A Level Biology Practice Exam

What effect do spiracles have on an insect's gas exchange process?

1. Increase water loss

2. Control air movement

3. Enhance nutrient intake

4. Reduce metabolic waste

The correct answer is: Control air movement

Spiracles play a crucial role in the gas exchange process of insects by acting as valves that regulate the movement of air in and out of the tracheal system. By opening and closing, spiracles can control the flow of oxygen from the environment into the insect's body and the expulsion of carbon dioxide produced during respiration. This regulation is vital for maintaining the right balance of gases, particularly in response to the insect's metabolic needs and environmental conditions. Insects face the challenge of conserving water, especially those living in dry environments. Thus, the ability of spiracles to close helps minimize water loss, demonstrating their dual role in gas exchange and water conservation. While spiracles do not directly enhance nutrient intake or reduce metabolic waste, their primary function in controlling air movement is essential for efficient respiration. This regulation ultimately supports the insect's overall physiological processes, including energy metabolism and homeostasis.