species are more likely to
survive – “Survival of the Fittest”
Gutted!
Yum
4) These survivors will pass on their
better genes to their offspring who
will also show this beneficial variation.
A smaller example…
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Consider the four steps of natural selection in the example of
some bacteria that has become resistant to penicillin:
Bacteria
1) Variation – some strains of bacteria
are resistant and some aren’t.
2) Competition – The non-resistant
bacteria are killed by the penicillin.
3) Survival of the fittest – the
resistant bacteria survive.
Penicillin
4) Passing on of genes – the resistant
bacteria reproduce and pass on
their adaptations to their
offspring.
Darwin vs Lamarck
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Darwin wasn’t 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 aren’t
used will eventually disappear.
Jean Baptiste
Lamarck
(1744 - 1829
Population and Pollution
The human population is
growing exponentially:
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Population
Time
This has a number of effects on the environment:
Farming –
less land available
for crops
Waste –
more waste needs
to be disposed of
Bigger
population
means…
Building –
more buildings
needed
Quarrying and mining –
raw materials and
sources of energy are
being used up
Pollution
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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
Power stations
produce CO2,
SO2 and NO2
Cars produce NO,
NO2 and CO
Acid
rain
These gases produce
acid rain (which
affects tress and
buildings) and worsens
the greenhouse effect
Pollution Indicators
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Lichens can be used as air
pollution indicators:
Lichens in clean
air
Lichens in very
clean air
Lichens in slightly
dirty air
Pollution Indicators
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The quality of water can be monitored
by looking at the species of insect in
the water:
In dirty water
leeches and midges
will survive
In average water
more species (like
the dragonfly and
cranefly) will
survive
In clean water a
lot more species
(like the mayfly
and caddisfly)
will survive
Deforestation
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Deforestation
Why it happens
Effects
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The Greenhouse Effect
We get heat
from the sun:
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A lot of this heat is
_______ back into space.
However, most of it is kept inside the
Earth by a layer of gases that prevent
the heat escaping by _______ and
then re-radiating it back again.
This is called the _________ Effect. It has always been around, but is
currently being made worse due to:
1) Burning (releasing CO2)
2) __________ (removing trees that remove CO2)
3) Increased micro organism activity (from rotting ______)
4) Cattle and rice fields (they both produce _______)
These changes will cause GLOBAL WARMING and RISING SEA LEVELS
Words – methane, radiated, absorbing, deforestation, waste, greenhouse
Sustainable Development
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Sustainable development is all about preserving the world for
tomorrow. There are three main strands:
1) Economic development
2) Social development
3) Environmental protection
Examples of sustainable development include:
1) Replanting trees after chopping them down
2) Limiting the number of fish allowed in a catch
3) Protecting endangered species