Question

Complete the following table (Carefully study the carbon, oxygen, and nitrogen cycles). 

Bio-geo-chemical cycles	Biotic processes	Abiotic processes
1. Carbon cycle
2. Oxygen cycle
3. Nitrogen cycle

Answer 1

Bio-geo-chemical cycles	Biotic processes	Abiotic processes
1. Carbon cycle	Release of oxygen and CO2 through photosynthesis and respiration respectively.	Release of CO2 in the atmosphere by the burning of fossil fuels, wood, etc.
2. Oxygen cycle	Release of O2 through photosynthesis and its consumption in processes like respiration etc.	Photodissociation of water vapour in the upper atmosphere, as a result of which oxygen is released when water molecules are split by light and combustion.
3. Nitrogen cycle	Nitrogen fixation, nitrification, ammonification	Nitrogen fixation in the atmosphere and denitrification