Final answer:
The ingestion of an insecticide that inhibits cytochrome c would lead to a halt in the electron transport chain, preventing the creation of a proton gradient necessary for ATP synthesis, thus the rate of ATP synthesis would be approximately zero.
Step-by-step explanation:
If a man presents to the ER after ingesting an insecticide that binds to and completely inhibits cytochrome c, several disruptions occur in the mitochondrial electron transport chain (ETC). The inhibition of cytochrome c would prevent the transfer of electrons to the next component in the ETC, cytochrome c oxidase (Complex IV), halting the mitochondrial respiratory chain at this step. This would cause a cessation in the production of the proton gradient necessary for ATP synthesis.
Given the explanation above, the correct answer to this question is that the rate of ATP synthesis would be approximately zero (Option C) as the ETC is a critical component of oxidative phosphorylation, in which the energy generated by the electron transfer is used to pump protons into the intermembrane space, creating a gradient that drives the synthesis of ATP by ATP synthase. When cytochrome c is inhibited, this process cannot occur, leading to an impaired energy production in the cell.
As a result of inhibited ETC, the concentration of protons in the intermembrane space would not increase, and therefore, the pH of the intermembrane space would be expected to increase or become more alkaline since fewer protons are being pumped into this space. Additionally, inhibition by a substance such as cyanide has a similar effect to the hypothetical poison in the emergency scenario; it prevents the utilization of oxygen, halting aerobic respiration and leading to decreased ATP production.