B13. Energy and Ecosystems (FINSIHED) Flashcards
(45 cards)
What are producers?
Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and mineral ions
What are consumers?
Organisms that obtain their energy by consuming other organisms rather than energy of sunlight directly
What are the types of consumers and what do they indicate?
Primary consumers, first in chain of consumers, feed off producers; Secondary consumers, consume primary consumers; tertiary consumers - consume secondary consumers, top of the chain
What are saprobionts?
Decomposers, group of organisms that break down the complex material in dead organisms into simple ones.
What is a food chain?
Describes a feeding relationship in which organisms are consumed in this order; Producers > primary consumers > secondary consumers > tertiary consumers
What is a torphic level?
Stage of the food chain eg. producer, primary consume
How is direction of energy flow represented in a food chain?
Arrow shows directional energy flow
What are food webs and why are they produced?
Food chains will be linked together forming a food web due to animals not relying on a single food source within a single habitat
What is biomass?
Total mass of living material in a specific area at a given time
What procedure is necessary to produce reliable biomass results and why?
Biomass is measured using dry mass per given area due to presence of varying amounts of water
How is energy of biomass estimated?
Calorimetry; Bomb calorimetry, sample of dry material is weighed and is then burnt in pure oxygen within a bomb; Bomb surrounded by water bath and the heat of combustion causes a temp rise in water
What is the source of energy for ecosystems?
The Sun
How efficient is energy absorption of the Sun’s energy?
1% - 3%;
What happens to the majority of the Sun’s energy?
Over 90% is reflected back by clouds and dust or absorbed by atmosphere; Not all wavelengths of light can be absorbed by photosynthesis; Limiting factors ie. low CO2 levels limit photosynthesis
What is gross primary production?
Total quantity of chemical energy stored in plant biomass in a given area or volume
What is net primary productivity?
Energy store from gross primary production left after factoring plants 20% - 50% net losses to respiration
What’s the equation for net primary production?
Net primary production = Gross primary production - respiratory losses
Why is less energy available in the upper trophic levels?
Some organisms aren’t consumed; Some parts are consumed but cannot be digested and are lost in faeces; Some of the energy is lost in excretory materials; Some energy lost as heat from respiration
Why is less energy available in mammals and birds?
High energy use due to high body temperature; More energy needed to maintain their body temperature when heat is constantly being lost to the environment
What is the equation for net production of consumers?
Net production = Chemical energy store of ingested food - ( Energy lost in faeces and urine + Energy lost in respiration)
What observations can be made while climbing the trophic levels?
Only 4 - 5 trophic levels due to insufficient energy to support; Total biomass decreases; Total amount of energy available decreases
How is energy conserved of livestock in farming?
Movement restricted, less energy used in muscle contractions; Environment kept warmer, less heat loss; Feeding controlled to optimum amount; Predators are excluded
How does energy flow in an ecosystem and is this a problem?
Energy enters ecosystem as sunlight is lost as heat; Heat cannot be recycled; Linear unidirectional flow; Not a problem as the Sun supplies the energy
What is the simple sequence all nutrient cycles follow?
Nutrient taken up by producers as simple inorganic molecules; Producer incorporates nutrients into complex organic molecules; Producer eaten, nutrient pases into consumer; Passes along food chain; When producers and consumers die their complex molecules are broken down by saprobiontic microorganisms that release the nutrient in its original simple form.
