Cellular Respiration

Cellular Respiration, although the inputs and outputs seem easy, the process is very convoluted and complicated. Lucky for you, we’re going to simplify it to a point that is appropriate for a High School Biology student.

Keep in mind that Photosynthesis & Cellular Respiration are reciprocal reactions. What that means is that the requirements of Cellular Respiration are the products of Photosynthesis! Likewise, the products of Cellular Respiration are the requirements of Photosynthesis! Its a 3 Billion year long symbiotic relationship! (And you thought your month-long high school girlfriend was a long-term commitment!)

Here is the jist of what Aerobic (meaning with Oxygen present) Respiration entails…


Aerobic Respiartion


  • Uses 2 ATP to break down Glucose
  • NADH & 4ATP (net gain +2 ATP)¬†are created.
  • The NADH goes to the Krebs Cycle.

Krebs Cycle

  • Uses Oxygen and Acetyl-CoA
  • Makes¬†2 ATP, NADH, & FADH2 (both of which are electron carriers)
  • Carbon Dioxide is given off as a byproduct.
  • The NADH goes on to the ETC

Electron Transport Chain

  • Uses Oxygen and NADH
  • Make 32 ATP and Water (used as an electron acceptor)