BIO 251

Which of the following is/are true of the molecule named hemoglobin?  A. It numbers approximately 1 to 2 million in each erythrocyte.  B. It can bind to only one molecule of oxygen.  C. It is a very simple protein structure.  D. It contains four folded chains of a protein named globin.

What secretory cell type is found in the adrenal medulla?  A. follicle cells  B. chromaffin cells  C. oxyphil cells  D. neuroglial cells  E. beta cells Feedback:Good work; your answer is correct! Question 2 of 25 4.0/ 4.0 Points The parathyroid glands are small structures located on the posterior thyroid gland that produce parathyroid hormone (PTH), which regulates blood ________ levels.