Which group is at risk for bone abnormalities when calcium is deficient?

• A. Old, sedentary animals
• B. Adult herbivores
• C. Young, rapidly growing animals
• D. Insects

Answer: (C)

Calcium is required for bone mineralization during growth. In young, rapidly growing animals the skeleton is actively ossifying and the demand for calcium is high. When calcium is deficient, minerals cannot be laid down properly at the growth plates, leading to rickets-like deformities such as bowed limbs and other skeletal abnormalities. This makes juveniles the most vulnerable group to calcium deficiency.

In contrast, older animals have closed growth plates, so calcium deficiency tends to weaken bone or cause osteomalacia rather than the pronounced deformities seen in growing youngsters. Adult herbivores can experience bone thinning if intake is chronically low, but the dramatic growth-related bone problems are most likely in rapidly growing young. Insects don’t form vertebrate bones, so calcium deficiency doesn’t produce the same bone deformities seen in vertebrates.