Ch 13

Question 1

Macro essential elements

Answer 1

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

Question 2

Micro essential elements

Answer 2

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

Question 3

Criteria for essentiality

Answer 3

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

Question 4

Chlorosis

Answer 4

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

Question 5

Necrosis

Answer 5

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

Question 6

Mobile elements

Answer 6

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

Question 7

Immobile elements

Answer 7

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

Question 8

Physical weathering

Answer 8

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

Question 9

Chemical weathering

Answer 9

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

Question 10

Course sand

Answer 10

largest soil particles; 2.0 to 0.2 mm

Question 11

Fine sand

Answer 11

0.2 to 0.02 mm

Question 12

Silt

Answer 12

0.02 to 0.002 mm

Question 13

Clay

Answer 13

finest particles; smaller than 0.002 mm technically known as micelles

Question 14

Field capacity

Answer 14

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

Question 15

Cation exchange

Answer 15

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

Question 16

Soil acidity

Answer 16

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

Question 17

Endodermis and selective absorption

Answer 17

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

Question 18

Mycorrhizae

Answer 18

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

Question 19

Nitrogen fixation

Answer 19

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

Question 20

Nitrogenase

Answer 20

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

Question 21

Nitrogen reduction

Answer 21

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

Question 22

Nitrogen assimilation

Answer 22

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

Question 23

Nitrifying bacteria

Answer 23

they oxidize ammonium to nitrite and others oxidize nitrite to nitrate

Question 24

Nitrification

Answer 24

the conversion of ammonia to to nitrate by microbes

Question 25

Carnivorous plants

Answer 25

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

Question 26

Ant plants

Answer 26

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

Question 27

3 examples of how/ where plants store minerals

Answer 27

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