Energy flow through the ecosystem Flashcards
What are producers?
Green plants and trap solar energy and manufacture sugars from simple raw materials by photosynthesis
What is the sun’s energy passed from?
One trophic level to another
What are herbivores?
Primary consumers - animals that feed on plants
What are carnivores?
Animals that deed on other animals
What do both herbivores and carnivores form?
A feeding or trophic level with energy passing from each level to a higher one when materials are eaten
What does energy leave the system as?
Heat
What is energy lost as at every level?
Respiration, and through excretion of waste products
What limits the length of the food chain?
The loss of energy at each level so usually limited to 4 or 5
What is the route which energy passes between trophic levels?
The sequence from plant to herbivore to carnivore food chain
What are detritivores?
Organisms such as earthworms which feed on small fragments of organic debris called detritus made up of non-living organic material such as fallen leaves and the remains of dead organisms.
What are decomposers?
Microbes such as bacteria and fungi that obtain nutrients from dead organisms and faeces. They complete the process of decomposition started by detritivores.
Where does the energy from one organism to another in the food chain originate from?
Sunlight
What does photosynthetic efficiency (PE) indicate?
The ability of a plant to trap light energy
What’s the equation for photosynthetic efficiency (PE)?
Quantity of energy falling on the plant
What is Gross primary productivity (GPP)?
The rate at which products such as glucose are formed (mostly used up in respiration by plant)
What is the GPP equation?
GPP - respiration = Net production
What is Net primary productivity (NPP)?
This represents the food available to primary consumers. In crop plants it represents the yield which may be harvested.
How do you work out NPP?
What is left after respiration.
What is secondary productivity?
The rate at which consumers accumulate energy in the form of cells or tissues.
How can the energy transfer be calculated between each trophic level?
Energy available after transfer
———————————————– x 100
Energy available before transfer
Do herbivores or carnivores have a lower secondary productivity?
Herbivores have a lower one than carnivores as carnivores are more efficient at energy conversion than herbivores because they have a protein-rich diet is more readily and efficiently digested. 20% of energy is lost in the faeces of carnivores whereas 60% is lost in herbivores.
Why are herbivores not able to eat all vegetation available to them?
Can’t eat roots or woody parts of grass and they are unable to digest cellulose without the aid of bacteria so pass out of body as faeces containing high proportion of undigested matter.
What is the most accurate way of representing feeding relationships in a community?
Pyramid of energy which provides a quantitative account of the feeding relationships in a community.
What does the pyramid of energy show?
The quantity of energy transferred from one trophic level to the next per unit area or volume per unit time. This represents the total energy requirement of each successive trophic level in a food chain.
Why are pyramids of energy never inverted?
Because as material is passed up through the food chain energy is always lost through respiration as heat and in excretion so size of bars always increase sharply.
What is primary succession?
The introduction of plants/animals into areas that have not previously supported a community e.g. bare rock pr site of volcanic eruption
What is secondary succession?
The reintroduction of organisms into a bare habitat previously occupied by plants and animals. If the original vegetation is removed e.g. by fire or by tree felling, the area rapidly become re-colonised by a succession of different plants and animals
What is known as a climax community?
A stable environment where there is no further change.
How is bare rock colonised?
1) The first organisms to colonise the bare rock are algae and lichens called pioneer species and form a pioneer community.
2) This together with the weathering of the rock and the accumulation of dead and decomposing organic materials leads to the formation of primitive soil.
3) Wind-blown spores allow mosses to appear and as the soil develops grasses become established
4) As the soil builds up feep-rooted shrubs appear.
5) Over a very long time trees such as oak become established. This is known as climax community.
What happens in secondary succession?
Seeds, spores and organs of vegetative reproduction ,ay remain in the soil and dispersal of plants and migration of animals will assist in colonisation of the habitat .
How can human interference affect succession and natural development of climax community?
1) Grazing by sheep
2) Farming of land
3) Deforestation and soil erosion
Why are heather moors managed and how?
To provide ideal conditions for game birds such as the red grouse. This is because adult grouse feed mainly on young succulent heather shoots but because heather goes through cycle of pioneer then building then mature and then degenerative they are burned every 12 years. This is due to the pioneer phase supplying the best food for adult grouse and then building stage provides best shelter for nesting so without management the heather would pass the mature to the degenerate phase and conditions would become unsuitable for the breeding of grouse.
