Question

What is the effect of carbon dioxide on the rate of respiration in plants?

• A. Rate of respiration in plants decreases with increase in $C{O}_2$ concentration
  
• B. Carbon dioxide has no effect on respiration rate
• C. Rate of respiration first increases then decreases with increase in $C{O}_2$ concentration
  
• D. Rate of respiration in plants increases with increase in $C{O}_2$ concentration

Answer 1

The correct option is A Rate of respiration in plants decreases with increase in $C{O}_2$ concentration


As the carbon dioxide concentration increases, the rate of respiration in plants decreases. This is because high $C{O}_2$ concentration would result in closing of the stomata. High $C{O}_2$ concentration induces the calcium sensors to increase the calcium ion concentration. The closing or opening of stomata is dependent on the calcium ion concentration. When the calcium ion concentration is more inside the cell, then the stomatal pore closes but when calcium ion concentration is less, stomatal pore opens. Thus rate of respiration is inversely proportional to the concentration of carbon dioxide.