Periphlaneta americana has thermoreceptor sensillae on

Options

A. (a) 1st, 2nd 3rd segments of tarsus of legs
B. (b) 3rd, 4th and 5th segments of tarsus of legs
C. (c) 15th segment of anal cerci
D. (d) Pedicel of antenna

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the location of thermoreceptor sensillae in the organism Periplaneta americana, which is the scientific name for the American cockroach.

2. **Identifying the Structure**: The thermoreceptor sensillae are specialized sensory structures that help the cockroach detect temperature changes in its environment. This is crucial for maintaining its body temperature, as cockroaches are poikilothermic (cold-blooded) animals.

3. **Locating the Sensillae**: The thermoreceptor sensillae are located on the legs of the cockroach. Specifically, they are found on the tarsus, which is the distal part of the leg composed of several segments.

4. **Identifying the Specific Segments**: The tarsus consists of five segments (podomeres). The thermoreceptor sensillae are present on the 1st, 2nd, and 3rd segments of the tarsus.

5. **Evaluating the Options**: Given the options provided:
- Option A: 1st, 2nd, and 3rd segments of tarsus (Correct)
- Option B: 3rd, 4th, and 5th segments of tarsus (Incorrect)
- Option C: 15th segment of anal cerci (Incorrect, as this contains tactile receptors)
- Option D: Pedicle of antenna (Incorrect, as this also contains tactile receptors but not thermoreceptor sensillae)

6. **Conclusion**: The correct answer is Option A, which states that the thermoreceptor sensillae are located on the 1st, 2nd, and 3rd segments of the tarsus of the legs.

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