Brown's Biology AQA GCSE Additional Science-BIOLOGY 2
Biology Unit B2.8 Speciation
for GCSE Additional Science or GCSE Biology
REVISION NOTES GUIDE SUMMARY: What do you need to know
for the examinations? What do you need to able to do in the exams? In AQA GCSE Science
A examinations HT means for higher tier students only.
Sorry, but I don't have much time to answer questions, but if you see any
apparent errors or wish to comment, please
email me. All my notes, learning
objectives, comments for exam revision are based on the official AQA GCSE Science A Key Stage 4
AQA GCSE Science BIOLOGY 2 Unit
Know and understand that changes in the environment of
plants and animals may cause them to die out.
Know and understand that the fossil record shows that new
organisms arise, flourish, and after a time become extinct.
Know and understand that the record also shows changes
that lead to the formation of new species.
You should be able to use your
skills, knowledge and understanding to suggest reasons why scientists
cannot be certain about how life began on Earth.
AQA GCSE Science BIOLOGY Unit B2.8.1 Old and new species
a) Know and understand that evidence for early forms of
life comes from fossils.
b) Know and understand that fossils are the
'traces' or ‘remains’ of organisms from many
years ago, which are found in rocks which we find dating back thousands or
millions of years ago..
c) Know and understand that many early forms of life were soft-bodied,
which means that they have left few traces behind.
d) Know and understand that we can learn from
fossils how much or how little different organisms have changed as life
developed on Earth.
From fossils we can get some
idea on what the animals and plants looked like e.g. general shape, skeletal
structure and sometimes, though very rarely, detail of internal
Generally speaking, the deeper
the layer of rock containing fossils, the older the fossils and this means
we can follow the development and evolution of a species or the origin of
new species by looking at similarities and differences, but its the gradual
changes in the structure of plants and animals over millions of years that
shows the evolutionary path of a species.
e) Know and understand that extinction may be caused by:
changes to the
environment over geological time - eg think of plate tectonic movement over
millions of years from warm equatorial areas to cold arctic areas of the
new predators - one species can
consume another!, we humans have been responsible for many extinctions by
new diseases - eg an animal's
immune system unable to cope with a new mutant bacteria or virus,
new, more successful, competitor
for food invading a particular habitat,
a single catastrophic event, eg massive volcanic
eruptions, collisions with asteroids (huge impact 65 million years ago may
be responsible for the extinction of dinosaurs), onset of an ice age
through the cyclical nature of
speciation - the evolution of a new species.
f) Know and understand that new species arise as a result of:
A species is group of similar
organisms that can interbreed to give fertile offspring.
Speciation is the development of
a new species and can happen when populations of the same original species
becomes so different (genetically) that they can no longer interbreed to
give fertile offspring.
Speciation can occur via isolation – two
populations of a species become separated, eg geographically,
In the two geographical regions,
the climate might be different, the other plants and animals may be
However, if each population can
survive, by the process of natural selection, two distinct species can
evolve (or perhaps one population remains the same, but the other has to
adapt to a different environment).
For Foundation Tier students ideas are restricted to knowledge and understanding of
HT only: genetic
variation – each population has a wide range of alleles that control their
HT only: natural selection – in each population, the alleles that
control the characteristics which help the organism to survive are selected
and passed on to the next generation - 'survival of the fittest'.
HT only: speciation – the populations become so different that successful
interbreeding is no longer possible.
GCSE Science-Biology courses
AQA GCSE Science A BIOLOGY *
EDEXCEL GCSE Science BIOLOGY
OCR GCSE 21st Century
Science A - BIOLOGY * OCR GCSE Gateway
Science A BIOLOGY
AQA GCSE Sciences - Revision
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