A dog and a tick would have a parasitic relationship. Seeing as how, if anything, the tick is harming the dog and the dog isn't getting anything in return, but the tick is getting both a food supply and a host, their relationship would be classified as parasitic.
CAPACITY..
Limiting factors determine carrying capacity. The availability of abiotic factors (such as water, oxygen, and space) and biotic factors (such as food) dictates how many organisms can live in an ecosystem. Carrying capacity is also impacted by the availability of decomposers.
BIODIVERSITY...
While food and water supply, habitat space, and competition with other species are some of the limiting factors affecting the carrying capacity of a given environment, in human populations, other variables such as sanitation, diseases, and medical care are also at play.
I think it should be the lung.
Primary succession need soil, when secondary succession uses remainder soil
It cannot be skeletal or muscular system as those do not protect from bacteria and sunlight. neitger does the nervous system, so it is the integumentary system.