ASVAB Practice

Photosynthesis and Cellular Respiration

Photosynthesis (in chloroplasts):

CO₂ + H₂O + light → glucose (C₆H₁₂O₆) + O₂

Plants capture light with chlorophyll, use it to fix CO₂ into glucose, and release oxygen as a byproduct. The foundation of nearly all food chains.

Cellular Respiration (in mitochondria):

Glucose + O₂ → CO₂ + H₂O + ATP

Breaks down glucose to release stored energy.

• Aerobic respiration: Requires oxygen; produces ~36–38 ATP per glucose molecule.
• Anaerobic respiration (fermentation): No oxygen; produces only 2 ATP; produces lactic acid (muscle cells) or ethanol + CO₂ (yeast).
• Most ATP is produced in the electron transport chain on the inner mitochondrial membrane.