Final answer:
The larger cross-sectional area of a limb bone enables it to bear more weight. Bones remodel to become stronger and withstand increased stress according to Wolff's Law, reflecting an adaptation of the skeletal system to varying stress levels.
Step-by-step explanation:
The more weight a limb bone bears, the larger its cross-sectional area.
Bones are structured to withstand various types of stresses. In response to mechanical stress, such as weight-bearing activity, bones undergo a process known as remodeling. Remodeling allows bones to adjust their strength in accordance with the level of stress they encounter, which is essential to maintaining skeletal health and function. This biological adaptation is explained by Wolff's Law, which states that bone in a healthy person or animal will adapt to the loads under which it is placed. If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading. The remodeling is achieved by increasing the bone's cross-sectional area which enhances its ability to support greater weight.
As a reference, we can observe that weight-bearing bones such as the femur have considerable cross-sectional areas to support the weight of the body. On the other hand, bones not subjected to heavy loads, such as the bones of the wrist or ankle, have lesser cross-sectional areas. This adaptive feature of the skeletal system ensures that the bones are able to provide the necessary support and withstand the stresses that they encounter on a daily basis.