SB9 Flashcards
Define population
All organisms of the same species living with one another in a habitat
Define community
All of the populations of different species living together in a habitat
Define ecosystem
The community of organisms and non-living components of an area and their interactions
Describe mutualism
The interaction between two organisms where both benefit as a result of their relationship
Describe parasitism
The interaction between two organisms where only one organism, the parasite, benefits whilst the host does not
What are abiotic factors?
The non-living aspects of an ecosystem.
Examples of abiotic factors.
Name 3
- light intensity
- temperature
- moisure levels
- soil pH
- wind
- CO2 levels (for plants)
- O2 levels (for fishies)
What are biotic factors?
Give some examples.
The living components of an ecosystem
e.g. competition, predation
Describe how competition affects communities
● The presence of competitors affects population distribution
and size
● Better adapted species will outcompete other species, causing their populations to decline
What piece of apparatus is used to
measure the abundance and distribution
of organisms in an area?
Quadrat
What piece of apparatus is used to study
the distribution of organisms across a
gradient?
Belt transect
Define biomass
The total mass of living material
What are trophic levels?
The stages in a food chain
What does a pyramid of biomass represent?
It represents the dry mass of living material at each trophic level of a food chain.
Why is a pyramid of biomass almost always
pyramid-shaped?
As you move along the food chain biomass is lost so the bars decrease in length
