Question

Explain photosynthesis in plant living in desert

Answer 1

Dear student.

• In desert plants, the CO₂ is stored in the form of an acid before use in photosynthesis.
• Stomata open at night (when evaporation rates usually lower) and are usually closed during the day.
• The CO₂ is converted to an acid and stored during the night. During the day, the acid is broken down and the CO₂ is released to RUBISCO for photosynthesis.
• This is called CAM Photosynthesis. (Crassulacean Acid Metabolism).

Crassulacean acid metabolism is a carbon fixation pathway present in some plants such as desert plants. These plants fix carbon dioxide during the night, storing it as the four-carbon acid, malate. The malate is then reduced to a three-carbon compound oxaloacetic acid and the CO₂ is released during the day, where it is concentrated around the enzyme RuBisCO, thus increasing the efficiency of photosynthesis. The CAM pathway allows stomata to remain shut during the day, reducing transpiration; therefore, it is especially common in plants adapted to arid conditions.

Regards.