Gas Exchange In Other Organisms

Question 1

What is an insects exoskeleton covered in?

Answer 1

-chitin - impermeable to gases

Question 2

What type of system do insects have?

Answer 2

-air filled tracheal system
-open circulatory system

Question 3

What is a spiracle?

Answer 3

-opening in the exoskeleton
-has valves
-allows air to enter + flow into tracheae

Question 4

What is tracheae?

Answer 4

-tubes leading to tracheoles
-rigid rings of cartilage covered in chitin

Question 5

What are tracheoles?

Answer 5

-single cell extended to form hollow tube
-run between cells + into muscle fibres
-for gas exchange

Question 6

What does a sphincter do?

Answer 6

-closes spiracles

Question 7

What is tracheal fluid?

Answer 7

-cells around tracheoles undergo aerobic respiration
-producing lactic acid
-lowers water potential of cells
-causing water in fluid to move into cells
-reducing volume + drawing air down into tracheoles

Question 8

What is the order of gas exchange in an insect?

Answer 8

-air enters through trachea
-smaller tracheoles - gas exchange between air + fluid
-diffusion gradient - oxygen down gradient from air to cells
-carbon dioxide down the gradient cells to air

Question 9

How is water constantly pushed over the surface of gills?

Answer 9

-pressure difference created by opening of mouth

Question 10

What is buccal cavity?

Answer 10

-mouth space

Question 11

What is operculum?

Answer 11

-opens + closes for water flow over gills

Question 12

How many pairs of gills does a fish have?

Answer 12

-5 pairs of gills

Question 13

What do gills do?

Answer 13

-absorb O2 dissolved in water and release CO2

Question 14

What is the structure of gills?

Answer 14

-gills on each side of head
-each gill arch attached to 2 stacks of filaments
-lamellae on surface - covering capillaries

Question 15

What is the mechanism of gills?

Answer 15

-capillaries ensure counter current flow
-blood along gill arch + filaments to secondary filaments - opposite to water flow
-absorbing max O2 with high concentration

Question 16

Features of filaments?

Answer 16

-very thin
-folded into secondary lamellae = large SA

Question 17

Movement through gills

Answer 17

-mouth - over gills - O2 into blood - out through opercular opening

Question 18

What happens when the mouth is open?

Answer 18

-lowers the floor of buccal cavity
-increases volume of water
-shuts the operculum
-increases volume of opercular cavity

Question 19

What does increased volume do to the opercular cavity?

Answer 19

-pressure falls in opercular cavity
-raising buccal cavity
-increasing the pressure of water
-causes water to flow over gills in opercular cavity
-closes mouth
-opens operculum
-increasing water pressure
-forcing it out of operculum
-movements of operculum are coordinated with movements of buccal cavity