Research shows that teacher effectiveness is the single most important school-based factor in student success. Students who have highly effective teachers for three years in a row will score 50 percentile points higher on achievement tests than students who have less effective teachers three years in a row (Sanders & Rivers, 1996).
A cuticle /ËkjuËtÉªkÉl/ , or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of cuticle are non-homologous, differing in their origin, structure, function, and chemical composition.
If a plant is going to live on dry land, it must be able to prevent this dessication. Cuticle is the answer. Cuticle is a waxy covering that can be found on essentially all exposed surfaces: leaves, stems, flowers, fruits but not roots. This waxy surface inhibits the loss of water. As stems grow, corky bark tissue replaces cuticle in function. Why do roots not have a cuticle coating? Cuticle controls water loss. However, this causes another problem: gas exchange. All plants require CO2 for photosynthesis. In an aquatic environment with no cuticle, diffusion works fairly well for exchange of these gases (so long as the tissues are not too thick and dense).