Mastering Biology Answer Keys (Chapter 28)

Chap 28: Nutrient Cycling 15 pts Due: 11:59pm on Sunday, March 9, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Activity: Food Webs In an ecosystem, phytoplankton are _____. secondary consumers primary consumers tertiary consumers detritivores producers Part B An earthworm that feeds on the remains of plants and animals is acting as a _____. tertiary consumer detritivore producer primary consumer secondary consumer Part C When a human eats a steak, the human is acting as a _____. tertiary consumer primary consumer detritivore producer secondary consumer Part D A cow eating grass is an example of a _____. primary consumer producer secondary consumer tertiary consumer detritivore Part E A human who just ate a hamburger is eaten by a shark while swimming. The shark is acting as a _____. tertiary consumer Activity: Energy Flow and Chemical Cycling Which of these provides your body with energy? fats Plants use _____ as a source of energy. light Part C What element is found in all organic compounds? carbon Part D Plants obtain carbon from _____. water carbon dioxide sugar oxygen glucose Part E What name is given to organisms that convert the carbon in organic compounds into carbon in carbon dioxide? autotrophs heterotrophs plants recyclers decomposers Part F Where do plants get the energy to make organic molecules? minerals glucose vitamins light water Part G Which of these is NOT an organic molecule? carbohydrates minerals proteins glucose lipids Part H Where do plants get the carbon they use to make organic molecules? glucose oxygen water starch carbon dioxide Activity: Pyramids of Production Part A _____ are secondary consumers. Producers Herbivores Plants Cows Carnivores Part B Approximately _____% of the energy at one trophic level is passed on to the next highest trophic level. 0–5 5–10 10–15 15–20 90–100 Part C 10,000 kcal of producer could support approximately _____ kcal of tertiary consumer. 1,000 100 10 1 0 Activity: The Nitrogen Cycle Part A Nitrifying bacteria convert _____ to _____. nitrogen gas ... ammonium nitrogen gas ... nitrates ammonium ... nitrites nitrates ... nitrogen gas ammonium ... nitrogen gas Part B _____ removes nitrogen from the atmosphere. Denitrification Nitrification Mineralization Nitrogen fixation Assimilation Part C Assimilation is indicated by the letter(s) _____. B A C C and D D and E Part D Nitrogen-fixing bacteria is(are) indicated by the letter(s) _____. A C and D B and C D and E A and B Part E Nitrification is indicated by the letter(s) _____. B and C B and E A D and E B Part F Denitrifying bacteria convert _____ to _____. nitrates ... nitrogen gas nitrogen gas ... nitrates nitrogen gas ... nitrites nitrogen gas ... ammonium ammonium ... nitrogen gas Part G Nitrifying bacteria convert _____ to _____. ammonium ... nitrites nitrogen gas ... nitrates ammonium ... nitrogen gas nitrogen gas ... ammonium nitrates ... nitrogen gas Part H _____ removes nitrogen from the atmosphere. Assimilation Mineralization Denitrification Nitrification Nitrogen fixation Part I Which one of these is a nitrate? NH4 – NH2 NO3 – NO2 – SH Part J Which one of these is a nitrite? NO3 – NH2 NO2 – PO4 – NH4 – Activity: The Carbon Cycle Click here to complete this activity. Then answer the questions. Part A What name is given to the process by which detritivores return carbon to the atmosphere? ANSWER: What name is given to the process by which detritivores return carbon to the atmosphere? burning predation photosynthesis predation and photosynthesis decomposition Part B Which of these removes carbon from the atmosphere? logging trees rabbits burning fossil fuels, such as oil bobcats algae Part C Detritus is composed of _____. detritivores dead organic matter inorganic minerals excreted wastes dead organic matter and excreted wastes Activity: Water Pollution from Nitrates Part A Which of these are the two major sources of nitrate pollution in rivers? the burning of fossil fuels by factories and cars animal wastes and the burning of fossil fuels by cars animal wastes and fertilizers fertilizer runoff and the burning of fossil fuels by cars animal wastes and the burning of fossil fuels by factories Part B Aquatic nitrate pollution can result in _____. algal bloom oxygen depletion fish kills hypoxia an algal bloom that, when the algae die and are decomposed by bacteria, leads to hypoxia and the death of fish Activity: The Greenhouse