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34 Cards in this Set
- Front
- Back
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define a habitat |
A place where a community of organisms lives |
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Define ecosystem |
Made up of all the interacting biotic (living) and abiotic (non living) features in a specific area |
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Define population |
A group of interbreeding organisms of one species in a habitat |
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Define community |
All the populations of different organisms living and interacting in a particular place at the same time |
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Define niche |
An organisms role within the environment |
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Define ecology |
The study of inter relationships between organisms and the environment |
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Define abiotic factors and give 3 examples |
Non living temperature light intensity oxygen availability Altitude ( topography) humidity food availability |
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Define biotic factors and give 3 examples |
Living factors predation pollution disease parasites competition |
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Define abundance |
The total number of individuals of a species within a given area |
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Give two ways abundance can be measured |
Percentage cover - how much of the quadrat is covered Frequency - how many of the quadrats the species occurs in |
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Name two sampling techniques |
Random sampling (frame quadrats) or systematic sampling (along transects) |
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Describe the method of random sampling |
lay out two tapes at right angles in the area of study obtain a series of coordinates using random numbers (from calculator or computer) place quadrat at coordinates record species within it |
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Describe the method of systematic sampling along a transect |
Lie tape across ground in a straight line any organism over which the line passes is recorded |
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What is a belt transect |
Two parallel lines normally a metre wide species within the lines are recorded |
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Equation for population size (mark release recapture) |
Estimated population = total number of individuals in the first sample x total number of individuals in the second sample
\ number of marked individuals recaptured |
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Describe the techniques of mark release recapture |
A known number of animals are caught they are marked in some way they are released back into the community some time later a given number of individual is collected randomly number of marked individuals is recorded |
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Mark release recapture relies on assumptions name 3 |
Proportion of marked to unmarked is the same in sample as it is in the population as a whole marked individuals in the first sample distribute themselves evenly the population has a definite boundary ( no immigration or emigration) there are few if any deaths and births method of marking is not toxic or makes indivula more liable to predation mark is not lost or rubbed off
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Describe the Population growth curves (3 main features) |
1. Slow growth- small number of individuals slowly reproduce 2. Rapid growth - ever increasing number of individuals continue to reproduce (gradient of curve is steep) 3. Population growth declines until size remains more or less stable (due to food supply or increased predation) |
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What happens to population size over time And why |
Decreases due to limiting factors which causes population to slow/cease |
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Define intraspecific competition |
Competition between members of the same species eg food water breeding sites |
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Define interspecific competition |
Competition between members of different species |
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Define predation |
Where one organism consumes another |
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What is the main problem with investigating predation in a lab |
In a lab the prey rarely escape whereas in the wild prey can escape so the population will fall low but rarely become extinct |
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Describe the effect of predator- prey relationships on population size (5 points) |
Predators eat prey reduce population size fewer prey predators are in greater competition predator population is reduced Fewer predator, fewer prey eaten prey population increase predator population increases (more food available) |
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Apart from predator prey relationships wha can effect population size |
Disease and climatic factors |
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Factors that effect human populations |
food availability disease predstors climate wars birth rate death rate |
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Define immigration |
Where individuals join a population from the outside |
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Define emigration |
Where individuals leave a population |
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Equation for population growth |
(Births+ immigration) - (deaths + emigration) |
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Equation for population growth rate |
Population change in period /. X100 population at start |
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Factors affecting birth rate (5 points) |
Economic conditions - LEDC have higher birth rates religion- some are opposed to birth control and some encourage larger families social pressures - some cultures large families improves social standing birth control - contraception and abortion political factors - governments influence birth rates through education and taxation policies
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Equation for birth rates |
Total birth rates / total population x1000
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Factors affecting death rates (7 points possible) |
Age profile - more elderly means higher death rate life expectancy at birth - economically developed countries live longer Food supply safe drinking water and sanitation medical care natural disasters war |
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Equation for death rate |
Number of deaths / total population x 1000 |
