Physical laws govern energy flow and chemical cycling in ecosystems [2].

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1 GUIDED READING - Ch ECOSYSTEMS NAME: Please print out these pages and HANDWRITE the answers directly on the printouts. Typed work or answers on separate sheets of paper will not be accepted. Importantly, guided readings are NOT GROUP PROJECTS!!! You, and you alone, are to answer the questions as you read. You are not to share them with another students or work together on filling it out. Please report any dishonest behavior to your instructor to be dealt with accordingly. Get in the habit of writing legibly, neatly, and in a NORMAL, MEDIUM-SIZED FONT. AP essay readers and I will skip grading anything that cannot be easily and quickly read so start perfecting your handwriting. Please SCAN documents properly and upload them to Archie. Avoid taking photographs of or uploading dark, washed out, side ways, or upside down homework. Please use the scanner in the school s media lab if one is not at your disposal and keep completed guides organized in your binder to use as study and review tools. READ FOR UNDERSTANDING and not merely to complete an assignment. Though all the answers are in your textbook, you should try to put answers in your own words, maintaining accuracy and the proper use of terminology, rather than blindly copying the textbook whenever possible. 1. What is an ecosystem? 2. a. Where does energy enter most ecosystems? [2] b. How and by whom is this energy converted into chemical energy and passed through the ecosystem? [2] c. How is it lost? [2] Remember energy cannot be recycled! 3. Besides the energy flow that you described in question 2, chemicals such as carbon and nitrogen cycle through ecosystems. So energy an ecosystem and matter. [2] Physical laws govern energy flow and chemical cycling in ecosystems [2]. 4. What does the First Law of Thermodynamics state?

2 5. How does the Second Law of Thermodynamics explain why energy needs to continually be resupplied to ecosystems? 6. a. Both energy and matter can be neither nor. [2] b. This concept is outline by the Law of. 7. What do we mean when we say that just like individual organisms, ecosystems are open system? 8. How are organisms assigned to trophic levels? 9. a. Quick review (not from this chapter). What is a trophic level? b. We can measure the efficiency of energy conversion in an ecosystem, as well as whether a given nutrient is being gained or lost from an ecosystem. What trophic level supports all others? [2] c. What do these organisms do? 10. List three groups of organisms that are photosynthetic autotrophs. [2] 11. What are the primary producers of the deep-sea vents? [2] 12. What is the difference between a primary, secondary, and tertiary consumer?

3 13. a. What are detrivores (a.k.a. decomposers)? b. What are the two important groups of detrivores and how do they obtain their energy? c. What is their role in they cycling of chemicals? d. Detrivores are critical to life on Earth. What would be the result of the loss of decomposers in ecosystems? 14. State the trophic level of each of the following: a. Cows = b. Grass = c. Human = d. Mushroom = Energy and other limiting factors control primary production in ecosystems [2]. 15. List three reasons why in the end only a small fraction of the visible light that hits Earth is converted to chemical energy by photosynthetic organisms. a. b. c. 16. a. What is an ecosystem s primary production? b. Distinguish between gross and net primary production. c. Write an equation that shows the relationship between gross and net primary production.

4 17. You may recall from Chapter 54 that biomass is the total mass of all individuals in a trophic level. Another way of defining net primary production is as the amount of NEW biomass added in a given period of time. Why is net primary production, or the amount of new biomass/unit of time and area, the key measurement to ecologists? [2] 18. Which ecosystem would tend to have a greater biomass/unit area, a prairie or a tropical rain forest? Explain. [2] 19. Let s say that a student is trying to estimate total primary production of plants in a prairie ecosystem for one year. Once each quarter, the student cuts a plot of grass with a lawnmower and then collects and weighs the cuttings to estimate plant production What components of plant primary production is the student missing with this approach? [1] 20. What are two factors that limit primary productivity in aquatic ecosystems? [2] 21. a. What is a limiting nutrient? [2] b. What is the limiting nutrient off the shore of Long Island, New York? [2] c. What is the limiting nutrient in the Sagrasso Sea? [2] 22. Phytoplankton growth and overgrowth or blooms can be caused by the addition of nitrates and phosphates to their aquatic habitat. What are common sources of each of these? [2] 23. Why are areas of upwelling so high in primary productivity compared to the rest of the oceans? 24. a. What is eutrophication and what effect does it have on life in the regions where it takes place?

5 b. What are factors that contribute to eutrophication? 25. Unlike nutrients and light, what are the two main factors that control primary production in terrestrial ecosystems? 26. What is the most productive terrestrial ecosystem in the world and why? 27. How can an ecologist experimentally determine the factors that limit primary production in an ecosystem? 28. Which nutrients soil do at times limit primary production in terrestrial ecosystems and how do farmers combat this? Energy transfer between trophic levels is typically only 10% efficient [2]. 29. What is referred to as an ecosystem s secondary production? 30. What does production efficiency refer to? 31. a. What is trophic efficiency? b. Why should this number always be lower than production efficiency?

