Ecosystems Flashcards
(31 cards)
What is an ecosystem?
Any group of living or non living things and the relationships between them
What is a habitat?
The place where an organism lives
What is a population?
All the organisms of one species who live in the same place at the same time and can breed together
What is a community?
All the populations of diff species who live in the same place at the same time who can interact with each other
What are producers?
Plants which supply chemical energy to all other organisms
What are consumers?
Primary- herbivores
secondary-carnivores
tertiary-carnivores
What are decomposers?
Bacteria, fungi and some animals which feed on waste material
What are some examples of abiotic factors?
- pH
- humidity
- temperature
- conc of pollutants
- storms
What are cyclic changes?
Changes which repeat themselves in a rhythm:
- Movement of tides
- changes in day length
What are directional changes?
They go in one direction and tend to last longer than the lifetime of organisms within the ecosystem:
-erosion of a coastline
What are unpredictable/erratic changes?
No rhythm and no constant direction:
-lightning or hurricanes
On a graph showing the effects of abiotic factors on species performance where are the levels of existence?
-lowest:
Survival
Growth
Reproduction
What are each levels of the food chain called?
Tropic levels
Why is some biomass lost at each trophic level?
- respiration releases energy from glucose which is eventually converted to heat and materials are lost through CO2 and water
- biomass lost through dead organisms which is only available to decomposers
- biomass lost through waste material such as bones and hair
What does a pyramid of numbers represent?
- The area of each bar in the pyramid is proportional to the number of individuals as an approximation for the total biomass at that level
- can be drawn for individual food chains or whole ecosystems
What is a pyramid of biomass?
-The area of each bar is proportional to the dry mass of all organisms at that trophic level
How would an ecologist find dry mass?
- Ecologist must put all organisms into an oven at 80•c so that all the water in them has been evaporated, once mass stops reducing, water is removed
- can be destructive so they may measure wet mass and calculate the dry mass according to data
How can you calculate the efficiency of biomass transfer?
Biomass at higher trophic level / biomass at lower trophic level x100
What is gross primary productivity?
The rate at which plants convert light energy into chemical energy through photosynthesis
Why is gross primary productivity inefficient at the start of the food chain?
- Only 40% of light energy enters plants for photosynthesis
- only half of it is used in glucose production
- not all of this is used for production of molecules contributing to growth
- the rest is respired
What is net primary productivity
The chemical energy converted from light energy that is avaliable to the next trophic level
How can humans make energy conversion of primary productivity more efficient?
- light levels, early planting, light banks
- breeding plants that are genetically advantageous, drought resistant, resistant to fungal infection
- growing plants in greenhouses to provide warmer temp
- crop rotation to increase avaliable nutrients
- pesticides and herbicides
Why might secondary productivity be inefficient?
Primary consumers may not eat all of a plant, much food is also respired so less biomass to pass on to the next trophic level
How can humans make energy transfer of secondary productivity more efficient?
- breeding animals just before childhood as they invest more energy into growth than adaults
- selective breeding of animals with increased egg production
- animals treated with antibiotics
- no grazing for pig and cattle maximises energy allocated to muscle meat