Effect Which of these would NOT contribute to a global increase in temperature? deforestation increasing the use of gasoline-burning vehicles increasing the industrial release of carbon dioxide planting trees increasing the amount of animal life on Earth Part B Switching from fossil fuels to _____ energy would significantly decrease the release of carbon dioxide into the atmosphere. solar nuclear geothermal solar and geothermal solar, nuclear, and geothermal Part A An organism gets carbon by using carbon dioxide in the atmosphere to make sugar molecules. This organism is a producer. primary consumer. decomposer. higher-level consumer. None of the above Part B Which organisms play a role in returning carbon to the atmosphere? Producers only. Producers, consumers, and decomposers. Consumers and decomposers, but not producers. Decomposers only. Consumers only. Part C Every carbon atom in the organic molecules that make up your body MUST recently have been part of a primary consumer. a decomposer. a higher-level consumer. a producer. a sugar molecule made in one of your chloroplasts. Part D Imagine following a single carbon atom through the carbon cycle. Which of the following is a possible path for the carbon atom to take? The atmosphere; a decomposer; then back to the atmosphere. The atmosphere; a plant; a higher-level consumer; then back to the atmosphere. The atmosphere; a decomposer; a higher-level consumer; then back to the atmosphere. The atmosphere; a plant; an herbivore; another plant; then back to the atmosphere. The atmosphere, a plant, a herbivore, a decomposer, then back to the atmosphere Part E Which process or processes return carbon to the atmosphere? Breakdown of large organic molecules into smaller organic molecules by decomposers Cellular respiration and photosynthesis Photosynthesis only Cellular respiration and the breakdown of large organic molecules into smaller organic molecules by decomposers Cellular respiration only What information is presented on the y-axis of the graph? global surface warming, in °Fahrenheit time, in 100-year intervals global surface warming, in °Celsius global surface temperature, in °Celsius Part B What does the yellow line represent? Today’s World: The amount of global warming that is likely to occur if CO2 emissions cease immediately and CO2 concentrations continue at their current level. Business as Usual: The amount of global warming that is likely to occur if governments and individuals take no action to slow the increase in CO2 emissions. Sustainable World: The amount of global warming that is likely to occur if governments and individuals take significant actions to slow the increase in CO2 emissions. Part C Which line is not a computer-generated forecast? the black line representing 20th century data the yellow line representing Today’s World the blue line representing a Sustainable World the red line representing Business as Usual Part D How did the global surface temperature change between 1900 and 2000? It decreased by about 0.7 °C. It increased by about 0.7 °C. It increased by about 0.7 °F. It remained relatively constant. Part E According to the Business as Usual scenario, how will the global surface temperature change in the century between 2000 and 2100? It will increase by about 2.0 °C. It will increase by about 2.0 °F. It will increase by about 3.5 °C. It will increase by about 3.5 °F. It will increase by about 4.5 °C. Part F Which prediction has the greatest degree of certainty? Sustainable World Business as Usual Today’s World Part G Which of the following statements is supported by the graph? If CO2 emissions cease immediately, global temperatures will stabilize near the 1900 level. Because there is so much uncertainty in the forecasts, no conclusions can be drawn about how actions to reduce CO2 emissions will affect the rate of global warming. All of the computer-generated forecasts predict some global warming, but reducing the level of CO2 emissions will significantly slow the rate of increase. Interpreting Graphs and Data: Input of Nitrogen to Earth’s Ecosystems Can you interpret the graph to answer these questions? Source: United Nations. 2007. Millennium Ecosystem Assessment. Part A What information is presented on the y-axis of the graph? time, measured in 20-year intervals the amount of nitrogen humans add to Earth’s ecosystems each year the amount of nitrogen stored in Earth’s ecosystems the amount of nitrogen added to Earth’s ecosystems each year Part B What is the natural rate of nitrogen fixation in Earth’s ecosystems? 