Gas exchange in fish and insects

Question 2

Do small organisms have a small or large SA to volume ratio?

Answer 2

large

Question 3

How does an increased SA (needed for gas exchange) impact water loss?

Answer 3

Water will be lost/evaporate more easily due to the high SA

Question 4

What are the internal tubes that insects have for gas exchange?

Answer 4

tracheae

Question 5

What are tracheoles?

Answer 5

smaller dead-ended tubes that come off of the tracheae and extend to all the tissues in the insect

Question 6

What 3 ways can respiratory gases move in and out of the tracheal system of insects?

Answer 6

• along a diffusion gradient
• mass transport
• tracheoles ends are filled with water

Question 7

How does water in the tracheoles’ ends allow for respiratory gases to be exchanged?

Answer 7

• major activity –> anaerobic respiration –> lactate is produced
• lactate lowers water potential of muscle cells
• water moves into cells from tracheoles by osmosis
• volume of water in tracheoles decreases, which draws in more air

Question 8

What are gills made up of?

Answer 8

gill fillaments, which are stacked up, and made up of gill lamellae (which are perpendicular)

Question 9

What is the essential feature of the counter-current exchange system?

Answer 9

water flows over surface in opposite direction to the flow of blood

Question 10

How does the counter-current exchange principle allow for efficient gas exchange?

Answer 10

maintains a concentration gradient, which allows for oxygen to diffuse from water into the blood

Question 11

Give 3 ways insects limit water loss

Answer 11

• small SA to volume ratio
• waterproof coverings (chitin)
• spiracles (can be closed if insect is at rest)

Question 12

Why might some insects have gills?

Answer 12

• higher metabolic rate
• uses more
  oxygen

Question 13

Why would reduction in movement reduce water loss in insects?

Answer 13

• less respiration so less gas exchange
• so spiracles open less so less water loss