Unlike herbivores and omnivores, predators have traditionally been thought not to balance nutrient intake because of the assumption that animal tissue as a food source varies little and is nutritionally balanced. But chemical analysis of invertebrate prey reveals remarkable variation in nutrient composition among species; even within species, nutrient composition may vary considerably. Greenstone suggested that predators may select food items according to their nutrient contents. Jensen et al (2011) have shown experimentally that even sit-and-wait invertebrate predators with limited mobility can work to address nutrient deficiencies. The wolf spider, for instance, has been shown to regulate nutrient intake by extracting more dry mass from a prey item if it contains a higher proportion of a nutrient that was deficient in the previous prey.
key:DC
1. The passage supplies information for answering which of the following questions?
A. Do invertebrate predators with full mobility address nutrient needs in the same fashion as sit-and-wait invertebrate predators with limited mobility?
B. Why would there be a considerable variation in nutrient composition within prey of a given species?
C. Is all of the nutrient content of invertebrate prey contained in the dry mass?
D. What would a wolf spider do if a fly it was eating contained a higher proportion of a certain nutrient than was present in the spider’s recent prey?
E. How is a wolf spider able to determine that some prey it is eating contains a higher proportion of a nutrient that was deficient in the previous prey?
2. Which of the following best describes the organization of the passage as a whole?
A. A phenomenon is described, and an interpretation is offered.
B. A claim is made, and the corroborating evidence is evaluated.
C. A hypothesis is presented and undermined by recent findings.
D. A contrast is noted and shown to be specious based on recent findings.
E. A series of assumptions is presented and shown to be based on sound reasoning.