2020 teragrams of nitrogen per year 2020 kilograms of nitrogen per year 100 teragrams of nitrogen per year 100 kilograms of nitrogen per year Part C What does the red graph line represent? input of nitrogen from burning fossil fuels input of nitrogen from fertilizer and industrial processes input of nitrogen from all human activities input of nitrogen from legumes grown on farms Part D In 1960, what was the total amount of nitrogen released by human activities? ANSWER: In 1960, what was the total amount of nitrogen released by human activities? about 25 kilograms about 25 teragrams about 270 teragrams about 50 kilograms about 50 teragrams Part E During which period did the total amount of nitrogen released by human activities increase most rapidly? 1920–1940 1940–1960 1960–1980 1980–2000 2000–2020 Part F Which factor was the major contributor to the rapid increase in the total human input of nitrogen between 1960 and 2000? a rapid increase in fertilizer use and industrial processes Part G In the year 2000, the total human input of nitrogen into Earth’s ecosystems was almost twice the natural rate of nitrogen fixation. supported Part H Is the following statement supported or not supported by the data shown in the graph? By the year 2100, the increasing use of fertilizer will cause the total human input of nitrogen into Earth’s ecosystems to be about three times the natural rate of nitrogen fixation. supported not supported cannot be determined from the graph Source: Leighton, P.A. 1961. Photochemistry of air pollution. Academic Press, New York. Part A What does the y-axis show? time of day, in four-hour intervals concentration of pollutants, as percentages concentration of pollutants, in parts per billion concentration of pollutants, in parts per million Part B What was the concentration of volatile organic compounds (VOCs) at 8:00 A.M.? 0.15 ppm 0.15% 0.35 ppm 0.35% 0.18 ppm Part C What is most likely to have caused the increase in atmospheric nitrogen oxide (NO) between 4 A.M. and 7 A.M.? emissions of heavy metals from smelting plants generation of electricity in coal-fired plants reactions driven by sunlight exhaust from vehicles during morning rush hour Part D In which period was the concentration of photochemical smog highest? 11:00 P.M. to 3:00 A.M. 12:00 noon to 4:00 P.M. 11:00 A.M. to 3:00 P.M. 8:00 A.M. to noon Part E What is most likely to have caused the rapid increase in photochemical smog between 8 A.M. and 11 A.M.? reactions of nitrous oxides (NOx) and VOCs with oxygen in sunlight Part F What is most likely to have caused the levels of ozone and photochemical smog to decline after 4:00 P.M.? The rate of photosynthesis declined as the sun began to go down. The production of pollutants declined as smelters and factories closed down for the night. The production of smog declined as the afternoon rush hour began. The production of smog declined as the amount of sunlight decreased. SubmitMy AnswersGive Up Part G Which of the following factors would be most likely to lead to an overall increase in the level of photochemical smog? installation of scrubbers on factory smokestacks windy weather increased use of public transportation increased fuel efficiency in automobiles a temperature inversion ABC News Video: Ocean Acidification Watch the ABC News video (3:39 minutes). Then answer the questions below. Part A What is the main reason that the oceans are becoming more acidic? the dumping of garbage and sewage into the oceans absorption by the oceans of carbon dioxide generated by burning fossil fuels large crude oil spills in the oceans fertilizer runoff in major rivers flowing into the oceans Part B How much carbon dioxide from the atmosphere is absorbed by the oceans on a daily basis? ANSWER: 20 million metric tons Correct Part C What is the chemical reaction responsible for the oceans becoming more acidic? ANSWER: carbon dioxide reacts with seawater, forming carbonic acid Correct Part D How are oyster larvae affected by ocean acidification? ANSWER: Oyster larvae cannot grow shells in acidified ocean waters. Correct Part E Which of the following are consequences of ocean acidification? Select all that apply. ANSWER: Corals and coral reefs are not able to form their hard skeletons. Animals in the oceans cannot get enough oxygen. Ocean temperatures are