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| A chemical bond formed between an electropositive atom and a strongly electronegative atom, such as oxygen or nitrogen. |
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| the energy required to increase the surface area of a gas-liquid interface |
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| the attraction of water to a solid phase such as a cell wall or glass surface, primarily due to the formation of hydrogen bonds |
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| extensive hydrogen bonding in water aiding in the mutual attraction between molecules. |
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energy required to raise the temperature of a substance by a set amount.
*Important for plans; helps buffer temperature fluctuations. |
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| movement of water, for small distances, within the cell wall or capillary tube, due to water's adhesion, cohesion, and surface tension |
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| the maximum force per unit area that a continuous column of water can withstand before breaking. (rise of water column in capillary tube) |
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pressure generated by compression of water into a confined space.
-measured in units called pascals(Pa) or megapascals(MPa) |
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| describes how readily water can move across a membrane |
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spontaneous movement of substances from regions of higher to lower concentration.
at level of a cell, this is the dominant mode of transport! |
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| diffusion of water across a selectively permeable barrier |
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membranes of plant cells are this....
they allow water and other small, uncharged subtances to move across them more readily than larger solutes and charged substances |
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| a quantitative expression of the free energy associated with a substance |
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the chemical potential of water divided by the partial molal volume of water.
measure of the free energy of water per unit volume |
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| solute potential/osmotic potential |
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| represents the effect of dissolved solutes on water potential. solutes reduce the free energy of water by diluting the water |
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| ------- causes water to move downward unless the force of ------ is opposed by an equal and opposite force. |
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| integral membrane proteins that form water selective channels across the membrane, allow H2O to move very quickly into cell |
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| the process by which proteinswithout a sorting signaltravel to and from different cellular compartments. |
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| determines the direction and movement of water |
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| What is the importance of the water potential concept in plant physiology? |
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| Solute(osmotic) potential, gravity, pressure potential |
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| What are the components of water potential? |
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| large internal hydrostatic pressures in cell walls. essential for many physiological processes, including cell enlargement,stomatal opening, transport in the phloem, and various transport processes across membranes. |
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| The pressure exerted by water inside the cell against the cell wall |
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| Turgor pressure tends to be positive in all cells except for the xylem (which can contain negative pressure when sucking up water) |
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| Can plant cells have negative turgor pressure ? |
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| soil hydraulic conductivity |
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| measure of the ease with which water moves through the soil, it varies with the type of soil and its water content |
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| filamentous outgrowths of root epidermal cells that greatly increase the surface area of the root, which provides greater capacity for absorption of ions and water from the soil |
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| in this pathway water moves through cell walls and extracellular spaces without crossing any membranes as it travels across the root cortex |
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| in this pathway, water travels across the root cortex via the plasmodesmata |
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| in this pathway, water crosses the plasma membrane of each cell in its path twice (once on entering and once on exiting) |
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a band within the radial cell walls of the endodermis that contains the wax-like, hydrophobic substance suberin.
*At the endodermis, water movement through the apoplast pathway is obstructed by this..... |
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elongated, spindle-shaped cells that are arranged in overlapping vertical files;
present in both angiosperms and gymnosperms, ferns, and other groups of vascular plants |
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non-living water-conducting cells with perforated ends walls;
found only in angiosperms, a small group of gymnosperms called the Gnetales, and some ferns. |
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| a stack of two or more vessel elements |
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plants that develop root pressure frequently produce liquid droplets on the edges of their leaves called.....
