Chapter 3, Problem 1Q

Summary Introduction

To explain: Whether the reaction “$\text{light}\text{energy}\text{+}{\text{CO}}_{\text{2}}\text{+}{\text{H}}_{\text{2}}\text{O}\to \text{sugars}\text{+}{\text{O}}_{\text{2}}\text{+}\text{heat}\text{energy}$” occurs in a single step or not.

Introduction: Photosynthesis is a process by which carbon dioxide and water are used to produce glucose molecules using energy from sunlight. During this process, oxygen gas is evolved. The process of conversion of light energy to the chemical energy occurs in two phases of reactions, that is, the light-dependent reaction and carbon fixation reaction (dark reactions).

Explanation of Solution

The above given Equation characterizes the chemical reaction of photosynthesis. Photosynthesis continues through a number of reactions steps that are catalyzed by many distinct enzymes. Hence, this reaction involves various steps, and not a single step.

Conclusion

The reaction “$\text{light}\text{energy}\text{+}{\text{CO}}_{\text{2}}\text{+}{\text{H}}_{\text{2}}\text{O}\to \text{sugars}\text{+}{\text{O}}_{\text{2}}\text{+}\text{heat}\text{energy}$” involves various steps.

Summary Introduction

To explain: The reason for heat production in the given reaction.

Introduction: In photosynthesis, organisms utilize light energy to produce high energy sugar molecules that are taken as food. In some reactions, due to the rapid vibration of chemical bond energy, heat is dispersed to the cellular environment that causes disorder in molecular event of the cell.

Explanation of Solution

The given Equation describes the “outcome” of photosynthesis. In photosynthesis, energy conversion takes place in various steps. Throughout photosynthesis, light energy is converted into chemical-bond energy, which undergoes rapid molecular motion to produce heat energy. As law of thermodynamics explains that in photosynthesis, enzymes speed up the energetically favorable reaction. They create energy rich and highly ordered molecules from small ones that requires the involvement of energy. In this reaction, sugars are the most complex molecules that are produced and increase the ordered state in the cell. Further, according to the second law of thermodynamics, during various stages of photosynthesis, higher disorders are generated. This is because heat is generated in various reactions along the pathway, which leads to the production of complex sugar as final products.