dropping. Clams, mussels, lobsters, and shrimp are not able to form strong enough shells. All attempts used; correct answer displayed Part F Because of ocean acidification, the price of which of the following foods is most likely to increase? ANSWER: shellfish Part A - Question 1 Which of the following is the best statement regarding the graph of atmospheric CO2 concentrations? There has been a catastrophic increase in atmospheric CO2 concentrations over the past 50 years. Atmospheric CO2 concentrations have increased by more than 15% over the past 50 years. Atmospheric CO2 concentrations have increased by more than 100% over the past 50 years. There has been negligible change in atmospheric CO2 concentrations over the past 50 years. Part B - Question 2 Which of the following is the best statement regarding the graph in Step 2 showing atmospheric CO2 and surface temperature changes over the past 50 years? This data set represents the strongest evidence available for anthropogenic global warming. The data demonstrate that, in spite of increases in CO2 concentrations, there has only been a minimal rise in average surface temperatures. This data set is meaningless because CO2 concentrations and surface temperatures are constantly fluctuating over geologic time scales. This data is consistent with the hypothesis that increased atmospheric concentrations of CO2 may be causing an increase in average surface temperatures. Part C - Question 3 Assume that you wanted to give the impression that, although CO2 levels have indeed increased over the past 50 years, they have not had a significant impact on average surface temperatures. Which of the scales shown in Step 3 would be the best choice? scale 1 scale 2 scale 3 scale 4 none of the available scales Part D - Question 4 For which of the scales shown in Step 3 is the increase in CO2 concentrations less than 10%? scale 1 scale 2 scale 3 scale 4 all of the scales none of the scales Part E - Question 5 Choose the list of predicted trajectories for CO2 concentration that matches them in order with the aggressive, moderate, and minimal control scenarios. C, A, B B, A, C A, B, C C, B, A Part F - Question 6 If the USA adopted and maintained a policy of minimal control of CO2 emissions, what level would we expect its emissions to be in 2020? 2716 MMT 135,800 MMT 440 MMT none of the above can't tell from this data Part G - Question 7 Assuming that increasing CO2 concentrations are directly linked to increased surface temperatures, which scenario should result in a reduction of temperatures to below their 1960-1990 averages by 2040? moderate control aggressive control minimal control all of the scenarios none of the scenarios Chapter 28 Reading Quiz Question 1 Part A Which is a true statement regarding nutrients and energy in an ecosystem? Nutrients are atoms and molecules that cannot be converted to different molecular forms whereas energy is redistributed and subsequently converted to other molecular forms. Nutrients are not required for life whereas energy is required. Energy is created by photosynthesizing plants as nutrients are recycled. Nutrients cycle within an ecosystem whereas energy moves through in a continuous one-way flow. Nutrients are used in a continuous one-way flow whereas energy is recycled. Chapter 28 Reading Quiz Question 2 Part A What is the definition of nutrients? Nutrients are the heat, light, and ultraviolet rays that reach Earth, which are utilized in chemical reactions to power life. Nutrients are molecules that collect and store energy. Nutrients are the pigment molecules that absorb specific wavelengths of sunlight, which subsequently store energy in chemical bonds. Nutrients are atoms and molecules that organisms obtain from their living or nonliving environment and that are required for survival. Chapter 28 Reading Quiz Question 3 Part A How is the energy radiated to Earth from the sun captured for use by life-forms on Earth? It is captured by the inorganic substances found on Earth. It is absorbed as heat by Earth and this is converted to energy used by life-forms. It is captured by animals and these subsequently make it available to plants. It is captured by photosynthetic organisms. Chapter 28 Reading Quiz Question 4 Part A What happens to the solar energy trapped by pigments such as chlorophyll? Solar energy is converted to the abiotic portion of ecosystems. Solar energy is used to decompose biological molecules. Most