Gaseous Exchange Systems

Question 1

What is a tissue?

Answer 1

A group of cells working together to perform a shared function, and often with similar structure

Question 2

What is an organ?

Answer 2

A structure made up of groups of different tissues, working together to perform specific functions

Question 3

What is an organ system?

Answer 3

A group of organs with related functions, working together to perform certain functions within the body

Question 4

Put the following into order from smallest to largest:

Tissue, organ, cell, organ system

Answer 4

Cell –> tissue –> organ –> organ system

Question 5

Muscle is an example of…

Answer 5

A tissue

Question 6

What two things are needed for aerobic respiration?

Answer 6

Oxygen and glucose

Question 7

Name two adaptations that exchange surfaces have in animals and plants to maximise the rate of diffusion.

Answer 7

• A large surface area

- A short diffusion pathway

Question 8

What gives the respiratory system a large surface area?

Answer 8

Alveoli

Question 9

Oxygen has a short diffusion distance in the gas exchange system. Why is this?

Answer 9

• The walls of the capillaries are one cell thick

- The walls of the alveoli are one cell thick

Question 10

Blood is constantly moving through the capillaries, and ventilation constantly occurs in the alveoli. What does this create?

Answer 10

A steep concentration gradient

Question 11

What two things happen inside the lungs?

Answer 11

• Oxygen is absorbed (to be used in respiration)

- Carbon dioxide (a product of respiration) is transferred from the blood into the air

Question 12

What is the scientific name of the windpipe (where air passes from the mouth to the lungs)?

Answer 12

The trachea

Question 13

What is the name for the muscles between the ribs?

Answer 13

Intercostal muscles

Question 14

What is the name for the muscle below the lungs?

Answer 14

The diaphragm

Question 15

What is the function (job) of the rings of cartilage in the trachea?

Answer 15

They help to keep the trachea open as air is drawn in

Question 16

What is the name for the air sacs in the lungs where gas exchange takes place?

Answer 16

Alveoli

Question 17

How do alveoli provide a very large surface area for gas exchange?

Answer 17

• They are very small (around 300 micrometres), so have a large surface area to volume ratio
• There are many of them (around 700 million)

Question 18

Describe what happens to the diaphragm and intercostal muscles when you inhale (breathe in).
How does this impact the volume and pressure in the lungs?

Answer 18

• Diaphragm contracts
• Intercostal muscles contract
• Volume inside lungs increases
• Pressure in lungs decreases
• So air moves in

Question 19

Describe what happens to the diaphragm and intercostal muscles when you exhale (breathe out).
How does this impact the volume and pressure in the lungs?

Answer 19

• Diaphragm relaxes
• Intercostal muscles relax
• Volume inside the lungs decreases
• Pressure inside the lungs increases
• So air moves out

Question 20

Where does gas exchange occur in fish?

Answer 20

Gills

Question 21

What is meant by counter-current flow in the gills?

Answer 21

Water that flows over the gills flows in the opposite direction to the blood.

Question 22

Name three adaptations that gills in fish have for efficient gas exchange.

Answer 22

Any three from:

• the large surface area of the gills
• the large surface area of the blood capillaries in each gill filament
• the short distance required for diffusion – the outer layer of the gill filaments and the capillary walls are just one cell thick
• the efficient ventilation of the gills with water - there is a counter current flow of water and blood