BIO 204 week 4 Photosynthetic Stages Worksheet

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Photosynthetic Stages Worksheet

Write a 50- to 75-word response for each question.

Include your references and in-text citations. APA formatted references should go at the end of this document and each response should have an in-text citation.

Question Student response
Explain how CO2 enters leaves. What environmental factors control stomatal movement? How are these factors related to physical and chemical properties that control the opening and closing of stomata? When it comes to entering the leaves CO2 gains access to the leaves through tiny holes present in the leaves called the stomata. The environmental factor which controls stomatal movement is the intensity of light. When light is present the photosynthesis process takes place, calling for more CO2, therefore making the stomata opening more open. During darkness the openings are smaller and serve as release for excess (“ Botany: An introduction of Plant Biology”)
What are primary stages in the photosynthetic carbon reduction (PCR) cycle? Explain the role of each stage. Draw a diagram of the stages, you may utilize the drawing tools in Microsoft® Word to aid your explanation. When it comes to the process of photosynthetic carbon reduction cycle, also known as the Calvin cycle, there are three main steps to keep in mind: fixation, reduction, and regeneration. During the first step of fixation CO2 is taken in the plant through the use of ribulose bisphosphate (RuBP). During the next step of reduction NADPH and ATP are consumed and used to convert 3-phosphoglyceric acid to glyceraldehydes 3-phosphate. In the last step of the cycle, regeneration, the remainder of the ATP is consumed and the 3-phosphate is converted back to RuBp, starting the cycle all over again with a new CO2 molecule. (“Berg, J.M., Tymoczko, J.L., Stryer, L. Biochemistry. 5th edition. New York: W H Freeman; 2002.)
Explain how the ATP and NADPH produced by the photosynthetic electron transport chain are used in the PCR cycle. The ATP and NADPH produced by the photosynthetic electron transport chain are used in the Calvin cycle to reduce carbon dioxide to sugar. ATP acts as the energy source breaking off one of its phosphates groups and adding it to the phosphoglyceric acid and then the NADPH comes in to reduce the new compound by adding electrons to it and essentially helping to form sugar. The cycle uses the ATP and NADPH to convert three molecules of carbon dioxide to one molecule of a 3-carbon sugar. (“Botany: An introduction of Plant Biology”)
What roles do light and Rubisco play in regulating the PCR cycle? Explain your answer. The most important enzyme in the Calvin cycle is the one that starts the cycle off, that enzyme is ribulose-1-5-biphosphate carboxylase, also known as Rubisco. Rubisco catalyzes the transformation of the sugar and carbon dioxide to the phosphoglycerates. If Rubisco does not give the go ahead the whole process comes to a stop, therefore it is a major factor in the PCR cycle. Light is responsible for the formation of the energy needed for the cycle to occur, therefore without it the cycle comes to a halt as well. (‘Zhang, N., & Ports, A) (1999).
Explain how cells release energy through glycolysis, respiration, and fermentation. Identify pathways in each stage. Describe each stage’s role in releasing energy. As far as glycolysis is concerned, glucose serving as the nutrient for organisms, thus having a complete of its energy being stored with the ATP ( Adenosine Tri Phosphate), the energy currency of the cell which breaks down during the requirement of it and can make available to the living being with a complete energy and hence in this way cells release the energy through glycolysis. While in case of respiration, the energy is being released by photorespiration, that enables the plant to absorb more oxygen and a less concentration of carbon dioxide is stored with it and hence the energy releases due to unavailability of the required amount of concentration of carbon dioxide. In case of fermentation, it releases energy without oxygen. In cellular respiration, the cells involved breaks up the glucose into the smaller molecules which in turn releases a small amount of energy continuously. (“Wilson, J., & Hunt, T. (2002).
What is the role of enzymes in degrading starch and sugar? Explain your answer. Hydrolysis is the breaking down of a complex molecule, into smaller units, with the addition of water and utilizing enzymes as organic catalysts. Many carbohydrates like disaccharides and polysaccharides must be broken down to simple sugars or monosaccharide, so that they can be transported through the bloodstream to cells to be used for energy during respiration. Starch is a long chain of glucose molecules joined end to end by dehydration synthesis. To break the glycosidic bonds between the molecules, hydrolysis occurs. Enzymes used during these reactions are called glycosidase. Sucrose or table sugar is a popularly consumed disaccharide.  When hydrolyzed, it yields glucose and a fructose sugar. The enzyme sucrose is necessary to catalyze this reaction.  Lactase, another enzyme helps to hydrolyze lactose or milk sugar into simpler sugars. Amylase, an enzyme in saliva, helps to begin the digestion of starch in the mouth. Without enzymes, the breaking down or degradation of these large molecules would take too long. Enzymes allow chemical reactions to occur at a rapid pace at body temperature. (“Zhu, Z.-P., Hylton, C. M., Rössner, U., & Smith, A. M.”) (1998).
Discuss some similarities and differences between respiration and fermentation. As far as the similarity of both the respiration and photosynthesis is concerned, both are oxidation reactions and oxygen is being required for the respiration but for the fermentation process, there is no need of oxygen to remain within. While being from the point of view to put out the difference between them, it rather states that respiration helps in releasing more energy in comparison to the fermentation. Respiration takes place in aerobic conditions while the fermentation is an anaerobic process (“Ferrier, D. (2014).
Aerobic organisms are usually larger than anaerobic organisms. Suggest how this might be related to respiration. Many cells within the various plants are able to generate ATP (Adenosine Tri Phosphate) with either the help of the oxygen (aerobic) or without oxygen (anaerobic). Since, both the process helps to convert the starch, amino acids or the sugar in the ATP. But in case of aerobic respiration with the availability of oxygen, the sugar stores per molecule is much more than that of anaerobic respiration and hence can be said that aerobic organisms are usually larger than anaerobic organisms.( “Brown, A. H., & Weis, D. (1959).


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