Question

1) Regarding the products and reactants in glycolysis (Choose All)

A) although 4 ATPs are synthesized for every glucose molecule, there is a net gain of only 2 ATPs/glucose

B) ATP is both a reactant and a product

C) NAD+ is a product; NADH is a reactant

D) glucose is a reactant that is converted to 2 pyruvate products

2) Glycolysis...(Choose All)

A) is anaerobic; no oxygen is required

B) is probably the most widespread metabolic pathway among organisms

C) occurs in only higher organisms

D) evolved relatively recently, since it requires the O2-rich atmosphere we have today

3) During which stages of cellular respiration are electron carriers reduced?

A) the CAC (citric acid cycle)

B) pyruvate oxidation

C) glycolysis

D) the ETC (electron transport chain)

Answer 1

(1) Glycolysis is a pathway that converts a glucose molecule into two molecules of pyruvate.

• The overall pathway consumes two molecules of ATP and yields 4 molecules of ATP. Therefore, the net yield of ATP comes out to be two molecules per glucose molecule. Thus, ATP is both a reactant as well as a product.
• NAD+ is reduced in this pathway to form NADH. Therefore, NADH is a product and NAD+ is a reactant,

Therefore, only statements A, B and D are true. Statement C is false.

(2) In the given question, only statement B is correct. Rest all are incorrect.

• Glycolysis is the only respiration pathway that can occur both aerobically as well as anaerobically. It is not exclusive only to anaerobic cellular respiration.
• From prokaryotes to eukaryotes, the range of organisms that utilize this pathway for cellular respiration is tremendous.
• Since, this pathway is not exclusively aerobic or anaerobic, it has not evolved recently.

(3) The electron carriers in cellular respiration are NAD+ and FAD+ which are reduced during glycolysis, Citric acid cycle and pyruvate oxidation to produce NADH and FADH, respectively. Hence, options A, B and C are correct.