The compound which do not involve in the electron transfer in any process of living beings:

The correct answer is option 'C' - Transferrin.

Explanation:

In living beings, various compounds and molecules are involved in electron transfer processes. These processes are crucial for many physiological functions, such as respiration, photosynthesis, and energy production. However, not all compounds participate in electron transfer reactions.

Electron Transfer in Living Beings:

- Electron transfer is a fundamental process in living beings that involves the movement of electrons from one molecule to another.
- This process is essential for the generation of energy, as well as for the maintenance of redox balance in cells.
- Many compounds, such as cytochromes, ferredoxins, and plastocyanin, play vital roles in electron transfer reactions in different organisms.

Cytochromes:

- Cytochromes are a class of proteins that contain heme groups, which are capable of accepting and donating electrons.
- They are involved in various electron transfer reactions, particularly in the electron transport chain during cellular respiration.
- Cytochromes transfer electrons from one protein complex to another, facilitating the production of ATP, the energy currency of cells.

Ferredoxins:

- Ferredoxins are small iron-sulfur proteins that act as electron carriers in many metabolic pathways.
- They are involved in both electron transfer and redox reactions, shuttling electrons between different enzymes and proteins.
- Ferredoxins play a crucial role in processes such as photosynthesis, nitrogen fixation, and the synthesis of various compounds.

Plastocyanin:

- Plastocyanin is a copper-containing protein found in plants and algae.
- It acts as an electron carrier in the electron transport chain of photosynthesis, transferring electrons from cytochrome bf complex to photosystem I.
- Plastocyanin is essential for the production of ATP and the reduction of NADP+ to NADPH during photosynthesis.

Transferrin:

- Transferrin is an iron-binding protein found in blood plasma.
- It is involved in the transport of iron ions throughout the body and plays a vital role in iron homeostasis.
- However, transferrin does not participate in electron transfer reactions in living beings.

Conclusion:

In summary, out of the given options, cytochromes, ferredoxins, and plastocyanin are compounds that participate in electron transfer processes in living beings. On the other hand, transferrin, although important for iron transport, does not engage in electron transfer reactions.