Exam 21: Energy Flow and Food Webs

Compared to carnivores, herbivores tend to have _______ assimilation energies because _______.

In which sequence are the organisms' expected production efficiencies correctly ranked from highest to lowest?

Bald eagles, which feed mainly on fish, tend to have much higher concentrations of toxins than the fish have. The same situation occurs for many top predators. This phenomenon is referred to as

In a simplified food web, mice eat grain grown by a farmer before it can be harvested. The mice are consumed by several species of snakes, which are consumed by hawks. The mice represent which trophic level?

If a cow with an assimilation efficiency of 10% and a production efficiency of 20% eats 50 kg of grass, the expected increase in biomass of the cow would be

Which of the following was a finding of Flecker and Townsend's studies of an aquatic trophic cascade?

Refer to the figure. Figure 4 You are studying how a contaminant moves through a food web and have collected the data shown in Figure 4. Suppose that for Figure 4B, you only sample individuals from a single trophic level. Based on this scenario, answer the following questions: a) To which trophic level do individuals in Figure 4B belong? Explain your answer. b) Based on both Figure 4A and 4B, do you see any evidence that your sampling of individuals graphed in 4B was biased? Why or why not? c) If a species in this food web must consume a diet of 30% meat, which individuals would it need to hunt to have the lowest possible risk of exposure to the contaminants?

You are comparing the transfer of energy from primary producers to primary consumers in two different ecosystems, area 1 and area 2. In area 1, primary consumers have a 60% consumption efficiency and a 20% assimilation efficiency. In area 2, primary consumers have a 20% consumption efficiency and a 70% assimilation efficiency. For each area, explain these differences in consumption and assimilation efficiencies by answering the following questions: a) In which area are primary producers more easily consumed? Explain. b) In which area are primary producers more easily digested? Explain. c) Based on consumption patterns, which primary producers likely invested more heavily in defenses, those in area 1 or 2? Explain. d) Based on your answers to a-c, predict the resource levels for each area. Also predict which area would most likely be found within a desert ecosystem, and which would most likely be found within a temperate deciduous forest ecosystem. Explain your answers.

Which statement about the limitations of food webs is false?

Refer to the table. Table 1 You are studying how energy flows in a food web. The data in Table 1 shows the dietary composition of species in your study area (for species A-H). To read the data table, start at a species in column 1, read to the right across that row to find the number of individuals consumed, then read straight up to determine the species that it consumed. For example, species C consumed 15 individuals of species A. In preparation for constructing a food web for your study area, you need to determine the dietary preferences of your species. For each species, quantify the percent of the total diet comprised by each of the species consumed. Enter your data into a table (this will be referred to as Table 3), and for each species, place an asterisk next to its most preferred prey. Why is this type of analysis helpful to conduct in preparation for constructing a food web diagram? Give two reasons and explain your answers.

In Dyer and Letourneau's demonstration of a terrestrial top-down trophic cascade, the top predators were

In his studies of ecosystems in the rocky intertidal zone, Paine emphasized that

Tuna often eat sardines and other small fish. Suppose the consumption efficiency of tuna is 40%, the assimilation efficiency is 30%, and the production efficiency is 20%. If tuna eat 1,500 kg of sardines and other small fish, how much will be used to produce tuna biomass?

Refer to the table and figure. Table 3 Figure 1 Re-draw the food web from Figure 1 including the most important interactions only, which you identified in Table 3 (this will be referred to as Figure 2). What is one advantage of focusing on the most important interactions? What kind of experimental manipulation would you do to confirm that you have identified the important interactions correctly?

Allochthonous inputs are often more important in aquatic ecosystems than terrestrial ecosystems. Which location would an ecologist hypothesize that allochthonous inputs would be the most important?

In bottom-up control, energy flow through the ecosystem is determined primarily by the

Which statement about the portfolio effect is true?

Rank the amount of algal standing crop at the end of the three treatments in the Flecker and Townsend experiments from highest to lowest.

In the early 1970s, May criticized Elton and Odum's argument that simpler food webs should be more easily perturbed than more complex ones. May's criticisms were based mainly on his

A beetle that feeds exclusively on dead wood is an example of a(n) _______ and is part of the _______ trophic level.