7. The passage mentions which of the following as a consequence of isolating a 10-hectare tract of rain forest?
Answer: E
A species of birds could no longer find enough food.
Isolating a 10-hectare tract of rain forest resulted in the disappearance of ant-following birds, which depend on army ants to flush out other insects for food. Without the presence of these ants in the smaller tract, the birds could not find sufficient food to survive.
A) The soil became deprived of valuable nutrients.
This option is incorrect as the passage does not discuss the nutrient content of the soil as a consequence of isolating the 10-hectare tract. Instead, it focuses on the interdependence of species and the direct impact on bird populations due to food availability.
B) More plant than animal species were adversely affected.
This statement is not supported by the passage, which emphasizes the specific consequences for animal species, particularly the ant-following birds. The focus is on the interconnectedness of species rather than a comparison of effects on plants versus animals.
C) A species of birds was forced to rely more heavily on ants as a source of food.
This option misrepresents the situation. The passage indicates that the birds were unable to find sufficient food due to the absence of army ants, rather than relying more heavily on them. The lack of ants led to the birds' disappearance, not an increased reliance.
D) Army ants were forced to change their sources of food.
This choice is incorrect because the passage does not mention any change in the diet of army ants. Instead, it highlights that the survival of these ants was compromised due to the smaller size of the tract, which affected their ability to thrive and, consequently, the birds that depended on them.
E) A species of birds could no longer find enough food.
The passage clearly illustrates that ant-following birds vanished from the 10-hectare plots because they could not find enough food without the army ants. This statement accurately reflects the consequences of isolating the tract.
Conclusion
The correct answer, E, reflects the critical relationship between the birds and army ants, demonstrating how the isolation of a 10-hectare tract led to a lack of food resources for the birds. All other options fail to capture the specific ecological consequences described in the extract and misinterpret the dynamics between the species involved.