INDLS Oxygen Cycle

What percentage of the atmosphere is composed of free oxygen?

• 21%

• 30%

• 50%

• 10%

Which two processes are described as complementary in maintaining the balance of oxygen in the atmosphere?

• Evaporation and condensation

• Respiration and combustion

• Photosynthesis and combustion

• Photosynthesis and respiration

What is the role of oxygen in the process of respiration?

• It helps in breaking down food to release carbon dioxide.

• It combines with carbon to form carbon dioxide.

• It acts as a catalyst in the digestion of food.

• It is used to produce sugars and other organic molecules.

Which process adds oxygen to the atmosphere by dissociating water vapor?

• Decomposition

• Photo dissociation

• Combustion

• Fermentation

What happens to oxygen during its cycle in nature?

• It combines with various elements to form compounds.

• It is permanently converted to ozone.

• It remains in its free form without combining.

• It is only consumed by living organisms.