Gas exchange in fish and insects

Question 1

what is the main site of gas exhange in insects?

Answer 1

tracheae ( trachea = singular).

Question 2

explain the structure of an insects gas exchange system.

Answer 2

The tracheae, branch off into smaller tubes, called tracheoles, which then further extend into the insects muscle tissue.

At the bodys surface, tracheae, end in tiny spiracles called spiracles.

( See page 42 for diagram).

Question 3

what are the 4 adaptations for efficient gas exchange in insects?

Answer 3

1. One cell thick wall at end of tracheole.
2. tracheoles are highly branched ( numerous).
3. muscle contractions move alot of air through the trachea.
4. end of tracheoles are filled with fluids.

Question 4

explain how having a One cell thick wall at end of tracheole an advantage to insect gas exhange

Answer 4

So that there is a short diffusion path way for O2 and CO2.

Question 5

explain how having highly branched and numerous tracheoles and advantage to insect gas exhange

Answer 5

provides a larger surface are for gas exchange, therefore higher rate of diffusion.

Question 6

explain how having muscle contractions move alot of air through the trachea an advantage to insect gas exhange

Answer 6

This maintains a steep concentration gradient between O2 and CO2.

Question 7

explain how having the ends of tracheoles filled with water an advantage to insect gas exhange

Answer 7

muscle contractions move this fluid into surrounding tissue, thus causing air to be drawn into tracheoles.

• because diffusion through air is quicker than through the liquid, this allows for a faster diffusion into the muscle tissue.

Question 8

how do insects limit water loss?

Answer 8

through their water proof exoskeleton.
and
through their spiracles which can be open or closed.

Question 9

explain the structure of a fish gas exhange system.

Answer 9

Gills are the main site of gas exhange in fish.They consist of gill arches , to which stacks of gill fillaments are attached to.on the surface of each gill fillament, there is a plate like structure known as the Lamella.
Each lamella, contains capillaries, which are attached to blood vessels, exiting from the gill arch.

Question 10

explain how oxygen and carbon dioxide diffuses in and out of a fish gill.

Answer 10

water is constantly moving through the lamelae, as the fish swims.
The water contains a high concentration of oxygen, when compared to that of the bloof of the fish.
oxygen from the water, then diffuses into the capillaries , and CO2 diffuses into the water.

Question 11

state and explain the two adaptations for gas exhange in fish.

Answer 11

1. Countercurrent flow : blood and water flow in opposite directions, across the lamelae.
   - This enables the fish to maintain a steep concentration gradient of O2 and CO2.
2. Fish contains a large number of lamelae, which increase the surface are, for the diffusion of O2 and CO2.