Question

What are the total number of ATP molecules generated at the end of every respiration cycle in each cell?

• A. 36
• B. 46
• C. 38
• D. 32

Answer 1

The correct option is C 38

In every respiration cycle, at the cellular level, energy is produced which can be used by the cells.
The glucose absorbed by the villi is transported to every cell in the body.
The glucose obtained by every cell is a carbon compound but not a form of energy that can be directly utilized by the body. So, it is broken down into pyruvate which is a three carbon compound to release energy.

$C_6{H}_{12}{O}_6\to 2Pyruvat{e}_{2}ATP+2NADH$

The ATP and NADH are energy molecules which can be used by the cells. The above process is called Glycolysis.
Pyruvate further undergoes a cycle of changes to release more energy and carbon dioxide. The energy obtained in this process is utilized by the cells.

$Pyruvate\to 6C{O}_2+2ATP+8NADH+2FAD{H}_2$

Each NADH gives 3 molecules of ATP and each $FAD{H}_2$ gives 2 molecules of ATP.
Breakdown of glucose released 4 ATP, 10 NADH and $2FAD{H}_2$ molecules. Calculating the energy in terms of ATP molecules,

10 NADH = 10 $\times$ 3 = 30 ATP molecules
$2FAD{H}_2$ = 2 $\times$ 2 = 4 ATP molecules

Therefore, a total of 38 ATP molecules are obtained at the end of every respiration cycle in a cell.