Final answer:
It is false that osteoblasts break down old bone; instead, osteoblasts are responsible for bone formation by synthesizing and secreting the bone matrix. The correct cells that break down bone are called osteoclasts, which dissolve bone tissue by releasing lysosomal enzymes and acids.
Step-by-step explanation:
The statement that osteoblast cells are responsible for breaking down old bone by secreting acid is false. In fact, it is osteoclasts that perform this function. Osteoclasts are multinucleated cells that resorb bone tissue by releasing lysosomal enzymes and acids that dissolve the bony matrix, thereby releasing minerals such as calcium and phosphate back into the blood.
On the other hand, osteoblasts are involved in bone formation. They are bone cells with a single nucleus that synthesize and secrete the organic and inorganic components of the bone extracellular matrix, which includes collagen fibers. When these secretions mineralize, they form the bone matrix, thus contributing to the growth and repair of bone tissue. After secreting the bone matrix, osteoblasts can become trapped within it and differentiate into osteocytes, which maintain bone tissue.