Which statement is not true with regard to the circulatory system of coockroach ?

Options

A. Blood of cockroach is colourless
B. There is no respiratory pigment in hemolymph
C. Blood does not function as an oxygen carrier
D. Heart of cockroach is myogenic

Answer

To determine which statement is not true regarding the circulatory system of cockroaches, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Evaluate the first statement**: "Blood of cockroach is colorless."
- This statement is **true**. The blood of cockroaches, known as hemolymph, is indeed colorless due to the absence of respiratory pigments.

2. **Evaluate the second statement**: "There is no respiratory pigment in hemolymph."
- This statement is also **true**. Cockroaches have an open circulatory system, and their hemolymph lacks respiratory pigments, which means they do not have components like hemoglobin that are responsible for oxygen transport.

3. **Evaluate the third statement**: "Blood does not function as an oxygen carrier."
- This statement is **true** as well. Since cockroach blood does not contain respiratory pigments, it cannot carry oxygen, which is typically the function of blood in organisms with such pigments.

4. **Evaluate the fourth statement**: "Heart of cockroach is myogenic."
- This statement is **false**. The heart of a cockroach is neurogenic, meaning its rhythmic contractions are controlled by nerve impulses rather than by muscle tissue itself. In contrast, a myogenic heart would be one where the muscle cells generate the rhythm.

### Conclusion:
The statement that is not true regarding the circulatory system of cockroaches is: **"Heart of cockroach is myogenic."**