of carbon dioxide, the rate of photosynthesis ..
Much discussion has been had about the affects of climate change on plantlife, but how will rising carbon dioxide concentrations affect the photosynthetic process itself? Since CO₂ is a reagent in photosynthesis, would we expect higher CO₂ to mean an increased rate of photosynthesis in a real-world context? Has there been any research on this?
Factors affecting the rate of photosynthesis 3
A) sunlight concentration B) temperature C) chlorophyll concentration D) carbon dioxide availability Effects of the variables and there concentrations: The amount of sunlight will decide the rate of photosynthesis as there will be a an increased rate of photosynthesis due to the increased availability of photons of light....
However, plants haven't just been growing slowly all that time - several mechanisms for increasing photosynthetic efficiency have evolved. The most influential systems involve concentrating carbon dioxide in a particular area, excluding oxygen, and concentrating RuBisCO in that same area. This avoids the oxygen competition for the active site and allows RuBisCO to operate more efficiently. The key adaptation here is C4 photosynthesis - the system which is present in most grasses and many of the most productive plants on Earth (e.g. maize, sugarcane, Miscanthus). It has evolved at least 62 times independently. It works by having RuBisCO concentrated within 'bundle sheath' cells which are surrounded by a layer of suberin wax. This layer prevents CO₂ escaping and O₂ from getting in. CO₂ from the atmosphere is then fixed in different cells - 'mesophyll cells' - by another enzyme - Phosphoenolpyruvate carboxylase (PEPC), resulting in a four-carbon molecule (hence C4). This 4-carbon acid, (malate or oxaloacetate depending on the system) is then shuttled into the bundle sheath cells. There, the CO₂ is released again by a variety of enzymes depending on the system, creating a high CO₂ concentration in the cell where RuBisCO can then work efficiently.
Factors affecting the rate of photosynthesis
Not all of this eight billion tons of surplus carbon dioxide remains in the atmosphere, Plants remove some of it. When the atmospheric concentration rises, plants use more carbon dioxide for photosynthesis. In a few years, however, the increase in the rate of photosynthesis is balanced by advances in the rate of respiration and decay processes. The net result is only a slight increase in the carbon dioxide content of the biosphere.
Photosynthesis Flashcards | Quizlet
We have only to extrapolate existing records of temperature and fossil-fuel consumption to predict the climate of the future. Quite accurate records of the amount of fossil fuel consumed in the world each year show that in the past 100 years man has added about 360 billion tons of carbon dioxide to the atmosphere. As a result the atmospheric concentration has increased by about 13 per cent. The carbon dioxide theory predicts that such an increase should raise the average temperature of the earth one degree F. This is almost exactly the average increase recorded all over the world during the past century! If fuel consumption continues to increase at the present rate, we will have sent more than a trillion tons of carbon dioxide into the air by the year 2000. This should raise the earth's average temperature 3.6 degrees.