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.

50 Which of the following statements can be inferred from this passage? (A)Cats are more intelligent than dogs. (B)Large size meat eating animals tend to sleep a lot. (C)Plant eating animals tend to have a larger brain size. (D)Dogs and cats are suggested to live on a vegetarian diet.

1. Very rapid speciation occurred when cichlid fishes were isolated in Lake Victoria. Widespread extinction was dramatically seen when ______. (A) hybridization stopped (B) fishing was prohibited (C) predatory fishes were added (D) artificial selection stopped (E) insect larvae stocks were depleted

2. Which one of the following statements about endosymbiosis and the origin of the eukaryotic cell are FALSE? (A) Mitochondria are the descendents of purple nonsulfur bacteria. (B) The chloroplasts of red and green alga are the descendents of cyanobacteria. (C) Not all compartments of the eukaryotic cell are derived from the endomembrane system. (D) The brown algae acquired their chloroplasts by engulfing a prokaryotic cell with chloroplasts. (E) None of these choices are correct.

3. Which of the following groups is most threatened by global extinctions? (A) amphibians (B) birds (C) plants (D) mammals (E) fish

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

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

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.