Biology 15, Evolution

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What are the steps of natural selection?
In a population there is genetic variation. Some individuals have more favourable characteristics to their environment making them more likely to survive and therefore reproduce,passing on these favourable alleles to offspring. Those without will die
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What is Lamarck's theory of evolution
He believed characteristics gained in a lifetime were heritable. He believed giraffes began with short necks which elongated to reach more leaves. This longer neck was then passed to its offspring which would then grow or shrink to reach leaves
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What is Darwin's theory of evolution
He believed in natural selection. A giraffe will have had a mutation in their genes which caused them to have a longer neck which was more favourable to their environment. The allele with this characteristic would be passed on to their offspring
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What is speciation and what causes it?
Speciation is the formation of a new species. It begins with a species being isolated, generally geographically. Genetic variation happens followed by natural selection and eventually speciation
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What is a species?
A group of organisms that can reproduce to form a fertile offspring
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What are some of the causes of extinction?
-Changes to environment (temperature, rivers forming etc) -New predators -New diseases -New competition -Extinction happens when the species can't adapt quickly enough to the changes
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Why was Darwin's theory of evolution not immediately accepted?
-The theory challenged the Christian creation story and the idea that God created all living things -There was insufficient evidence at the time of publication to convince many scientists -The mechanism of inheritance and variation was not known
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What experiment did Mendel carry out?
Mendel crossed different height peas together. To start he crossed a tall pea plant and a dwarf pea plant. The offspring of them was 4 tall pea plants. He then crossed 2 of the tall offspring pea plants, producing 3 tall plants and a dwarf pea plant
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What conclusions did Mendel reach from his experiment?
1. Characteristics are determined by "hereditary units" 2. Hereditary units are passed on to offspring unchanged from both parents, one unit from each parent 3. Hereditary units can be dominant or recessive
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What are the ways that fossils can be formed?
1. From gradual replacement by minerals, forming a rock like substance. Happens for things like teeth and bones 2. From casts and impressions from clay hardening around the object 3. From preservation in places where no decay happens e.g amber/ice
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Why are there few traces of early life forms on earth?
Many early life forms were soft-bodied so tended to decay completely. Fossils that were formed have largely been destroyed by geological activity e.g tectonic plate movement may have crushed fossils formed in the rock
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What are some of the causes for extinction?
-Quick changes to environmental conditions -New predators -New diseases -New competition -These factors cause extinction when the species can't adapt quickly enough to keep up with the changes
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Give an example of bacteria that is resistant to antibiotics?
MRSA, often affects people in hospitals and can be fatal if it enters the bloodstream
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What is the Linnaean classification system?
-Kingdom (Animal, plant, fungi, protista, prokaryotes) -Phylum -Class -Order -Family -Genus -Species ~Pneumonic: Kill Professor Carl Or Face Great Sadness
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Why is a binomial naming system useful?
The name is the same in all languages( universal language). It consists of an organisms genus and species
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How does Carl Woese's classification system from Linnaeus' ?
He first sorted into 3 domains: ~Archaea (primitive bacteria, including extremophiles) ~Bacteria (true bacteria, including cyanobacteria) ~Eukaryota (cells with DNA enclosed in a nucleus-protists, fungi, plants and animals)
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How has new technology helped improve classidication?
-Microscope developments mean scientists can compare internal structures of cells -More is known about the biochemistry of organisms and their biochemical processes -The genome of organisms can now be compared
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What is Lamarck's theory of evolution

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He believed characteristics gained in a lifetime were heritable. He believed giraffes began with short necks which elongated to reach more leaves. This longer neck was then passed to its offspring which would then grow or shrink to reach leaves

Card 3

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What is Darwin's theory of evolution

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What is speciation and what causes it?

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What is a species?

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