4.2 Energy Flow Flashcards
What does it mean if an organism is photoautotrophic? give examples
All green plants, and some bacteria, are photoautotrophic – they use sunlight as a source of energy
What is the initial source for most communities?
This makes light the initial source of energy for almost all communities
What is an exception to a community that uses sunlight as its primary energy source?
In a few ecosystems the producers are chemoautotrophic bacteria, which use energy derived from chemical processes
What process makes use of light energy?
Light energy is absorbed by photoautotrophs and is converted into chemical energy via photosynthesis
What is light energy used for?
This light energy is used to make organic compounds (e.g. sugars) from inorganic sources (e.g. CO2)
Why do heterotrophs consume autotrophs?
Heterotrophs ingest these organic compounds in order to derive their chemical energy (ATP)
What happens when organic compounds are broken down?
When organic compounds are broken down via cell respiration, ATP is produced to fuel metabolic processes
What is light energy converted into?
Energy enters most ecosystems as sunlight, where it is converted into chemical energy by producers (via photosynthesis)
How is chemical energy stored?
This chemical energy is stored in carbon compounds (organic molecules) and is transferred to heterotrophs via feeding
What is a trophic level?
The position an organism occupies within a feeding sequence is known as a trophic level
What occupies the first trophic level?
Producers always occupy the first trophic level in a feeding sequence
What occupies the second trophic level?
Primary consumers feed on producers and hence occupy the second trophic level
What occupies the consequent trophic levels (2+)?
Further consumers (e.g. secondary, tertiary, etc.) may occupy subsequent trophic levels
What is a food chain?
A food chain shows the linear feeding relationships between species in a community
What do arrows in a food chain represent?
Arrows represent the transfer of energy and matter as one organism is eaten by another (arrows point in direction of energy flow)
What is the sequence of organisms in a food chain?
The first organism in a food chain is always a producer, followed by consumers (primary, secondary, tertiary, etc.)
How can energy stored in organic molecules be released?
Energy stored in organic molecules (e.g. sugars and lipids) can be released by cell respiration to produce ATP
What is ATP used for?
This ATP is then used to fuel metabolic reactions required for growth and homeostasis
What is a by-product of respiration?
A by-product of these chemical reactions is heat (thermal energy), which is released from the organism
In what ways can energy be lost?
Not all energy stored in organic molecules is transferred via heterotrophic feeding – some of the chemical energy is lost by:
Being excreted as part of the organism’s faeces
Remaining unconsumed as the uneaten portions of the food
Into what 3 forms can energy produced by an organism be converted into?
kinetic, electrical and light energy
What is an example of a use of kinetic energy?
during muscular contractions
What is an example of a use of electrical energy?
during the transmission of nerve impulses
What is an example of a use of light energy?
producing bioluminescence