Question

which statement is false about the nitrogen cycle? *
all organisms need nitrogen to build proteins
nitrogen makes up 78% of the atmosphere
the human body can use nitrogen gas directly from the atmosphere

Explanation:

• Proteins contain nitrogen, so all organisms need nitrogen to build proteins. This statement is true.
• Nitrogen indeed makes up about 78% of the Earth's atmosphere. This statement is true.
• The human body cannot use nitrogen gas (\(N_2\)) directly from the atmosphere. Nitrogen gas needs to be converted into forms like nitrates (\(NO_3^-\)) or ammonia (\(NH_3\)) through processes like nitrogen fixation (by bacteria) before it can be used by plants and then by animals (including humans) in a usable form for building proteins and other nitrogen - containing compounds.

Answer:

The false statement is "The human body can use nitrogen gas directly from the atmosphere".