Chapter 8

Question 1

What is the respiratory structure?

Answer 1

• the respiratory surface that enables gaseous exchange to occur between respiring organism cells and their outer evironment

Question 2

How are the respiratory structures of large-sized organisms adapted for
efficient exchange of gases? (5)

Answer 2

• Large ratio of total surface area to volume (TSA/V) for the efficient exchange of respiratory gases.
• A thin respiratory structure that is one cell thick, allows the diffusion of respiratory gases to occur.
• The surface of the respiratory structure is always moist for respiratory gases to dissolve in them.
• The respiratory structure is complete with a network of blood capillaries (except for insects), that allows for the efficient delivery of respiratory gases.

Question 3

Explain the insect respiratory structure. (4)

Answer 3

• breathing system is the tracheal system
• spiracles in thorax & abdomen allows intake of air into the air tube system (tracheal system)
• trachea branches out to form tracheole (respiratory surface)
• some insects have air sacs (speed up delivery of respiratory gas during active body movements)

Question 4

What are the adaptations/characteristics of the tracheole that allows efficient respiratory gaseous exchange? (2)

Answer 4

– A large number of tracheoles provides a large total surface area for the exchange of gases.
– The tracheole wall is thin and moist. This allows oxygen gas to diffuse into the cells while carbon dioxide quickly diffuses out of the cells into the tracheole.

Question 5

What are the fish respiratory structure and its adaptations?(4)

Answer 5

-respiratory structure is gills
- gills made up of filament supported by gill arch
Adaptation of lamella for rapid exchange of respiratory gases:
- filament has many thin & flat projections called lamella (large number of filament & lamellae gives large TSA for efficient gaseous exchange)
- lamella membrane is thin & many blood capillaries for easy absorption & transport of oxygen & carbon dioxide

Question 6

What is the frog respiratory structure & its adaptations?(skin:3, lungs:4)

Answer 6

When inactive, frog uses skin for gaseous exchange:
• The skin is thin and highly permeable to respiratory gases.
• The moist skin allows respiratory gases to dissolve in it.
• Beneath the skin, there are many networks of blood capillaries to transport respiratory gases.
Lungs:
• The surface of the lungs is folded to increase the total surface area for the exchange of gases (Figure 8.3).
• The thin lung membrane eases the diffusion of respiratory gases.
• The moist lung walls enable respiratory gases to dissolve in them.
• The lungs are also rich with a network of blood capillaries to transport respiratory gases.

Question 7

What is the human respiratory structure and its adaptations? (5)

Answer 7

• respiratory structure is alveolus
  characteristics of alveolus for efficient respiratory gaseous exchange:
  • A large number of alveoli provides a large total surface area for the diffusion of respiratory gases.
  • The alveolus wall is always moist. Oxygen and carbon dioxide can dissolve easily, and diffuse through the walls into the blood capillaries.
  • The alveolus is surrounded by a large network of blood capillaries to hasten the diffusion of respiratory gases.
  • The thin alveolus wall, that is as thick as one cell, makes the diffusion of gases much easier.

Question 8

Similarities between the respiratory structures of humans and animals (4)

Answer 8

• All respiratory structures have a large ratio of total surface area to volume for an efficient exchange of respiratory gases.
• All respiratory structures are thin and this makes the diffusion of respiratory gases much faster.
• All respiratory structures are moist and this allows respiratory gases to dissolve in them.
• The respiratory structure is complete with a network of blood capillaries (except insects), that allows for efficient transport of respiratory gases.

Question 9

Differences between the respiratory structures of humans and animals (2 characteristics)

Answer 9

Respiratory structure:
Insects:
-Tracheole

Fish:
-Filament and lamella

Frogs:
-Skin and lungs

Humans:
-Alveolus

How the large ratio of total surface area to volume for the respiratory structure is achieved:
Insects:
Large number of tracheoles

Fish:
Large number of filaments and lamellae

Frogs:
• The surface in the lungs is folded
• Overall skin surface

Humans:
Large number of alveoli