question archive The mitochondrion and chloroplast work together through a series of energy transformations to enable green plants to thrive
The mitochondrion and chloroplast work together through a series of energy transformations to enable green plants to thrive
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The mitochondrion and chloroplast work together through a series of energy transformations to enable green plants to thrive.
The reaction C6H12O6 + 6O2 → 6CO2 + 6H20 provides an overall summary of the exergonic release of some 2,870 kJ of energy per mole of glucose oxidised, which, in turn, yields approximately 30 ATP per mole of glucose oxidised (where ATP is the universal energy currency).
a) Given Cellular Respiration is not 100% efficient and considering the first Law of Thermodynamics: apart from ATP synthesis, explain how else energy is released when glucose is oxidised. [2 marks]
Your answer:
b) Considering a plant cell, discuss this statement: "The mitochondrion is responsible for most but not all the ATP produced for cellular work in this cell."
In your answer, include a very brief description of all the processes that produce this ATP in the cell, and where these processes occur. [5 marks]
Your answer:
c) Discuss this statement: "Photorespiration is considered by many to be a wasteful process and therefore an evolutionary oversight."
In your answer, state what is meant by photorespiration and describe the biological adaptation (mechanism) CAM (Crassulacean Acid Metabolism) plants have evolved that concentrates carbon and thus enables these plants to minimise photorespiration.
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a) Energy is released as heat.
b) In the chloroplast, an organelle that is unique to plant cells, photosynthesis takes place. Photosynthesis produces ATP in order for the plant to make glucose.
c) Photorespiration is the process by which plants utilize oxygen and release carbon dioxide. Basically, it is the opposite of photosynthesis. CAM plants mitigate photorespiration by performing carbon dioxide fixation and the Calvin cycle at different times.
a) The efficiency of cellular respiration is estimated by chemists to be about 40%, with the remaining 60% being given off as heat.
b) During photosynthesis, a plant utilizes water, carbon dioxide, ang light energy in order to produce molecules of energy called ATP, and then they use this ATP to build glucose. The process of photosynthesis occurs in the chloroplasts of the plant cell. Therefore, in addition to mitochondrial ATP synthesis, plants can also produce ATP by photsynthesis in their chloroplasts.
c) On the molecular level, photorespiration occurs when the enzyme rubisco that is used in the Calvin cycle acts on oxygen instead of carbon dioxide. It is considered wasteful because it spends energy. To minimize the effect of photorespiration, CAM plants perform carbon dioxide fixation and the Calvin cycle at different times.
