CHAPTER 4 : BIOGEOCHEMICAL CYCLES Flashcards
The water cycle distributes water among atmosphere,
biosphere, surface, and groundwater.
Material Cycles
what are the
essential elements that also move through biological, atmospheric, and earth systems (biogeochemical
cycles).
Carbon, nitrogen, and phosphorous
•The most familiar material cycle
•Most of the earth’s water is stored in the oceans
Hydrologic Cycle
Solar energy continually ___ the water, and winds distribute water vapor around the globe.
evaporates
Water that ___ over land surfaces, in the form of rain, snow, or fog, supports all terrestrial (land-based) ecosystems
condenses
Living organisms emit the moisture they have consumed through
___ and ___
respiration and perspiration
what is responsible
•for metabolic processes within cells,
•for maintaining the flows of key nutrients through ecosystems,
•for global-scale distribution of heat and energy
water
The ___ carried back to the ocean each year by surface
runoff or underground flow is the renewable supply available for
human uses and sustaining freshwater-dependent ecosystems.
40,000 km³
This cycle begins with the intake of carbon dioxide (CO2)
by photosynthetic organisms
Carbon-Oxygen Cycle
dual purpose of carbon for organisms
(1) it is a structural component of organic molecules, and
(2) the energy-holding chemical bonds it forms represent
energy “storage”
Photosynthesis produces plant cells from
carbon in the air (plus hydrogen and oxygen in
water). __ is eventually
released during respiration, closing the cycle.
Carbon dioxide
Processes that release carbon into the atmosphere are referred to
as ___
carbon sources (cellular respiration & combustion)
while ___ are processes that
absorb more carbon than they release
carbon sinks’ (forest and oceans)
The path followed by an individual carbon
atom in the carbon-oxygen cycle may
be quite ____, depending on how it is used in an
organism’s body.
direct and rapid
why is carbon dioxide is one of the so-called greenhouse gases
because
it absorbs heat radiated from the earth’s surface, retaining it
instead in the atmosphere
nitrogen cycle
Nitrogen fixation
Nitrification
Assimilation
Ammonification
Denitrification
NO3-
nitrate
NH4+
ammonium
it is the most important nutrient for proper growth and development
of plants because of its vital role in biochemical and physiological
functions (Leghari et al., 2016)
nitrogen cycle
how many nitrogen are stored in the atmosphere
78%
bacterial activity is essential
before the plant can use nitrogen in a process called ___
nitrogen fixation
Nitrogen cycle affects atmospheric concentrations of the three most
important human-caused greenhouse gases:
carbon dioxide,
methane, and nitrous oxide
In natural ecosystems, nitrogen is often the ___.
When a nutrient is limiting,
adding more of it will increase
growth, e.g., it will cause plants to grow taller than if nothing
were added
limiting nutrient
step by step process of water cycle
evaporation
condensation
precipitation
step by step process of carbon cycle
emission
respiration
decomposition
combustion
step by step process of nitrogen cycle
nitrogen fixation
nitrification
denitrification
___ is a vital nutrient for plant growth and productivity. It is stored in rocks and found in the atmosphere only in small particles of dust
Phosphorus (P)
Phosphorus is a key component of molecules that store energy, such as ___
ATP, DNA and lipids
what means ATP
adenosine triphosphate
step by step process of phosphorus cycle
Weathering
Absorption by plants
Absorption by animals
Return of phosphorous back in the ecosystem
Phosphorus is found in the rocks in abundance. That is why the phosphorus
cycle starts in the earth’s crust. The phosphate salts are broken down from
the rocks. These salts are washed away into the ground where they mix in the
soil.
weathering
The phosphate salts dissolved in water are absorbed by the plants.
Absorption by plants
The animals absorb phosphorus from the plants or by consuming plant-eating
animals.
Absorption by animals
When the plants and animals die they are decomposed by microorganisms
Return of phosphorous back in the ecosystem
The ultimate source of phosphorus
rocks
The phosphorus cycle is really a ___
one-way path
The release of phosphorus from rocks and mineral compounds is normally ___, but mining of fertilizers has greatly speeded its use and movement in the environment.
very slow
