Q5.1. Which type of organism in this tutorial can get its nitrogen from nitrogen fixation (converting N2 gas into ammonia), allowing it to grow even if easily used forms of nitrogen are not available in its water or food? a. Cyanobacteria b. Daphnia c. Bosmina d. Trout Q5.2. A company is growing algae in big tanks to make fish food. However, the algae are not growing very quickly, and they suspect either phosphorus, nitrogen, or iron is limiting. What could the company do to figure out which nutrient is limiting? a. Add phosphorus to one tank, nitrogen to another, and iron to a third, and see which treatment increases algal growth. b. Add phosphorus, iron, and nitrogen to all tanks, and see which nutrient increases algal growth. c. Add phosphorus to all tanks, because phosphorus is the nutrient that limits algal growth. d. Add nitrogen to all tanks, because nitrogen is the nutrient that limits algal growth. Q5.3. What would a biologist say is the role of nutrients in an ecosystem? a. Nutrients are substances that prevent eutrophication and oxygen loss in lakes. b. Nutrients are elements that are permanently destroyed when organisms decompose. c. Nutrients are carbohydrates that fuel photosynthesis for primary producers. d. Nutrients are elements from which organisms construct the molecules of life.
10. Multiple Choice Questions: I need 10 answers for all 10 questions. Correct Answer only Xpert!!
Q5.1. Which type of organism in this tutorial can get its nitrogen from nitrogen fixation (converting N2 gas into ammonia), allowing it to grow even if easily used forms of nitrogen are not available in its water or food?
a. Cyanobacteria
b. Daphnia
c. Bosmina
d. Trout
Q5.2. A company is growing algae in big tanks to make fish food. However, the algae are not growing very quickly, and they suspect either phosphorus, nitrogen, or iron is limiting. What could the company do to figure out which nutrient is limiting?
a. Add phosphorus to one tank, nitrogen to another, and iron to a third, and see which treatment increases algal growth.
b. Add phosphorus, iron, and nitrogen to all tanks, and see which nutrient increases algal growth.
c. Add phosphorus to all tanks, because phosphorus is the nutrient that limits algal growth.
d. Add nitrogen to all tanks, because nitrogen is the nutrient that limits algal growth.
Q5.3. What would a biologist say is the role of nutrients in an ecosystem?
a. Nutrients are substances that prevent eutrophication and oxygen loss in lakes.
b. Nutrients are elements that are permanently destroyed when organisms decompose.
c. Nutrients are carbohydrates that fuel photosynthesis for primary producers.
d. Nutrients are elements from which organisms construct the molecules of life.
Q5.4. Researchers conducted an experiment to determine whether nitrogen or phosphorus is limiting algal growth in a lake. They estimated algal
a. Algal growth is limited by nitrogen.
b. Algal growth is limited by phosphorus.
c. Algal growth is not limited by either nutrient.
d. There is not enough data to determine what limits algal growth.
Q5.5. As you saw in Section 2 ("DO or Die"), adding nutrients to a lake has direct effects (such as stimulating the growth of phytoplankton) and indirect effects throughout the community (such as drastic effects on fish populations). Suppose you triple (3x) the phosphorus input in a lake where phosphorus is limiting, and phytoplankton populations grow dramatically. Based on your observations, which of the following predictions is most likely to follow the phytoplankton bloom?
a. Decomposition decreases, dissolved oxygen increases, and fish populations grow.
b. Decomposition increases, dissolved oxygen decreases, and fish populations die off.
c. Decomposition increases, dissolved oxygen decreases, and fish populations grow.
d. Decomposition increases, dissolved oxygen increases, and fish populations die off.
Q5.6. Which of the following statements about eutrophication is TRUE?
a. Eutrophic bodies of water are characterized by murky water with large phytoplankton blooms.
b. Climate change will not affect eutrophication because phytoplankton growth is unrelated to temperature. c.Eutrophication is rarely associated with human activities like sewage discharge and fertilizer use.
d. Eutrophication can harm fish and other aquatic species but never causes health problems for humans.
Q5.7. After exposure to a biomagnifying toxic substance for long period of time, which type of organism would you expect to have the highest concentration of the toxic compound in its tissue?
a. Predatory fish
b. Zooplankton
c. Phytoplankton
d. All these would have about the same concentration.
Q5.8. How can an increase in algal population size kill fish?
a. Algae clogs the gills of the fish, preventing them from breathing.
b. Algae clogs the mouths of the fish, preventing them from eating.
c. The algae use up the oxygen in the water as they photosynthesize.
d. When the algae die, their decomposers use up the oxygen in the water.
Q5.9. As you saw in Section 2 ("DO or Die"), fish are sometimes lost from lakes as eutrophication occurs. Given what you've learned in this tutorial about why these fish kills occur, which of the following might help prevent fish kills as phosphorus concentrations increase?
a. Installing aerators that increase the oxygen concentration in the water
b. Periodically adding more algae to the lake throughout the year
c. Adding excess nutrients to promote increased algal growth in the lake
d. Trawling the lake with specialized nets to filter out extra zooplankton
Q5.10. You are studying the effect of a new pollutant on an ecological community in a lake that has three mysterious species. You sample the concentration of the pollutant in each species for 4 years after the pollutant first appeared. The graph below displays your data. Each species is represented by a different color and marker.
Which option below most likely describes the nature of the pollutant and the trophic levels of each of the three species?
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