In Ecology, certain factors that affect the size of a population can either be dependent on size or not. Density-dependent factors are those factors that affect population of organisms in dependence of how dense the population is. Examples of these density dependent factors are diseases, predation etc.
For example, a certain disease will spread faster among a population of organisms whose size is dense but slower in a scarcely densed population. Hence, disease as a factor is dependent on population size. Note that; Drought, Climate, and Natural Disasters will wipe out a population irrespective of its size.
The bone indicated by the arrow is femur bone. It should be classified as the long bone. Other example for long bones would be tibia and fibula. Short bone would be carpal or tarsal bones. Flat bone could be found in skull. Irregular bone would be the vertebrae or pelvic.