Japanese Stiltgrass Is an Invasive Plant That Was Accidentally Introduced

question 38

Multiple Choice

Japanese stiltgrass is an invasive plant that was accidentally introduced to the United States in the early 1900s. It can be found on roadsides and in forests, and it has many impacts on native plants and animals. Biologists Jayna DeVore and John Maerz studied the effect of Japanese stiltgrass on American toads in their natural habitat. They enclosed American toads in cages with lycosid spiders and/or Japanese stiltgrass. The four treatments were (A) lycosid spiders and Japanese stiltgrass, (B) lycosid spiders without Japanese stiltgrass, (C) lycosid spiders and Japanese stiltgrass, and (D) no lycosid spiders and no Japanese stiltgrass. They compared the survival of American toads across the treatments (left graph) . They also measured the density of lycosid spiders in different areas where Japanese stiltgrass was absent vs. present (right graph) .
Source: DeVore, J. L., & Maerz, J. C. (2014) . Grass invasion increases top‐down pressure on an amphibian via structurally mediated effects on an intraguild predator. Ecology, 95(7) , 1724-1730.
-American toads consume insects. An American toad that is consuming herbivorous insects is considered a

• A) secondary consumer.
• B) primary consumer.
• C) primary producer.
• D) tertiary consumer.

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Definitions:

Initial Outlay

The initial investment amount required to start a project or purchase an asset.

Future Cash Inflows

Expected incoming funds or earnings generated from investments, operations, or financial activities in the future.

Discount Rate

The discount rate that's used to estimate the present value of future cash flows within discounted cash flow analysis.

Net Present Value

Net Present Value (NPV) is a financial metric used to evaluate the profitability of an investment, calculated by summing the present values of incoming and outgoing cash flows over a period of time.