solar energy is reflected and some is absorbed as heat by Earth and its atmosphere. Solar energy is stored in chemical bonds in biological molecules needed to sustain life on Earth. Chapter 28 Reading Quiz Question 5 Part A What is the term used to describe organisms that capture solar energy and release oxygen as a by-product? tertiary consumers carnivores primary consumers heterotrophs producers Chapter 28 Reading Quiz Question 6 Part A The second law of thermodynamics states that when energy is converted from one form to another, the amount of useful energy decreases. How does this relate to energy flow through biological systems? As producers, plants must liberate heat as they synthesize carbohydrates. As energy is passed from producer to consumer, some energy is lost as heat. It is necessary for animals to absorb solar energy (heat) to metabolize biological molecules for the energy they contain. A biological system cannot create or destroy energy. Chapter 28 Reading Quiz Question 7 Part A At what point in the cycle of energy through various trophic levels are nutrients released for recycling? during metabolism by higher-level consumers during metabolism by primary consumers during metabolism by producers during metabolism by decomposers Chapter 28 Reading Quiz Question 8 Part A Organisms that acquire energy and most of their nutrients prepackaged in the molecules that comprise the bodies of other plants and animals are called __________. heterotrophs carnivores abiotic herbivores detritivores Chapter 28 Reading Quiz Question 9 Part A Which of the following is a true statement? Oceans contribute 65% of the Earth's total productivity. The amount of life that a particular ecosystem can support is determined by the energy captured by the producers in that ecosystem. Tropical rain forests are examples of low net primary production areas because of the lack of available nutrients. The productivity of a particular ecosystem is dependent solely on the availability of nutrients for growth. Chapter 28 Reading Quiz Question 10 Part A Which of the following is an example of an ecosystem where productivity is high? cave ocean desert estuary Chapter 28 Reading Quiz Question 11 Part A Which of the following ecosystems has the highest net primary productivity? continental shelf ocean coniferous forest tundra tropical rain forest Chapter 28 Reading Quiz Question 12 Part A Which of the following is the dominant producer in land-based ecosystems? plants zooplankton omnivores phytoplankton Detritivores Chapter 28 Reading Quiz Question 13 Part A The term used to describe the feeding relationship of an individual within a particular trophic level eating an individual in the level below it is __________. food web biological magnification food chain energy pyramid Chapter 28 Reading Quiz Question 14 Part A What would describe a hawk that eats a mouse that eats plants? a producer an herbivore a tertiary consumer a secondary consumer Chapter 28 Reading Quiz Question 15 Part A Which is the definition of zooplankton? a group of microscopic protists and bacteria that are the dominant producers (first trophic level) in most aquatic food chains animals, such as a bear, that eat both plants and animals a group of aquatic consumers (second trophic level) composed mainly of protists and small shrimp-like crustaceans a group composed primarily of fungi and bacteria that secrete digestive enzymes outside of their bodies Chapter 28 Reading Quiz Question 16 What is the significance of detritivores and decomposers in the food chain? They supply energy for phytoplankton, which is composed of microscopic protists and bacteria. They function outside the food web of a given community. They are considered to be primary producers, not consumers. They remove the "refuse of life," such as fallen leaves, fruit, and the wastes and dead bodies of other organisms as they feed on these materials. Chapter 28 Reading Quiz Question 17 Part A Which of the following is an example of a detritivore? earthworms bacteria hawks phytoplankton fish Chapter 28 Reading Quiz Question 18 Part A Why is it that when you exercise on a cold day, you warm up? Your body begins to produce energy-containing molecules, such as sugar. Metabolic processes speed up. Perspiration evaporates, producing heat. Splitting the chemical bonds of adenosine triphosphate for energy for muscle contraction releases heat that warms you. Chapter 28 Reading Quiz Question 19 Part A Assume you are constructing an energy pyramid for a marsh ecosystem. You determine that the maximum energy available at the base is 1,500 calories. How many calories are available at the tertiary consumer trophic level? 