Final answer:
A round cross section of a long bone suggests it will have equal strength in all directions, due to the uniform distribution of stress, making them efficient at bearing weight and resisting compression and tension.
Step-by-step explanation:
The question regarding a round cross section of a long bone suggests that the bone will have equal strength in all directions. This is due to the fact that bones, especially long bones like the femur, humerus, or tibia, are designed to bear weight and resist various stresses including compression and tension uniformly. Their round shape facilitates this by distributing forces evenly across the bone, making them less likely to fracture under uniform stress.
Furthermore, bones are much more prone to break from excessive twisting or bending rather than from straightforward tension or compression. Hence, a round cross-sectional shape contributes to their ability to support loads similar to that of concrete and steel, as they possess a shear modulus that is as large as steel's, allowing them to be long and thin yet strong.