In glycolysis, glucose is broken down. 2 ATP are required for glycolysis to begin, resulting in a creation of 4 ATP. This is a net of 2 ATP. NADH is created from , not the other way around. While 7 of the 10 steps of glycolysis are reversible, the other 3 are irreversible. Finally, if ATP is plentiful, there is no need for glycolysis to speed up (it will actually likely slow down).

Glycolysis is the only of the above choices that occurs in the cytoplasm. The remaining occur in different parts of the mitochondria. The Krebs cycle occurs in the mitochondrial matrix. Both oxidative phosphorylation and the electron transport chain occur along the inner mitochondrial membrane.

 in unrelated to the Krebs cycle and the electron transport chain.  is produced during the pentose phosphate pathway, which is a branch off of glycolysis. The first phase of the pentose phosphate pathway is called the oxidative phase, and is where  is created. During the second phase, five-carbon sugars are created, the most important being ribose-5-phosphate.

In glycolysis, glucose is oxidized, and the final products are 2 pyruvate, 2 ATP, and 2 NADH. The first step is irreversible, and is the conversion of glucose to glucose-6-phosphate by the enzyme hexokinase. The only remaining answer choice is "every step is irreversible." That statement is false. Steps 1,3, and 10 are irreversible, but the remaining steps are reversible.

Fructose is mainly metabolized by the liver from sugar, honey and fruits. Fructose can be converted to fructose-1-phosphate and then to dihydroxyacetone phosphate (DHAP) and glyceraldehyde.

NADPH is a molecule created during the oxidative phase of the pentose phosphate pathway. It is used in anabolic reactions, specifically in the formation of fatty acids. Another important role is that it acts as an anti-oxidant. Finally, NADPH is easily discriminated from NADH in the body because of an additional attached phosphate group. This allows the body to regulate the concentrations of the two similar molecules independently.

A dehydrogenase is an enzyme that removes hydrogen ions from a molecule, thereby oxidizing it.Lactate dehydrogenase converts lactate to pyruvic acid and NADH to NAD+ in glycolysis.The reaction is reversible, in which case it provides pyruvate for gluconeogenesis.Lactate dehydrogenase is present in most tissues with some isoforms more frequent than others. For example, isoenzyme LDH-1 is found in the heart, red blood cells, and brain.

Complex I (NADH-CoQ reductase) contains iron-sulfur proteins, and complex II (succinate-CoQ reductase) contains both heme and iron-sulfur proteins. Thus, iron deficiency would compromise the function of complex I and II. The other enzyme complexes do not have iron-containing proteins, thus, they would not be impaired by an iron deficiency.

Complex IV (cytochrome oxidase) contains two copper centers,  and , thus a copper deficiency would result in loss of function of enzyme complex IV. The other enzyme complexes do not contain copper, thus, they would not be impaired by a copper deficiency.

Complex II of the electron transport chain catalyzes the following reaction:

It uses the enzyme succinate dehydrogenase. The immediate result of this complex's loss of function would be a buildup of succinate, since that molecule can no longer be oxidized to fumarate. The multitude of problems that can arise come from this crucial step of the citric acid cycle not being able to move forward.