Which ecosystems do not have
symbiotic relationships?
a. deserts
b. all ecosystems contain symbiotic relationships.
c tropical rainforests

The correct option is B. All ecosystems contain symbiotic relationships.

Explanation:

Symbiotic relationship can be described as a relationship between the organisms of two species. It might be harmful for both the species, beneficial for both the species or just beneficial to one of the species. All ecosystems will have some kind of symbiotic relationships. Hence, option B is correct.

Other options like Option A is false because the desert ecosystem does has symbiotic relationships. For example, the Gobi woodpecker lives on a cactus in a desert. In return it eats the insects and other parasites which harm the cactus.

 

Su sencilla fórmula es la siguiente: Entonces la densidad se expresa como número de individuos por área. ... En una población la densidad de población aumenta según los nacimientos y las inmigraciones que sucedan. La densidad disminuye si se presentan muertes o emigraciones de los individuos de dicha población.