(A) What causes warm-water vents to form?
(B) Do vent faunas consume more than do deep-sea faunas of similar size?
(C) Do bacteria live in the vent water of smokers?
(D) What role does hydrogen sulfide play in chemosynthesis?
(E) What accounts for the locations of deep-sea smokers?
17. The information in the passage suggests that the majority of deep-sea faunas that live in nonvent habitats have which of the following characteristics?
(A) They do not normally feed on particles of food in the water.
(B) They are smaller than many vent faunas.
(C) They are predators.
(D) They derive nutrition from a chemosynthetic food source.
(E) They congregate around a single main food source.
18. The primary purpose of the passage is to
(A) describe a previously unknown natural phenomenon
(B) reconstruct the evolution of a natural phenomenon
(C) establish unequivocally the accuracy of a hypothesis
(D) survey explanations for a natural phenomenon and determine which is best supported by evidence
(E) entertain criticism of the author’s research and provide an effective response
19. Which of the following does the author cite as a weakness in the argument that bacterial chemosynthesis provides the foundation for the food chains at deep-sea vents?
(A) Vents are colonized by some of the same animals found in other areas of the ocean floor.
(B) Vent water does not contain sufficient quantities of hydrogen sulfide.
(C) Bacteria cannot produce large quantities of food quickly enough.
(D) Large concentrations of minerals are found in vent water.
(E) Some bacteria found in the vents are incapable of chemosynthesis.
20. Which of the following is information supplied in the passage that would support the statement that the food supplies necessary to sustain vent communities must be many times that of ordinary fallout?
I. Large vent faunas move from vent to vent in search of food.
II. Vent faunas are not able to consume food produced by photosynthesis.
III. Vents are more densely populated than are other deep-sea areas.
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
21. The author refers to “smokers” (line 38) most probably in order to
(A) show how thermal shock can provide food for some vent faunas by stunning small animals
(B) prove that the habitat of most deep-sea animals is limited to warm-water vents
(C) explain how bacteria carry out chemosynthesis
(D) demonstrate how advection compensates for the lack of food sources on the seafloor
(E) present evidence that bacterial chemosynthesis may be an inadequate source of food for some vent faunas
22. Which of the following can be inferred from the passage about the particulate matter that is carried down from the surface of the ocean?
(A) It is the basis of bacterial chemosynthesis in the vents.
(B) It may provide an important source of nutrition for vent faunas.
(C) It may cause the internal temperature of the vents to change significantly.
(D) It is transported as large aggregates of particles.
(E) It contains hydrogen sulfide.