(dew) |
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| microscopic regions in tracheary elements where the secondary wall is absent and the primary wall is thin and porous, facilitating sap movement between one tracheid and the adjacent one |
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| the adjacent pits of adjoined tracheid cells, a low resistance path for water movement between tracheids |
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| the porous layer between pit pairs, consisting of two thinned primary walls and a middle lamella |
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| the perforated end walls of vessel elements |
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| the water content of a soil after it has been saturated with water and excess water has been allowed to drain away *the moisture holding capacity of soils* |
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| a model for sap ascent in the xylem up the stem of the plant, stating that evaporation of water from the leaves at the top of the stem causes a tension (negative turgor pressure!!) that pulls water UP the long water columns in the xylem |
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| water content of the soil (or soil water potential) from which plants cannot retain turgor and therefore remain wilted even if all water loss through transpiration stops |
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| a positive hydrostatic pressure in the xylem of roots |
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| a wax-like lipid polymer similar to cutin that acts as a barrier to water and solute movement through the Casparian strips of the endodermis and other places |
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| a central thickening found in the pit membranes of tracheids in most gymnosperms |
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| a functional unit in the chloroplast that HARVESTS LIGHT ENERGY to power electron transfer and to generate a proton motive force used to synthesize ATP |
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| a system of photoreactions that absorbs far-red light 700nm, oxidizes plastocyanin and reduces ferredoxin |
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| system of photoreactions that absorbs red light 680nm, oxidizes water and reduces pastoquinone. |
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| a small, water-soluble, copper-containing, protein that transfers the electrons between the cytochrome b6f complex and P700, this protein is found in the lumenal space |
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small, nonpolar molecule that diffuses readily in the nonpolar core of the thylakoid membrane.
a mobile electron carrier connecting PSII and PSI |
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| a group of light absorbing green pigments active in photosynthesis |
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| a group of pigment molecules that cooperate to absorb light energy and transfer it to a reaction center complex |
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| pigmented glycosylated flavonoids responsible for most of the red, pink, purple, and blue colors in plants |
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| reaction in which a carboxylase catalyzes the formation of a carbon-carbon bond between CO2 ad the carbon atom of an organic molecule |
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| the chemical process by which electrons or hydrogen atoms are added to a substance |
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biochemical pathway for the reduction of CO2 to carbohydrate, the cycle involves three phases:
1)CARBOXYLATION of ribulose 1,5-bisphosphate with atmospheric CO2 (catalyzed by rubisco)
2) REDUCTION of the formed 3-phosphoglycerate to trioses phosphate by 3-phosphoglycerate kinase and NADP-glyceraldehyde-3-phosphate dehydrogenase
3) REGENERATION of ribulose 1,5-bisphosphate through the concerted action of ten enzymatic reactions |
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| synthetic reactions occuring in the stroma of the chloroplast that use the high-energy compounds ATP |
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| plants in which the first stable product of photosynthetic CO2 fixation is a 3-carbon compound |
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plants in which the first stable product of CO2 assimilation in mesophyll cells is a four-carbon compound that is immediately transported to bundle sheath cells and decarboxylated.
The CO2 released enters the Calvin cycle |
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| plants that fix CO2 during the night into a four-carbon compound that, after storage in the vacuole, is transported out of the vacuole and decarboxylated during the day. The CO2 released is assimilated by the Calvin cycle in the chloroplast stroma |
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| sum of the electrical charge gradient and the pH gradient across a membrane, resulting from a concentration gradient of protons |
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a unit of measurement that characterizes waves, in particular light energy.
the number of wave crests that pass an observer in a given time |
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| the formation of ATP from ADP and an inorganic phosphate using light energy stored in the proton gradient across the thylakoid membrane (electron returns to photosystem II) |
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| non cyclic photophosphorylation |
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| the electrons excited by light in photosystem II, that go to photosystem I will not return, and instead will produce NADPH |
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| a discrete physical unit of radiant energy |
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| a plant protein which fixes carbon in photosynthetic organisms and accepts oxygen in place of carbon dioxide |
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a unit of measurement for characterization of light energy,
distance between successive wave crests |
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| carotenoids involved in nonphotochemical quenching (quenched state of photosystem II) |
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| arrangement of the reaction center and antenna complexes of photosystem II and photosystem I and the electron transport chain that links them by their midpoint redox potential |
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