Question

Cytochrome $b_6$ and cytochrome f occur in:
A) Ribosomes
B) Mitochondria
C) Chloroplasts
D) Lysosomes

Answer 1

Hint: Cytochromes are the reduction-oxidation proteins which are present in the plant cell. They contain heme and central iron atoms. It acts as a cofactor and takes part in the electron transport chain. Cytochromes are important electron transport centres in photosynthesis.

Complete answer:
The cytochrome b6f complex is an enzyme found in the membrane bound compartments or thylakoid membrane in chloroplasts of plants, cyanobacteria, and green algae, that catalyses the transfer of electrons from plastoquinol to plastocyanin.

Both cytochrome B6 and f are present in the chloroplast. The cytochrome b6f complex is analogous to the cytochrome $bc_1$ complex of mitochondria and photosynthetic purple bacteria. The major role of cytochrome is to transfer energy within the cell. It plays an important role in the transport of electrons in the thylakoid membrane in the chloroplast for photosynthesis.
 Ribosomes: The role of ribosomes is to synthesize proteins in the cell. It does not contain any cytochrome complex .
Mitochondria: It is called the powerhouse of the cell. Cytochrome c is associated with the inner membrane of mitochondria.
Lysosomes: They are called the suicidal sacs of the cell. It does not contain any cytochrome complex.

Hence, the correct answer is option (C).

Note: Chloroplasts are organelles that are helpful in the process of photosynthesis and help to provide food and water to the plant and storage of energy and food in them. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants.