Gas exchange in fish and insects

Question 1

All insects possess an exoskeleton. What are its properties?

Answer 1

-Rigid
-Has a waxy coating
-Impermeable to gases

Question 2

What is a spiracle?

Answer 2

A spiracle is an opening in the exoskeleton of an insect which has valves.

Question 3

What is the function of the spiracle?

Answer 3

It allows air to enter the insect and flow into the system of tracheae.

Question 4

What are tracheae?

Answer 4

They are tubes which lead onto tracheoles.

Question 5

What keeps the tracheae open?

Answer 5

Rings of cartilage

Question 6

Where do a large number of tracheoles run between?

Answer 6

Cells into the muscle fibres.

Question 7

What are the muscle fibres the site of?

Answer 7

The site of gas exchange.

Question 8

How do flying insects create a mass flow of air into the tracheal system?

Answer 8

-Closing the spiracles
-Using abdominal muscles to create a pumping mechanism for ventilation.

Question 9

What happens to the fluid found in the narrow ends of the tracheoles during flight?

Answer 9

-It is drawn into the respiring muscle so gas diffuses across quicker. (This creates a SHORTER DIFFUSION PATHWAY)

Question 10

EQ** Describe how the structures of the insect tracheal system provide a large surface area for gas exchange.

Question 11

EQ** Adult flies have a very different body structure from that of maggots.
* Flies have complex and well-developed exchange surfaces and transport systems.
* Maggots have only a small number of tracheae and a small volume of tracheal fluid.
Suggest why maggots do not need such well-developed exchange surfaces and transport systems.