Question

The electron transport chain is common to both respiration and photosynthesis. However, there are some differences in the steps involved in the electron transport chain in both processes. The table lists some steps in the electron transport chain. Which of these CORRECTLY shows where the steps take place?

A) P: both mitochondria and chloroplast, Q: only mitochondria, R: only chloroplast, S: both mitochondria and chloroplast
B) P: only mitochondria, Q: both mitochondria and chloroplast, R: both mitochondria and chloroplast, S: only chloroplast
C) P: only chloroplast, Q: both mitochondria and chloroplast, R: both mitochondria and chloroplast, S: only mitochondria
D) P: only mitochondria, Q: only chloroplast, R: both mitochondria and chloroplast, S: both mitochondria and chloroplast

Answer 1

The electron transport chain operates differently in respiration than in photosynthesis, with its components located in the mitochondria during respiration and in the chloroplasts during photosynthesis. Specific details about what processes P, Q, R, and S refer to are needed to accurately determine their location in the cell.

Step-by-step explanation:

The electron transport chain (ETC) is a series of protein complexes located in different parts of the cell, depending on whether the process is aerobic respiration or photosynthesis. In the context of aerobic respiration, the ETC is located within the inner mitochondrial membrane of eukaryotic cells, and in the plasma membrane of prokaryotic cells. Here, electrons are passed along a series of reactions that eventually reduce molecular oxygen, producing water. During photosynthesis, the ETC is located within the chloroplasts. Here, the flow of electrons through the ETC results in the reduction of NADP+ to NADPH. The electron transport chain in photosynthesis operates somewhat differently than in respiration, with light energy being used to drive the transfer of electrons. In reference to the question about where different steps (P, Q, R, S) of the electron transport chain take place, it appears that we need more details about what steps P, Q, R and S refer to in order to accurately assign them to either mitochondria, chloroplasts, or both. However, the principles discussed here will aid in interpreting the processes that occur within both mitochondria and chloroplasts for electron transport.