7.2 Ecology (organisation of an ecosystem) 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
What do food chains show?
food chains show the feeding relationships of different organisms and the flow of energy between the organisms
Define biomass
the total mass of living material
What are trophic levels
the stages in a food chain
What do arrows in a food chain represent?
the direction of biomass transfer
Describe a simple food chain
producer –> primary consumer –> secondary consumer –> tertiary consumer
What is a producer?
an organism that makes its own food
What types of organisms are primary producers?
photosynthetic organisms like green plants and algae that trap energy from the sun
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 a tertiary consumer?
an organism that feeds on secondary consumers
What is a predator?
a consumer that kills and eats other animals
What is a prey?
an animal that is killed and eaten by another animal
Describe the pattern of predators and prey in a stable community
the numbers of predators and prey rise and fall in cycles
Why are producers the first trophic level?
- producers provide all biomass for the food chain (production of glucose via photosynthesis)
- the rest of the food chain involves the transfer of this biomass
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
When considering the abundance of organisms, what is meant by the term ‘mean’?
the average number of organisms
When considering the abundance of different organisms, what is meant by the term ‘mode’?
the most populous organism
When considering the abundance of organisms, what is meant by the term ‘median’?
the organism that represents the middle value when the numbers of each organism are arranged from lowest to highest
Describe how materials cycle through the living and non-living components of an ecosystem
- organisms take in elements from their surroundings. e.g. soil, air
- elements converted to complex molecules which become biomass
- elements transferred along food chains
- elements returned to environment during excretion and decomposition of dead organisms
Give 3 molecules which are cycled through ecosystems
oxygen, carbon dioxide and water
Describe the carbon cycle
- plants fix carbon dioxide into organic molecules during photosynthesis
- the organic carbon-containing molecules are passed onto organisms that eat the plants
- carbon dioxide is released back into the atmosphere by respiration from animals and plants
- burning fossil fuels also releases carbon dioxide into the atmosphere
Why is the carbon cycle important?
carbon-containing molecules such as glucose are important for living organisms to grow and provide energy for vital functions within cells
Describe the water cycle
- water from lakes and oceans evaporates
- the evaporated water condenses into clouds and returns to earth as precipitation
- the water from precipitation is useful for life on land
- the water then returns to rivers and oceans through surface runoff
Why is the water cycle important
living organisms require water and the water cycle provides organisms on land with a continuous supply of water
