Chapter 25 Cycling Carbon Exam 2 Review Sheet 1 What did the measurements taken by keeling tell us about the yearly carbon cycle He began a program to monitor carbon dioxide levels in the atmosphere in1958 Two patterns emerged 1 Carbon dioxide levels oscillate on a yearly basis Oscillation is seasonal fluctuations in Co2 concentration What trend did he see in the concentration of atmospheric CO2 in the last 50 years 2 Carbon dioxide levels have increased steadily to the present day since measurements began There has been a 25 increase in Co2 levels over the past 50 years 2 What is the difference between correlation and causation Correlation Indicates that two events or processes occur together Increased Co2 levels in the atmosphere and the industrial revolution happen at the same time Causation A relationship in which one event leads to another causes the other 3 How long have atmospheric CO2 levels been increasing and what do scientists know is causing this increase CO2 levels have been increasing for the past 400 000 years Only fossil fuels having the correct ratio of all three carbon isotopes to account for the pattern of isotopic change in atmospheric CO2 Considers the interplay between physical and biological processes How do they know this They know this because the curve representing the changing atmospheric levels of CO2 over the past 400 000 years shows an oscillation pattern that seems to reflect the interglacial and glacial periods 4 What is responsible for the seasonal fluctuations in atmospheric CO2 levels Seasonal fluctuations can be explained by the imbalance between photosynthesis and respiration in the summer and winter months Atmospheric CO2 levels fluctuate regularly up and down with the seasons Seasonal photosynthesis higher in the summer Rates of respiration remain constant throughout the year 5 What physical processes are involved in the carbon cycle The physical process that are involved the carbon cycle are volcanism chemical weathering and oxidation of coal oil and ancient organic matter 6 What processes remove carbon from the atmosphere and what processes return carbon to the atmosphere The process that remove carbon from the atmosphere include the weathering of rocks and photosynthesis Those that add CO2 to the atmosphere include volcanoes the oxidation of ancient organic matter in sedimentary rock and respiration 7 What is the difference between the short term and long term carbon cycles In the short term carbon cycle the CO2 pattern is steadily oscillating and increasing over the last 200 years since the start of the industrial revolution Correlation In the long term carbon cycle there has been a ups and downs in the levels the CO2 Short term and long term carbon cycles are linked by the slow leakage of organic matter from biological communities to sediments accumulating on the sea floor Is there a difference in the types of processes involved Yes there is a difference The processes involved in the short term are photosynthesis and respiration and for sure human activities and the burning of fossil fuels In the long term carbon cycle it is the weathering of rocks removes CO2 Volcanoes and Oxidation of ancient organic matter in sedimentary rock adds CO2 to the atmosphere Chapter 26 Bacteria and Archaea 1 What are the features a prokaryotic cell Most bacterial cells are small spheres rods spirals or filament Shapes are very small are 200nm to 2 micrometers Rely on diffusion and size is limited because of cell wall doesn t allow aid of the wall Prokaryotic cells are cells that lack a nucleus and no membrane surrounds the prokaryotic DNA they include Bacteria and Archaea 2 What type of genome do bacterial and archaeal organisms have Bacterial genome is circular some bacteria can also carry smaller circles of DNA called plasmids Structural support is provided by a cell wall made of peptidoglycan Archaeal Organisms they are extremophiles living in extreme environments characterized by low pH high salt or high temperatures but others live in less extreme environments like the upper oceans or soil 3 Know the different types of horizontal gene transfer and be able to define them The different types of horizontal gene transfer are Conjunction DNA from a donor cell is transferred through a pilus into the recipient cell Transformation DNA released into the environment by dead cells is taken up by a recipient cell and Transduction DNA is transferred from a donor to a recipient cell by a virus 4 Know the different types of metabolism that bacteria and archaea can use and be able to identify if an organism is an autotroph chemotroph chemoautotroph photoheterotroph photoautotroph from a description The different types of metabolism that bacteria and archaea can use are Autotrophic metabolism Oxygenic photosynthesis oxygen producing Plant photosynthesis Anoxygenic photosynthesis Carbon dioxide gets reduced to carbohydrates does not use oxygen Chemoautotroph metabolism Chemoautrophy microorganism which use chemoautrophy are called chemoautrophs In which chemical energy is used to convert CO2 to organic molecules is unique to Bacteria and Archaea An organism that oxidizes H2S to gain energy and utilizes CO2 as a carbon source would be classified as chemoautotroph Heterotrophic metabolism aerobic respiration oxygen utilizing it breaks down carbohydrates using oxygen to generate ATP energy Fermentation yields only a modest amount of energy Photoheterotroph obtaining energy from sunlight and using performed organic compounds as a source of compounds as source of carbon instead of CO2 Photoautotroph Chemotroph 5 What is the difference between oxygenic and anoxygenic photosynthesis Oxygenic photosynthesis is oxygen producing Plant photosynthesis Anoxygenic photosynthesis Carbon dioxide gets reduced to carbohydrates does not use oxygen 6 What are oxidation reduction reactions Reactions in which electrons are removed from oxidation or added to reduction a molecule Reactions happen in pairs In photosynthesis the CO2 is reduced to carbohydrates In respiration the Carbohydrates are oxidized to CO2 O2 serves as electron acceptor In all known photosynthetic eukaryotes photosynthesis is oxygenic O2 producing Respiration in most eukaryotic cells are aerobic uses O2 7 What are the geochemical cycles that bacteria and archaea are involved in Sulfur Cycle Plants and algae can take up sulfur and incorporate it into proteins but bacteria and archaeon dominate the sulfur cycle by means
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