Which metal among the following is present in human blood?

Options

A. Titanium
B. Mercury
C. Gold
D. Iron

Explanation

To determine which metal is present in human blood, we can follow these steps:

### Step 1: Identify the Components of Blood
Human blood consists of various components, including red blood cells (RBCs), white blood cells, plasma, and platelets. Among these, RBCs play a crucial role in transporting oxygen throughout the body.

**Hint:** Think about the primary function of red blood cells in the body.

### Step 2: Understand the Role of Hemoglobin
RBCs contain a protein called hemoglobin, which is responsible for carrying oxygen. Hemoglobin is made up of four subunits, each containing a heme group.

**Hint:** Recall what hemoglobin does and how it relates to oxygen transport.

### Step 3: Examine the Composition of Hemoglobin
Each heme group in hemoglobin contains an iron atom at its center. This iron atom is essential because it binds to oxygen molecules, allowing RBCs to transport oxygen from the lungs to the rest of the body.

**Hint:** Focus on what element is found in the heme group of hemoglobin.

### Step 4: Analyze the Given Options
The options provided are titanium, mercury, gold, and iron. We need to determine which of these metals is found in hemoglobin.

**Hint:** Compare the options with the information you have about hemoglobin.

### Step 5: Conclusion
Since we have established that hemoglobin contains iron, and that iron is crucial for the function of RBCs in carrying oxygen, we can conclude that the metal present in human blood is iron.

**Final Answer:** The metal present in human blood is Iron (Option D).