active transport
movement of material across the cell membrane against its concentration gradient, requiring the cell to expend energy
apoplast
the continuous network of cell walls and extracellular spaces in plants through which materials can pass without having to go into the cell itself
aquaporin
a transport protein in a cell membrane that allows for osmosis, the diffusion of water across a semipermeable membrane.
Casparian strip
a water-impermeable ring within the roots that regulates water uptake
cortex
endodermis (inner layer) of the root
humus
the layer of decaying plants and animals found in the upper levels of soil that provides nutrients to plants
macronutrient
a nutritional element plants need in quantities greater than 1 milligram per gram of mass of the plant
micronutrient
a nutritional element needed by plants in quantities less than 100 micrograms per gram of mass of the plant
mutualistic relationship
a relationship between organisms of different species in which both organisms benefit
mycorrhiza (plural, mycorrhizae)
the symbiotic relationship between plant roots and fungus found within the soil
nitrogen fixation
the conversion of atmospheric nitrogen into ammonia, a form that is more usable by plants
nodule
a structure found on the roots of nitrogen-fixing plants that contain symbiotic bacteria that fix nitrogen
osmosis
the movement of water molecules across a semipermeable membrane from an area of lower concentration of solute to higher concentration of solute
phloem
the series of tissues that transport sugars and other materials from the leaves of plants to their roots
plasmodesma (plural, plasmodesmata)
a small channel between mesophyll cells and bundle-sheath cells through which molecules pass between carbon fixation in the mesophyll cells and the Calvin cycle in the bundle-sheath cells; this channel extends through the cell wall of a plant cell and directly connects the cytoplasm of adjacent plant cells
pressure flow model
a model of plant transport based on the osmotically generated pressure that moves materials between sources and sinks
root
organ of a vascular plant that provides water and mineral support and anchors a plant to the soil
sink
the location in plants where the synthesized materials are transported, such as the roots
source
the location in plants where the synthesized materials originate, such as the leaves
stoma (plural, stomata)
small opening mostly found on the undersides of leaves that allows for gas exchange between the plant and the external environment
strigolactone
molecule produced by plant roots that signals to attract mycorrhizae hyphae
symbiosis
the ecological relationship between two or more organisms that live in direct contact
symplast
the network in cell interiors of plant cells through which materials can pass uninterrupted via plasmodesmata
translocation
the transport of materials through the phloem of vascular plants
transpiration
the loss of water from the plant leaves through the stomata as a result of temperature and humidity (faster at higher temperatures and slower in humid conditions)
transpiration-cohesion-tension model
the model used to describe how water is pulled from the roots, up the stems, and out of the leaves.
water potential
the tendency of water to move from areas of high concentration to those of low concentration
xylem
a vein-like tissue that carries water from roots and stems to leaves