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AQA Biology Unit 1
This PowerPoint supports sections B1.4, B1.5, B1.6,
B1.7 and B1.8 of the 2011 AQA Biology Unit 1 module
W Richards
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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Extreme environments
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Mountains
The Arctic
Deep sea
volcanic vents
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!
Extinct Species
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What factors
have caused
these species
to become
extinct?
Sabre-toothed tigers
and mammoths
Dodo
Endangered Species
What factors
have caused
these species
to become
endangered?
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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
Measuring Environmental Changes
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Recording
temperature changes
Measuring rainfall
Recording oxygen
levels
Biomass
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Plants use glucose from photosynthesis to produce starch and
cellulose. This plant material is called “biomass”:
Food chains
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A food chain shows where the biomass or energy goes in a
food chain (in other words, “what gets eaten by what”):
Cabbage
Rabbit
Plants convert the sun’s
energy into food through
photosynthesis
Stoat
Fox
The arrows indicate where
the energy is going
Pyramids of biomass
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In this food chain we can see that the mass of organisms in
each stage is less than in the previous stage:
Cabbage
Rabbit
Stoat
Fox
We can draw a “Pyramid of Biomass” to show this pattern:
Mass of foxes
Mass of stoats
Mass of rabbits
Mass of cabbages
Energy flow in a food chain
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Consider the energy flow in this food chain:
100%
10%
Cabbage
Rabbit
1%
Stoat
0.1%
Fox
Clearly, not all of the ___’s energy that becomes stored in the _______
will end up in the fox. Only around ______ is passed on to the next stage
in each food chain.
Energy is lost to the surroundings at each stage because of a number of
reasons:
1) Each organism has to ____, keep warm etc
2) Energy is lost through faeces (______)
Words – 10%, move, sun, waste, cabbage
Recycling ourselves
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Microbes are the key to this – they break down waste and
dead bodies so that the products can be used by plants for
growth. Microbes work best in warm, moist conditions where
there is plenty of oxygen.
The Carbon Cycle
Burning
fossil fuels
also releases
CO2
6. These microbes
also release CO2
through
respiration
5. Animals (and plants)
die and their remains
are fed on by microbes
and detritus feeders
CO2 in air
4. Animals
release CO2
through
respiration
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2. Plants and algae
release CO2 through
respiration
1. CO2 is taken in
by plants and
algae for
photosynthesis
and turned into
carbohydrates,
fats and proteins
3. The carbon taken in
by plants is then eaten
by animals and the
animals that eat them
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:
Sexual Reproduction
The human egg and
sperm cell contain 23
chromosomes each.
When fertilisation happens the egg
and sperm fuse together to make a
single cell. This cell has 46
chromosomes (23 pairs) and
continues to grow.
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Genes, Chromosomes and DNA
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An example - Boy or Girl?
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X
Girl
Y
XX
X
XY
Boy
Mother
Boy or Girl?
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Son
Father
Daughter
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 Plants by tissue culture
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1) Scrape off a
few cells from
the desired plant
2) Place the scrapings
in hormones and
nutrients
3) 2 weeks later
you should have
lots of genetically
identical plants
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
Uses of Genetic Engineering
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With genetic engineering I can
produce milk that contains:
• Extra protein
• Lower levels of cholesterol
• Human antibodies
Genetic engineering can also be used
to grow bigger crop yields and to
develop plants that are resistant to
pesticides and herbicides.
Genetic engineering - Insulin
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Step 1: Using enzymes “cut out”
the part of the human
chromosome that is responsible
for producing insulin.
Step 2: Using another enzyme cut
open a ring of bacterial DNA. Other
enzymes are then used to insert the
piece of human DNA into it.
Step 3: Place it into a bacterium which will
start to divide rapidly. As it divides it will
replicate and make millions of them, each
with the instruction to produce insulin.
Commercial quantities of insulin can then
be produced.
Genetic Engineering
Yes
No
Should genetic engineering
be allowed?
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Evolution
Charles Darwin
(1809-1882)
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Evolution is the theory of slow,
continual change of organisms over
a very long time. All living things
on the Earth have supposedly
developed from the first simple
life forms that arrived
3,000,000,000 years ago.
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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The main evidence for my theory came
from fossil records. However, these
records didn’t exist when I came up
with my theory. Also, there was
little evidence about how species
evolved so few people believed my
ideas.
These days scientists understand that
the process that causes evolution is
called “Natural selection” and it
works like this:
Natural Selection
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1) Each species shows variation:
2) There is competition within each
species for food, living space,
water, mates etc
Get off
my land
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.
An example – the peppered moth
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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
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