Which of the following lacks respiratory pigment in Blood ?

Options

A. Earthworm
B. Cockroach
C. Rat
D. All of these

Answer

To determine which organism lacks respiratory pigment in their blood, we can analyze the options provided: earthworm, cockroach, and rat.

### Step-by-Step Solution:

1. **Identify the Organisms**: The question presents three organisms: earthworm, cockroach, and rat. We need to evaluate each for the presence of respiratory pigments in their blood.

2. **Examine the Earthworm**:
- Earthworms have a respiratory pigment called hemoglobin, which is present in their blood.
- Hemoglobin in earthworms helps in the transport of oxygen and carbon dioxide, facilitating gaseous exchange.

3. **Examine the Cockroach**:
- Cockroaches do not have hemoglobin as their respiratory pigment. Instead, they have a fluid called hemolymph, which is colorless (white) and does not contain respiratory pigments.
- Oxygen is transported directly to tissues through a network of tracheae, rather than through blood.

4. **Examine the Rat**:
- Rats, being mammals, also possess hemoglobin in their blood, which gives it a red color due to the presence of iron.
- Hemoglobin in rats serves the same function as in earthworms, aiding in oxygen transport.

5. **Conclusion**:
- Based on the analysis, the cockroach is the organism that lacks respiratory pigment in its blood. Therefore, the correct answer is the cockroach.

### Final Answer:
The organism that lacks respiratory pigment in blood is the **cockroach**.

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