Which mineral element is common in heme proteins cytochromes and non-heme protein—ferredoxin ?

Explanation

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for the common mineral element found in heme proteins (specifically cytochromes) and non-heme proteins (specifically ferredoxin).

2. **Understand Heme Proteins**: Heme proteins, such as cytochromes, contain a heme prosthetic group. The heme group is a complex of iron and porphyrin, which is essential for their function.

3. **Understand Non-Heme Proteins**: Non-heme proteins like ferredoxin contain iron in a different form. Ferredoxin is characterized by iron-sulfur clusters, which are crucial for its role in electron transfer.

...