Question

Q1. Which type of organism in this lab 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?CyanobacteriaDaphniaBosminaTroutQ2. A company is growing algae in big tanks to make fish food. However, the algae is 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?Add phosphorus to one tank, nitrogen to another, and iron to a third, and see which treatment increases algal growth.Add phosphorus, iron, and nitrogen to all tanks, and see which nutrient increases algal growth.Add phosphorus to all tanks, because phosphorus is the nutrient that limits algal growth.Add nitrogen to all tanks, because nitrogen is the nutrient that limits algal growth.Q3. The graphs below represent algae abundance in a limiting-nutrient experiment. Based on the graphs, which nutrients are limiting the growth of algal species A and B in the experiment? (Hint: Recall what a graph of population size vs. nutrient input should look like—straight or sloped—if the nutrient is limiting and also if it is not limiting.)Algae A is limited by nitrogen and Algae B is limited by phosphorus.Algae A is not limited by either nutrient and Algae B is limited by phosphorus.Algae A is limited by phosphorus and Algae B is not limited by either nutrient.Algae A is not limited by either nutrient and Algae B is limited by nitrogen.Q4. Algae need nutrients like carbon, nitrogen, and phosphorus, among others, in order to grow. Could carbon ever limit algae growth?No. Carbon is abundant everywhere and so it can never be a limiting nutrient for algae.No. Algae are too small to ever require more carbon than what is available in the environment.Yes. Because carbon is needed by algae to grow, it has the potential to limit growth.Yes. Whenever phosphorus is added to a lake, algae grow and therefore use more carbon as well.Q5. As you saw in “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?1) Decomposition decreases, DO increases, fish populations grow, and zooplankton abundance increases.2) Decomposition increases, DO decreases, fish populations die off, and zooplankton abundance increases.3)Decomposition increases, DO decreases, fish populations grow, and zooplankton abundance decreases.4) Decomposition increases, DO increases, fish populations die off, and zooplankton abundance decreases.Q6. Which of the following statements about eutrophication is FALSE?Eutrophication occurs when populations of phytoplankton in a body of water grow very large.The eutrophication of a body of water can occur gradually over many years.Eutrophication occurs when a nutrient required for phytoplankton growth is in limited supply.Eutrophication is sometimes associated with compounds that are hazardous to human health.Q7. After exposure to a bioaccumulating toxin for long period of time, which type of organism would you expect to have the highest toxin concentration?FishZooplanktonPhytoplanktonAll these would have about the same toxin concentration.Q8. How can an increase in algal population size kill fish?Algae clogs the gills of the fish, preventing them from breathing.Algae clogs the mouths of the fish, preventing them from eating.The algae use up the oxygen in the water as they photosynthesize.When the algae die, their decomposers use up the oxygen in the water.Q9. As you saw in “DO or Die”, fish are sometimes lost from lakes as eutrophication occurs. Given what you’ve learned in this lab about why these fish die-offs occur, which of the following might help maintain the entire ecological community as phosphorus concentrations increase?Installing aerators that increase the oxygen concentration in the waterPeriodically adding more algae to the lake throughout the yearAdding nitrogen to balance the increase in phosphorus and promote algal growthTrawling the lake with specialized nets to filter out extra zooplanktonQ10. 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.Which option below most likely describes the nature of the pollutant and the trophic levels of each of the three mysterious species?The pollutant is bioaccumulating in the community. Species B is a producer, Species A is a primary consumer, and Species C is a predator.The pollutant is bioaccumulating in the community. Species C is a producer, Species B is a primary consumer, and Species A is a predator.The pollutant is causing eutrophication of the lake. Species A is a producer, Species B is a primary consumer, and Species C is a predator.The pollutant is neither bioaccumulating in the community nor causing eutrophication. Species C is a producer, Species B is a primary consumer, and Species A is a predator.