If a thyroid tumor secreted an excessive amount of calcitonin, we would expect __ a rise in blood calcium concentration an elevated level of osteoblast activity a reduced rate of endochondral ossification an elevated level of osteoclast activity increasingly brittle bones

## Step 1<br />Calcitonin is a hormone that is secreted by the thyroid gland. Its primary function is to regulate the concentration of calcium in the blood. <br /><br />## Step 2<br />When the concentration of calcium in the blood is too high, calcitonin is released. This hormone then acts to decrease the concentration of calcium in the blood.<br /><br />## Step 3<br />One of the ways calcitonin does this is by inhibiting the activity of osteoclasts. Osteoclasts are cells that break down bone, releasing calcium into the bloodstream.<br /><br />## Step 4<br />By inhibiting the activity of osteoclasts, calcitonin effectively reduces the amount of calcium being released into the bloodstream, thus lowering the concentration of calcium in the blood.<br /><br />## Step 5<br />Therefore, if a thyroid tumor were to secrete an excessive amount of calcitonin, we would expect to see a reduced rate of endochondral ossification. This is because the excessive calcitonin would inhibit the activity of osteoclasts, leading to a decrease in the breakdown of bone and thus a reduced rate of endochondral ossification.