Topic 4.2: Energy Flow Flashcards
Importance of sunlight
Initial source for almost all communities
Autotrophs that do not use light as energy source
Producers derive energy from chemical processes
How is light converted into chemical energy (e.g., organic compounds)?
Photosynthesis
How is light converted into useful chemical energy by autotrophs?
It is used to make organic compounds from inorganic sources
How is chemical energy obtained by heterotrophs?
Ingestion (feeding) of organic compounds produced by photoautotrophs to derive their chemical energy
How is energy stored in organic molecule released?
a) Released by cell respiration (in autotrophs / heterotrophs)
b) ATP is produced via cell respiration to fuel metabolic reactions.
Are energy process in living organisms 100% efficient? If not, how much?
No. They are ~10% efficient, with about 90% available energy lost between trophic levels.
Reasons for energy loss
a) Heat is a by-product of metabolic reactions
b) Not all the parts of an organism can be swallowed, digested and used
c) Some organisms die before being eaten by an organism in the next trophic level
What is a consequence of the energy loss between trophic levels?
It restricts the length of food chains and the biomass of higher trophic levels.
What forms of energy can chemical energy produced by an organism converted into?
a) Kinetic energy (e.g., muscular contractions)
b) Electrical energy (e.g., during the transmission of nerve impulses)
c) Light energy (e.g., producing bioluminescence)
Can an organism convert heat energy into any other form of energy?
No
What is a consequence of not being able to convert heat into other forms of usable forms of usable energy?
a) Heat is lost from living organisms and ecosystems, so it is radiated into the atmosphere.
b) Ecosystems require a continuous influx of energy from an external source (e.g., sunlight)
Definition of Energy Flow
Process of passing energy from one organism to another through feeding
Definition of Food Chain
Representation of the flow of energy through the trophic levels of a feeding relationship.
What do the arrows in a food chain represent?
Transfer of energy and matter as one organism is eaten by another
Definition of Trophic Levels
Feeding position of an organism in a food chain
Name of the Trophic Levels
a) Level 1
b) Level 2
c) Level 3
d) Level 4
a) Producer
b) Primary consumer
c) Secondary consumer
d) Tertiary consumer
Definition of Biomass
The total mass of a group of organisms – consisting of the carbon compounds contained in the cells and tissues
Relationship between trophic level and its biomass
a) Biomass disminished along food chains with the loss of CO2, H2O and waste products to the environment (e.g., urea)
b) Higher trophic levels store less energy as carbon compounds and have less biomass
Relationship between biomass and energy
Since organic compounds store energy, the amount of energy in a trophic level can be measured as biomass
Definition of pyramids of energy
Diagram that shows the amount of energy available at each trophic level
Units of the energy at a given trophic level
kJ m-2 year-1
Will pyramids of energy appear inverted? Why?
No. As so much energy is lost as heat and after many trophic levels, no much energy is left.
How much energy is transferred from one trophic level to the next?
~ 10%
