The Krebs cycle or the TCA cycle produces 2 C O 2 for every 1 molecule of acetyl CoA . This occurs in Step 3 and Step 4 of the Krebs cycle. In Step 3, isocitrate is oxidized to become alpha-ketoglutarate by the rate-limiting enzyme, isocitrate dehydrogenase . In Step 4, alpha-ketoglutarate undergoes a redox reaction, oxidizing to become succinyl-CoA , also releasing C O 2 in the process. Each step generates the coenzyme, NADH , an electron carrier which is going to be important in the next stage of cellular respiration, the electron transport chain.
It's because there is no water left on the surface, which helps cooling down the planet and the atmosphere contains thick and excessive carbon dioxide which traps the heat, causing the planet to heat up.
