Question

How is gaseous exchange accomplished in an insect?

• A. Insects use skin as a gas-exchange surface; blood is circulated near the skin and picks up oxygen and releases carbon-dioxide
• B. They have feather-like gills through which blood and water flow in a counter current mechanism for efficient gas exchange
• C. Insects have primitive lungs called book lungs, which are a series of internal plates that provide surfaces for exchange of gases between the blood and air.
• D. Insects have trachea that carry air deep into the body where exchange occur directly with the tissue

Answer 1

The correct option is D Insects have trachea that carry air deep into the body where exchange occur directly with the tissue

Insects, being larger and having a hard, chitinous and therefore impermeable exoskeleton, have a more specialized gas exchange system. Insects have no transport system so gases need to be transported directly to the respiring tissues. There are tiny holes called spiracles along the side of the insect.

The spiracles are openings of small tubes running into the insect's body, the larger ones being called tracheae and the smaller ones being called tracheoles. The ends of these tubes, which are in contact with individual cells, is where gaseous exchange takes place.

Hence the correct option is D.