B19- Population and Ecosystems Flashcards
What is ecology?
Is the study of the relationships between organisms and their environment, including both biotic and abiotic environmental factors.
What are ecosystems?
Are dynamic systems made up of a community and all the abiotic factors of its environment. There is little or no loss or gain between one and other ecosystems.
What is a population?
Is a group of individuals of one species that occupy the same habitat at the same time and can potentially interbreed. An ecosystem can only support a certain size of population, called the carrying capacity.
What is competition?
Competition occurs when multiple individuals share limited resources.
What is intraspecific competition?
Individuals of the same species compete for food, water, breeding sites, etc.
What is interspecific competition?
Interspecific competition occurs when different species compete for the same resources. Population changes are directly influenced by birth and death rates, though environmental factors like food availability may affect individual characteristics rather than overall population numbers.
What is a community?
A community is all the populations of different species living and interacting in a particular space at the same time.
What is a habitat?
A habitat is where an organism normally lives and is characterised by physical conditions and the other types of organisms present. Within an ecosystem there are many habitats, called microhabitats, which have their on microclimate.
What is a ecological niche?
An ecological niche defines how an organism interacts with and fits into its environment, encompassing its role, position, and interactions within its habitat.
What are limiting factors of growth in a population?
Growth in a natural population eventually slows down or even stops at a certain size, the carrying capacity. This is due to certain factors (or the lack of those) that limit growth - limiting factors.
What is niche speration?
Species X and Y are two species of flowering plant. That tolerate different selection pressures therefore avoid direction competition by occupying two different niches.
How to calculate growth of human population?
Population Growth=[births+ immigratation]- [death+e migration]
What is predation?
Predator- an organism that feeds on another organisms, prey
Describe how you could estimate the size of a population of sundews in a small marsh. (5 marks)
Use a grid
Method of obtaining random coordinates/numbers e.g. calculator/computer/random numbers table/generator;
Count number/frequency in a quadrat/section
Large sampleandcalculate mean/average number (per quadrat/section);
Valid method of calculating total number of sundews, e.g. mean number of plants per quadrat/section/m2multiplied by number of quadrats/sections/m2in marsh;
Do not allow ‘scale up’ without further qualification. Do not award if % cover determined.
Describe how you would determine the mean percentage cover for beach grass on a sand dune (3 marks)
Method of randomly determining position (of quadrats) e.g. random numbers table/generator;
Ignore line/belt transect
Large number/sample of quadrats;
Accept many/multipleIgnore point quadratIf a specified number is given, it must be 20 or more
Divide total percentage by number of quadrats/samples/readings;
The mark-release-recapture method can be used to estimate the size of a fish population (lines 13–14) (4 marks)
Capture/collect sample, mark and release;
Ensure marking is not harmful (to fish)
OR
Ensure marking does not affect survival (of fish);
Accept examples e.g., marking should not be toxic.
Allow (time for) fish to (randomly) distribute before collecting a second sample;
(Population =) number in first sample × number in second sample divided by number of marked fish in second sample/number recaptured;
What is a pioneer species?
make up pioneer community, first ones to colonise an inhospitable environment
What is a climax community?
ultimate, stable community with a balanced equilibrium of species (few, if any, species replacing established ones). Abiotic factors will determine the dominant species
What is secondary succession?
When the land, what already sustained life suddenly changes. This is more rapid, than primary succession.
Succession occurs in natural ecosystems. Describe and explain how succession occurs (5 marks)
(Colonisation by) pioneer species;
Pioneers/species/organisms change the environment/habitat/conditions/factors;
(Environment becomes) less hostile for other/new species.
Change/increase in diversity/biodiversity;
(To) climax community;
