Populations in ecosystems Flashcards
1
Q
What is an ecosystem?
A
- ecosystems are dynamic systems made up of a community of all the non living and living factors in an environment
2
Q
What is a population?
A
- a population is a group of individuals of one species that occupy a habitat and can potentially interbreed
3
Q
What factors affect populations?
A
- abiotic factors like temperature,ph,light and water, aspect, soil, wind speed, humidity
- biotic factors such as predation, competition
- disease
4
Q
What forms a community?
A
- different species form a community
5
Q
What is a community?
A
- all the populations of different species living and interacting in a particular place at at the same time
6
Q
What is a niche?
A
- How an organism fits into the environment
- Refers to where an organism lives and what it does there
- this includes all the biotic and abiotic conditions an organism has adapted to in order to survive and reproduce and maintain a viable population
7
Q
What is carrying capacity?
A
- the maximum stable population size of a species that an ecosystem can support
- this varies with abiotic and biotic factors
8
Q
How can abiotic factors affect population size?
A
- temperature: each species has an optimum temperature at which is best to survive. the further from this, the fewer individuals that can survive
- light: light is essential for metabolic processes such as photosynthesis
- Ph: - affects enzymes
- water: when water is scarce, populations are small and only consist of species suited for dry conditions
9
Q
What is interspecific competition
A
- when organisms of different species compete with each other for the same resources
10
Q
what is the competitive exclusion principle?
A
- when two species are competing, one will have a competitive advantage and eventually as the resource is limited for both species, one will go extinct
11
Q
What is intraspecific competition?
A
- competition between organisms of the same species. The avaliability therefore affects population size
12
Q
What is the cycle of predation?
A
- predators will eat prey
- this means that the population of prey will decrease, and with that predators will have less prey and compete for a limited population
- this means better adapted predators will survive and the lesser ones will not
- this means with less predators, the prey will increase
- therefore with more prey, predators will increase
13
Q
What is sucession?
A
- describes how an ecosystem changes over time as ecosystems are dynamic
14
Q
What is primary succession?
A
- A series of successional changes that alter the abiotic environment and make it less hostile for more complex and adapted species to survive
- this occurs on bare land and rock that may have been exposed by new rock forming
15
Q
what is the first step of primary succession?
A
- primary succession occurs when the pioneer species first colonises a hostile environment. This is often lichen
16
Q
what are features of a pioneer species?
A
- they reproduce asexually
- wind dispered seeds
- rapid germination
- the ability to photosynthesise
- the ability to fix nitrogen
- tolerance to extreme conditions
17
Q
what is step two of primary succession?
A
- the pioneer species such as lichen die and decompose, producing humus
- this produces soil for other species with more nutrients
18
Q
What is step three of primary succession?
A
-in the later stages of succession, it hits climax community
19
Q
what is climax community
A
- the most complex and largest community of animals and plants that an ecosystem can support
20
Q
what are features of succession?
A
- increased biodiversity
- increased biomass
- increased species richness and density
- a less hostile environment
- increased complex food chains
21
Q
what is secondary succession?
A
- this happens when land has been cleared of all plants by fires or deforestation
- from the intact soil, the pioneer species recolonise land
- however, the process is quicker and there are more complex species
