Answer:
Gas exchange occurs at two sites in the body: in the lungs, where oxygen is picked up and carbon dioxide is released at the respiratory membrane, and at the tissues, where oxygen is released and carbon dioxide is picked up.
Explanation:
The correct answer is A, parathyroid gland.
The parathyroid hormone is secreted by the parathyroid gland which <span>inhibits osteoblasts, stimulates osteoclasts,</span> reduces the calcium output by the kidneys and promotes absorption of the calcium by the small intestines. Calcitonin, secreted by the thyroid gland, also works to a similar effect.
Nucleic acids because the DNA of a organic compound is part of the nuculis family