ENERGY FIXATION AND FLOW Flashcards
What is the result of energy conversion?
Some energy being lost as heat
Why does an ecosystem depend on a constant input of energy?
Because an ecosystem has many organisms, each of which require an input of energy.
Where does the input for almost all ecosystems come from?
The sun in the form of solar radiation (light energy)
What do the plants do with the incident solar radiation?
They fix some of the light energy into chemical energy in organic molecules.
Most of the organic molecules produced are ……………..
Carbohydrates
What molecules are also made from the fixed light energy?
Lipids, proteins, and nucleic acids.
What do all the organic molecules together make up?
The biomass of the plant.
State two sources of energy loss in a plant
Heat lost in photosynthesis reactions
Energy used for respiration
What is the primary productivity?
The rate of accumulation of biomass by plants
What is the gross primary productivity?
The total yield of organic matter from photosynthesis.
What is the net primary productivity?
The biomass remaining after respiration
Where might you find low primary productivity?
Open oceans and the arctic tundra
Where might you find a high primary productivity?
Coral reefs and tropical rainforests
What is productivity measured in to allow a fair comparison between different ecosystems?
Mass of dry matter per square metre per year.
What does the nap represent and what does it determine?
It represents the plant organic matter available to herbivores to use as food, and therefore determines the animal biomass the ecosystem can support.
What do plants make from inorganic molecules and light to keep themselves alive?
Complex molecules
What do all other organisms need to stay alive? How do they obtain these?
They need nutrients which are obtained by consuming complex organic molecules
How is the energy of plants transferred through different organisms in the ecosystem?
By feeding
What can be drawn to show an energy transfer pathway?
A food web
What do the arrows indicate on a food web?
The direction of energy transfer
If two organisms are of the same trophic level what does to indicate?
They have the same position in food chains
What is the first trophic level (T1)
Producers, they are able to use inorganic molecules to form complex molecules
What type of organisms are producers?
Autotrophs, commonly photosynthetic (photoautotrophs)
What is the name given to an organism that isn’t an autotroph?
Heterotrophs
