bio 1020 unit 5 vocab

Absorption: in terms of photosynthesis, this describes light energy that is "captured" or retained by pigment molecules

absorption spectrum: a graph showing the amount of light absorbed by individual pigments at various wavelengths

accessory pigments: molecules that absorb light energy and pass it to the principal pigment, chlorophyll a

action spectrum: a graph showing photosynthetic activity by a plant at various wavelengths

Carotene: an accessory orange-colored pigment

chlorophyll a: a green pigment; this is the principal pigment in all photosynthetic organisms

chlorophyll b: an accessory green pigment

Chromatogram: a "developed" chromatography strip in which pigments have been separated from one another

Chromatography: a method of separating pigment molecules in a solution based on the different solubilities of pigments in the chromatography solvent

Cuticle: a waxy non-cellular layer on the outer surface of the plant leaf that prevents water loss by evaporation

Epidermis: the outermost layer of cells in plants

FT50: the floating time for 50% of the discs in a floating disc assay

guard cells: specialized epidermal cells that occur in pairs on leaf surfaces and regulate the opening into the interior of the leaf

palisade layer: chloroplast-bearing cells in the interior of the leaf that are oriented with their long axes perpendicular to the leaf surface

Pigment: a molecule that absorbs light energy

Reflection: in terms of photosynthesis, this describes light energy that is not absorbed by pigment molecules, but is turned back

Rf: the ratio of fronts for pigments and the solvent on a chromatogram

spongy layer: loosely-packed chloroplast-bearing cells in the interior of leaves, characterized by lots of air space

Stomata: openings on leaf surfaces through which air passes to the leaf interior (singular is stoma, plural is stomata)

Transmission: in terms of photosynthesis, this refers to light energy that is not absorbed by an object, but passes through it; it is the same light that is also reflected by the object

Wavelength: a measure of the quality of light (technically, the distance between the peaks of two waves; informally, the color of light)