Evolution - Spec.

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  • Created by: rachel
  • Created on: 25-03-13 15:32
Define the term variation.
Differences within or between species.
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Discuss the fact that variation occurs within as well as between species.
Variation occurs within a species (e.g. eye colour, hair colour, hight) & between species which are obvious differences (e.g. Birds fly, whereas Dogs do not).
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Describe what continuous variation is using examples of a range of characteristics found in plants, animals & microorganisms.
2 extremes & full range of values in the middle. Most individuals are close to the mean, but there is a minority at each extreme. Characteristic is coded for by multiple genes & environment has large effect on it e.g. height of humans &length of leaf
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Describe what discontinuous variation is using examples of a range of characteristics found in plants, animals & microorganisms.
Distinct categories & no intermediate values. May be equal spread between categories or there may be more of one type than another. Characteristic coded for by 1 gene which the environment has no effect on (e.g. sex, blood groups & flagella).
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Explain genetic causes of variation.
Our genes define our characteristics & the combination of alleles that we inherit from parents is unique. Unless person has identical twin, there's little chance of 2 people having same combination of alleles, so everyones characteristics are unique.
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Explain environmental causes of variation.
Many characteristics can be affected by the environment - if a tree that would normally grow to 6m was planted where there was little soil/water e.g. a rock crevice, it might only grow to 1.5m. If a pet was overfed, it would become obese.
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Outline the behavioural adaptations of organisms to their environments.
An aspect of behaviour of an organism that helps it to survive the conditions it loves in. Example: An earthworm withdraws into a burrow when touched to avoid being eaten.
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Outline the physiological/biochemical adaptations of organisms to their environments.
An adaptation that ensures correct functioning of cell processes. Example: Yeast can produce enzymes to respire different sugars that are present.
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Outline the anatomical adaptations of organisms to their environments.
A structure that enhances the survival of the organism. Example: Bacteria have flagella to enable them to move independently.
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What were Darwin's 4 observations?
1) Offspring appear genetically similar to their parents. 2) No two individuals are identical. 3) Organisms have the ability to produce large numbers of offspring. 4) Populations in nature tend to remain fairly stable in size.
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What were the consequences of the 4 observations made by Darwin in proposing his theory of natural selection?
Struggle to survive. Natural Selection. Evolution. Development of species.
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Define the term speciation.
The formation of a new species.
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Discuss the evidence supporting the theory of evolution with reference to fossils.
Fossils show changes over time. There are ways to date fossils. Simplest species are found in oldest rocks. Fossils can show links between groups of organisms. Many fossils are organisms that no longer exist. Possible to compare DNA extracted.
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Discuss the evidence supporting the theory of evolution with reference to DNA.
Genes can be compared by sequencing the bases in DNA. Most distantly related species have more differences in their DNA; therefore they must have evolved as a different species further back in time.
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Discuss the evidence supporting the theory of evolution with reference to Molecules.
Two closely related species will have similar, or identical, biological molecules as they will have separated more recently.
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Outline how variation (V), adaptation & selection are major components of evolution (E)
V occurs before E can take place. V arrises due to random mutation & sex. Once V exists -> individuals with selective advantage over others. Individuals with mutation -> survive & reproduce. Offspring inherit mutation. Next generation better adapted.
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Discuss why the evolution of pesticide resistance in insects has implications for humans.
Pesticides kill pests. Insecticide applies a very strong selection pressure - all susceptible insects will die, leaving only those with the resistance. They will pass on resistance to next generation, so whole population will be resistant to insectic
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Discuss why the evolution of drug resistance in microorganisms has implications for humans.
Antibiotic will kill any microorganisms that don't have resistance, leaving behind only the ones that do. They pass on their genes to next generation & soon entire population will possess resistance. MRSA may become untreatable -> epidemic.
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Other cards in this set

Card 2

Front

Discuss the fact that variation occurs within as well as between species.

Back

Variation occurs within a species (e.g. eye colour, hair colour, hight) & between species which are obvious differences (e.g. Birds fly, whereas Dogs do not).

Card 3

Front

Describe what continuous variation is using examples of a range of characteristics found in plants, animals & microorganisms.

Back

Preview of the front of card 3

Card 4

Front

Describe what discontinuous variation is using examples of a range of characteristics found in plants, animals & microorganisms.

Back

Preview of the front of card 4

Card 5

Front

Explain genetic causes of variation.

Back

Preview of the front of card 5
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