Question

The three boxes in this diagram represent the three major biosynthetic pathways in aerobic respiration. Arrows represent net reactants or products.

Arrows numbered 4, 8 and 12 all can be:

• A. ATP
• B. $H_{2}O$
• C. $FA{D}^{+}$ or $FAD{H}_2$
• D. NADH

Answer 1

The correct option is A ATP

Process of respiration includes three major pathways -
pathway A is glycolysis - generate 4 ATP
pathway B is Krebs cycle - generate 8 ATP
pathway C is oxidative phosphorylation - generate 12 ATP

Arrows numbered 4, 8 and 12 are all be ATP.

Arrow 1 - ADP or NAD+
Arrow 2 - Pyruavate
Arrow 3 - NADH
Arrow 4 - ATP
Arrow 5 - ADP, NAD+ or FAD+
Arrow 6 and 7 - $FAD{H}_2$ and NADH (either one can be 6 or 7)
Arrow 8 - ATP or $C{O}_2$
Arrow 9 and 10 - $O_2$ and ADP (either one can be 9 or 10)
Arrow 11 and 12 - $H_{2}O$ and ATP (either one can be 11 or 12)