Final answer:
CAM plants fix CO2 at night and perform photosynthesis during the day, similar to C4 plants in photosynthetic chemistry, but with a temporal rather than spatial separation of the carbon fixation process. The correct option is (b) C4 plants.
Step-by-step explanation:
Plants with crassulacean acid metabolism (CAM) adopt a unique strategy to optimize water use efficiency by separating the processes of carbon fixation and the rest of photosynthesis in time. They fix CO2 at night and carry on the photosynthetic process during daylight hours.
Despite this temporal separation of processes, CAM plants share the most similarities in their photosynthetic chemistry with C4 plants. Both CAM and C4 plants utilize PEP carboxylase for the initial fixation of CO2 and store the resulting four-carbon compounds. However, while C4 plants separate this process spatially between mesophyll and bundle sheath cells, CAM plants do so temporally, with CO2 fixation happening at night when stomata are open and photosynthesis occurring during the day when stomata are closed to conserve water.
Furthermore, just like C4 plants, CAM plants eventually use the Calvin Cycle for the synthesis of sugars, albeit during the day in the case of CAM plants. This adaptation helps CAM plants, such as cacti and other succulents, thrive in arid environments where water conservation is crucial. In essence, the key difference between CAM and C4 plants is the temporal versus spatial organization of carbon fixation. To answer the student's question: CAM plants are most similar to C4 plants in their photosynthetic chemistry.
Given this information, we can conclude that the correct option answer is (b) C4 plants.