Download Life on Earth - The Bicester School

B3
Life on Earth
Bicester Community College Science Department
B3 Key Questions
 How
do different species depend on each
other?
 How has life on Earth evolved?
 What is the importance of biodiversity?
Bicester Community College Science Department
How do different species depend on
each other?
species is a group of organisms that can breed
together to produce fertile offspring.
 Adaptation of living organisms to their environment
increases the species’ chance of survival by
making it more likely that individuals will survive to
reproduce.
 There is competition for resources between different
species of animals or plants in the same habitat.
 Changes affecting one species in a food web may
have an impact on other species that are part of
the same food web.
A
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How do different species depend on each other?
Bicester Community College Science Department
How do different species depend on
each other?
A
change in the environment may cause a
species to become extinct, for example, if:



the environmental conditions change beyond its
ability to adapt
a new species that is a competitor, predator or
disease organism of that species is introduced
another species (animal, plant or microorganism) in
its food web becomes extinct
Bicester Community College Science Department
How do different species depend on
each other?



Nearly all organisms are ultimately dependent on energy from
the Sun.
Plants absorb a small percentage of the Sun’s energy for the
process of photosynthesis.
This absorbed energy is stored in the chemicals which make
up the plants’ cells.
Bicester Community College Science Department
How do different species depend on
each other?

Energy is transferred between organisms in an
ecosystem:



when organisms are eaten
when dead organisms and waste materials are fed on by
decay organisms (decomposers and detritivores)
Energy is lost from a food chain at each stage via heat,
waste products and uneaten parts, limiting the length of
food chains.
Bicester Community College Science Department
How do different species depend on each other?
Bicester Community College Science Department
How do different species depend on each other?
Bicester Community College Science Department
How has life on Earth evolved?
 Life
on Earth
began
approximately
3500 million
years ago.
 Life on Earth
(including
species that
are now
extinct)
evolved from
very simple
living things.
Bicester Community College Science Department
How has life on Earth evolved?
is variation between individuals of the same
species.
 Some of this variation is genetic so can be passed
on to offspring.
 Genetic variation is the result of changes that
occur in genes (mutations) and may occasionally
produce new characteristics.
 There
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How has life on Earth evolved?
 Variation
 Inheritance
 Selection
 Time
 Adaptation
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How has life on Earth evolved?
 New
species can
be produced by
the combined
effect of:




mutations
environmental
change
natural selection
isolation
Bicester Community College Science Department
How has life on Earth evolved?
 Evidence
for evolution is provided by the fossil
record and from analysis of similarities and
differences in the DNA of organisms.
Bicester Community College Science Department
What is the importance of biodiversity?

Organisms are classified into
groups according to similarities and
differences in characteristics
including:



Classification of living and fossil
organisms can help to:




physical features
DNA
make sense of the diversity of
organisms on Earth
show the evolutionary relationships
between organisms
Organisms are classified at different
levels.
These levels can be arranged in an
order progressing from large
groups containing many organisms
with a small number of
characteristics in common (e.g.
kingdom) to smaller groups
containing fewer organisms with
more characteristics in common
(e.g. species)
Bicester Community College Science Department
What is the importance of biodiversity?
 Biodiversity
including:



refers to the variety of life on Earth
the number of different species
the range of different types of organisms, e.g. plants,
animals and microorganisms
the genetic variation within species
Bicester Community College Science Department
What is the importance of biodiversity?
 Biodiversity
is important for the future development
of food crops and medicines
 Sustainability means meeting the needs of people
today without damaging the Earth for future
generations
 Maintaining biodiversity to ensure the conservation
of different species is one of the keys to
sustainability.
 Large-scale monoculture crop production is not
sustainable because it does not maintain
biodiversity.
 Sustainability can be improved, for example by
considering the materials used, energy used and
pollution created.
Bicester Community College Science Department
Common B3 mistakes…
make sure you don’t do these!
 Students
often:
 have difficulty in explaining how adaptation
develops through evolution (e.g. in the beaks of
'Darwin's finches')
 have difficulty in explaining why crops might be
genetically modified
 may not realise that for animal populations to rise or
fall significantly there should be a change in a
contributing factor
 may not recognise the concept of a common
ancestor or divergence
 may report incorrectly that humans use natural
selection to breed domestic animals
Bicester Community College Science Department
Links from B3 to other topics
 More
about ecosystems in B7.4 Further biology
 Sustainable development in C2 Material choices
Bicester Community College Science Department