Tracheal System in Cockroach
The tracheal system in a cockroach is responsible for the exchange of gases, allowing the insect to breathe. It consists of a network of tubes called tracheae that extends throughout the body, delivering oxygen directly to the cells.
Opening of the Tracheal System
The opening of the tracheal system in a cockroach is through structures called stigmata. Stigmata are tiny pores or spiracles located on the lateral sides of the body segments. There are a total of 10 pairs of stigmata in a cockroach, with one pair on each of the thoracic and abdominal segments.
Function of Stigmata
The stigmata serve as the openings of the tracheal system, allowing oxygen to enter and carbon dioxide to exit the body. They are surrounded by specialized muscles known as the spiracular muscles, which control their opening and closing.
Respiratory Process
1. When a cockroach takes in air, the spiracular muscles relax, allowing the stigmata to open.
2. Oxygen from the environment enters the tracheal system through the open stigmata.
3. The oxygen then diffuses through the tracheae and reaches the cells of the body, where it is utilized for cellular respiration.
4. Carbon dioxide, a waste product of cellular respiration, diffuses out of the cells and enters the tracheae.
5. The carbon dioxide is then expelled from the body through the open stigmata.
Conclusion
The tracheal system in a cockroach opens to the outside through the stigmata, which are tiny pores located on the lateral sides of the body segments. These stigmata allow for the exchange of gases, enabling the cockroach to breathe and carry out cellular respiration.

Tracheal System in Cockroaches
The tracheal system in cockroaches is responsible for gas exchange, allowing oxygen to enter the body and carbon dioxide to exit. This system consists of a network of tubes called tracheae that deliver air directly to the tissues.

Opening of the Tracheal System
The tracheal system in cockroaches opens to the outside through small openings called stigmata. These stigmata are located along the sides of the body and allow air to enter and exit the tracheal tubes. The stigmata are connected to the tracheae, which branch out into smaller tubes called tracheoles that deliver air to the cells.

Function of Stigmata
The stigmata play a crucial role in the respiratory system of cockroaches by allowing for the exchange of gases with the external environment. They regulate the flow of air into and out of the tracheal system, ensuring that oxygen is delivered to the tissues and carbon dioxide is removed.

Importance of Stigmata
The presence of stigmata on the body of cockroaches is essential for their survival, as they rely on efficient gas exchange to sustain their metabolic processes. Without these openings, the tracheal system would be unable to deliver oxygen to the cells and remove waste gases.
Therefore, the correct answer to the question is option 'c) stigmata', as these are the openings through which the tracheal system in cockroaches connects to the external environment for gas exchange.