3.3.2 Gas Exchange

Question 1

Why don’t insects breathe in oxygen (2)

What does this do to them

Answer 1

Don’t have lungs
Circulatory system doesn’t carry oxygen/CO2

Limits their size

Question 2

What’s the breathing system in insects called

Answer 2

The tracheal system

Question 3

How does air enter an insect

Where does it then pass to

Answer 3

Through holes in the exoskeleton (spiracles)

Air then passes into tubes (tracheae)

Question 4

What’s prevents the collapse of tracheae tubes

Answer 4

Strengthening rings

Question 5

What do tracheae branch out into

What are these like

Answer 5

Tracheae branch out into tracheoles that have thinner,more permeable walls for gas exchange

Question 6

What do tracheoles form close to repairing tissue (directly into muscle)

Answer 6

A network of tubes

Question 7

What can tracheoles do (2)

Answer 7

Enter cells + take oxygen straight to mitochondria

Exchange CO2 + H2O

Question 8

How many adaptions to insects have for gas exchange

Answer 8

4

Question 9

How can insects control ventilation and water loss

Answer 9

Can open + close their spiracles

Question 10

How many spiracles do insects have

Answer 10

A pair on each 3 segments of abdomen

Question 11

What helps draw air further into the tracheole

Answer 11

Their ends have water in so during exercise the muscle cells undergo anaerobic respiration producing lactate which is soluble

Lactate lowers water potential of muscle cells so water leaves tracheoles + enters muscles by osmosis

Question 12

How do insects muscles help allow mass transport of gases

Answer 12

They contract + squeeze the tracheae pushing air through them

Question 13

What produces the gradient needed for diffusion through an insect

Answer 13

The muscle cells using oxygen for respiration maintaining a low concentration

Question 14

How can insects control air flow

Answer 14

In the head,thorax + abdomen tracheae may be connected to air sacs and some insects can actively pump these for air flow

Question 15

How can water be lost by insects

Answer 15

By opening spiracles

Question 16

3 ways of reducing water loss in insect

Answer 16

1. Reducing SA:volume ratio
2. Waterproof covering
3. Closing spiracles

Question 17

What exoskeleton is covered with a waterproof wash cuticle

Answer 17

Insects hard exoskeleton made of chitin

Question 18

Why is it harder to breathe in water

Answer 18

1% oxygen
Oxygen levels vary
Diffuses slower
Harder to move as water is dense

Question 19

What in fish is adapted for efficient gas exchange

Answer 19

Fish gills

Question 20

How many gills do fish have

Answer 20

2, one on either side of face

Question 21

What are gills made up of

How do they appear

Answer 21

Made up of folded,layered tissue

Appear feathery

Question 22

What do gills contain many of

Answer 22

Many filaments

Question 23

What is there on each filament

4 ways this is useful

Answer 23

Many lamellae

Useful as:

• larger SA
• increase ventilation
• good blood supply
• short diffusion pathway

Question 24

In a fish, what increases SA for gas exchange as they have a rich blood supply nearby and a thin membrane

Answer 24

Filaments + lamellae

Question 25

What is the main adaption of gills

Answer 25

Counter current flow

Question 26

How do blood and water flow in a fish

Answer 26

In opposite directions

Question 27

What’s counter current flow

Answer 27

When the blood supply to the gills flows in the opposite direction to the water to maintain concentration gradient

Question 28

What does counter current flow ensure

Answer 28

That oxygen continually diffuses into the blood

Question 29

5 parts of plants to know

Answer 29

``` Upper epidermis Lower epidermis Spongy mesophyll Palisade mesophyll Veins with xylem + phloem ```

Question 30

What happen in the lower epidermis

Answer 30

Gas exchange

Question 31

What does the upper + lower epidermis protect plant from (3)

Answer 31

Damage,infection,dehydration

Question 32

What does spongy mesophyll have the most of | What does this allow gases to do

Answer 32

Has the most air pockets | So Gases can diffuse in all directions

Question 33

What process happens in the palisade mesophyll

Answer 33

Photosynthesis

Question 34

What does the xylem and phloem do

Answer 34

Transport substances

Question 35

What do all parts of a plant do (leaves,stem,roots,flowers)

Answer 35

Respire

Question 36

How do parts of plant above soil get their oxygen

Answer 36

Through pores

Question 37

What are the pores in leaves called

Answer 37

Stoma (1-stomata)

Question 38

What’s the size of the stoma controlled by

Answer 38

Guard cells

Question 39

What are dicots

Answer 39

Most flowering plants that produce 2 leaves when first grow from a seed

Question 40

When is stoma forced to open and how

Answer 40

When moisture is plentiful so the guard cells swell with water allowing gas exchange as stoma is open

Question 41

What does stoma do when plant loses too much water/water in environment gets less plentiful

Answer 41

Guard cells deflate closing the stoma, preventing further gas/water loss

Question 42

What plants can photosynthesise in the dark

Answer 42

Xerophytes

Question 43

Why are guard cells in xerophytes different

Answer 43

To help them cope with dry (arid) conditions

Question 44

4 adaptations of xerophytes for dry (arid) conditions

Answer 44

``` Thick cuticle Hairy stomata Sunken/in pits Rolled up leaves Smaller SA:volume Small needle-like leaves ```

Question 45

Why do xerophytes have thick cuticles

Answer 45

To prevent water loss by evaporation

Question 46

Why do xerophytes have hairy stomata

Answer 46

As the hairs trap moisture/nutrients

Question 47

Why do xerophytes have rolled up leaves

Answer 47

As it decreases their surface area to protect from wind

Question 48

How does having a smaller SA:volume ration in a plant prevents water loss

Answer 48

As there will be less stomata