Gaseous Exchange in other Organisms

Question 1

What is the buccal cavity?

Answer 1

The mouth of a fish

Question 2

What is countercurrent flow?

Answer 2

When two fluids flow in opposite directions

Question 3

What are filaments?

Answer 3

Slender branches of tissue that make up the gill. They are often called primary lamellae.

Question 4

What are lamellae?

Answer 4

Often called secondary lamellae they are folds of the filament to increase surface area. They are also called gill plates.

Question 5

What is the operculum?

Answer 5

A bony flap that covers and protects the gills.

Question 6

What is the spiracle?

Answer 6

An external opening or pore that allows air in or out of the trachea.

Question 7

What is the tracheal fluid?

Answer 7

The fluid found at the ends of the tracheoles in the tracheal system.

Question 8

What is the tracheal system?

Answer 8

A system of air-filled tubes in insects.

Question 9

What do the gills do?

Answer 9

Absorb oxygen dissolved in the water and release carbon dioxide into the water.

Question 10

How many pairs of gills would most fish have?

Answer 10

5

Question 11

Where does gaseous exchange take place?

Answer 11

At the secondary lamellae or gill plates.

Question 12

Explain the countercurrent system in fish.

Answer 12

Blood flows along the gill arch and out along the filaments and secondary lamellae.
Blood flows through the capillaries in the opposite direction to the flow of water over the lamellae.

Question 13

Why is a countercurrent system necessary?

Answer 13

It absorbs the maximum amount of oxygen from the water.

Question 14

How do fish keep water flowing over the gills?

Answer 14

By using a buccal-opercular pump.

Question 15

Describe the motion of the buccal-opercular pump.

Answer 15

The floor of the mouth moves downwards, drawing water into the buccal cavity.
The mouth closes and the floor is raised again pushing water through the gills.

Question 16

What happens to the operculum during the buccal-opercular pump?

Answer 16

The operculum moves out when the fish closes its mouth and shuts when the fish opens its mouth.

Question 17

Insects have an open circulatory system. What does this mean?

Answer 17

They do not have any blood vessels and the body fluid acts as both the tissue fluid and the blood.

Question 18

How does an insects tracheal system work?

Answer 18

Air enters the system via a pore in each segment called a spiracle. The air is transported throughout the body via tracheae. These divide into smaller tubes called tracheoles. The ends of the tracheoles are open and filled with fluid called tracheal fluid.

Question 19

Where does gaseous exchange happen in insects?

Answer 19

At the ends of the tracheoles between the air in the tracheoles and the tracheal fluid.

Question 20

What happens to the tracheal fluid during activity?

Answer 20

When tissues are active the tracheal fluid can be withdrawn into the body fluid in order to increase the surface area of the tracheole wall exposed to the air.

Question 21

How have locusts adapted the way the they ‘breath’?

Answer 21

They can alter the volume of their abdomen by specialised breathing movements. As the abdomens expands spiracles at the front of the body open. As the abdomen reduces in volume spiracles at the end of the body open releasing air.

Question 22

How does movements of the wings affect the volume of the tracheal system in insects?

Answer 22

In some insects the movements of the flight muscles can repetitively expand and contract the air sacs in the insect, ventilating the system.
In other insects, movements of the wings alters the volume of the thorax.