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Flashcards in Ch 13 Deck (27):

Macro essential elements

needed in large quantities; calcium, nitrogen, potassium, phosphorus, magnesium and sulfer


Micro essential elements

needed in low quantities; trace; iron, boron, chlorine, copper, manganese, molybdenum and zinc


Criteria for essentiality

1- element must be necessary for complete, normal plant development through a full life cycle; element must be required for plant growth, differentiation, reproduction or survival
2- element must be necessary and have no substitute that is effective or works in the same way
3- element must be acting within the plant not outside it



common symptom due to mineral deficiency; yellowing of leaves due to lack of chlorophyll



death of patches of tissues because of lack of certain elements or by bacterial, viral and fungal infections


Mobile elements

chlorine, magnesium, nitrogen, phosphorus, potassium and sulfur; can be translocated to younger tissue


Immobile elements

boron, calcium and iron; after they have incorporated into plant tissue they remain in place


Physical weathering

breakdown of rock by physical forces such as wind, water movement and temperature changes; ice is an important agent; produces a variety of sizes of soil particles


Chemical weathering

involves chemical reactions and the most important agents are acids produced by decaying bodies, especially those of plants and fungi; many organisms secrete acids and carbon dioxide combined with water forms carbonic acid; acid dissolves in water dissociates to proton and anion


Course sand

largest soil particles; 2.0 to 0.2 mm


Fine sand

0.2 to 0.02 mm



0.02 to 0.002 mm



finest particles; smaller than 0.002 mm technically known as micelles


Field capacity

water that remains in the soil is held by capillary adhesion/ cohesion; much of this water is available to roots


Cation exchange

in soil, the release of an essential element cation from a soil particle and its replacement by a proton


Soil acidity

soil pH, the concentration of free protons in the soil solution is important for cation exchange and the retention of cations in the soil during heavy rain; soil pH affects the chemical form of certain elements causing them to change solubility


Endodermis and selective absorption

elements enter roots by crossing the plasma membrane and selecting elements by the presence or absence of molecular pumps control entry of ions and molecules; or elements enter by diffusing along the cell walls and intercellular spaces



the roots of most plants form a symbiotic association with soil fungi; the symbiosis permits plants to absorb phosphorus efficiently


Nitrogen fixation

the conversion of N2 gas into nitrate, nitrite or ammonium; all forms of nitrogen that are substrates for a variety of enzymes



an enzyme that uses N2 as a substrate; it forces electrons and protons onto nitrigen reducing it from 0 to -3 oxidation state; ammonium is the product


Nitrogen reduction

the process of reducing nitrogen in the nitrate ion NO3- from an oxidation state of +5 to the -3 oxidation state of ammonium which is also the oxidation state of nitrogen in amino acids, nucleic acids and many other biological compounds


Nitrogen assimilation

the actual incorporation of ammonium into organic molecules in the plant body; process is similar to that of an electron transport chain: reduced nitrogen passes through a series of carriers that function repeatedly but in the long run are not changed


Nitrifying bacteria

they oxidize ammonium to nitrite and others oxidize nitrite to nitrate



the conversion of ammonia to to nitrate by microbes


Carnivorous plants

plants that catch animals; trap and digest the animals; how they get their reduced nitrogen


Ant plants

flowering plants and ferns that also obtain reduced nitrogen from animals; their roots are attached to tree trunks or branches and bark is a nitrogen-poor soil; ants live in ant-plant stems and as they die and decompose the plants absorb the nitrogenous compounds


3 examples of how/ where plants store minerals

1-Nitrogen is concentrated by being converted to compounds with multiple amino groups such as asparagine, citrulline, etc.
2-Phosphates and sulfates are isolated in the central vacuole in the same form in which they are used metabolically
3-amino acids are stored as particles of protein, protein packed so tightly that it typically crystallizes into a structure called a protein body; in seeds