Which of the following statements about hemoglobin are true?
1) Oxygen molecules bind to the heme portion of hemoglobin
2) Hemoglobin can carry up to 2 oxygen molecules
3) When carbon dioxide binds to hemoglobin, a molecule called carbaminohemoglobin is formed.
O Both 1 and 2
O Both 2 and 3
O 1 only
Both 1 and 3