3.7.4.1 Populations in ecosystems Flashcards
Species
organisms can interbreed to produce fertile offspring
Population
group of the same species in the same area
Community
groups of different species within the same area
Ecosystem
the community and the non living aspects
Habitat
small part of ecosystem where a population lives
Abiotic factors
non living parts of a habitat
Biotic factors
living parts of a habitat
Biotic factors
living parts of a habitat
Niche
the role a species has in its community / environment
2 species being unable to occupy the same niche means that …
both species are able to be successful in the same ecosystem
Is competition biotic or abiotic?
biotic
If individuals are more similar, what does this mean for the competition?
competition more intense
Intraspecific competition
competition within the same species
Interspecific competition
competition between different species
Intraspecific competition and competition and population
- variation in population means some organisms are able to compete (survival of the fittest)
- availability of resources determine size of population
- relatively stable population
Interspecific competition and competition and population
one population will grow and the other will shrink - individuals of different species occupying parts of same niche, one species will have competitive advantage over the other
Open system
- nature
- both biotic & abiotic factors can change
- not controlled
Closed system
- for microbes in lab
- start with limited resources
- controlled factors (e.g. conc of sugar, o2)
4 stages of population growth curve (open system)
- lag phase
- log phase
- effects of limiting factors
- carrying capacity
Extra stage of population growth curve (closed system)
death (where cell death outnumbers cell division)
In death stage why would cell death outnumber cell division?
- less or no sugars (glucose - less or no respiration)
- more toxins (waste products trapped e.g. CO2 & ethanol increase acidity)
What happens during the log phase?
lots of reproduction / lots of cell division in unicellular organisms
What happens during carrying capacity phase?
stabilising number of individuals
What happens if predator increases and why?
- decrease in prey population
- more predation
What happens if prey increases and why?
- increase in predator population
- more food for predators, able to survive and reproduce
