Question

What are the waste products of respiration?

Answer 1

Respiration can be aerobic or anaerobic. 

Aerobic respiration is the process where organisms use the inhaled oxygen for set of metabolic processes to convert the nutrients into consumable energy form 'ATP'. Oxygen is used in Aerobic respiration to drive this nutrients to ATP cycle. In aerobic respiration, end products are Energy (ATP), CO2, and water. Out which CO2 is waste product. 

Anaerobic respiration is the process same as aerobic respiration with major difference that anaerobic organisms does not use Oxygen to create energy. Usually, this reaction generates los less ATP than aerobic respiration. Waste products that are generated from this type of respiration are Lactic Acid which is then oxidised to CO2 and water, H2S, Acetic Acid, and Nitrite/nitrogen gas. 

Answer 2

In humans respiration is carried in the presence of oxygen O2 which yields CO2, H2O and energy packets ATP. H2O and ATP are used in metabolic processes while CO2 is waste product so it is exhaled to the environment.
C6H12O6+6O2 ---------> 6CO2+6H2O+36ATP
If respiration is carried out in the absence of Oxygen O2 respiration yields lactic acid which later gives CO2 and H2O.