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19 Cards in this Set
- Front
- Back
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Variation |
The differences that exist between individuals |
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Intraspecific variation |
Variation within a species |
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Interspecific variation |
Variation between different species |
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Continuous variation |
No distinct categories |
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Discontinuous variation |
Distinct categories |
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How is variation caused by genetic factors? |
Different species have different genes Individuals of the same species have the same genes, but different versions of them (alleles) The genes and alleles make up the genotype Differences in genotype result in variation in phenotype |
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How is variation caused by both genetic factors and environmental factors? |
Genetic factors determine the characteristics an organism is born with Environmental factors can influence how some characteristics develop |
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Behvioural adaptations |
Ways an organism acts that increase its chance of survival |
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Physiological adaptations |
Processes inside an organism's body that increase its chance of survival |
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Anatomical adaptations |
Structural features of an organism's body that increase its chance of survival |
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Darwin's Theory of Evolution: What were his observations? What was the theory? |
Observations: Organisms produce more offspring than survive There's variation in the characteristics of members of the same species Some of these characteristics can be passed on from one generatio not the next Individuals best adapted to their environment are more likely to survive Theory: Individuals in a population show variation in their phenotypes Predation, disease and competition create a struggle for survival Individuals with better adaptations are more likely to survive, reproduce and pass on their adaptations to their offspring The number of individuals with adaptations increases Over generations this leads to evolution as the favourable adaptations become more common in the population |
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What evidence is there for evolution? |
Fossil record evidence DNA evidence |
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How do fossils support evolution? |
By arranging them in chronological order, gradual changes in organisms can be observed that provide evidence of evolution |
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How does DNA support evolution? |
The theory of evolution suggests that all organsims have evolved from common ancestors Closely related species diverged more recently Evolution is caused by gradual changes in the base sequence of organisms' DNA So organsims that diverged away form each other recently should have more similar DNA |
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How do molecules provide evidence for evolution? |
The similarities in other molecules provide evidence Organisms that diverged away from each other more recently have more similar molecules, as less time has passed for chnages in proteins and other molecules to occur |
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How can the evolution of antibiotic resistance be explained by natural selection? |
There is variation in population of bacteria Genetic mutations make some bacteria naturally resistant to an antibiotic if the population of bacteria is exposed to that antibiotic, only the individuals with resistance will survive to reproduce The alleles which cause the antibiotic resistance will be passed on to the next generation, and so the population will evolve to become resistant to the drug |
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Implications of antibiotic resistance for humans |
Infections caused by antibiotic resistant bacteria are harder to treat There could come a point where a bacterium has developed resistance to all known antibiotics |
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How can the evolution of pesticide resistance be explained by natural selection? |
There is a variation in the population of insects. Genetic mutations make some insects naturally resistant to pesticide If the population of insects is exposed to pesticide only the individuals with resistance will survive to reproduce The alleles which cause the pesticide resistance will be passed on to the next generation, and so the population will evolve to become more resistant to the chemical |
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Implications of pesticide resistance for humans |
Crop infestations with pesticide resistant insects are harder to control if disease carrying insects become pesticide resistant then the spread of the disease could increase A population of insects could evolve resistance to all pesticides in use |
