Yeast cells primarily engage in a process known as fermentation, but they are also capable of aerobic respiration in the presence of oxygen. To understand which chemical equation reflects a process in yeast cells, we need to consider both fermentation and aerobic respiration.
1. Fermentation: In the absence of oxygen (anaerobic conditions), yeast cells convert sugar (glucose) into carbon dioxide (CO₂) and ethanol (alcohol), producing a small amount of ATP (energy).
Simple balanced equation for fermentation:
[tex]\[ \text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_2\text{H}_5\text{OH} + 2\text{CO}_2 + \text{ATP}\][/tex]
2. Aerobic Respiration: In the presence of oxygen, yeast cells can perform aerobic respiration. This process utilizes oxygen to fully break down sugar into carbon dioxide and water, producing a significant amount of ATP.
Balanced equation for aerobic respiration:
[tex]\[ \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}\][/tex]
Evaluate the options:
A. [tex]\( \text{CO}_2 + \text{H}_2\text{O} + \text{light energy} \rightarrow \text{O}_2 + \text{sugar} \)[/tex]
- This equation represents photosynthesis, not a process that occurs in yeast cells.
B. [tex]\( \text{O}_2 + \text{sugar} \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{light energy} \)[/tex]
- This is not accurate for yeast cells or any respiration process. The production of light energy is not a characteristic of cellular respiration.
C. [tex]\( \text{O}_2 + \text{sugar} \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{ATP energy} \)[/tex]
- This represents the process of aerobic respiration, which can occur in yeast cells when oxygen is present.
D. [tex]\( \text{CO}_2 + \text{H}_2\text{O} + \text{ATP energy} \rightarrow \text{O}_2 + \text{sugar} \)[/tex]
- This equation does not represent a process in yeast cells. It seems to imply reverse respiration or photosynthesis, which is not relevant for yeast.
Conclusion:
The correct chemical equation representing a process that takes place in yeast cells is:
[tex]\[ \text{O}_2 + \text{sugar} \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{ATP energy} \][/tex]
Therefore, the answer is C.
