17. In the human retina,

(A) cone cells can detect color, but rod cells cannot

(B) cone cells are more sensitive than rod cells to light

(C) cone cells, but not rod cells, have a visual pigment

(D) rod cells detect short wavelength UV light

(E) rod cells require higher illumination for stimulation than do cone cells

13. Most gastric ulcers are caused by (A) overuse of aspirin and/or ibuprofen. (B) excessive mental stress. (C) bacteria. (D) overconsumption of alcohol.

14. Which gland requires iodine to produce its hormones? (A) adrenal medulla. (B) pineal. (C) pituitary. (D) thyroid.

15. The activity of acetylcholine in a synapse is terminated by its _. (A) active transport across the presynaptic membrane (B) diffusion across the presynaptic membrane (C) active transport across the postsynaptic membrane (D) diffusion across the postsynaptic membrane (E) degradation on the postsynaptic membrane

16. Which neurotransmitter excites muscle cells? (A) Acetylcholine (B) epinephrine (C) endorphin (D) nitric oxide (E) gamma-aminobutyric acid (GABA)

18. Which of the following cells are involved in cell-mediated immunity and also respond to class I MHC molecule-antigen complexes? (A) cytotoxic T cells (B) plasma cells (C) helper T cells (D) macrophages (E) B cells

19. Damage to the frontal lobe, such as experienced by Phineas Gage, leads to _. (A) the loss of a sense of balance. (B) the loss of all short-term memory (C) altered emotional responses (D) greatly increased long-term memory

20. Which of the following is the best definition of autoimmune disease? (A) a condition in which B cells and T cells respond independently to antigens and do not interact correctly (B) a condition in which the adaptive immune system fails to recognize the second infection by the same antigen (C) a condition in which self molecules are treated as nonself (D) a condition in which the immune system creates random antibodies without being triggered by an antigen

21. Which of the following correctly identify which organs develop from different embryonic tissue layers in a frog? | Endoderm | Mesoderm | Ectoderm | | :---------- | :--------- | :---------- | | (A) Brain | Heart | Epidermis | | (B) Liver | Heart | Brain | | (C) Notochord | Liver | Eye lens | | (D) Liver | Nerves | Muscles |

22. Which of the following is an endocrine gland that raises blood calcium levels? (A) parathyroid (B) thyroid gland (C) pituitary gland (D) testes

23. An excess of T3 and T4 in the blood is hyperthyroidism, which in its most common form is called (A) goiter. (B) sterility. (C) Graves' disease. (D) botulism.