Gas Exchange Insects

Question 1

What is the internal network of tubes in insects called?

Answer 1

• Insects have evolved an internal network of tubes called trachae

Question 2

What prevents the trachaea from collapsing?

Answer 2

Tracheae are supported by strengthened rings to prevent them from collapsing.

Question 3

How are the tracheoles present in the insect?

Answer 3

• They extend throughout all the body tissues of the insect
• Through this way atmospheric air with the oxygen it contains, is brought directly to the respiring tissues, as there is a short diffusion pathway from a tracheole to any body cell

Question 4

What are the three ways in which gasses move in and out of the tracheal system

Answer 4

• Along a diffusion gradient
• Mass transport
• The ends of the tracheoles

Question 5

How is oxygen taken in via the diffusion gradient in insects?

Answer 5

• When cells are respiring oxygen is used up
• The concentration towards the ends of the tracheoles falls as a result
• A diffusion gradient is created that causes gaseous oxygen to diffuse from the atmosphere to the along the trachae and trachaeoles into the cells.

Question 6

How is a diffusion gradient created in insects?

Answer 6

• When cells are respiring oxygen is used up
• The concentration towards the ends of the tracheoles falls as a result
• A diffusion gradient is created

Question 7

How is a carbon dioxide gradient produced in insects?

Answer 7

• Carbon dioxide is produced by insects during respiration
• This will create a diffusion gradient in the opposite diretoin
• This causes gaseous carbon dioxide to diffuse along the tracheoles and the trachea from the cells into the atmosphere

Question 8

What is carbon dioxide produced by?

Answer 8

Carbon dioxide is produced by insects during respiration

Question 9

Why are gasses exchanged quickly via diffusion?

Answer 9

• Diffusion in air is much more rapid than in water

* Therefore, respiratory gasses are exchanged much more quickly via this method

Question 10

How do gasses move in and out of the trachael system via mass transport?

Answer 10

• Contraction of muscles in insects can squeeze the trachea enabling mass movements of air in and out

Question 11

How does mass transport affect speed of gas exchange?

Answer 11

Speeds up gas exchange

Question 12

What happen happens to muscle cells during periods of major activity?

Answer 12

• Muscle cells around the tracheoles respire to carry out some anaerobic respiration
• Lactate is produced as a result, which is soluble and lowers the water potential of the muscle cells.

Question 13

How does water cause gas exchange in insects?

Answer 13

• Muscle cells around the tracheoles respire to carry out some anaerobic respiration
• Lactate is produced as a result, which is soluble and lowers the water potential of the muscle cells.
• Water moves into the cells from the tracheoles by osmosis
• The water in the ends of the tracheoles decreases in volume, and as a result draws air further into them
• The final diffusion pathway is a gas rather than a liquid, and thus diffusion speed is increased.
• Increases rate at which air is moved in the tracheoles, but leads to greater water evaporation

Question 14

How does water in ends of tracheoles affect rate of diffusion?

Answer 14

• Water in ends of tracheoles decreasing in volume draws air into them
• This means the diffusion pathway is a gas as opposed to being a liquid.
• Rate of diffusion is faster in a gas than liquid

Question 15

What have insects evolved for gas exchange?

Answer 15

Insects have evolved an internal network of tubes called tracheae

Question 16

How are the tracheae supported in the insect body?

Answer 16

Strengthened rings, which prevent them from collapsing

Question 17

What is the surface area to volume ratio of single celled organisms?

Answer 17

• Single celled organisms are small, therefore they have a large surface area to volume ratio

Question 18

How is oxygen absorbed by single celled organisms?

Answer 18

• Oxygen is absorbed by diffusion across their surface

* The surface is covered by only a cell surface membrane

Question 19

How does carbon dioxide get exchanged in single celled organisms?

Answer 19

• Carbon dioxide from respiration diffuses out across their body surface

Question 20

How do gasses enter and leave the tracheae?

Answer 20

Spiracles ( Tiny Pores ) on the body surface

Question 21

What controls the opening and closing of spiracles?

Answer 21

Valves

Question 22

Why do insects keep spiracles closed normally?

Answer 22

• When spiracles are open, water vapour may evaporate from the insect, therefore they are kept closed to prevent water loss.
• Periodically open to allow gas exchange.

Question 23

What are some limitations of the tracheal system?

Answer 23

• Relies on diffusion to exchange gasses between the environment and cells
• For diffusion to be effective, diffusion pathway must be short, which limits the size of insects
• Length of Diffusion pathway limits the size than an insect can attain

Question 24

What limits the size of an insect?

Answer 24

Length of diffusion pathway, as they rely on diffusion for gaseous exchange.