Download Worksheet 20: The Carbon cycle

General Ecology (BIO 160) Worksheet #20 Dept. of Biological Sciences
Sacramento State
Worksheet 20: The Carbon cycle 1. Before life evolved on Earth, our atmosphere had a very different chemical composition than it does today. Answer the questions based on the data below. (pgs 448‐452, 589‐591) CO2 O2 Temperature
Earth
before life
today
98%
0.03%
trace
21%
13oC
290oC
a. Explain how and why CO2 and O2 changed after life evolved on Earth. b. Where did all of the carbon in the CO2 go after life evolved on Earth? c. Explain how and why temperature declined after life evolved on Earth. d. How are the processes of photosynthesis and decomposition involved in the carbon cycle? e. Using an illustration to show its potential path through the carbon cycle, trace a carbon atom through at least four different reservoirs. Begin with an atom in an oil reserve off the coast of California. Be sure to explain how your carbon atom could move from one reservoir to another. General Ecology (BIO 160) Worksheet #20 Dept. of Biological Sciences
Sacramento State
2. Answer True or False. If false, correct the sentence. (pgs 448‐452) a. _____ Because plants photosynthesize, they take up CO2 but do not release it. b. _____ In warm, wet ecosystems (i.e. tropical rainforest), carbon cycles through the ecosystem quickly compared to cool, dry ecosystems. c. _____ The process of decomposition adds carbon to the atmosphere. d. _____ Biomass is the smallest global reservoir of carbon and thus this pool has the fastest turnover rate. e. _____ CO2 in the atmosphere can be dissolved in the ocean. 3. Explain how carbon dioxide (CO2) concentrations in the atmosphere vary diurnally (daily) and seasonally. What is the cause of these cyclic patterns of CO2 concentrations? What is the cause of consistent increases in atmospheric CO2 concentrations? (pgs 450, 589‐591) 4. Draw the global carbon cycle, showing its major reservoirs (as boxes) and exchanges (as arrows). Indicate the relative sizes of the reservoirs by the sizes of your boxes. (pgs 448‐451, course manual)