Cоmbined Skills 1Mutuаlism is а relаtiоnship in which twо organisms live together or cooperate with each other for mutual benefit. 2For example, termites eat wood but are unable to digest its cellulose. 3The cellulose is digested by protozoa that live in the termite’s gut. 4Termites benefit from the presence of the protozoa by getting food digested, and the protozoa benefit by being protected by the termite’s body. 5In fact, under normal conditions the protozoa would be unable to live outside of the termite’s body. 6Another interesting example of a mutualistic relationship is that of ants and acacia trees in Central and South America. 7 For a long time, scientists knew that the bull thorn acacia housed large numbers of ants. 8Careful study of this relationship has revealed the reason. 9The acacia tree provided a home for ants in the form of large thorns on its stems. 10Sometimes ten or fifteen ants can fit into one thorn. 11The tree also produces special growths on its leaves called beltian bodies. 12Chemical analysis of these structures revealed that they are full of glycogen, which is also called animal starch. 13The plant has a biochemical pathway that produces food used by ants. 14The acacia derives benefits too. 15Ants, protective of their food and housing, attack any predators that attempt to eat the acacia. 16In addition, the ants destroy other plants that, if allowed to grow, would shade the acacia and cut off its light. 17Bull thorn acacias are often found alone in open clearings because the ants have mowed down all the surrounding vegetation. The relationship between sentences 1 and 2 is _____.
Chаpter 6 Relаtiоnships II 1Femаle emplоyment and small families make divоrce more likely in modern societies. 2A major result of the massive entry of women into the labor force has been to decrease the dependence of wives on their husbands for economic support. 3This change has had beneficial effects. 4For instance, a woman need no longer to cling to a brutal or drunken husband merely because she has nowhere elso to turn. 5But it also encourages some women to give up on a relationship more quickly. 6Also, husbands have greater economic freedom to divorce wives who work because working wives are seldom granted a great deal of alimony. The main pattern of organization for the above passage is _____.