Three weeks after a river rafting trip, three family members experienced symptoms of coughing, fever, and chest pain. During the rafting trip, the family had consumed crayfish that they caught along the river banks. An examination of the patients' sputum revealed helminth eggs, and serum samples were positive for antibodies to Paragonimus. All of the family members recovered following treatment
with praziquantel. In the Paragonimus life cycle,
A) the crayfish are the definitive host and humans are the intermediate host.
B) humans are the definitive host and crayfish are the intermediate host.
C) both humans and crayfish are intermediate hosts.
D) both humans and crayfish are definitive hosts.
E) the source of the infection was the river water.
B
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Indicate whether the statement is true or false.
Which of the following statements would be LEAST acceptable to most zoologists?
A) The first fossils resembling lancelets appeared in the fossil record around 530 million years ago. B) Recent work in molecular systematics supports the hypothesis that lancelets are the basal clade of chordates. C) The extant lancelets are the immediate ancestors of the fishes. D) Lancelets display the same method of swimming as do fishes.
Speculate on the benefits that antibiotic-producing bacteria may gain from engaging in a mutualistic relation-ship with leaf cutter ants
a. They are selected for producing antibiotics. b. The bacteria are actively transmitted by the ants. c. The ants control the amount of food that the bacteria can obtain. d. There don't have to be benefits for the bacteria for the ant-bacteria relationship to persist.
The most commonly used unit for measuring cell size is a ____
a. decimeter (dm) b. centimeter (cm) c. millimeter (mm) d. micrometer (?m) e. nanometer (nm)