Biochemical Cycles Flashcards
What are Biochemical Cycles?
- Include biological organisms & geological processes= includes processes that occur on many spatial scales from cellular to planetary
- Arise from a fixed number of atoms of each type of element
Carbon is the major…
Constituent of the bodies of organisms
What is carbon the major constituent of the bodies of organisms?
- BC carbon atoms help form the framework of all organic compounds
- Almost 20% of weight of human body is carbon
What is the most significant carbon-containing compound?
- CO2
- It makes up .03% of the volume of the atmosphere
- And it reacts spontaneously with water to form bicarbonate ions (HCO3-)
What are Biogeochemical cycles?
- Emphasize that the cycles of chemical elements involve biological processes & organisms, & geological (abiotic) systems & processes
- They cross the boundaries of ecosystems
What do Biogeochemical cycles include?
- Include processes that occur on many spatial scales from cellular to planetary
- They also include processes that occur on multiple time scales= biochemical reactions (secs) to the weathering of rocks (millennia)
What is the most significant carbon-containing compound in abiotic environments of organisms?
-Carbon dioxide= makes up .03% of the volume of the atmosphere= 750 billion metric tons
How does CO2 react with water?
-It reacts spontaneously w/ water to form bicarbonate ions= HCO3-
How is the carbon cycle like in terrestrial ecosystems?
- Plants & other photosynthetic organisms take in CO2 from the atmosphere & use it in photosynthesis to synthesize the carbon-containing organic compounds
- This is sometimes called carbon fixation
What does Fixation refer to?
-The metabolic reactions that make nongaseous compounds from gaseous ones
How do photosynthetic plants & animals obtain energy?
-They both break down some of the organic compounds available to them via aerobic cellular respiration
How is the carbon cycle in aquatic ecosystems?
- It is similar to the process for terrestrial ecosystems
- BUT inorganic carbon is present in the water has CO2 & HCO3- ions
What does CO2 & HCO3- have in common?
- They both are present in the water of aquatic ecosystems
- They both act as sources of carbon for photosynthesis by algae & aquatic plants
What kind of microbes provide an additional dimension to the global carbon cycle?
-Microbes that break down organic compounds by anaerobic cellular respiration
What are Methanogens?
-They are microbes that produce methane CH4
What is a major source for Methane?
-Wetland ecosystems bc methogens live in oxygen free sediments
What happens to Methane when it enters the atmosphere?
- It is oxidized abiotically to CO2
- BUT the CH4 that remains isolated from oxygen can last for a lot of time
What are the 2 dimensions of the global carbon cycle?
- Microbes that break down organic compounds
- And that some parts of the cycle may proceed faster than others
What effect would different parts of the global carbon cycle proceeding faster than other parts?
-There will be an imbalance of the cycle which can cause burned fossil fuels to rapidly return to the atmosphere= higher concentration of CO2 levels= global warming
What are the 2 green house gases?
- Methane
- Carbon dioxide
What is the distinctive feature of the Water cycle?
-It is that since water is a compound, it can be synthesized & broken down
How is water synthesized in the water cycle?
-It is synthesized during aerobic cellular respiration
How is water split in the water cycle?
-It is chemically split during photsynthesis
What is the relationship between water synthesizing & splitting in the water cycle?
-The rates are equal= constant amount of water cycles throughout the biosphere
What a key part of the water cycle?
-The liquid from the earth’s surface evaporates into the atmosphere
Why does evaporation occur faster when there’s more solar radiation on the earth’s surface?
-Bc the change of water states from liquid to gas requires a lot of thermal energy
How does evaporation occur?
- It occurs directly from the surfaces of bodies of water
- BUT 90% of the water passes through plants, trees, grasses & then that water leaves from their leaves & other surfaces
what is Transpiration?
-The process of water evaporating through the plant’s leaves or other surfaces before it reaches the atomosphere
How does evaporated water exist in the atmosphere?
-As a gas
What causes the formation of clouds?
- The condensation of gaseous water (water vapor) into droplets or crystals
- If these droplets/ crystals are big enough they’ll fall to the surface of the earth as precipitation (rain/snow)
What is Groundwater?
- The water underground the bodies of water (NOT surface water)
- It is the most important reservoir of water on land= representing over 95% of freshwater in the U.S
- It consists of 2 subparts
How does Groundwater occur?
-It occurs via Aquafiers
What are Aquafiers of Groundwater?
- They are permeable underground layer of rock, sand, & gravel that are often saturated with water
- BUT water flows through here MUCH slower than surface water (few mm to a meter per day)
What are the 2 subparts of Groundwater?
- The upper layer= water table
- The lower layer= confined layers of groundwater
What is the Upper layer of groundwater?
- It constitutes the “water table”
- It is unconfined in a sense that it flows into streams & is partly accessible to roots of plants
What is the Lower layer of groundwater?
- It is confined layers of groundwaters
- These layers are out of reach to streams & plants but can be tapped by wells
How is groundwater recharged?
-It is recharged by water that percolates downward from above= precipitation
What is nitrogen a component of?
- All proteins & nucleic acids
- It is also the chemical element that is the SHORTEST in supply relative to the needs of organisms
Why is nitrogen the shortest supply since the atmosphere is so rich with is?
-It is bc nitrogen is in chemical form (N2) so plants & organisms have no way to use nitrogen in its chemical form
What is the source of nitrogen for animals?
-The major source are nitrogen-containing organic compounds synthesized by plants, algae, & other microbes
What is the source of nitrogen for plants & algae?
-The 2 most common sources= NH3 & NO3- (nitrate ions)
What how is Nitrogen balanced within plants & algae?
- Certain prokaryotic microbes can synthesize ammonia & nitrate from N2 in the atmosphere= makes atmospheric oxygen accessible for plants & algae
- While other prokaryotes turn NH3 & NO3- into N2= making the nitrogen inaccessable
What is Nitrogen Fixation?
- The synthesis of nitrogen containing compounds from N2
- SPECIFICALLY the synthesis of NH3 to N2
What is the steps of Nitrogen Fixation?
- The synthesis of NH3 from NH2
- then other prokaryotic microbes oxidize part of it to form NO3-= nitrification
What is the nitrogen base complex?
-They are enzymes that allow certain prokaryotes to accomplish nitrogen fixation
What is Dentrification?
-The ability that other prokaryotes have to convert the nitrogen in NO3- into N2 or other nitrogenous gases like N2O)
What is the form of waste that Nitrogen can take?
- Most animals excreting nitrogen from proteins like NH3
- While humans & other mammals excrete nitrogen as Urea in their urine
- Many microbes convert the urea to NH3
What is the Phosphorus cycle?
-Phosphorus only occurs in the liquid & solid states= DOES NOT enter the atmosphere
