Gas Exchange: Insects

Question 1

What is the most common gas exchange arrangement in insects?

Answer 1

Tracheal systems.

Question 2

What is the relationship between the size of an organism and the surface area : volume ratio?

Answer 2

The smaller an object is, the greater the SA : V ratio.

Question 3

A single celled organism such as paramecium gains oxygen and removes carbon dioxide through what process?

Answer 3

Simple diffusion.

Question 4

Why cannot insects use simple diffusion to gain oxygen and lose carbon dioxide?

Answer 4

Due to the waxy exoskeleton.

Question 5

How does air move into the tracheae?

Answer 5

Through pores on the surface called spiracles.

Question 6

What are tracheae?

Answer 6

They are microscopic air-filled pipes used for gas exchange.

Question 7

How do insects move air in and out of the spiracles?

Answer 7

Through rhythmic abdominal movements.

Question 8

What are the three main features of the tracheal system?

Answer 8

Trachea, Tracheoles and Spiracles.

Question 9

Explain the results of the insect flying on respiration:

Answer 9

The muscle cells start to respire anaerobically producing lactate. This lowers the water potential of the cells and therefore water moves from the tracheoles into cells by osmosis. This decreases volumes of tracheoles and more atmospheric air is drawn in.

Question 10

What minimises water loss from an insect?

Answer 10

The waxy cuticle as it is impermeable to water.

Question 11

What is the downside of having a waxy cuticle in terms of gas exchange?

Answer 11

It is also virtually impermeable to gases as well as water.

Question 12

What system do insects use to exchange gases?

Answer 12

The tracheal system.

Question 13

What are spiracles?

Answer 13

Holes in the cuticle that allow air in and out of the body.

Question 14

What causes changes in the opening of spiracles?

Answer 14

Carbon dioxide levels.

Question 15

If a high carbon dioxide level is detected, what will happen?

Answer 15

The spiracles are open.

Question 16

What molecule lines the tracheoles?

Answer 16

Nothing, they are unlined.

Question 17

What do the trachea lead to?

Answer 17

The tracheoles.

Question 18

What is the name for the first tubes which the spiracles lead into?

Answer 18

Trachae.

Question 19

The walls of the trachea are lined with Chitin, what is the function of this?

Answer 19

Supports them and makes them impermeable to gases.

Question 20

Where does gas exchange occur?

Answer 20

Tracheoles.

Question 21

How does the trachea allow the respiratory system to work independently of the circulatory system?

Answer 21

The blood has no direct role in transporting respiratory gases.

Question 22

The walls of the trachea are lined with what?

Answer 22

Chitin, which supports them and makes them impermeable to gases.

Question 23

How does air move down the tracheal system?

Answer 23

In smaller or more inactive insects gases use simple diffusion. In larger or more active insects air can be actively pumped by the thorax or abdomen.

Question 24

What stimulates spiracles to open?

Answer 24

High levels of carbon dioxide.

Question 25

What is the possible function of the thorax and abdomen in circulation of respiratory gases?

Answer 25

In larger and more active organisms, they contract to move air through the tracheal system.

Question 26

Which structure is responsible for the opening and closing of the spiracles?

Answer 26

The sphincters.

Question 27

Explain the function of the water present at the bottom of the tracheoles.

Answer 27

To aid diffusion and maintain osmotic levels when lactic acid is produced.

Question 28

What is the relationship between the activity levels and number of spiracles opened?

Answer 28

The more active an insect is, the more spiracles will open as they need to remove more waste products.

Question 29

Where is the site of water loss in an insect?

Answer 29

Spiracles.

Question 30

Which are larger in the insect; the trachea or tracheoles.

Answer 30

Trachea.

Question 31

What are the walls of the trachea made from?

Answer 31

(Impermeable) Chitin.

Question 32

What is the role of a sphincter?

Answer 32

Opening and closing the spiracles.

Question 33

Insects have tiny hairs surrounding the spiracles, what is the function of these tiny hairs?

Answer 33

To reduce evaporation and consequently reduce water loss.