Carbon Dioxide In Organisms And Ecosystems

440 Words2 Pages
Essay: Carbon dioxide in organisms and ecosystems. An outline of what would have been the plan for an excellent essay is below. It is not prescriptive – there would be other good things to include and other equally good ways of structuring your answer. Brief Introduction: - Though carbon dioxide makes up only 0.04% of the atmosphere, it has many very important roles in organisms and ecosystems. Photosynthesis: - Outline what photosynthesis is/why autotrophs do it - Describe how carbon dioxide is used in photosynthesis. As it is used in the light independent stage (LIS), you should focus on this, not the light dependent stage (LDS). Respiration: - Outline what respiration is/why organisms all have to do it - Describe how carbon dioxide is produced in respiration. As it is produced in the link reaction and the Krebs cycle, you should focus on this, not on glycolysis and the electron transfer chain. Exchange of carbon dioxide between an organism and its environment: - Pick a couple of contrasting organisms (e.g. protoctists or plants and humans) and describe the surfaces where carbon dioxide is exchanged between the organism and its environment. Link in size, surface area/volume ratio, level of activity, environment to why these organisms have very different gas exchange requirements and surfaces. Transport of carbon dioxide: - In large organisms, carbon dioxide must be transported between the gas exchange surface and the cells where it is produced/needed. - In mammals, most carbon dioxide is transported dissolved in blood plasma as hydrogen carbonate ions. - The presence of carbon dioxide has an effect on how saturated haemoglobin is with oxygen (curve shifts to the right – Bohr shift). Effect of increased carbon dioxide concentration on organisms: - Increased carbon dioxide concentration leads to an increased heart rate
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