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| 6430933480 | Of the 5 essential elements in important biological molecules, which are readily available and which are often the limiting nutrients in plant growth? | Readily available: => hydrogen => oxygen => carbon Often limiting nutrients => nitrogen => phosphorous | 0 | |
| 6430933481 | How plants are dependent on microbes | Microbes play an enormous role in the cycling of these elements, making them available in forms that can be used by plants. Plants capture minerals and transform them into organic forms, making them available to animals. | 1 | |
| 6430933482 | inorganic forms of nitrogen | dinitrogen (N2 gas) **the most abundant yet the least biologically active (most inert) ammonia (NH3) Nitrate (NO3-) Nitrite (NO2-) | 2 | |
| 6430933483 | organic forms of nitrogen | amino acids nucleic acids urea **organic nitrogen may be in the form of living organisms, soil organic matter, or in the intermediate products of organic matter decomposition | 3 | |
| 6430933484 | Nitrogen gas | nitrogen gas comprises about 80% of earth's atmosphere but organisms cannot use it unless it has been reduced to ammonia | 4 | |
| 6430933485 | Ammonia is produced by (3 ways) | 1) Nitrogen fixation => soil microbes like Rhizobium or aquatic microbes like cyanobacterium Anabaena => process requires a lot of energy (will study more about this process later) 2) Ammonification aka Mineralization (decomposition) 3) Nonbiological nitrogen fixation => A small, insignificant amount of nitrogen fixation occurs by lightning, volcanic eruptions, and ultraviolet light as well as from man-made processes like internal combustion engines. |  | 5 |
| 6430933486 | Mineralization (aka ammonificatioin) Cycle of death, decay, mineralization, and assimilation into new living tissue. | Mineralization is the process of converting complex organic material into inorganic forms (i.e. ammonia). Microorganisms (aerobic and anaerobic bacteria and fungi) do this to plants and animals when they die. **It is the microbial decomposition of organic material, producing ammonia. **Microbial action causes the hydrolysis of proteins and nucleic acids, releasing amino acids and nucleotides, which are then further metabolized by microorganisms into ammonia. And in this way, the cycle makes its rounds. The microbes convert the inorganic material into usable forms by plants. Plants then converts it into organic material. Animals eat it. And so on. microbes => plants => animals => animals/plants dye => microbes => plants => animals | 6 | |
| 6430933487 | You have ammonia. Now what? Two pathways for the use of ammonia | 1) Assimilation of ammonia => The ammonia in soil can be directly absorbed MOSTLY BY MICROORGANISMS (very little by plant roots) and assimilated into cell material => once assimilated into proteins and nucleic acids, the assimilated nitrogen travels through the food chain 2) Nitrification - Oxidation of ammonia to nitrate => Strictly aerobic bacteria can oxidize ammonia to nitrite and then further to nitrate => The resulting nitrate is a preliminary source of nitrogen for most plants **Since an inorganic compound is the source of electrons, these bacteria are considered to be chemolithotrophic |  | 7 |
| 6430933488 | Plant's nitrogen source | Plants cannot readily absorb dinitrogen, ammonia, or organic nitrogen. **They require nitrate or urea in the soil as their source of nitrogen. | 8 | |
| 6430933489 | Whether it is absorbed directly, modified before use by plants, or converted into a form unusable by plants, nitrate must be reduced. Three pathways for nitrate reduction: | 1) Nitrate assimilation (NO3- => NH3) => for plants, the most efficient uptake of nitrogen is in the form of nitrate => once absorbed by plants, the nitrogen in nitrate is reduced to ammonia in order to be incorporated into nucleotides and amino acids => this assimilated nitrogen serves as a source of nitrogen for consumers further along the food chain 2) Assimilatory nitrate reduction (NO3- => NO2- => NH3) 3) Dissimilatory nitrate reduction aka denitrification => Anaerobic respiration using nitrate or nitrite as terminal electron acceptor => Nitrate reduction (NO3- => NO2-) => Denitrification (NO2- => N2) | 9 | |
| 6430933490 | Nitrification | Nitrification (oxidation of ammonia into nitrate): NH3 => NO3- Nitrate assimilation (reduction of nitrate into ammonia): NO3- => NH3 Assimilitary nitrate reduction: NO3- => NO2- => NH3 Denitrification aka dissimilatory nitrate reduction: -Nitrate reduction NO3- => NO2- -Denitrification NO2- => N2 | 10 | |
| 6430933491 | Animals nitrogen source | Organisms cannot use N2 unless it has been reduced to ammonia (NH3). really? | 11 | |
| 6430933492 | Nitrogen cycle (pathways involving the conversion of different forms of nitrogen) has: Assimilatory pathways Dissimilatory pathways | Assimilatory pathways: when products can be directly or indirectly assimilated by living things Dissimililatory pathways: when products cannot be assimilated without significant modification | 12 | |
| 6430933493 | ammonium + bacteria = ? | nitrate (nitrification) | 13 | |
| 6430933494 | nitrification | ammonium -> nitrite -> nitrate changing ammonium to nitrate through oxidation | 14 | |
| 6430933495 | denitrification | microbes removing nitrates ammonium + bacteria = nitrate (nitrification) | 15 | |
| 6430933496 | runoff | nitrogen from fertilizers and ammonium is moved in water from land to water | 16 | |
| 6430933497 | volcanoes as well as electrical storms can cause... | ammonium to form in soil | 17 | |
| 6430933498 | nitrogen fixation | nitrogen -> ammonium (this is caused by nitrogen fixation and high energy processes) | 18 | |
| 6430933499 | ammonification | organic nitrogen compounds to NH3 | 19 | |
| 6430933500 | assimilation | NH3 -> NO3- -> biological tissues (aka it puts NH3 and NO3- into biological tissues) | 20 | |
| 6430933501 | steps of the nitrogen cycle | - ammonification - nitrification - nitrogen uptake by plants - nitrogen fixation (released into atmosphere) OR... eaten by animals (decomposition) - denitrification | 21 | |
| 6430933502 | STEP ONE | ammonification - there is ammonium | 22 | |
| 6430933503 | STEP TWO | nitrification - ammonium to nitrates | 23 | |
| 6430933504 | STEP THREE | nitrogen is absorbed by plants | 24 | |
| 6430933505 | STEP FOUR | nitrogen fixation (released to atmosphere) OR... plants are eaten by animals (then decomposition) | 25 | |
| 6430933506 | STEP FIVE | denitrification | 26 |
