Official approaches to squatter settlements and the housing of the urban poor have changed over time from policies of clearance and relocation to schemes which promote the involvement of the private sector and nongovernmental organizations in supporting poor residents to improve their own housing and neighborhoods.n this article, the main debates surrounding squatter settlements are outlined, focusing on definitional issues and their geographical distribution. The changing nature of policies toward these settlements is also covered.
Lichen. Lichen is a structure that commonly grows on trees; it is a result of a symbiotic relationship between algae and fungi. The fungus provides a structure that collects water and nutrients that the algae takes advantage of; the algae in turn uses its chlorophyll to produce food for both itself and the fungus.Species of the Trentepohlia genus are commonly found in lichens.he fungus provides a structure that collects water and nutrients that the algae takes advantage of; the algae in turn uses its chlorophyll to produce food for both itself and the fungus. Species of the Trentepohlia genus are commonly found in lichens.
Some species of green algae, particularly of genera Trebouxia of the class Trebouxiophyceae and Trentepohlia (class Ulvophyceae), can be found in symbiotic associations with fungi to form lichens.reen algae have chloroplasts that contain chlorophyll a and b, giving them a bright green color, as well as the accessory pigments beta carotene and xanthophylls, in stacked thylakoids. The cell walls of green algae usually contain cellulose, and they store carbohydrate in the form of starch.