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35 Cards in this Set
- Front
- Back
What are the biotic factors that control the size of a population? |
•Competition •Predation •Parasitism •Symbiosis |
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Define competition |
The struggle between organisms of the same or different species for one or more limited resources. |
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What do plants compete for? |
Light, water, minerals, space. |
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What do animals compete for? |
Food, water, territory, mates. |
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What is intraspecific competition? |
Competition between members of the same species. Eg. two rams fighting for a mate. |
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What is interspecific competition? |
Competition between members of two different species. Eg. blackbird and a thrush competing for an earthworm. |
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What is contest competition? |
A type of competition where one of the organisms wins the resource and the other loses. It involves a physical contest between the two organisms. |
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What is scramble competition? |
All of the competing organisms get some of the resource. Often none get sufficient resources to survive. Eg. large number of seeds germinating in a seed box - all grow starggly as they compete for water, light, minerals, space. |
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Give three advantages of competition/predation. |
1. Reduces size of population and maintains it at a sustainable level. 2. Helps maintain bio diversity as one species does not thrive at the expense of another. 3. Important role in evolution ie. members of a species compete - the fitter ones (better adapted ones) survive, reproduce and pass on their better genes. This produces a better adapted population. |
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Define adaptation |
A modification of structure or behaviour that improves an organism's chances of survival and reproduction. |
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What do organisms do to avoid competition? |
They adapt. |
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Give four examples of structural modification. |
Thorns(rose) Sting(nettle/bee) Spikes(hedgehog) Shell(snail) |
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Give two examples of behavioural modification. |
Hibernation(bears) - to withstand cold, less energy required, during time of poor food availability. Nocturnal activity (owl) - less organisms competing for food. |
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Define predation |
The hunting capturing and killing of prey. |
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Adaptations of hawk(predator). |
•Great speed •Pointed beak •Powerful wings •Very well developed eyesight |
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Adaptations of ladybird(predator) |
Strong mouth parts for chewing prey. |
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Adaptations of mouse (prey) |
•Small for concealment from prey. •Grey/brown in colour for camouflage. •Great speed to avoid predator. |
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Adaptations of greenfly |
Green for camouflage. |
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Give three factors that affect predator prey relationships |
1. Food availability 2. Concealment 3. Movement of predators |
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Define parasite |
An organism that feeds on an organism of a different species causing it harm. |
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What are endoparasites? |
Parasites that live inside their host Eg. tapeworm living in the intestines. |
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What are ectoparasites? |
Parasites that live on the outside of a host Eg. a flea on a dog. |
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Three differences between parasite and predator. |
1. Parasites tend to be smaller than the host (flea on dog). Predators tend to be bigger (hawk and mouse). 2. Parasites often attack from within the host ( tapeworm). Predators attack from outside. 3. Parasites tend to do limited damage (so they don't eliminate food source). Predator kills and eats their prey. |
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Give two functions of parasites. |
•Rate of reproductions may be reduced maintaining the population of a species at a sustainable level. •Role in evolution - stronger, fitter members of the species survive and reproduce and pass on the better genes. |
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Define symbiosis |
This is a relationship between two different species living together to the benefit of at least one of the species. |
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What are the three categories of symbiosis? |
1. Parasitism 2. Mutualism 3. Commensalism |
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What is parasitism? |
Type of symbiosis where the parasite gains and the host is badly affected. Eg. liver fluke living in the bile duct of a sheep. |
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What is mutualism? |
Type of symbiosis where both species gain. Eg. symbiotic bacteria living in the intestines. |
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What is commensalism? |
Type of symbiosis where one species gains and the other is unaffected. Eg. Lichen growing on a tree. |
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Define exotic species |
An introduced, alien, nonnative species. A species living outside it's native distributional range, which has arrived there by human activity, either deliberate or accidental. |
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Two possible disadvantages of exotic species. |
1. Competition with native species : grey squirrel competes with native red squirrel for resources. 2. Potential predators of native species : the mongoose was introduced to Hawaii to control rats which had previously been accidentally introduced. Unfortunately, the mongoose also eats many native Hawaiian animals. |
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Three possible benefits of exotic species |
1. Food source. 2. Biological control : for the control of a nuisance species Eg. a small wasp was introduced from China to help control the European corn borer, one of the most destructive insects in north America, making it a recent example of a long history of classical biological control efforts for this major pest. 3. Aesthetic eg. pandas. |
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Four reasons for failure of attempted introductions of exotic species. |
•Failure to adapt •Preyed upon by native predators •Insufficient numbers for successful breeding. •Competition with native species |
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How may an exotic be spread? |
•Escaping from captivity eg. animals kept as pets ( racoons, minks ). •Dispersal of seeds. •Through fruits - border control will not allow fruits/veg through. |
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When does an exotic species have a good chance of becoming established in a new environment? |
If there is a vacant niche. •May occur if the exotic species is adapted to the new environment. •May not occur if the new species is not adapted to the environment. |