Question

Which of the following is not associated with the electron transport system?
A. Formation of ATP
B. Movement of $H^{+}$ into the thylakoid space
C. Cytochromes
D. Absorption of solar energy

Answer 1

Hint:-The electron transport chain is a part of the respiratory process which is used to release and utilize the energy stored in $NAD{H}^{+}{H}^{+}$ and FADH2. To achieve this,$NAD{H}^{+}{H}^{+}$ and FADH2 are oxidized through the electron transport system. The electrons are then passed to the oxygen to produce water.

Complete Answer:-The pathway through which the electrons are passed from one carrier to another is known as the electron transport chain. It is present in the inner mitochondrial membrane. Electrons that are formed during the Kreb cycle are oxidized by an enzyme known as NADH dehydrogenase in complex I. The electrons are then transferred to complex II, complex III, and then to complex IV. Cytochromes are small proteins that act as the electron mobile carrier that helps in the transfer of electrons at complex III and IV.
The passing of electrons is done in exchange for hydrogen ion transfer. At each step when the electrons are passed over to the next complex, hydrogen ions are moved into the intermembrane space (thylakoid space). When the electrons are transferred from these complexes with the help of carriers, they are attached to the enzyme ATP synthase and produce ATP from the ADP. Thus, ATP formation is also involved in this process. However, no absorption of solar energy takes place in the whole process. So the correct option is (D) Absorption of solar energy.

Note:- The electron transport chain is an aerobic process but the use of oxygen in this process is limited to one step only. Oxygen is used for the removal of hydrogen from the system. In the last step, oxygen works as a hydrogen acceptor.