Question

Assertion: In Periplaneta americana opening and closing of stigmata is influenced by $CO2$ tension in haemolymph and oxygen tension in the tracheae.
Reason: The air enters into tracheoles and oxygen from the air is taken into the cells and $CO2$ is released into the hemolymph.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

Answer 1

The cockroach is the largest species of common cockroaches, and sometimes considered a pest. In certain regions of the U.S., it's informally referred to as the death bringer, though isn't a real waterbug since it's not aquatic. It's additionally referred to as the ship cockroach, kakerlake, and city canary.

Complete answer:
The respiratory system of a cockroach consists of a series of rigid tubes, known as trachea connected to the outside via pairs of openings known as spiracles. Air enters the system via the spiracles. The tracheal branches stepping into associate organs finish in a very special cell known as tracheoles.
Insects lose most of their water through the spiracles. they do not have a lot of water to lose as they're tiny. Therefore, insects generally only open their spiracles once they want a lot of $O2$, rise in $CO2$, a product of respiration, additionally causes the spiracles to open a lot of. The expulsion of $CO2$from the body of the roach happens in bursts once the spiracles square measure open.
When air enters the tracheoles, its high partial pressure, $O2$ diffuses quicker into the tissues. At the constant time the $CO2$, rather than passing into the tracheal system, go into the hemolymph. $CO2$ goes a lot quickly into the hemolymph thanks to its bigger solubility in it.
So, the correct option should A.

Note: They do an exchange of gases by using an economical respiratory system that uses air crammed tubes, known as trachea, to deliver on to cells. The flows in as required into the tracheal system through valves on the insect, known as spiracles. But, sometimes, they shut their spiracles and stop breathing.