The overall equation in this section,


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shows the cycle between photosynthesis and oxidation. Pathways operating in opposite directions cannot be exergonic in both directions.


a. Which of the two pathways in this cycle is exergonic and which is endergonic?

Verified step by step guidance

1. Understand the terms: Exergonic reactions release energy, while endergonic reactions require energy input.
2. Identify the two pathways: Photosynthesis and oxidation (cellular respiration).
3. Photosynthesis converts carbon dioxide and water into glucose and oxygen, requiring energy from sunlight, making it an endergonic process.
4. Oxidation (cellular respiration) breaks down glucose into carbon dioxide and water, releasing energy, making it an exergonic process.
5. Conclude that photosynthesis is endergonic and oxidation is exergonic.

Key Concepts

Photosynthesis

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy, specifically glucose, using carbon dioxide and water. This process occurs in chloroplasts and involves two main stages: the light-dependent reactions and the Calvin cycle. It is endergonic, meaning it requires energy input, primarily from sunlight.

Oxidation

Oxidation refers to the chemical process in which a substance loses electrons, often associated with the release of energy. In biological systems, oxidation typically involves the breakdown of glucose during cellular respiration, which is an exergonic process that releases energy. This energy is then used to fuel various cellular activities.

Exergonic and Endergonic Reactions

Exergonic reactions are those that release energy, making them spontaneous and often associated with processes like oxidation. In contrast, endergonic reactions require an input of energy to proceed, such as photosynthesis. Understanding the energy dynamics of these reactions is crucial for analyzing metabolic pathways and their interconnections.