Biology, Genetics & Bone Healing MCQs

Which of the following intracellular signaling proteins is primarily activated following the binding of Bone Morphogenetic Protein-2 (BMP-2) to its cell surface receptor?

A patient with recurrent fractures and widespread diffuse osteosclerosis on radiographs is diagnosed with autosomal recessive osteopetrosis. The pathogenesis of this condition is most commonly due to a deficiency in which of the following enzymes?

During the healing of a diaphyseal fracture treated with rigid internal fixation providing absolute stability, bone healing occurs primarily via which of the following mechanisms?

A 70-year-old female with severe osteoporosis and a recent vertebral compression fracture is prescribed a bone-modifying agent.

She is initiated on teriparatide. What is the primary mechanism of action of this medication when administered as a daily subcutaneous injection?

What is the primary cellular abnormality that drives the initial phase of Paget disease of bone (osteitis deformans)?

A 10-year-old boy suffers a subtrochanteric femur fracture. Radiographs show a diffusely dense, 'bone-in-bone' appearance and loss of the medullary canal. The underlying cause of this condition is most commonly due to a defect in:

A 12-year-old boy with multiple palpable bony bumps around his knees and shoulders is diagnosed with Multiple Hereditary Exostoses (MHE). The genetic mutation associated with this condition typically affects the EXT1 or EXT2 genes. What is the normal physiological function of the proteins encoded by these genes?

A 4-year-old boy presents with severe bowing of the lower extremities. Laboratory tests reveal normal serum calcium, significantly decreased serum phosphate, normal PTH, and normal 25-hydroxyvitamin D. He is diagnosed with X-linked hypophosphatemic rickets. The defective gene (PHEX) in this condition leads to an overproduction or decreased degradation of which circulating factor?

During secondary bone healing of a closed tibial shaft fracture treated with a cast, what is the primary mode of ossification occurring within the relatively hypoxic central region of the fracture callus?

In the pathogenesis of Rheumatoid Arthritis, the chronically inflamed synovium forms a pannus that aggressively destroys cartilage and bone. Which cytokine is the primary mediator responsible for stimulating osteoclastogenesis and subsequent periarticular bone erosions?

Osteopetrosis is a rare genetic disorder characterized by dense, heavy, and brittle bones. The malignant infantile form is most commonly caused by a genetic defect that impairs the osteoclast's ability to acidify the resorption pit. A mutation affecting which of the following enzymes is responsible?

Denosumab is utilized in the management of severe osteoporosis and certain bone metastases. What is its exact mechanism of action at the cellular level?

Demineralized bone matrix (DBM) is widely used to supplement bone grafting in nonunions and fusions. Which of the following accurately describes its innate biological properties?

Which type of bone healing is expected when a diaphyseal fracture is treated with a rigid plate and screws causing absolute stability, and what cell type is primarily responsible for the initial bridging?

A 65-year-old female is diagnosed with osteoporosis and prescribed Alendronate. What is the primary cellular mechanism of action of this medication?

Bone morphogenetic proteins (BMPs) play a crucial role in bone healing by inducing the differentiation of mesenchymal stem cells into osteoblasts. Binding of BMP to its cell surface receptor leads to direct phosphorylation and activation of which intracellular signaling proteins?

Which of the following molecules binds directly to RANK on the surface of osteoclast precursors to stimulate their differentiation into mature osteoclasts?