Question

could a bacterium obtain energy from succinate as an electron donor and nitrate (no₃⁻) as an electron acceptor?
electron acceptor → electron donor e (mv)
fumarate + 2h⁺ + 2e⁻ → succinate +33
no₃⁻ + 2h⁺ + 2e⁻ → no₂⁻ + h₂o +420
options:
a. yes
b. no

Explanation:

To determine if a bacterium can obtain energy from succinate (electron donor) and nitrate (electron acceptor), we analyze the redox reactions. The reaction for succinate oxidation (rumarate + 2H⁺ + 2e⁻ → succinate) has a reduction potential (E°') of +0.03 V (reverse for oxidation: succinate → fumarate + 2H⁺ + 2e⁻, E°' = -0.03 V). The nitrate reduction reaction (NO₃⁻ + 2H⁺ + 2e⁻ → NO₂⁻ + H₂O) has E°' = +0.42 V. For a redox reaction to be spontaneous (produce energy), the overall cell potential (E°'_cell) must be positive. E°'_cell = E°'_acceptor - E°'_donor. Here, acceptor is nitrate (reduction, E°' = +0.42 V), donor is succinate (oxidation, E°' = -0.03 V). So E°'_cell = 0.42 - (-0.03) = 0.45 V (positive), meaning the reaction is spontaneous and energy can be obtained.

Answer:

A. Yes