Question

After the Aswan High Dam was built on the Nile River, the rate of parasitic blood-flukeinfection doubled in the human population near the dam. As a result of building the dam, the flow of the Nile changed. This changed the habitat, which resulted in an increase in its population of a certain aquatic snail. The snails, which were infected, released larvae of the fluke. These larvae then infected humans. This situation best illustrates that:

a.the influence of humans on a natural system is always negative in the long termb.the influence of humans on a natural system can have unpredictable negative impactsc.human alteration of an ecosystem does not need to be studied to avoid ecological disasterd.human alteration of an ecosystem will cause pollution and loss of finite resources

Answer 1

The doubling of parasitic blood-fluke infections after the Aswan High Dam's construction illustrates that human impacts on natural systems can have unpredictable negative effects, altering habitats and increasing disease risks.

Step-by-step explanation:

After the Aswan High Dam was built on the Nile River, the rate of parasitic blood-fluke infection doubled in the human population near the dam. This increase in infection rates illustrates that the influence of humans on a natural system can have unpredictable negative impacts. Construction of the dam altered the river's flow, creating a new habitat that favored the proliferation of a particular aquatic snail species that harbored the parasitic fluke larvae. These larvae infected humans, showing that human alteration of an ecosystem has complex repercussions, affecting both the ecological balance and human health.

Dams impact the natural water habitat by altering temperatures, chemistry, flow characteristics, and silt loads. This can lead to extensive changes in the ecology, affecting a wide variety of species. Damming rivers, a common practice for human needs, can reduce or eliminate populations that rely on seasonal flow changes, such as certain fish and amphibian species. The case of the Aswan High Dam serves as an example of the unintended ecosystem and health implications of significant infrastructural projects.

Answer 2

b.the influence of humans on a natural system can have unpredictable negative impacts

Step-by-step explanation:

The situation described best illustrated the fact that the disturbance of natural ecosystem by humans can have unpredictable negative impacts.

Option c is incorrect because human alteration of the ecosystem needs to be continuously studied to avoid ecological disasters.

Option d is incorrect because alteration of the ecosystem does not always end up in the pollution of the ecosystem and loss of finite resources.

While human alteration of the natural ecosystem often have long term negative impacts, many of these impacts can not be predicted until they happen. This makes option b to be more complete than option a.

The correct option is b.