Here's why:
* BTB is a pH indicator: BTB changes color based on the acidity or alkalinity of a solution.
* CO2 and pH: When CO2 dissolves in water, it forms carbonic acid (H2CO3), which increases the acidity of the solution.
* BTB color change: BTB is blue in basic solutions and yellow in acidic solutions. Therefore, the increase in acidity due to CO2 production will cause the BTB to turn yellow.
In summary, cellular respiration produces CO2, which makes the solution acidic, causing BTB to change from blue to yellow.
