51. Which one of the following statements is NOT common between oxidativephosphorylation and
photophosphorylation?
(a) Generation of ATP
(b) Involvement of a kinase
(c) Involvement of electron transport
(d) Involvement of oxygen

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Introduction

Both oxidative phosphorylation and photophosphorylation are processes involved in the production of ATP, which is essential for cellular energy. While they share some similarities, they occur in different cellular compartments and under different conditions. Let’s delve into these processes to better understand where they differ and identify the correct answer to this question.

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What are Oxidative Phosphorylation and Photophosphorylation?

• Oxidative Phosphorylation: This process occurs in the mitochondria of eukaryotic cells. It involves the electron transport chain (ETC) and the enzyme ATP synthase to generate ATP, using oxygen as the final electron acceptor. Oxygen plays a crucial role in this process.

• Photophosphorylation: This process takes place in the chloroplasts of plant cells during photosynthesis. It uses light energy to drive the electron transport chain, leading to the production of ATP. Oxygen is produced as a byproduct but is not involved in the same way as in oxidative phosphorylation.

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Analyzing the Options

Let’s break down the provided options to determine which statement does NOT apply to both processes:

• (a) Generation of ATP: True for both processes. Both oxidative phosphorylation and photophosphorylation result in the generation of ATP. In oxidative phosphorylation, ATP is generated by the electron transport chain and ATP synthase. In photophosphorylation, ATP is generated during the light-dependent reactions of photosynthesis.

• (b) Involvement of a kinase: True for both processes. In both processes, a kinase (specifically ATP synthase) is involved in the generation of ATP from ADP and inorganic phosphate.

• (c) Involvement of electron transport: True for both processes. Both processes involve an electron transport chain (ETC) to transfer electrons, creating a proton gradient that drives ATP synthesis. In oxidative phosphorylation, the ETC occurs across the inner mitochondrial membrane, while in photophosphorylation, it occurs across the thylakoid membrane of the chloroplast.

• (d) Involvement of oxygen: NOT true for both. Oxygen is a crucial electron acceptor in oxidative phosphorylation, but in photophosphorylation, oxygen is a byproduct of splitting water molecules during the light-dependent reactions of photosynthesis. The key difference here is that oxygen is consumed in oxidative phosphorylation, while it is released in photophosphorylation.

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Conclusion

The statement that is NOT common between oxidative phosphorylation and photophosphorylation is (d) Involvement of oxygen, as oxygen is consumed in oxidative phosphorylation but is released as a byproduct in photophosphorylation.

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Correct Answer: (d) Involvement of oxygen