the answer is... hydrocarbons
First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst.
Answer:NADH donates it electron to complex I a higher energy level than other complexes while FADH donates it electron to complex II a lower energy complex.
Explanation:
Both NADH and FADH are shuttle of high energy electrons originally extracted from food into the inner mitochondrial membrane.
NADH donate it electron to a flavoprotein consisting of FMN prosthetic group and an iron-sulphur protein in ETC complex-I. Two electrons and one hydrogen ion are are transferred from NADH to the flavin prosthetic group of the enzyme.
While the electrons from FADH2 enters the ETC (electron transport chain) at the level of co-enzyme Q (complex II). This step does not librate enough energy to act as a proton pump.
So NADH produces 2.5 ATP during the ETC and oxidative phosphorylation because it donates its electron to Complex I, which pump more electrons across the membrane than other complexes.