6 32. a. If an insect that eats plant seeds containing 100J of energy uses 30J of that energy for respiration and excretes 50J in its feces, what is the insect s net secondary production? b. What is its production efficiency? 33. Generally speaking, what percentage of energy available at one trophic level is available to the next? THIS IS A MUST KNOW! 34. Consider a food chain with 1,000 joules (an energy unit) available at the producer level. If this food chain is grass! grasshopper! lizard! crow, how much energy is found at the level of the crow? (See answer at the end of this Reading Guide.) Show your work here. [2] 35. a. What is the effect of this loss of energy at each trophic level on the number of top-level carnivores able to survive in an ecosystem? b. What is the effect of this energy loss on the length of food chains possible in an ecosystem? 36. a. What is a pyramid of net production? b. Draw a pyramid of net production for the food chain discussed in #33, labeling the producer or type of consumer present in each trophic level, the amount of energy available at each level in Joules, and the total input of solar energy that must be available to the primary producers in this food chain. (See Figure 55.10).

7 37. Why does the human carrying capacity of the Earth depend on our diet? 38. a. What is a biomass pyramid? b. Notice that most biomass pyramids have greatest biomass on the bottom of the pyramid. Label the trophic levels on the figure below. Explain why the second pyramid of biomass is inverted. Biological and geochemical processes cycle nutrients between organic and inorganic parts of an ecosystem [2]. Be sure to really know your nutrient cycles shown in Figure a. Let s focus on the Water Cycle first. What the biological importance of this water cycle? b. Explain the roles of evaporation, transpiration, and rainfall (precipitation) in this cycle. [2] i. Evaporation

8 ii. Transpiration iii. Precipitation/Rain c. Label the Water Cycle illustration below. 40. a. Next, let s focus on the Carbon Cycle. What is the biological importance of this cycle? b. In what forms is Carbon made available to life / In what ways does carbon enter living systems and leave them?

9 c. As a review, write the equation for photosynthesis here: d. As a review, write the equation for cellular respiration here: e. What is the role of microorganisms in the cycle? f. What are the major reservoirs of carbon? g. Label the Carbon Cycle illustration below. 41. a. Now, let s focus on the Terrestrial Nitrogen Cycle. What is the biological importance of nitrogen? b. What are the forms available to life?

10 c. What are the major reservoirs of nitrogen? d. What is the role of microorganisms in Nitrogen Fixation? e. What is the role of microorganisms in Nitrification? f. What is the role of microorganisms in Denitrification? g. Label the Nitrogen Cycle illustration below. 42. a. Finally, let s look at the Phosphate Cycle. What is the biological importance of phosphate? b. What is the form available to life?

11 c. What are the major reservoirs of phosphorus? d. Label the Phosphorus Cycle illustration below. 43. Review the Case Study: Nutrient Cycling in the Hubbard Brook Experimental Forest. What effect has deforestation been shown to have on chemical cycling?

12 44. Why does deforestation of a watershed increase the concentration of nitrates in streams draining the watershed? [1] 45. Why do you think nutrient availability in a tropical rain forest is particularly vulnerable to logging? [1] Human activities now dominate most chemical cycles on Earth [2]. 46. a. How has agriculture affected nitrogen cycling? [2] b. What is meant by the critical load? c. What are some negative consequences of nutrient enrichment and surpassing a region s critical load? [2] d. What are dead zones and how are they created? 47. a. What is acid rain?

13 b. In what ways have human activities contributed to acid precipitation? [2] c. What are some negative consequences of acid precipitation? [2] 48. a. Explain the process of biological magnification. [1] b. What are the effects of PCB (a chlorinated hydrocarbon industrial chemical) biomagnification? c. DDT is a pesticide banned in the U.S. but sold to and still used especially in the third world. Explain how DDT had an effect on populations of top-level feeders including pelicans, ospreys, and eagles. d. Which trophic levels are most affected and why? e. In the face of biological magnification of toxins, is it healthier for you to feed at a lower or higher trophic level? Explain. [1]

14 49. a. What is the greenhouse effect? b. What would life on Earth be like without this effect? [2] 50. a. What activities/occurrences are contributing to the great increase in atmospheric carbon dioxide? b. What are a few of the potential effects of this increase in greenhouse gases that cause an augmented greenhouse effect referred to as Global Warming?

15 51. a. What benefit is offered to us by the Ozone Layer (O 3 )? b. Explain the process by which atmospheric ozone is depleted? c. What are projected effects of this depletion? [2] 52. Please answer the Self-Quiz at the end of your chapter. Do your best to try it from memory first in order to test how well you grasped the material ***Solution to Question #34: Grass (1,000 J)! grasshopper (100 J)! lizard (10 J)! crow (1 J) References 1. Adapted from L. Miriello. 2. Adapted from Fred and Theresa Holtzclaw 3. Campbell et al Biology, A.P. Edition. Pearson: San Francisco.