Which one of the following is one of the paths followed by air or O2 during respiration in the adult male Periplaneta americana as it enters the animal body?
- Spiracle in metathorax, trachea, tracheoles, oxygen diffuses into cells
- Mouth, bronchial tube, trachea, oxygen enters cells
- Spiracles in prothorax, tracheoles, trachea, oxygen diffuses into cells.
- Hypopharynx, mouth, pharynx, trachea, tissues
Answer
(1) Spiracle in metathorax, trachea, tracheoles, oxygen diffuses into cells
Solution
As per NCERT, the respiratory system of cockroach consists of a network of tracheae that open through 10 pairs of small holes called spiracles on the lateral side of the body (2 pairs thoracic — in mesothorax and metathorax — and 8 pairs abdominal).
⇒ Thin branching tubes (tracheal tubes subdivided into tracheoles) carry oxygen from the air to all parts.
∴ Path: spiracle (e.g., in metathorax) → trachea → tracheoles → oxygen diffuses into the cells.
∵ There are no spiracles in the prothorax, and air does not enter through the mouth, option (1) is correct.
Answer: (1)