Nutrients Pollution
Surface Water Pollution
Oxygen Pollution
The one advantage of using DNS assay to detect maltose production is the formation of a soluble and colored product compound.
The reaction that occurs between maltose and DNS in the assay is a redox reaction (reduction and oxidation) such that maltose gets oxidized and becomes Maltonic Acid while the DNS gets reduced into reduced DNS. The intensity of orange/brown /red color of reduced DNS is proportionately related to the amount of Maltose in the solution.
Electricity could be discovered using batteries based on zinc or lead, but without copper wiring it would remain little more than a scientific curiosity. Electric motors and generators require large amount of wiring, so they are impossible to build on large scale in this world
I think it would be the sclereids cells
Photosynthesis puts oxygen in the atmosphere.