Question

The respiratory organs in cockroach are:
A. Lungs
B. Gills
C. Lenticels
D. Spiracles

Answer 1

A respiratory organ that is found in cockroach is a tiny loose opening to the mouth located behind each eye.

Complete solution:
Any animal in the vertebrate world has lungs. The lungs are two spongy and air-filled bodies on both sides of the thorax. The trachea, through its branches known as bronchi, takes inhaled air into the lungs. The bronchi breaks into smaller branches (bronchioles), then becomes microscopic finally.

The gill is a respiratory organ that collects dissolved oxygen from the water and excretes carbon dioxide in many aquatic species. The gills of some animals, including hermit crabs, have evolved to allow for breathing on the land if they are maintained moist.

A lenticel is a porous tissue composed of cells with wide intercellular spaces in the periphery of secondary organs and the bark of woody stems and roots of dicotyledonous flowering plants. It acts as a pore for direct gas exchange between the inner tissue and the atmosphere through the bark, which is otherwise impermeable to gases.

Spiracles are openings on the surface of some animals, typically leading to breathing systems. The spiracle is a tiny hole that opens up to the mouth behind each eye. Insects and some more spiders have spiracles to allow the air to reach the trachea. The tracheal tubes mainly inject oxygen directly into the tissues of the animals in the respiratory system of insects. The spiracles can be easily opened and closed to reduce the loss of water. Therefore, the cockroach's respiratory organs are spiracles.

Thus, the option (D) is the correct choice.

Note: In the cockroach, breathing happens through the spiracles – a narrow opening on the sides of the body. When oxygen-rich air enters the body of the cockroach through spiracles into the tracheal tubes, it spreads to various tissues and cells of the body. Here, oxygen is used to release energy.