Why does photosynthesis require biological catalysts?
The various reactions in photosynthesis require biological catalysts, which are called enzymes.
Photosynthesis occurs in 2 main steps, i.e. Hill's reaction or Light reaction and Blackmann's reaction or Dark reaction.
Light reaction occurs in presence of light. Dark reaction does not require light. The various steps of dark reaction occur, irrespective of presence or absence of light.
The various steps of dark reaction are controlled by enzymes, the biological catalysts. The enzymes differ from catalysts as their activity is controlled by a number of factors like temperature, pH of the medium, concentration of substrate or end products. Most of the reactions controlled by enzymes are reversible