20XX托福阅读历年真题精选5-托福考试.docx

文档介绍：20XX托福阅读历年真题精选5-
Questions 40-50
Pheromones are substances that serve as chemical signals between mem

20XX托福阅读历年真题精选5-
Questions 40-50
Pheromones are substances that serve as chemical signals between members of the
same species. They are secreted to the outside of the body and cause other individuals
of the species to have specific reactions. Pheromones, which are sometimes called
Line "social hormones," affect a group of individuals somewhat like hormones do an individual
(5) animal. Pheromones are the predominant medium of communication among insects
(but rarely the sole method). Some species have simple pheromone systems and produce
only a few pheromones, but others produce many with various functions. Pheromone
systems are the most complex in some of the so-called social insects, insects that live
in organized groups.


Questions 40-50
Pheromones are substances that serve as chemical signals between members of the
same species. They are secreted to the outside of the body and cause other individuals
of the species to have