Question

8 multiple choice 10 points
cyanide poisoning is a type of poisoning caused by exposure to certain cyanide-containing compounds, such as hydrogen cyanide or cyanide salts.
inhalation or consumption of these compounds can cause histotoxic hypoxia, a condition in which cells are no longer able to take up or utilize oxygen
during cellular respiration. as a result, atp production during respiration is significantly reduced.
based on the information above, which of the following is the most likely explanation for how cyanide causes histotoxic hypoxia?
cyanide inhibits the reduction of nad+ and fad during the krebs cycle.
cyanide inhibits the transport of pyruvate across the mitochondrial membrane.
cyanide inhibits the transfer of electrons to the final acceptor in the electron transport chain
cyanide inhibits the enzymatic breakdown of glucose during glycolysis.
9 multiple choice 10 points
unlike most other cells in the human body, mature red blood cells (rbcs) do not contain a nucleus or mitochondria. this allows rbcs to carry more
hemoglobin, and therefore oxygen, through the bloodstream.
based on the information above, which of the following is most likely true about rbcs?
due to a lack of mitochondria, rbcs do not produce atp.
co2 and ethanol are byproducts of atp production in rbcs.
oxygen is used as the terminal electron acceptor in rbcs.
rbcs generate lactate as a waste product.

Explanation:

• Question 8:
• In cellular respiration, the electron transport chain (ETC) has oxygen as the final electron acceptor. Cyanide binds to cytochrome c oxidase (Complex IV) in the ETC, preventing the transfer of electrons to oxygen. This halts the ETC, which is crucial for the production of a large amount of ATP through oxidative phosphorylation.
• The Krebs cycle (citric - acid cycle) produces NADH and FADH₂ (reduces NAD⁺ and FAD), but cyanide's main effect is on the ETC, not directly on the Krebs cycle's co - factor reduction.
• Pyruvate transport into the mitochondria is part of the transition from glycolysis to the Krebs cycle, and cyanide does not target this step.
• Glycolysis is the initial step of glucose breakdown (enzymatic breakdown) to pyruvate, and cyanide is not an inhibitor of glycolysis.
• Question 9:
• RBCs (red blood cells) lack mitochondria. But they can still produce ATP through glycolysis. Glycolysis occurs in the cytoplasm.
• In the absence of mitochondria (and thus no aerobic respiration or ethanol - producing fermentation, which occurs in some yeast and plant cells), RBCs undergo lactic acid fermentation.
• In lactic acid fermentation, pyruvate (the end - product of glycolysis) is reduced to lactate.
• Since there are no mitochondria (where the electron transport chain with oxygen as the terminal electron acceptor is located), oxygen is not used as a terminal electron acceptor in RBCs for ATP production.

Answer:

• Question 8: C. Cyanide inhibits the transfer of electrons to the final acceptor in the electron transport chain.
• Question 9: D. RBCs generate lactate as a waste product.