Bio 1m03 Exam Question With Verified Answers

Bio 1m03 Exam Question With Verified Answers Short term carbon cycle - answerPhotosynthesis to respiration Rates of respiration vs photosynthesis - answerRoughly equal Explain the seasonal variation in CO2 levels - answerFollows the seasonal activity of plants, plants become more active = less CO2 in the air. Plants die around winter seasons = more CO2 in the air. More pronounced in the Northern Hemisphere (where there are more plants) than the Southern Hemisphere. Equator remains largely unaffected, as climate is more constant there. Keeling curve - answerDaily record of global CO2 levels in the air that shows the rise and fall on a seasonal basis, and the overall increase on a yearly basis How did they figure out CO2 levels of the years before Keeling? - answerDrilled into ice (Law Dome)- trapped CO2 in the ice that could be measured What did scientists find after drilling into the Law Dome? - answerBefore industrial revolution (before early 1800s) , atmospheric CO2 levels varied little over the years (270 ppm - 280 ppm) What did Hans Suess find? - answerObserved that the ratio of 13C:12C (less 13C) isotope in atmospheric CO2 has declined as the total amount of CO2 increased. This allows us to conclude that burning of fossil fuels by industrialized societies has been a principal source of CO2 buildup in the Earth's atmosphere (ratio of 13:12 C in organic matter formed by photosynthesis matches the ratio found in the atmosphere) What pattern was found in 14C? - answer14C has also been decreasing. Modern organic matter has too much 14C compared to the atmospheric levels, meaning the source comes from burning ancient organic matter. How much CO2 do humans add to the atmosphere yearly - answer40 billion metric tons Where does human added CO2 end up - answerHalf in atmosphere, half in CO2 sinks (oceans, vegetations, forests, soils etc) What ion form does CO2 take in the oceans - answerBicarbonate (HCO 3-) and carbonate (CO3 2-) What are carbon sinks - answerA carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide from the atmosphere. What do glaciers tell us about long-term carbon cycling - answerVostok glacial ice shows 400k years of environmental history. For at least the last 400k years, CO2 levels oscillated between 285 and 180 ppm. Higher the CO2, generally higher the temperature (glacial expansion and retreat, ocean's ability to store inorganic carbon) What are the 5 carbon reservoirs - answerOrganisms (marine and terrestrial), atmosphere, soil, oceans and sedimentary rock. Long-term carbon cycle Marine biological activity (CO2) - answerNearly balanced, 90 GtC in, 92 GtC out Terrestrial biological activity (CO2) - answerNearly balanced, 119 GtC in, 120 GtC out Human activity (CO2) - answerVery unbalanced, 9.3 GtC in (land use and fossil fuels), 0.5 GtC out Sediments and sedimentary rock reservoir - answerLargest carbon reservoir on Earth (CaCO3 minerals coal, petroleum, natural gas). Fluxes - answerRate at which carbon flows from one reservoir to another. Long-term carbon cycle Plate tectonics and carbon cycle - answerSubduction leads to carbon returned to the Earth's mantle. Carbon comes out again through volcanoes and mid-ocean ridges/formation of new seafloor. Part of the long-term carbon cycle Primary producers - answerHarness energy from the sun to fix inorganic carbon into organic molecules Consumers - answerobtain carbon through the consumption of food Primary consumers - answerConsumes primary producers Secondary consumers - answerPredators/scavengers that feed on primary consumers Decomposers - answerReturns the carbon originally fixed by photosynthesis to the atmosphere by breaking down dead tissues Food webs - answerDefines the interactions in a habitat, tracing the passage of carbon atoms through the biological carbon cycle Trophic level - answerAn organisms typical place in the food web Producers - first trophic level