Alpha-glucans are present in the fungal cell wall. They provide nourishment for sporulation, and help to prolong the survival of the spores by blocking their oxygen intake which slows their metabolism. Alpha-glucans, unlike beta-glucans, are ubiquitous in the plant kingdom, and are not specific to yeast, fungi, grain and seaweed. These molecules that make up the cell wall of fungi and yeast provide a specific factor that allows them to be recognized not only by other yeast and fungi, but also by other plants, humans and animals. This recognition of fungi and yeast is an innate immune response that exists in both plants and animals to protect them from the old and ongoing threat of fungal invasion, infection, and even death. It is the branched chain beta-glucans, mannans and glycoproteins that provide the molecular recognition factors that trigger the protective immune responses (see: Wikipedia).