Question

how many electrons are removed from sugar during cellular respiration when it is broken into 6co2 and water?

Answer 1

Following is the reaction-

C6H12​​​​​O6  + 12(O) ~~~~~> 6CO2 + 6H2​​​​​​O

12 oxygen are used here and one oxygen can accept two electrons so total electrons transferred by glucose when oxidized into CO2 would be 24 or 12 pair.

Or you can calculate by counting the number of NADH and FADH2.

In glycolysis 2 NADH

In pyruvate to acetyl CoA conversion- 2 NADH

In TCA- 6 NADH and 2 FADH2

Total = 12

One NADH and FADH2 has taken 2 electrons. So total 24 electrons