4 a+b Flashcards
Define population
A species that occupy the same habitat
Define habitat
The place in which an organism lives
Define community
Populations of different species interacting
Define ecosystem
The interactions between the biotic and abiotic factors in an area
2 abiotic factors that affect animal population sizes
- Temperature
- Water availability
2 biotic factors that affect the population size
- The number of predators
- The presence of disease and pathogens
4 abiotic factors that affect communities
- Light intensity
- Temperature
- Soil pH
- Moisture levels
4 biotic factors that affect communities
- Number of predators
- Food availability
- Disease
- Human activity
What is a producer
An organism that makes its own food
What is a primary consumer
An organism that feeds on producers
What is a secondary consumer
An organism that feeds on primary consumers
What is biomass?
The dry mass of all of the living organisms in an area
Why is dry mass used for biomass?
Because the wet mass varies as the volume of water in the organism varies
How do you calculate the efficiency of biomass transfer
efficiency = (energy transferred / total energy available) × 100
Why are biomass transfers not 100% efficient
Energy is lost through:
- egestion (removal of faeces)
- excretion (removal of waste products e.g. urine)
- Respiration
- The production of inedible bones and shells