1,500 150 30 1.5 15 Chapter 28 Reading Quiz Question 20 Part A Considering the energy pyramid, which will be the predominant organisms in an undisturbed ecosystem? plants humans carnivores herbivores Chapter 28 Reading Quiz Question 21 Part A What general statement could you make about persistent toxic chemicals in the bodies of animals that occupy increasingly higher trophic levels? Biological magnification is the mechanism whereby a persistent poison, such as mercury, is taken up by consumers and passed down the trophic levels to the producers. The chemicals can become increasingly concentrated in the bodies as we go up the energy pyramid. The real danger to humans is consumption of producers containing toxic chemicals. As humans, we are not vulnerable to substances that build up in our bodies. Chapter 28 Reading Quiz Question 22 Which of the following elements is considered to be a macronutrient? molybdenum iodine iron nitrogen zinc Chapter 28 Reading Quiz Question 23 Part A Name the pathway a nutrient follows as it moves from the abiotic portions of ecosystems through communities and back to nonliving storage sites. biogeochemical cycles food chain energy pyramid hydrologic cycle Chapter 28 Reading Quiz Question 24 Part A How is the hydrologic cycle different from most nutrient cycles? The hydrologic cycle would continue even if life on Earth were to disappear. Water, but not nutrients, enters organisms of living communities. Nutrients are required for life but water is not. Nutrient cycles require water; hydrologic cycles require nutrients. Chapter 28 Reading Quiz Question 25 Part A Where do primary consumers acquire the carbon they need for growth? Consumers get carbon by inhaling carbon dioxide in the atmosphere. Primary consumers acquire carbon from that stored in producer's tissues. fossil fuels calcium carbonate Chapter 28 Reading Quiz Question 26 Part A Although the atmosphere contains about 78% nitrogen gas, only a few types of organisms are able to convert it into a form usable by plants and other producers. What organisms can combine nitrogen in the atmosphere with hydrogen atoms to form ammonia? consumers bacteria earthworms producers denitrifying bacteria Chapter 28 Reading Quiz Question 27 Part A You are studying runoff from fertilized fields that carries nutrients, such as nitrogen and phosphorus, to lakes in your area. You notice that runoff stimulates such an excessive growth of algae that its natural community interactions are disrupted. You can easily account for nutrients necessary to stimulate algal growth, but where do they get their energy? sunlight detritus phosphorus nutrient pool starch Chapter 28 Reading Quiz Question 28 Part A How are nitric oxide and sulfur dioxide involved in acid deposition (acid rain)? Once back on Earth in aquatic ecosystems, nitric oxide and sulfur dioxide form acids that cause the formation of low oxygen "dead zones" in aquatic ecosystems. Nitric oxide converts to nitric acid and sulfur dioxide converts to sulfuric acid in the atmosphere, where they dissolve in rainwater and fall to Earth. Nitric oxide and sulfur dioxide are the result of chemical fertilizers used to stimulate plant growth washing into bodies of water and, consequently, killing the phytoplankton. Once back on Earth in certain terrestrial ecosystems, nitric oxide and sulfur dioxide are removed as acids by deforestation in the Tropics. Chapter 28 Reading Quiz Question 29 Part A What is the major cause of the greenhouse effect? acid deposition due to nitric and sulfuric acid in the atmosphere increased primary producer activity disruption of nutrient cycles excessive carbon dioxide gas in the atmosphere increases in the nitrogen cycle Chapter 28 Reading Quiz Question 30 Part A Which of the following is a serious problem that will result from predicted rises in global temperature? Warmer temperatures will increase farm land productivity. Species will be lost because rises in global temperature will exceed the rate at which natural selection can allow most organisms to adapt. Higher temperatures will cause an increase in transpiration. There will be an exponential rise in the amount of carbon dioxide released into the atmosphere.