social order (social orders plural) The social order in a place is the way that society is organized there. n-var. ...the threat to social order posed by right-wing extremists. social science (social sciences plural). 1 n-uncount Social science is the scientific study of society. 2 n-count The social sciences are the various types of social science, for example sociology and politics. usu pl. social scientist (social scientists plural) A social scientist is a person who studies or teaches social science.
They have to be let in through special doors called stomata. Stomata can be on both sides of the leaf, but are usually concentrated on the bottom of the leaf to limit water loss due to evaporation. If you collect leaves from many different plants, youâll notice that they donât all look the same.
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).