Respiration

Question 1

ATP Production

Answer 1

1. H atoms dissociate from NADH and FADH2, and are split to form H+ and electrons
2. Electrons are passed down the ETC, comprising of a series of electron carriers of progressively lower energy levels to the final electron acceptor, oxygen, via redox
3. Energy released during the transfer is used to pump H+ via active transport from the mitochondrial matrix, across the inner mitochondrial membrane, into the intermembrane space
4. Since the intermembrane space is impermeable to H+, accumulation of H+ sets up an electrochemical and proton gradient between the intermembrane space and mitochondrial matrix for ATP synthesis by chemiosmosis
5. H+ diffuses down the proton gradient from the intermembrane space, back to the mitochondrial matrix through ATP synthase, releasing electrical potential energy, driving phosphorylation of ADP to ATP, catalysed by ATP synthase

Question 2

Function of oxygen OR Water formation

Answer 2

1. Oxygen is the final electron acceptor at the end of the electron transport chain
2. Electrons are accepted by oxygen, thus electron carriers along the ETC are oxidised, enabling continued NAD and FAD regeneration
3. This maintains electron flow along the ETC and the built up of proton gradient

Question 3

Why lesser glucose OR lesser yield of ATP

Answer 3

1. During aerobic respiration, for every glucose molecule broken down and oxidised, 2 ATP is formed each during glycolysis and Krebs Cycle, and 34 ATP is formed during oxidative phosphorylation, giving a total of 38 ATP
2. During anaerobic respiration, for every glucose molecule broken down and oxidised, 2 ATP is formed during glycolysis
3. This means that 19 times less glucose is needed during aerobic conditions compared to anaerobic conditions, to produce the same number of ATP for cell metabolism