8. The bulk of the reabsorption of useful materials by the kidney takes place in the ______.
(A) loop of Henle
(B) renal corpuscle
(C) collecting ducts
(D) distal convoluted tubule
(E) proximal convoluted tubule

4. Irregular dental hygiene and a high sugar diet may lead to tooth decay. Why? (A) Bacteria consume calcium. (B) Glucose forms a weak acid when dissolved in saliva. (C) High concentrations of sugar soften the tooth enamel. (D) Plaque degrades the tooth's protective mucosal layers. (E) Lactic acid fermentation is used to generate ATP under anaerobic conditions.

5. Which of the following regions of the human brain is critically important for controlling heart rate and breathing? (A) medulla oblongata (B) hippocampus (C) cerebellum (D) cerebral cortex (E) thalamus

6. Which of the following correctly indicates the hierarchy of skeletal muscle organization from "small" to "big"? (A) muscle fiber, sarcomere, myofibril, motor unit (B) myofibril, sarcomere, motor unit, muscle fiber (C) sarcomere, myofibril, muscle fiber, motor unit (D) myofibril, sarcomere, muscle fiber, motor unit (E) sarcomere, muscle fiber, myofibril, motor unit

7. The hormones epinephrine and norepinephrine constitute the "alarm" response of the body to stress. What secretes these hormones? (A) pancreas (B) pineal gland (C) thyroid gland (D) adrenal medulla (E) anterior pituitary gland

9. Increases in leptin levels will ______ appetite and ______ metabolic rate. (A) decrease, decrease (B) decrease, increase (C) increase, decrease (D) increase, increase (E) decrease, not change

10. Humans cannot survive at sea by drinking salt water. However, marine vertebrates such as sea turtles and various sea birds can survive by drinking salt water. What do they have that humans do not? (A) Salt glands. (B) They use ammonia as their primary nitrogenous waste. (C) Kidneys are extremely good at producing concentrated urine. (D) Body fluid concentrations are similar to or greater than those of seawater. (E) The ability to secrete salts and wastes into their intestinal contents like an insect. 

11. Otto Loewi performed an experiment in which he electrically stimulated the vagus nerve connected to one frog heart. Loewi also let the fluid bathing this first heart pass to a second chamber containing a second frog heart not connected to a nerve. What did Loewi observe? (A) There was no effect on the beating of either heart. (B) The first heart showed a decrease in beat rate and so did the second heart. (C) The first heart showed an increase in beat rate and so did the second heart. (D) The first heart showed a decrease in beat rate, but there was no change in the second heart. (E) The first heart showed an increase in beat rate, but there was no change in the second heart.

12. All of the following are primary functions of flowers EXCEPT: (A) meiosis (B) photosynthesis (C) egg production (D) pollen production (E) sexual reproduction

13. The series of metabolic events that occurs within tomato plants in response to wounding is ______. (A) a waterfall effect (B) the hypersensitive response (C) resistance to coevolution (D) a systemic response (E) a pathogen-specific response

14. The last common ancestor of all animals was probably a ______. (A) flagellated protest (B) unicellular yeast (C) unicellular chytrid (D) multicellular algae (E) multicellular fungus