Calculate the rate of photosynthesis mmhr for Elodea if when

Calculate the rate of photosynthesis (mm/hr) for Elodea if when measuring net photosynthesis, the water level moved up 7mm from the initial level in 10 min, and when measuring cellular respiration it took 15 minutes for the water level to mve down 1 mm.

Solution

Water level moved up by 7mm in 10 mins of photosynthesis and drop back to 1mm in 15 mins. In order to measure net photosynthesis, we have to find the level of water moved up during photosynthesis in 15 mins. Volume of water moved up in 15 mins of photosynthesis will be 7*1.5 = 10.5

In 15 mins water level down to 1mm from 7 mm so net downward movement of water in 15 mins is 7-1 = 6mm

So, net movement of water after photosynthesis and respiration is 10.5 – 6 = 4.5 mm in 15 mins.

So, the rate of photosynthesis for 15 mins is 4.5 mm

So, rate of photosynthesis in mm/hr will be 4.5*4 = 18mm/hr