a. This is an illustration of a limiting factor.A limiting factor basically limits the growth and abundance of living organisms within the ecosystem. It creates a chain reaction to all other organisms. In the illustration, the limiting factor is the absence of rain. It lowers the population of plants or the primary producers. Fewer plants would mean lesser food for insects which also affect the other consumers in the ecosystem.
b. The biotic and abiotic factors share an ecosystem.Abiotic factors comprise the nonliving conditions that exist in the environment. They determine which species are most likely to thrive. In this situation, the abiotic factor is rain. On the other hand, biotic factors are living things that affect the existence of other species in the ecosystem. In such case, flowers, insects, frogs and birds are the biotic factors. In general, both factors interact with one another to shape the environment.