What can you infer from the fact that nitrogen gas (\(N_2\)) is useless to animals?

• A. Animals cannot directly utilize atmospheric \(N_2\) because they lack the enzymes to break its triple bond.
• B. Nitrogen gas is highly soluble in water and easily absorbed by animal tissues.
• C. Animals convert nitrogen gas into glucose for energy.
• D. Animals use nitrogen gas directly for cellular respiration.

Answer: (A)

Verified step by step guidance

1. Understand the chemical structure of nitrogen gas (\(N_2\)). Nitrogen gas consists of two nitrogen atoms connected by a strong triple bond, which makes it chemically stable and difficult to break apart.
2. Recognize that animals lack the specific enzymes required to break the triple bond in \(N_2\). These enzymes, such as nitrogenase, are found in certain bacteria and archaea, not in animals.
3. Learn how nitrogen becomes biologically available. Nitrogen-fixing bacteria convert atmospheric \(N_2\) into ammonia (\(NH_3\)) or other compounds that can be used by plants and subsequently by animals through the food chain.
4. Clarify the incorrect statements in the problem. Nitrogen gas is not highly soluble in water, nor is it absorbed directly by animal tissues. Animals do not convert nitrogen gas into glucose or use it directly for cellular respiration.
5. Conclude that animals rely on nitrogen in a biologically available form, such as amino acids or nucleotides, which are obtained indirectly through their diet rather than directly from atmospheric \(N_2\).