Exam 5 Flashcards
Food chains
A linear sequence of organisms through which nutrients and energy pass.
Each organism occupies a trophic level.
Primary Producer»_space; Primary Consumer»_space; Secondary Consumer»_space; Tertiary (Apex) Consumer
Primary producer
the bottom of the food chain, usually photosynthetic organisms (plants and/or phytoplankton)
Primary consumer
consumes the primary producer.
Secondary consumers
usually carnivores that eat the primary consumers
Apex consumer
the highest-level consumer in the ecosystem
food web
a graphic representation of a holistic, nonlinear web of primary producers, primary consumers, and higher-level consumers used to describe ecosystem structure and dynamics
Photoautotrophs
plants, algae, and photosynthetic bacteria, serve as the energy source for a majority of the world’s ecosystems
Chemoautotrophs
These organisms synthesize complex organic molecules, such as glucose, for their own energy; usually they do this without sunlight and rather use other sources of energy. (Uncommon)
Heterotrophs
These organisms acquire energy from digesting living or previously living organisms
Abiotic features of an ecosystem
Energy flows, Water and nutrients cycle
Energy flows
This phrase implies that energy is not recycled in an ecosystem
Source of energy is (usually) the Sun, in the form of sunlight
Some energy is lost from the ecosystem as heat at each trophic level
Note that each trophic level also leads to detritus/detritivores
Water and nutrients cycle
This phrase implies that such chemicals are recycled in an ecosystem
Such chemicals may enter from other ecosystems, and exit to other ecosystems
Three factors for productivity within trophic levels
Gross primary productivity (GPP)
Net primary productivity(NPP)
Biomass
Gross primary productivity (GPP)
the rate at which photosynthetic primary producers incorporate energy from the sun
Net primary productivity(NPP)
the energy that remains in the primary producers after accounting for the organisms’ respiration and heat loss. The net productivity is available to the primary consumers at the next trophic level—as biomass
Biomass
the total mass, in a unit area at the time of measurement, of living or previously living organisms within a trophic level
Detritivores and decomposers
Bacteria and fungi are most prolific
Any organism that feeds on detritus (dead organic matter) is a detritivore
One influence of environment on NPP
Climate factors
Only about 10% of NPP energy becomes biomass in primary consumers—why so inefficient?
Primary consumers do not eat ALL primary producer biomass (some NPP is “left on the shelf”)
Not all NPP consumed is assimilated—what happens to energy not assimilated?
Of assimilated energy, some is used to maintain metabolic functions (respiration) and is lost as heat
Remaining energy is allocated to growth and reproduction—referred to as secondary production
Ecological efficiency between trophic levels
The measurement of energy transfer efficiency between two successive trophic levels is termed thetrophic level transfer efficiency (TLTE)and is defined by the formula:
production at present trophic level / production at previous trophic level * 100
Expressed as percent
Why isn’t energy transfer between trophic levels entirely efficient? Briefly describe some of the reasons why energy obtained by herbivores does not get passed on to the predators. What happens to energy that is not transferred from herbivores to their predators?
What compartments may carbon occur in?
Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized. Volcanic activity and, more recently, human emissions, bring this stored carbon back into the carbon cycle.
What forms may carbon take in those compartments?
Carbon dioxide gas exists in the atmosphere and is dissolved in water.
What role does photosynthesis play in the carbon cycle? What about cellular respiration?
converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas
atmospheric form of nitrogen is N2 gas
unavailable to almost all forms of life, except certain nitrogen-fixing bacteria
