3.1.5 Gas Exchange in Insects

Question 1

What are the adaptations for efficient diffusion in insects?

Answer 1

A large number of tracheoles creates a large surface area, walls of tracheoles are thin so there is a short diffusion path, and the use of oxygen and production of carbon dioxide to maintain a concentration gradient.

Question 2

What do all insects possess?

Answer 2

A rigid exoskeleton with a waxy coating that is impermeable to gases.

Question 3

What is a spiracle?

Answer 3

A valve-like opening in the exoskeleton of an insect.

Question 4

What does a spiracle allow?

Answer 4

Air to enter and leave the insect..

Question 5

Why are the spiracles closed most of the time?

Answer 5

To reduce water loss.

Question 6

What are tracheae?

Answer 6

Network of tubes within the insect breathing system which lead to tracheoles.

Question 7

What do tracheae walls have and why?

Answer 7

Reinforcement rings made of chitin, to strengthen them and keep them open as air pressure inside them fluctuates.

Question 8

Where is the site for gas exchange?

Answer 8

The muscle fibres.

Question 9

How does gas exchange occur through diffusion in insects?

Answer 9

Oxygen is used up by respiring tissues, causing a diffusion gradient and allowing more oxygen to diffuse in through spiracles, and carbon dioxide produced by cells diffuses out to the atmosphere across a concentration gradient.

Question 10

What are the three ways of gas exchange?

Answer 10

Along the diffusion gradient, mass transport, and the ends of the tracheoles are filled with water.

Question 11

How does gas exchange occur through mass transport in insects?

Answer 11

Muscles within insects can contract and relax, squeezing the trachea and pumping masses of gas in and out of spiracles in the tracheal system.

Question 12

How does gas exchange occur through tracheoles filled with water in insects?

Answer 12

During flight, the production of lactate in anaerobically respiring muscles lowers the water potential of muscle cells, causing water from the tracheoles to move into the cells by osmosis, and therefore reducing the water in the tracheoles and resulting in air being drawn further in.

Question 13

What do tracheoles maintain?

Answer 13

A short diffusion pathway.

Question 14

Where do tracheoles extent to and why?

Answer 14

Throughout the tissue, to deliver oxygen to respiring cells.