Lecture 5 -- The Biological Environment: Nutrient Cycles in the Biosphere Flashcards
What is the most common element in our body? After C, H, and O, what are the most common elements in our body?
Oxygen is the most common element, at 65%, carbon is 19%. hydrogen is 10%
-Nitrogen is at 3% and phosphorous is at 1%
What are the most important plant macronutrients? How is nitrogen used in plants? How is phosphorus used in plants? What are three examples of plant micronutrients?
Plant macronutrients:
Nitrogen, which produces proteins and amino acids
Phosphorous, which is responsible for nucleic acids (DNA), ATP (energy transport in the cell)
Potassium is a catalyst and transports ions
Micronutrients:Fe, Cu, Zn, Bo, Mn, Cl, Mo, I, Se
What kind of organism is Lobaria oregana and where is it found in forests? What function does it play in forest ecosystems? During the process of forest succession, when does lobaria show up?
Lobaria oregana is an epiphyte, found in the canapoy of forests
It is a nitrogen fixer in old-growth forest
What is an epiphyte?
A plant that grows on another plant, but is not a parasite. It derives its nutrients from the air, rain, and sometimes debris.
What organism “fixes” nitrogen? What organism is able to directly use N2 gas from the atmosphere? What does nitrogen “fixing” mean?
Some bacteria fixes nitrogen from the atmosphere, turning N2 into Ammonium (NH4) or nitrite, nitrate (NO2, NO3). Nitrate is the most common form used by plants.
How do humans alter the global nitrogen cycle? What nitrogen reservoir do they shift it from, and where to? How is commercial fertilizer made?
Humans input a lot of fixed nitrogen into the atmosphere and the ocean
How do fossil fuel emissions affect the nitrogen cycle?
It adds fixed nitrogen to the cycle
What forms of nitrogen are useable by plants?
NH3, NH4, NO2, NO3
Which process produces nitrogen that plants can use, nitrification or denitrification?
Nitrification
List a couple plant species that host n-fixing bacteria. In a plant-bacteria symbiosis, where do the bacteria live?
Types of N-fixing bacteria: free-living, symbiotic, cyanobacteria
Bacteria lives in the soil (?)
T/F: lichens are photosynthetic, like plants. All lichens can ‘fix’ nitrogen.
TRUE
What are the three forms of bioavailable nitrogen?
NH4, NO2, NO3
Which is greater, the total human release of fixed nitrogen, or the total natural nitrogen fixing in terrestrial habitats? Aside from making fertilizer, what are some other ways that humans alter the nitrogen cycle?
Why do you think atmospheric nitrogen deposition is expected to increase in the future in China and India, more than just about any other place?
The human release is greater. Fossil fuels and land clearing contribute.
Cina and Inida use more coal and have larger populations (more cultivated land)
What ecosystem types are expected to be the most impacted by nitrogen and phosphorus pollution in the future?
Coastal and inland water, temperate grassland
Which holds more phosphorus, the hydrosphere or the atmosphere?
The hydrosphere
