Which substance is needed by animals to survive and is released into the environment by plants during photosynthesis?

• A. Carbon dioxide (\(CO_2\))
• B. Glucose (\(C_6H_{12}O_6\))
• C. Oxygen (\(O_2\))
• D. Nitrogen (\(N_2\))

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the process of photosynthesis, which is the method plants use to convert light energy into chemical energy. During this process, plants take in carbon dioxide (\(CO_2\)) and water (\(H_2O\)) and use sunlight to produce glucose (\(C_6H_{12}O_6\)) and oxygen (\(O_2\)).
2. Step 2: Recall the chemical equation for photosynthesis: $6_{}\mathrm{CO}{2}_{}+6_{}H{2}_{}O\to C_{}{6}_{}H{\mathrm{12}}_{}O{6}_{}+6_{}O{2}_{}$. This equation shows that oxygen (\(O_2\)) is a byproduct of photosynthesis.
3. Step 3: Consider the needs of animals for survival. Animals require oxygen (\(O_2\)) for cellular respiration, a process that allows them to convert glucose (\(C_6H_{12}O_6\)) into energy. Without oxygen, animals cannot efficiently produce energy.
4. Step 4: Compare the options provided in the question. Carbon dioxide (\(CO_2\)) is used by plants during photosynthesis, not released. Glucose (\(C_6H_{12}O_6\)) is a product of photosynthesis but is primarily used by plants themselves. Nitrogen (\(N_2\)) is not directly involved in photosynthesis. Oxygen (\(O_2\)), however, is released by plants and is essential for animal survival.
5. Step 5: Conclude that the correct answer is oxygen (\(O_2\)), as it is the substance released by plants during photosynthesis and required by animals for survival.