Question

Grasshoppers, cockroaches and house flies breath by means of
A) Spiracles
B) Trachea
C) Cutaneous method
D) Bucco - pharyngeal cavity

Answer 1

It is the part of the respiratory system made of finer tubes open at the abdomen and thorax surface of insects.

Complete answer:
Mammals like humans have organ systems like respiratory systems for breath, smaller animals and insects use different ways for it. Insects like grasshoppers, cockroaches and houseflies have a simple gas exchange system for breathing containing air-filled tubes or tracheae. Trachea maintains the pressure balance inside the system. The finer tubes of tracheae connect to spiracles, a series of small openings at the surface of the thorax and abdomen. The oxygenated air enters the body of the cockroach via spiracles into the tracheal tubes from where it diffuses into various tissues and cells of the body. Oxygen is used up to release energy. The carbon-dioxide rich air reaches the trachea and from here it is moved to the outwards through the spiracles. The valves of the spiracles are made up of muscles, used for oxygen uptake and carbon dioxide release and can be opened and closed to reduce the water loss. The fine tracheal tubes are prolonged with the cuticle of the body surface. Threadlike ridges or spiral thickenings are present on the tracheae called taenidia, which branch frequently, make a reduced cross section and end up in fine thin-called tracheoles. The tracheoles are 1 µm in diameter. The tracheoles appear to penetrate between cells. Therefore the exchange of oxygen and carbon dioxide occur solely by gaseous diffusion. The taenidia keep the tracheae tumescent, thus allowing free passage for air exchange. Both lack of oxygen and accumulation of carbon dioxide provide stimuli to nerve centres that induce increased respiration during muscular activity. Thus, the tracheal system transports and exchanges respiratory gasses directly between tissues of insects.

Thus, the correct answer is option B. i.e; Trachea

Note: Insects exchange their gases by trachea (respiratory organ) connected to the spiracles which are a series of small openings on thorax and abdomen region.