What percentage of the atmosphere does oxygen form?

• 21%

• 78%

• 32%

• 15%

What is the term used for the circulation and recycling of oxygen within the biosphere?

• Oxygen cycle

• Nitrogen cycle

• Water cycle

• Carbon cycle

Which process releases oxygen in the biosphere?

• Corrosion

• Photosynthesis

• Combustion

• Respiration

What is the term for microbes that use oxygen for respiration?

• Obligate anaerobes

• Anaerobes

• Aerobes

• Facultative anaerobes

What is the chemical formula for water?

• H2O2

• CO2

• O3

• H2O

Which of the following is not a form in which oxygen is found?

• Ozone (O3)

• Carbon dioxide (CO2)

• Nitrogen (N2)

• Molecular oxygen (O2)

What is the term for microbes which do not need oxygen?

• Obligate anaerobes

• Facultative anaerobes

• Anaerobes

• Aerobes

What is the importance of oxygen in the biosphere?

• All of the above

• Synthesis of proteins, carbohydrates, and fats

• Formation of ozone (O3)

• Used in various chemical reactions

What is the chemical formula for carbon dioxide?

• CO2

• O3

• H2O2

• H2O

What is the term for the process of oxygen being used up in the biosphere?

• Photosynthesis

• Respiration

• Combustion

• Corrosion