Genetic populations and ecosystems - POPULATIONS/SUCCESSION Flashcards
Definition of ecosystem
Dynamic systems made up of a community and all the non living factors of its environment
Definition of community
All the populations of different species living and interacting in a particular place at the same time
Definition of population
Several found within an ecosystem and are a group of individuals of the same species that occupy a particular habitat at a particular time and are able to interbreed
Definition of habitat
The place where an organism lives and is characterised by the physical conditions and other types of organism present
Definition of carrying capacity
The maximum number the population can grow to in a given space
Give examples of abiotic factors
- Temperature
- Light intensity
- pH
- Humidity
- Wind speed
- Tidal range
- Wave speed
Give examples of biotic factors
- Intraspecific competition (between members of the same species)
- Interspecific competition (competition between members of different species)
- Predation
- Disease
What is the competitive exclusion principle?
No two species can occupy the same niche
What term is used to describe populations of different species living in the same habitat? (PPQ 1 mark)
Community
Explain the advantage of species occupying different niches (PPQ 1 mark)
Less interspecific competition for food
What is meant by an abiotic factor? (PPQ 1 mark)
A factor that is physical/non biological/non living
What is meant by the ecological term population? (PPQ 1 mark)
Total number of organisms/individuals of a species
Why does temperature affect population size?
- Temperature affects enzymes
- Temp too low, slower rate of reaction
- Temp too high, enzymes denature and rate decreases
Why does light affect population size?
- Light energy for photosynthesis
- Too low, less photosynthesis->less glucose=less respiration and less ATP for growth
Why does pH affect population size?
Enzymes denature at extreme pH, decreasing rate
Why does water affect population size?
Water for photosynthesis
Why does humidity affect population size?
- Humidity affects transpiration
- Increased humidity results in less transpiration as diffusion gradient reduced
Describe how you could estimate the size of the population of sundews in a small marsh (PPQ 5 marks)
- Use a grid
- Obtain random coordinates
- Count number in a quadrat
- Large sample and calculate mean/average number
- Calculate total umber of sundews
Describe how the mark-release-recapture method could be used to determine the population of lizards at the start of an investigation (PPQ 3 marks)
- Capture/collect and release
- Leave time to disperse
- (N1 x N2)/N3
Describe how you could use the mark-release-recapture method to estimate the number of lizards on an island (PPQ 4 marks)
- Capture/collect sample, mark them and release
- Method of marking lizards does not harm them
- Leave time for lizards to distribute
- (N1 x N2)/N3
When is systematic sampling used?
To see the change/trend from one area to another
What is the competitive exclusion principle?
When two species are competing for limited resources, the one that uses the resources more effectively will eliminate the other over time
Definition of predation
When one organism is consumed by another
Definition of succession
The changes that take place over time in the species that occupy a particular area
What is a pioneer species?
The species that colonises an inhospitable environment
Succession occurs in natural ecosystems. Describe and explain how succession occurs (PPQ 4 marks)
- Colonisation
- Pioneer species change the environment
- Environment becomes less hostile for other species
- Changes biodiversity
- Until climax community is reached
What are two features of a climax community?
- Abiotic factors constant
- Same species present/stable community
What is species diversity?
The number of different species (species richness) and the number of individuals of each species within any one community (species eveness)
Give some examples of farming practises that have directly removed habitats and reduced species diversity
- Removal of hedgerows
- Creation of monocultures
- Filling in ponds and draining marshes
- Over grazing of land
What is the realised niche?
An area that the organism lives in when biotic factors are considered
What is the ecological niche?
An area with the right abiotic conditions that an organism can live
Describe those features of a succession that would bring about an increase in the index of diversity (PPQ 3 marks)
- Initial environment is hostile
- Pioneer species colonise environment and make it more hospitable
- More species can grow
- More niches/habitats
Suggest one ethical argument for maintaining biodiversity (PPQ 1 mark)
- Prevent extinction
- Prevent loss of habitats
Suggest one economic argument for maintaining biodiversity (PPQ 1 mark)
Biodiversity may have financial importance in industries such as medicine and tourism
Do abiotic factors exert a density-dependent or a density-independent effect on a population? (PPQ 1 mark)
- Density independent
- Abiotic factors are unaffected by number of living organisms
