Ap Bio Ch36-37 Vocab

Front 1

Apoplast

Back 1

In plants, the continuum of cell walls plus the extracellular spaces.

Front 2

Bulk Flow

Back 2

The movement of water due to a difference in pressure between two locations.

Front 3

Casparian Strip

Back 3

A water-impermeable ring of wax in the endodermal cells of plants that blocks the passive flow of water and solutes into the stele by way of cell walls.

Front 4

Chemiosmosis

Back 4

An energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP.

Front 5

Circadian Rhythms

Back 5

A physiological cycle of about 24 hours that is present in all eukaryotic organisms and that persists even in the absence of external cues.

Front 6

Cohesion

Back 6

The binding together of like molecules, often by hydrogen bonds.

Front 7

Endodermis

Back 7

The innermost layer of the cortex in plant roots, a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder.

Front 8

Essential Nutrient

Back 8

A substance that an organism must absrb in preassembled form because it cannot be synthesized from any other mineral.

Front 9

Guttation

Back 9

The exudation of water droplets, caused by root pressue in certain plants.

Front 10

Horizons

Back 10

A distinct layer of soil, such as topsoil.

Front 11

Humus

Back 11

Decomposing organic material found in topsoil.

Front 12

Loam

Back 12

The most fertile of all soils, made up of roughly equal amounts of sand silt, and clay.

Front 13

Macronutrients

Back 13

A chemical substance that an organism must obtain in relatively large amounts.

Front 14

Micronutrient

Back 14

An element that an organism needs in very small amounst and that functions as a component or cofactor of enzymes.

Front 15

Mineral Nutrients

Back 15

An essential chemical element absorbed from soil in the form of inorganic ions.

Front 16

Mycorrhizae

Back 16

Mutualistic associations of plant roots and fungi.

Front 17

Nitrogen Fixation

Back 17

The assimilation of atmospheric nitrogen by certain prokaryotes into nitrogenous compounds that can be directly used by plants.

Front 18

Nitrogenase

Back 18

An enzyme complex, unique to certain prokaryotes, that reduces nitrogen to NH3.

Front 19

Nitrogen-Fixing Bacteria

Back 19

Microorganisms that restock nitrogenous minerals in the soils by converting nitrogen to ammonia.

Front 20

Nodules

Back 20

A swelling on the root of a legume. Are composed of plant cells that contain nitrogen-fixing bacteria of the genus Rhizobium.

Front 21

Osmosis

Back 21

The diffusion of water across a selectively permeable membrane.

Front 22

Plasmolyze

Back 22

To shrink and pull away from a cell wall, or when a plant cell protoplast pulls away from the cell wall as a result of water lose.

Front 23

Root Pressure

Back 23

The upward push of xylem sap in the vascular tissue of roots.

Front 24

Selective Channels

Back 24

Channels that only allow certain molecules to pass through.

Front 25

Sugar Sink

Back 25

A plant organ that is a net consumer or storer of sugar. Growing roots, shoot tips, stems, and fruits are these that are supplied by the phloem.

Front 26

Sugar Source

Back 26

A plant organ in which sugar is being produced by either photosynthesis of the breakdown of starch.

Front 27

Symplast

Back 27

In plants, the continuum of cytoplasm connected by plasmodesmata between cells.

Front 28

Tonoplast

Back 28

A membrane that encloses the central vacuole in a plant cell, separating the cytosol from the vacuole contents, called cell sap.

Front 29

Topsoil

Back 29

A mixture of particles derived from rock, living organisms, and humus.

Front 30

Transfer Cells

Back 30

A companion cell with numerous ingrowths of its wall, increasing the cell's suface area and enhancing the transfer of solutes between apoplast and symplast.

Front 31

Translocation

Back 31

The transport of organic nutrients in the phloem of vacular plants.

Front 32

Transport Proteins

Back 32

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.

Front 33

Turgid

Back 33

When a cell wall becomes very firm when it has a greater solute concentration than its surroundings, resulying in entry of water.

Front 34

Turgor Pressure

Back 34

The force directed against a cell wall after the influx of water and the swelling of a walled cell due to osmosis.

Front 35

Water Potential

Back 35

The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.