Chlorophyll: green photosynthetic pigment that absorbs sunlight and uses its energy to synthesise carbohydrates from CO2 and water; Nostoc: an example of Diazotroph that fix atmospheric nitrogen gas into a more usable form such as ammonia; Transpiration: evaporation of water from plant leaves; Rust of Wheat: a fungal plant disease that affects wheat, barley and rye stems, leaves and grains.