Chapter 23.5, Problem 29SSC

Interpretation Introduction

Interpretation:

The processes of photosynthesis, cellular respiration and fermentation should be compared and contrast.

Concept introduction:

The reaction in which one or more species that are reactants reacts with each other two form one or more different species that are products is known as chemical reaction.

Explanation of Solution

Cellular Respiration:

A set of metabolic reactions which takes place in the organism cell to convert chemical energy from molecules of oxygen into ATP that is adenosine triphosphate is known as cellular respiration. In this process, glucose breaks down in the presence of oxygen and produces carbon dioxide with release of water and energy.

The chemical reaction is:

${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{+6O}}_{\text{2}}\to {\text{6CO}}_{\text{2}}{\text{+6H}}_{\text{2}}\text{O+energy}$

Photosynthesis:

The process in which light energy converts into chemical energy and stores the energy in chemical bonds of sugar or sugar like species is known as photosynthesis. In this process, carbon dioxide reacts with water molecules to form glucose and oxygen.

The chemical reaction is:

${\text{6CO}}_{\text{2}}{\text{+6H}}_{\text{2}}\text{O+Energy}\to {\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{+6O}}_{\text{2}}$

According to the above two reactions, photosynthesis process is reverse of the cellular respiration process.

Fermentation:

A metabolic process which results chemical changes in organic substrates by the action of enzymes is known as fermentation. It is also defined as the energy is extracted from the carbohydrates in the absence of oxygen. In this process, glucose breaks down in the absence of oxygen.

The chemical reaction is:

${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}\to {\text{2C}}_{\text{2}}{\text{H}}_{\text{5}}\text{OH}+\text{2CO}$

Thus, in cellular respiration, glucose breaks down in the presence of oxygen whereas in photosynthesis carbon dioxide reacts with water in the presence of energy to form glucose. But, in fermentation process, glucose breaks down in the presence of enzyme to form ethanol and carbon monoxide.