Glossary

Abscission zone - an area of plants where leaves, flowers, or fruits detach

Active transport -movement of solutes across a membrane against their concentration gradient; requires energy from cellular metabolism

Adaxial meristem -tissue that thickens the leaf

Adventitious root -root that develops from a leaf or stem(not from another root)

Aerenchyma -tissue containing large amounts of intercellular spaces

Axil -the upper angle between twig or leaf and the stem from which it grows

Boundary layer - the thin, moist layer of air adjacent to a transpiring leaf

Casparian strip -the suberised layer covering the radial and transverse walls of endodermal cells

Cell membrane - the semi-permeable membrane that surrounds the cytoplasm and is next to the cell wall (also called the plasmalemma or plasma membrane)

Cellulose - most abundant polymer on Earth, a polysaccharide of glucose units that constitutes the main part of the cell wall

Cell wall - rigid wall that surrounds, protects and gives shape to plant cells

Collenchyma -type of cell that is elongated and has unevenly thickened primary cell wall; support growing regions of shoot

Cultivar - a variety that is selected for cultivation through hybridization and not found in nature

Cutin - the main waxy substance in the cuticle; consists of hydroxylated fatty acids

Cyanobacteria - a photosynthetic group of bacteria

Cytoplasm - all the material inside the cell membrane, but outside the nucleus

Dioecious - having pollen and ovule producing organs on different individuals of the same species

Electron transfer chain - a sequence of electron carriers that use the energy from electron flow to transport protons against a concentration gradient across the inner mitochondrial membrane

Enzyme - a biological catalyst, usually a protein, that can speed up chemical reactions by lowering its activation energy

Epidermal tissue - the outermost layer of cells that cover a plant

F1 generation - the first generation of offspring

Fatty acid - a long, mostly hydrocarbon chain that has an organic acid group at one end

Genetic drift - random changes in gene frequencies within the gene pool of a population

Genotype - an organism's genes, either individually or collectively

Ground tissue - tissue that occurs throughout the plant and whose functions include storage, metabolism, and support; consists of Parenchyma, Collenchyma, and Sclerenchyma

Herbaceous - non-woody

Heterozygous - a condition in which a gene has two different alleles in a diploid individual

Hybrid vigour (Heterosis) - a condition where cross-bred organisms are more fit than inbred organisms because they have more heterozygous loci

Hybrid - the offspring of different parents with different traits

Leaf primordium - a lateral outgrowth from the apical meristem that will eventually form a leaf

Lenticel - spongy areas in the cork surfaces of stems and roots of vascular plants; allows gas exchange across the periderm

Lignin - a complex phenylpropanoid polymer that makes cell walls stronger, more water proof

Lipid - a polymer that forms water-repellent cell membranes; serves as long-term stores of C and energy

Meristematic tissue - regions of specialised tissue whose cells undergo cell division

Osmosis - the diffusion of water or other solvent through a differentially permeable membrane

Oxidation - the loss of electrons from an atom or molecule that is involved in a redox (REDuction-OXidation) reaction; oxidation removes energy from one substance, which is coupled to addition of energy to another

Parenchyma tissue - tissue type characterised by relatively simple, living cells having only primary walls

Passive transport - movement of a substance through a biological membrane that does not require energy from cell metabolism; moves down a concentration gradient

Phenotype - an organism's observable features, either individually or collectively; the phenotype results from the interaction of the genotype of an organism with its environment

Phospholipid - a lipid that has two fatty acids and a phosphate group bound to a molecule of glycerol; phospholipids are important components of membranes

Plasmodesma (plasmodesmata) - a tiny, membrane-lined channel between adjacent cells

Polymer - a molecule consisting of many identical or similar monomers linked by a covalent bond

Primary growth - growth derived from the activity of the apical meristem

Protoplast - the entire plant cell, from the cell membrane inward

Ray cell - transports water and dissolved minerals radially in the stem

Reduction - the gain of electrons by an atom or molecule that is involved in an redox (REDuction-OXidation) reaction; reduction involves the addition of energy to one substance, coupled to simultaneous removal; of energy from another substance by oxidation.

Scarification - the cutting, abrading, or otherwise soften the seed coat to induce germination

Sclerenchyma - a type of cell that is rigid and produces thick, non-stretchable secondary walls; these cells support and strengthen non growing, non extending regions of plants, such as mature stems.

Secondary growth - growth derived from lateral meristems (e.g. Vascular cambium, cork cambium)

Seed bank - the ungerminated but still viable seeds that occur in natural storage in the soil

Solute - a substance dissolved in a solution

Stratification - the exposure of seeds to extended cold periods before they will germinate at warm temperatures

Transpiration - loss of water from the stems and leaves; occurs mostly through the stomata

Transport protein - a type of membrane protein that enables the transport of specific solutes across the membrane

Turgor pressure - pressure on inside of cell wall created by water moving into the cell

Vascular tissue - tissue specialised for long-distance transport of water and minerals; xylem and phloem

Water potential - the potential energy of water to move down its concentration gradient

Xanthophyll - a yellow carotenoid, zeaxanthin is the blue-light photoreceptor in shoot phototropism