Gas Exchange

Question 1

What does gas exchange occur over?

Answer 1

A gas exchange surface

Question 2

What is a gas exchange surface?

Answer 2

A boundary between the outside environment and the internal environment of an organism

Question 3

What do organisms need to diffuse across gas exchange surfaces as quickly as possible?

Answer 3

Oxygen

Carbon dioxide

Question 4

What 2 things do gas exchange surfaces have in common?

Answer 4

Large Surface Area

Thin so there is a short diffusion pathway

Question 5

What does maintaining a steep concentration gradient do?

Answer 5

Increase the rate of diffusion?

Question 6

What 3 things do a single-celled organism have to allow gases to be exchanged?

Answer 6

Large Surface Area
Thin surface
Short diffusion pathway

Question 7

Why do fish have special adaptations for gas exchange?

Answer 7

There is a lower concentration of oxygen in water than in air

Question 8

What is the gas exchange surface in fish?

Answer 8

Gills

Question 9

How do gills work?

Answer 9

Water containing oxygen enters through the fishes mouth and passes through the gills `

Question 10

What are gills made from?

Answer 10

Lots of thin plates called gill filaments

Question 11

What do gill filaments give?

Answer 11

A large surface area for gas exchange which increases the rate of diffusion

Question 12

What are the gill filaments covered in?

Answer 12

Lots of tiny structures called lamellae

Question 13

What does the lamellae on the gill filaments do?

Answer 13

Increase the surface area even more

Question 14

What does the lamellae have lots of?

Answer 14

Blood capillaries

Thin surface layer of cells to speed up diffusion between the water and the blood

Question 15

What is the counter current system in fish?

Answer 15

The system in which blood flows in one direction and water flows in the opposite direction across the gills of a fish

Question 16

In the gills of a fish what 2 things flow through the lamellae?

Answer 16

Blood flows through in one direction

Water flows over them in the other

Question 17

What does the counter current system cause?

Answer 17

Water with high oxygen concentration flows next to blood with a lower oxygen concentration

Question 18

What does the counter current system maintain?

Answer 18

A steep concentration gradient between the water and the blood

Question 19

What substance do plants need for photosynthesis?

Answer 19

Carbon dioxide

Question 20

What waste gas does phtotsynthesis produce?

Answer 20

Oxygen

Question 21

What do plants need for respiration?

Answer 21

Oxygen

Question 22

What waste gas does respiration produce?

Answer 22

Carbon dioxide

Question 23

What is the gas exchange surface in plants?

Answer 23

The surface of mesophyll cells in a leaf

Question 24

How are mesophyll cells adapted?

Answer 24

They have a large surface area

Question 25

Where are mesophyll cells in a plant?

Answer 25

Inside the leaf

Question 26

How do gases move in and out of a leaf?

Answer 26

Through pores in the epidermis

Question 27

What are the pores in the epidermis called?

Answer 27

Stomata

Question 28

What controls the opening and closing of the stomata?

Answer 28

Guard cells

Question 29

What can the stomata do?

Answer 29

Open to allow the exchange of gases and close if the plant is losing too much water

Question 30

What do insects have that they use for gas exchange?

Answer 30

Tracheae

Question 31

What are tracheae?

Answer 31

Microscopic air-filled pipes

Question 32

How does air move into the tracheae?

Answer 32

Through pores on the surface called spiracles

Question 33

Where does oxygen travel down in an insect?

Answer 33

Down the concentration gradient towards the cells

Question 34

What do the tracheae branch off into?

Answer 34

Smaller tracheoles

Question 35

What do tracheoles have?

Answer 35

Thin, permeable walls | Go into individual cells

Question 36

Why does the tracheoles in an insect go into individual cells?

Answer 36

The oxygen diffuses directly into the respiring cells | It is transported by the blood

Question 37

How is Carbon Dioxide from the cells transported?

Answer 37

It moves down its own concentration gradient towards the spiracles to be released into the atmosphere

Question 38

What are spiracles?

Answer 38

Pores on the surface

Question 39

What do insects do to move air in and out of the spiracles?

Answer 39

Rhythmic abdominal movements

Question 40

What do you tend to lose when exchanging gases?

Answer 40

Water

Question 41

What do insects do if they lose too much water?

Answer 41

Close their spiracles Have a waterproof, waxy cuticle over their body Tiny hairs around their spiracles reducing evoparation

Question 42

During the day, how is the plants stomata usually kept?

Answer 42

Open