We have till now seen that glucose has been broken down to release CO2 and eight molecules of NADH + H+ and two of FADH2 have been synthesised besides just two molecules of ATP in TCA cycle. You may be wondering why we have been discussing respiration at all – neither O2 has come into the picture nor the promised large number of ATP has yet been synthesised. Also what is the role of the NADH + H+ and FADH2 that is synthesised? Let us now understand the role of O2 in respiration and how ATP is synthesised.
Adjacent to a frequently-asked paragraph in the same chapter.
Practice This Concept
QuestionPredicted for NEET 2027
Which metabolic process contributes to only 2 ATPs despite involving many steps?
📖 Solution & NCERT Explanation
View solution & NCERT explanation
Correct answer: B — Krebs cycle
Only one GTP (converted to ATP) per turn is produced per acetyl-CoA.
❓ Frequently Asked Questions
What does NCERT say about We have till now?
We have till now seen that glucose has been broken down to release CO2 and eight molecules of NADH + H+ and two of FADH2 have been synthesised besides just two molecules of ATP in TCA cycle. You may be wondering why we have been discussing respiration at all – neither O2 has come into the picture nor the promised large number of ATP has yet been synthesised.
Has this concept appeared in NEET?
High probability for NEET 2027. Adjacent to a frequently-asked paragraph in the same chapter.
Which chapter is this from?
Respiration in Plants, Class 11 NCERT Biology.
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180
of the ReNEET 2026 paper (all subjects) was already in the MedicNEET question bank
MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.
176 of 180 ReNEET 2026 questions traced to MedicNEET17,000+ Biology questionsHindi + English