Flashcards
unit 4.2 natural selection
Flashcards do conjunto (19)
- 1Define natural selectionnatural selection is the process by which an environmental factor acts on a population & results in some organisms having a greater chance of survival & producing more offspring than others.
- 2Define selective agentan environmental factor that acts on a population during natural selection
- 3What is the difference between biotic factors & abiotic factors?Biotic factors are living things such as plants, animals, bacteria, fungi etc. Abiotic factors refer to non living things such as air and water.
- 4Define selection pressure.the effect of the selective agent on a population.
- 5Most selective agents act by killing individuals & are often less suited to surviving & refer to 'poorly adapted' or 'less fit'. Give an example.for example predators may find them easier to catch because they are slow runners, have poorer eyesight and are more easily seen.
- 6define sexual selectiona special case of natural selection, in which the environment factor is the selection of a mate.
- 7Define variationdifferences in characteristics due to different genes
- 8what is a more modern definition for natural selection?natural selection is the change of a particular genetic make up of a species over many generations due to environmental selection of a particular characteristic.
- 9Give evidence for natural selectionit only becomes obvious after many generations, this makes the effects of natural selection impossible to observe in organisms that have long generation times such as humans and elephants.
- 10What was the peppered moth?it was studied my Kettlewell and existed in 2 forms. the normal color was white with black specks.
- 11Explain Kettlewells experiment on peppered mothsHe placed 2 different colors of moths on tree trunks, observed birds feeding on the moths, counted the numbers of light & dark moths eaten.
- 12What are insecticides?a chemical that is sprayed onto crops to kill insects. it was only active for a few years but later had no effect.
- 13Define resistancethe inherited ability of a species to withstand chemicals
- 14How did Alexander Fleming find a way to kill bacteria?he discovered that some fungi make special chemicals to defend themselves against bacteria.
- 15Define antibioticsChemcials by organisms such as fungi to defend themselves against bacteria
- 16Name a dangerous type of bacteriaGolden Staph. it is resistant to many antibiotics and difficult to kill.
- 17Define biodiversitythe number and range of different species that exist.
- 18Define Speciationthe process by which one or more species splits into 2 or more species.
- 19What are the 3 steps of the process of speciation?variation, isolation and selection.
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- FlashCards sobre unit 4.2 natural selection, criado por zahraa almaialy em 19-03-2018.
- Criado por
- zahraa almaialy · mar 2018
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- 19 mar 2018
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