carbonyl cyanide m-chlorophenyl hydrazone (cccp) is an ionophore that allows the free passage of protons through membranes and is a metabolic poison of mitochondria. a researcher tested cccp on the green alga hydrodictyon africanum. results showed that co2 fixation was severely inhibited, whereas o2 release and production of nadph were only mildly affected. what is the most likely explanation of the results for the inhibition of carbon fixation?

Question

carbonyl cyanide m-chlorophenyl hydrazone (cccp) is an ionophore that allows the free passage of protons through membranes and is a metabolic poison of mitochondria. a researcher tested cccp on the green alga hydrodictyon africanum. results showed that co2 fixation was severely inhibited, whereas o2 release and production of nadph were only mildly affected. what is the most likely explanation of the results for the inhibition of carbon fixation?

A. CCCP disrupts the synthesis of ATP at the mitochondrial membrane.

B. CCCP inhibits the splitting of water at the thylakoid membrane.

C. CCCP inhibits the flow of electrons at the mitochondrial membrane.

D. CCCP disrupts the synthesis of ATP at the thylakoid membrane.

Answer 1

The most likely explanation for the inhibition of carbon fixation in this case would be option C. CCCP inhibits the flow of electrons at the mitochondrial membrane. Mitochondria play a crucial role in the production of ATP through oxidative phosphorylation, which involves the flow of electrons through the electron transport chain. Inhibition of this process would disrupt the energy supply needed for carbon fixation to occur. The fact that O2 release and production of NADPH were only mildly affected suggests that the primary disruption is occurring at the mitochondrial level rather than the thylakoid membrane, where water splitting and ATP synthesis in the chloroplasts take place.