Which chemical equation represents a process that takes place in yeast cells?

A. [tex]CO_2 + H_2O + \text{light energy} \rightarrow O_2 + \text{sugar}[/tex]

B. [tex]O_2 + \text{sugar} \rightarrow CO_2 + H_2O + \text{light energy}[/tex]

C. [tex]O_2 + \text{sugar} \rightarrow CO_2 + H_2O + \text{ATP energy}[/tex]

D. [tex]CO_2 + H_2O + \text{ATP energy} \rightarrow O_2 + \text{sugar}[/tex]



Answer :

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 (COâ‚‚) 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.

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