Biological Systems MCAT Practice Exam

In bone growth, what process involves the production of hyaline cartilage that is later replaced by bone?

1. Intramembranous ossification

2. Endochondral ossification

3. Fracture healing

4. Apoptosis

The correct answer is: Endochondral ossification

Endochondral ossification is the correct answer because it is the specific process by which hyaline cartilage is formed initially, and then subsequently replaced by bone tissue during the development and growth of long bones. This process is crucial during fetal development and continues in children as they grow. The first step involves the formation of a cartilage model in the shape of the future bone. This hyaline cartilage serves as a scaffold for bone development. As the process continues, this cartilage undergoes calcification and ultimately gets transformed into bone through the action of osteoblasts, which deposit bone matrix over the existing cartilage. This transition is vital for the elongation of long bones during growth spurts in childhood and adolescence. In contrast, intramembranous ossification, such as that occurring in the flat bones of the skull, happens directly from mesenchymal tissue without a cartilage intermediate. Fracture healing involves both intramembranous and endochondral ossification processes but is specifically focused on repairing damaged bone rather than normal growth. Apoptosis refers to programmed cell death and does not relate to the process of bone formation. Thus, endochondral ossification is the correct term to describe the production of hyaline cartilage that is replaced by bone.