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osmosis
the diffusion of water across permeable cell membranes that select for or against certain substances
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turgid
swollen and firm due to internal water pressure
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turgor pressure
the pressure developed in a cell as it becomes filled with water
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plasmolysis
shrinkage of cytoplasm away from the cell wall as a result of excess water loss
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root pressure
the pressure developed by living cells in a root forcing water up the xylem
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guttation
exudation of droplets of water, most often from leaf margins, as a result of water movement up a plant due to root pressure; from pores called hydathodes
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transpiration
the loss of water vapor from a plant, mostly from the stomata of leaves
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transpirational pull
the force exerted from transpiration from the leaves that draws water up through a plant
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cold hardening
the process whereby some species prepare for seasonal periods of low temperatures
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macronutrients
a mineral required by plants and animals in relatively large quantities
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micronutrients
a mineral required by plants and animals in relatively small quantities; trace element
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chlorosis
an abnormal yellowing of leaves due to a reduced chlorophyll content
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phospholipids
fatty membrane components that contain phosphorus
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necrosis
the death of a plant tissue
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N-P-K ratio
the relative proportions of nitrogen, phosphorus and potassium in a fertilizer
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humus
organic matter in the soil derived from the decomposition of plant and animal remains
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sand
an inorganic soil component, the particles of which range between 0.02 and 2 mm diameter
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clay
an inorganic soil component having particles less than 0.002 mm diameter
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silt
an inorganic soil component, the particles of which range between 0.002 and 0.02 mm diameter
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loam
a mixture of sand silt and clay
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water-holding capacity (field capacity)
the amount of water held in a soil after gravitational run-off
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pH
a measure of relative acidity or alkalinity
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acid rain
a mild sulfuric acid solution, the product of combining the air pollutant sulfur dioxide with atmospheric moisture
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chelates
an organic substance to which metals such as iron are bound and from which they are released
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granum (pl. grana)
a stack of platelike, pigment-containing structures in a chloroplast
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chlorophylls
a green plant pigment located in chloroplasts
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xanthophyll
a yellow or almost colorless photosynthetic pigment
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carotene
an orange-yellow pigment located in the chloroplasts
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anthocyanin
a water-soluble pigment, varying from red to blue
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variegation, variegated
an inherited, irregular pattern of color in a leaf or petal
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cellular respiration
the chemical breakdown of food substances, resulting in the liberation of energy
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light reaction
the first stage of photosynthesis
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carbon dioxide fixation
the second phase of photosynthesis, carbon dioxide from the atmosphere unites with the sugar ribulose diphosphate
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starch
the principle food-storage substance of higher plants; a carbohydrate consisting of numerous glucose units
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fermentation
the partial breakdown of food molecules to yield ethyl alcohol, carbon dioxide, and energy; occurs in the absence of oxygen
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9 macronutrients
- C carbon
- H hydrogen
- O oxygen
- N nitrogen
- P phosphorus
- K potassium
- S sulfur
- Ca calcium
- Mg magnesium
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6 micronutrients
- Fe iron
- Cu copper
- Zn zinc
- Mn manganese
- Mo molybdenum
- B boron
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