Exam 37: Communities and Ecosystems

Given that CO₂ is produced by cellular respiration, why does the amount of CO₂ in the atmosphere remain relatively constant? (When answering this question, exclude the impact of human activities on atmospheric CO₂.)

In an ecosystem, you would expect to find interspecific competition between

Carbon mainly cycles between the biotic and abiotic worlds through the processes of

When two different populations in a community benefit from their relationship with each other, the result is called

Which arrow shows CO₂ released as a product of cellular respiration?

One simple thing that you can do to help safeguard the environment is to eat a diet consisting only of

The freshwater leech is an organism that feeds off of the blood of other organisms such as frogs and turtles. Which interaction describes the relationship between freshwater leeches and frogs or turtles?

One reason it is important to understand community ecology is to

Camouflage typically evolves as a result of

Which statement about the phosphorus cycle is false?

Which process does not occur in ecosystems?

Consider the following marine community: Sea otters prey on sea urchins and therefore help maintain a healthy sea urchin population. Sea urchins prey on kelp. By helping to maintain viable sea urchin populations, the sea otters are also allowing enough kelp to grow and act as a habitat for other organisms. -In this marine community, the sea otter is a

Dinoflagellates are important to coral and coral-dwelling animals because they

The sum total of a population's use of the biotic and abiotic resources of its habitat constitutes its

A biology student takes fish, algae, pond plants, invertebrates, and bottom sediment from a local pond and establishes them in an aquarium. When the system is stable, the student seals it into a large, airtight glass box and leaves the box in a sunny location. After 3 months, the organisms in the aquarium appear alive and healthy. Which statement about the experiment is true?

A keystone species that is a predator will

What are the consequences if decomposers are removed from the carbon cycle?

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. -What hypothesis is best supported by these results?

In your backyard you overturn a large rock. In the damp soil underneath the rock, you see various insects scurrying for cover: one black spider, five black ants, two brown beetles, and three gray pillbugs. In this community of organisms, species richness is represented by

In a food chain consisting of phytoplankton → zooplankton → fish → humans, the humans are