3. In the countercurrent exchange system of fish gills,
(A)blood and water are separated by a thick polysaccharide barrier.
(B)blood and water flow in the same direction.
(C) blood flow in the gills reverses direction with every heartbeat.
(D)water flow over the gills reverses direction with every inhalation.
(E)blood and water flow in opposite directions.

19. Which description BEST represents the gradual model of speciation (i.e., the formation of new species)? (A) Speciation occurs regularly as a result of the accumulation of many small changes. (B) An isolated population differentiates quickly from its parent stock as it adapts to its local environment. (C) Speciation occurs under unusual circumstances and therefore transitional fossils are hard to find. (D) Species undergo little change over long periods interrupted only by short periods of rapid change.

20. Given the concept of invasive species in ecology and conservation biology, which of the following animals you may see in a forest in Taiwan is an invasive species, one that causes severe ecological damage and needs to be completely removed? (A) A stray dog(遊蕩犬) (B) A Formosan Reeve's muntjac (山羌) (C) A Formosan macaque (台灣獼猴) (D) A Leopard cat (石虎)

1. Which of the following animals displays radial symmetry? (A)a sea anemone (B)a fish (C) a worm (D)an alligator (E)a lobster

2.Geckos are able to walk up walls and across ceilings because of (A)the numerous setae on their toes establish molecular bonds with the surfaces of walls and ceilings. (B)the sticky adhesive secretions on their feet. (C) the little suction cups on their toes. (D)the sticky saliva licked onto the regions where the gecko is about to walk. (E)their sharp toenails that grasp surfaces.

4.The largest blood vessel in the human body is the (A)pulmonary artery. (B)aorta. (C) vena cava. (D)arteria maxima. (E)superior vena cava.

5. During which phase of the heartbeat does the heart fill with blood? (A)atrial phase (B)interphase (C) resting phase (D)diastole (E)systole

6. Which of the following cell types is responsible for humoral immunity? (A)macrophages (B)B cells (C) C lymphocytes (D)natural killer cells (E)neutrophils

7.Monoclonal antibodies are produced (A)when a female is pregnant. (B)by cancerous tumors. (C) when an animal is infected by a single type of pathogen. (D)by cells that are formed when a B cell is fused to a T cell. (E)by cells are created through the fusion of an activated B cell with a tumor cell.

8.Which of the following kinds of animals excrete their nitrogenous waste entirely as ammonia? (A)fish (B)birds (C) insects (D)garden snails (E)tropical insects

9. When the concentration of glucose in the blood rises following digestion of a meal, what is the hormonal response? (A)Both glucagon and insulin are released. (B)The total amount of insulin in the blood decreases. (C) Glucagon is released but not insulin. (D)Insulin is released but not glucagon. (E)Neither glucagon nor insulin is released.