Evolution

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  • Created by: ElishaG
  • Created on: 05-04-17 20:03
What is evolution?
The gradual process by which the present diversity of living organisms has developed over millions of years. How species change over time.
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What is natural selection?
A theory of how species change over time due to the selective forces present in the environment and how these forces affect the reproduction of individuals in a population.
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What are selective forces?
Some environmental factors that cause individuals to die/ be disadvantaged: predator, abiotic factors, competition, lack of resources.
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What are Charles Darwin's 4 basic observations/
1)Individuals within a species vary.2)Offspring resemble their parents/variation is inherited.3)More offspring are produced that can survive.4)Population sizes remain relatively constant.
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What were 4 reasons for people disagreeing with Darwin?
1)Religion- people believed humans came from God.2)Believed Earth was a few 1000 years old, theory required millions.3)Suggested competition and death were essential- went against Victorian view of nature.4)People disputed evidence- fossil records.
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Explain how fossils provide evidence for evolution.
1)Fossils show changes over time.2)Methods to date fossils.3)Show links/ relationships between species.4)Many fossilised organisms no longer exist.5)Can compare DNA extracted from some fossils.
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What are three sources of evidence to study evolution?
1)Palaeontology.2)Comparative anatomy.3)Comparative biochemistry.
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What is palaeontology?
Fossil records.
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Why are fossil records incomplete?
Due to many organisms being 'soft bodies' which' decompose before fossilisation takes place.
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What is comparative anatomy?
Similarities and differences between the anatomy of organisms.
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What is a homologous structure?
Same structure, different function, e.g. pentadactyl limb.
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What is an analogous structure?
Different structure, same function, e.g. wings.
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What is comparative biochemistry?
Similarities and differences between the chemical makeup of organisms, e.g. DNA, proteins.
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What is variation?
The presence of differences between individuals. There are two causes of variation in the living world, genetic and environmental.
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What is intraspecific variation?
Variation between members of the same species.
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What is interspecific variation?
Variation between members of different species.
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What are two types of variation?
1)Continuous.2)Discontinuous.
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Does continuous variation have categories?
No- there is a range from one extreme to another.
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Does discontinuous variation have categories?
Yes- there are distinct categories.
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Is continuous variation quantitative and qualitative?
Quantitative.
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Is discontinuous variation qualitative or quantitative?
Qualitative.
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How many genes is continuous variation controlled by?
Many- polygenic.
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How many genes is discontinuous variation controlled by?
One- monogenic.
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What influence does the environment have on continuous variation?
Large influence.
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What influence does the environment have on discontinuous variation?
Small/no influence.
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What are examples of continuous variation?
Height/mass/length.
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What are examples of discontinuous variation?
Blood group/ colour.
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What are examples of interspecific variation in plants?
Flower colour/height/xerophytic/hydrophytic/drought resistance.
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What are examples of intraspecific variation in plants?
Number of leaves/heights.
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What are examples of interspecific examples in prokaryotes?
Gram +/-, pathogenic or not, shape.
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What are examples of intraspecific examples in prokaryotes?
Number of plasmids/number of ribosomes/number of mesosomes/thickness of capsule.
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What is an adaptation?
A feature that enhances survival and long term reproductive success.
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What is reproductive success?
Production of offspring that have offspring of their own.
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What are the three categories of adaptation?
1)Behavioral.2)Physiological.3)Anatomical.
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What is behavioural adaptation?
An aspect of the behaviour of the organism that helps it to survive the conditions it lives in.
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What is a physiological adaptation?
Something that ensures the correct functioning of a cell's processes.
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What is an anatomical adaptation?
Means structural, structural adaptations to the body which increase the chance of survival.
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What are shared anatomical features between the marsupial mole and placental mole?
1)Cylindrical body.2)Small eyes.3)Strong front legs.4)Short fur.5)Short tail.6)Nose with tough skin for protection.
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What are non shared anatomical features of the marsupial mole?
1)White/cream fur.2)No fur on tail.3)Short fur.
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What are non shared anatomical features of the placental mole?
1)Black fur.2)Fur on tail.3)Long nose.
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What are 7 things to include when answering questions about natural selection?
1)Variation in population.2)Cause of variation.3)Struggle for existence- selection pressure.4)Which is better adapted.5)Which is less well adapted and selected against.6)Fate of better adapted.7)Changes in allele frequency.
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Card 2

Front

What is natural selection?

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A theory of how species change over time due to the selective forces present in the environment and how these forces affect the reproduction of individuals in a population.

Card 3

Front

What are selective forces?

Back

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Card 4

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What are Charles Darwin's 4 basic observations/

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Card 5

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What were 4 reasons for people disagreeing with Darwin?

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