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Description
Flashcards by zahraa almaialy, updated more than 1 year ago
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Created by zahraa almaialy
about 6 years ago
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| Question | Answer |
| Define natural selection | natural 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. |
| Define selective agent | an environmental factor that acts on a population during natural selection |
| What 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. |
| Define selection pressure. | the effect of the selective agent on a population. |
| Most 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. |
| define sexual selection | a special case of natural selection, in which the environment factor is the selection of a mate. |
| Define variation | differences in characteristics due to different genes |
| what 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. |
| Give evidence for natural selection | it 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. |
| What was the peppered moth? | it was studied my Kettlewell and existed in 2 forms. the normal color was white with black specks. |
| Explain Kettlewells experiment on peppered moths | He placed 2 different colors of moths on tree trunks, observed birds feeding on the moths, counted the numbers of light & dark moths eaten. |
| What 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. |
| Define resistance | the inherited ability of a species to withstand chemicals |
| How did Alexander Fleming find a way to kill bacteria? | he discovered that some fungi make special chemicals to defend themselves against bacteria. |
| Define antibiotics | Chemcials by organisms such as fungi to defend themselves against bacteria |
| Name a dangerous type of bacteria | Golden Staph. it is resistant to many antibiotics and difficult to kill. |
| Define biodiversity | the number and range of different species that exist. |
| Define Speciation | the process by which one or more species splits into 2 or more species. |
| What are the 3 steps of the process of speciation? | variation, isolation and selection. |
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