Question

How many ATP are formed from ${ NADPH }^{ + }$ to ${ NAD }^{ + }$?
 (a) 2 ATP
 (b) 3 ATP
 (c) 6 ATP
 (d) 4 ATP

Answer 1

Hint: The formation of ${ NADPH }^{ + }$ and NAD+ is a type of redox reaction where oxidation and reduction both take place with the consumption and liberation of ATP molecules. The production of ATP from NADPH is very common in the electron transport chain.

Complete answer:
The consumption and formation of ATP and NADPH are common in the photosynthesis and respiration process, but the formation of ATP from ${ NADPH }^{ + }$ to ${ NAD }^{ + }$ where1 ${ NADPH }^{ + }$ form 3 ATP molecule takes place in the ETC during cellular respiration.
ETC takes place in mitochondria therefore it is also called a mitochondrial respiratory chain. In the citric acid cycle glucose is completely oxidized without the liberation of energy, liberation of energy needs oxidation of NADH and ${ FADH }_{ 2 }$. In Complex I of the ETC cycle NADH oxidizes by the enzyme NADH dehydrogenase with the liberation of the electron. This electron gets a transfer to ubiquinone and ubiquinone also gets one more electron from ${ FADH }_{ 2 }$, and both this electron gets transfer into Complex II after that ubiquinone gets oxidize with the transfer of an electron from to cyt C in Complex III and Complex IV.
In this number of ATP synthesized is dependent upon electron donor where oxidation of 1NADH gives 3ATP and 1${ FADH }_{ 2 }$ gives 2ATP.

Additional Information: After the Kreb cycle terminal oxidation takes place in two processes (i) ETC and (II) oxidative phosphorylation.
In oxidative phosphorylation, ${ FADH }_{ 2 }$ is also liberating ATP molecules,1 ${ FADH }_{ 2 }$ gives rise to 2 ATP molecules. For the synthesis of ATP, the enzyme required is ATP synthetase which is present on the head of Fo-F1 or elementary particles. The enzyme ATP synthetase only becomes active when there is a proton gradient, a higher concentration of proton on the Fo side, and a lower concentration on the F1 side. When electrons flow from higher to lower side ATP liberate from ADP by enzyme ATP synthase. In this process also the formation of 3ATP takes place.
So, the correct answer is 3 ATP.

Note: In cellular respiration, the net gain of ATP is 38. Glycolysis produces a total of 8 ATP, pyruvic acid to acetyl produce 6 ATP, Kreb cycle produces 24 ATP. The majority of ATP is produced by NADH, only in the Kreb cycle, ${ FADH }_{ 2 }$ produces ATP with NADH.