In a salt marsh in Georgia, the quantity of solar radiation reaching the ground during the summer is 7,000,000cal/m2/day. The gross productivity of the producers in the salt marsh (mostly microscopic algae) is 0.0040 g/cm2/day. The average rate of respiration (the respiration requirement) is 35% of the gross primary productivity. Ecologists have found that 1 gram of salt marsh producers (the algae) is equivalent to 2,920 calories. a. Calculate the net primary productivity of the system, in g/m2/day. b. Calculate the efficiency of photosynthesis