Energy and Ecosystems - Finished Flashcards
What is an ecosystem?
A biological system made up of living (biotic) components and the non-living (abiotic) factors with which they interact
How does energy enter an ecosystem?
Sunlight is the source of energy, so sunlight enters an ecosystem in the form of light energy
Photosynthesis converts light energy to chemical energy
only SOME light is absorbed and used in photosynthesis. The rest of the light is reflected by the leaf OR transmitted (passed through the light without being absorbed)
What is Photosynthetic efficiency?
(PE) the ability of a plant to trap light energy (so it becomes part of the organic products of photosynthesis)
How do you calculate photosynthetic efficiency?
(quantity of light energy incorporated into product/quantity of light energy falling on the plant) x 100
PE is usually very low = 1%
What is primary production?
The production of new organic matter in plants
What is primary productivity?
The rate of production of new organic matter in plants
What units are used to measure primary productivity?
kj/m2/yr or kg/m2/yr (if biomass)
What is Gross Primary Production?
The TOTAL amount of energy fixed inside new organic products in plants
What is Gross Primary Productivity?
The RATE at which energy is fixed inside new organic products in plants
Why is Gross Primary Production not used?
a substantial amount of gross production is respired by a plant
What is Net Primary Production? (NPP)
The total amount of energy left in plants after respiratory losses are subtracted from the GPP. This is the energy in plants
Give the equation to show NPP
GPP - respiration = NPP
How does energy flow through consumers?
energy transfer from one consumer to another at each stage (trophic level) of a food chain is shown by arrows.
How is energy lost through consumers.
Not all parts of the plants are eaten
Energy loss through waste products (Urine & Faeces)
Energy loss in from of heat from respiration
How much of the energy is passed on to the next consumer after the herbivore?
only about 10% of the energy consumed ends up in the herbivores biomass - This is available to the next consumer in the food chain.
How can you reduce energy loss in Herbivores bred for meat?
If animals are kept in small enclosed spaces less energy is used in repiration and to stay warm so energy loss is reduced.
How do you calculate the efficiency of energy transfer?
(Energy available AFTER transfer / energy available BEFORE transfer) X 100
What limits the length of the food chain?
The loss of energy from each trophic level in a food chain limits the length of the chain to 4/5 organisms
What are the 2 different types of productivity?
Primary - Plants - autotrophs
Secondary - Animals - heterotrophs/consumers
Who has better productivity? Herbivores or Carnivores?
Carnivores
Herbivores live a cellulose rich diet so it is difficult to digest. Much of what they consume remains undigested so it ends up egested in the form of faeces
Carnivores have a protein rich diet and is more efficiently digested.
What is a pyramid of energy?
A diagram showing the quantity of energy transferred from one trophic level to the next
As organic material passes up the foodchain, the size of th bars in the pyramid decrease due to energy loss.
What is a habitat?
A place/environment where organisms live
What is a community?
A group of organisms of different species living in a shared location where they may potentially interact
What is the definition of succession?
The change in the composition of species whic make up a community over time. This happens due to changes in the environment.
What is a Pioneer Species?
The first organisms to colonise a habitat
What is the definition of Sere?
a stage in succession
What is a Climax Community?
The stable community which has reached equilibrium (undergoes no further succession) e.g matured woodland
What is Primary Successsion?
Occurs on an entirely new habitiat which has never been colonised
What is Secondary Succession?
THe series of community changes which take place on a previously inhabited, but disterbed or damaged habitat.
Some soil, spores and seeds will remain from the previous community and so the area can be rapidly re-colonised by plants and animals
In what ways can human interference effect the natural stages of succession?
Grazing sheep
Deforestation
Using land to grow crops
Deliberate burning of heather moors to prevent woodland stage so it is a suitable habitat for Grouse.
