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Darwin
Made 4 main observations;
1. offspring are generally similar to their
parents
2. no 2 individuals are identical
3. organisms can produce large numbers of
offspring
4. populations tend to remain stable in size

- When too many young are produced ­
competition for food and resources
- Some…

Page 2

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2. Better adapted individuals
survive and pass on their
characteristics
3. Over time a number of changes
may give rise to a new species

Natural selection.

Process in which an environmental
factor determines which individuals
will survive
They are `selected'
Undergo a `selection pressure'
If it is not `selected'- it…

Page 3

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2. Predators- individuals may be
better adapted not to be seen,
or escape
3. Diseases ­ some may be
resistant
4. Physical and chemical factors-
if an organism can survive in
e.g a desert, or somewhere v.
Cold, it has a selective
advantage

Speciation = formation of a new
species…

Page 4

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OR reproductive barriers e.g.
biochemical change ­ prevents
fertilisation, physical change ­ sex
organs may no longer be compatible or
behavioural change- courtship dance
might not be recognised)
So some individuals can't reproduce with
others
So variations will only spread down part
of the group
Eventually become very different
=…

Page 5

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4. What could the fossils of brachiopods
be used for?
5. What is interesting about the
relationship between armadillos and
glyptodonts?
6. Give the 3 important discoveries within
the study of fossils in times since
Darwin.
7. What is the problem with the fossil
record?
8. Describe the 3 types…

Page 6

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5. Next generation are better
adapted for survival




Remember- genetic variation is
what makes a difference-
environmental variations can't be
passed on!!
If a new species evolves- diversity
is increased
Having a lot of populations that
are genetically different but can
still interbreed also increases
diversity e.g. humans
Evolution always…

Page 7

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e.g. bacteria becoming resistant
to antibiotics- HOW?!
What is this causing?

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