The products of tissue respiration are_________

Step 1: Analyze the question It asks for the products of tissue (cellular) respiration. Products are what is formed, not what is used up.

Step 2: The concept Tissue respiration is the breakdown of food substances (usually glucose) inside the cells, releasing energy. In the presence of oxygen (aerobic respiration), the equation is:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (38 ATP)

• Reactants (used up): glucose and oxygen
• Products (formed): carbon dioxide, water, and energy

Step 3: Check each option

• A. glucose, oxygen, and water: Glucose and oxygen are reactants, not products. Wrong.
• B. oxygen, water, and energy: Oxygen is a reactant. Wrong.
• C. glucose, carbon dioxide, and energy: Glucose is a reactant. (It is a product of photosynthesis, not respiration.) Wrong.
• D. water, carbon dioxide, and energy: All three are products of respiration. Correct.

Step 4: Answer The correct option is D.

Exam tip: Remember that respiration and photosynthesis are opposites.

• Photosynthesis: CO₂ + H₂O + light → glucose + O₂
• Respiration: glucose + O₂ → CO₂ + H₂O + energy

So the products of respiration (CO₂, H₂O, energy) are the raw materials of photosynthesis, and vice versa. If you see glucose or oxygen listed as a product of respiration, eliminate that option immediately.