Populations Flashcards
Define:
Population
All the organisms of one species in a particular habitat.
Define:
Habitat
The place where the organism lives.
Define:
Community
Populations of different species in a habitat make up a community .
Define:
Ecosystem
All the organisms living in a particular area and all the non-living (abiotic) conditions.
Define:
Abiotic
The non-living factors of an ecosystem.
Define:
Biotic
The living factors in an ecosystem.
Define:
Niche
The role that a species plays within it’s habitat.
Define:
Adaptation
A characteristic that a species has which increases chance of survival and reproduction.
What interactions does a niche include?
Biotic and abiotic interactions.
How many species can occupy a niche?
One.
A niche is unique.
Investigating populations…
What type of sample is best to use?
Random
Investigating populations…
Describe how to take a random sample.
1) Select an area to take the sample from
2) Divide the area up into a grid and number the sections.
3) Use a random number generator to select a site.
4) Use an appropriate technique e.g. Mark-release-recapture for animals, or a quadrat for plants.
5) Return habitat to natural state.
Investigating populations…
Describe the mark-release-recapture method
Firstly, capture a certain number of the species.
Mark them in a way that is not harmful to them, e.g. a small paint mark.
Release the sample back into site.
After leaving a suitable amount of time, return to the site and recapture the same size sample.
Count the number of marked species.
Investigating populations…
How can you calculate a total population estimation?
MULTIPLY the number of organisms CAUGHT in the first sample and the number CAUGHT in the second sample.
DIVIDE this figure by the number of MARKED organisms in the SECOND sample.
Investigating populations…
How can percentage cover be calculated?
By taking the average of all samples collected.
Investigating populations…
Describe the use of a quadrat.
Place or throw randomly in area that is being investigated, insuring it does not damage any wildlife.
Count number of each organisms in each square of the quadrat.
Repeat for more reliable results.
Investigating populations…
Describe a line transect.
Place a tape measure of certain length along the transect line and count the number of each species that touch the tape measure.
Investigating populations…
Describe a belt transect.
Place quadrats next to each other along the transect line and count the species on all squares.
Investigating populations…
What do quadrats and belt transacts help to calculate?
Species frequency
Percentage cover
Investigating populations…
Name some ethical issues that should be minimised as much as possible when investigating populations.
Soil/ foot erosion Damage to wildlife Litter Stress to organisms being captured Harm to organisms being captured (e.g. mark in way that does not affect them, handle organisms as little as possible)
Human populations…
Which two factors are used to calculate population growth?
Birth rate
Death rate
Human populations…
Define birth rate
The number of live births each year per 1000 people.
Human populations…
Define death rate
Number of deaths per 1000 people in population.
Human populations…
Give the calculation for population growth rate (per thousand/ year)
Pop. growth rate = BR -DR
Human populations…
Which graph shows BR, DR and TP?
The Demographic Transition Model (DTM)
Human populations…
In the DTM, what is shown by the difference in BR and DR?
Natural Increase (NI)
Human populations…
What other type of graph/ chart is used to show population?
Population pyramids.
