3.3.2 Gas Exchange

Question 1

5 key ways that the tracheal system of insects is adapted for gas exchange

Answer 1

The tracheoles have thin walls (so there is a short diffusion distance to cells)
There are a large number of highly branched tracheoles (so there is a short diffusion distance and a large surface area for gas exchange)
Tracheae provide tubes full of air (so there is a fast rate of diffusion into insect tissues)
Fluid in the tracheoles moves out during exercise (to create a larger surface area for gas exchange)
The abdominal pumping of muscles moves air (to maintain a concentration gradient)

Question 2

Insects have a specialist internal gas exchange system called the…system

Answer 2

Tracheal

Question 3

What are the 3 structural features/ main parts of the tracheal system in insects

Answer 3

Tracheae
Tracheoles
Spiracles

Question 4

How do gases enter and leave insects (what structure is there)

Answer 4

Spiracles

(These are holes along the side of the insect (along the length of the abdomen) which can open and close by valves)

Question 5

What do insects have that prevents water loss (Its a hard and stiff covering around their body and is made of chitin)

Answer 5

Exoskeleton

Question 6

What texture is the exoskeleton (waterproof covering) of insects

Answer 6

Hard and rigid

Question 7

3 features of insects that help prevent water loss

Answer 7

Exoskeleton (it’s hard and made of chitin)
Spiracles (they open and close to minimise water loss)
Small surface area to volume ratio (minimise area over which water is lost)

Question 8

What is the exoskeleton (hard covering of insects) made of

Answer 8

Chitin

Question 9

What helps to keep the tracheae in insects open

Answer 9

Rings of chitin

Question 10

In the tracheal system of insects what do the tracheae branch into (which extend into all of the insect’s body tissues)

Answer 10

Tracheoles

Question 11

Why is it important for gas exchange that the tracheoles have thin walls

Answer 11

It creates a short diffusion pathway

Question 12

What structure of the tracheal system in insects increases surface area

Answer 12

The tracheoles as they have lots of branches

Question 13

What do the muscles in the insects’s abdomen do which speeds up the movement of air in and out of the insect

Answer 13

Contract

Question 14

How does muscle contraction in the abdomen of insects heal to maintain the oxygen and CO2 concentration gradients

Answer 14

It speeds up the movement of air in and out of the insect

Question 15

If the tissues in insects respire quicker, why does it increase the rate of diffusion of oxygen in from the air

Answer 15

More respiration= more oxygen being used up= lower oxygen concentration in tissues
So there is a steeper concentration gradient of oxygen between the tissues and air

Question 16

Why does anaerobic respiration of the muscle cells in insects help increase the rate of diffusion of oxygen

Answer 16

Anaerobic respiration releases lactic acid
This lowers the water potential of the muscle cells
Water moves from the tracheoles into the muscle cells by osmosis
This means there is less water in the tracheoles so oxygen can diffuse at a faster rate through the tracheoles and then into the cells (as oxygen diffuses at a faster rate through air than water)

Question 17

Which out of water and air has a higher concentration of oxygen

Answer 17

Air

Question 18

How does water (containing oxygen) enter the fish

Answer 18

Through the mouth

Question 19

How does water leave the fish

Answer 19

Through an opening behind the gills

Question 20

Which are bigger out of gill filaments and gill lamellae on a fish

Answer 20

Gill filaments
(The gill filaments are what have the lamellae on- the lamellae are at right angles to the filaments)

Question 21

Gill filaments on fish are covered with lots of tiny structures called

Answer 21

Lamellae

Question 22

Each gill on a fish is made up of lots of thin plates called …

Answer 22

Gill filaments

Question 23

What is meant by counter current flow in fish

Answer 23

Water and blood flow in opposite directions so blood always meets water with a higher concentration of oxygen.
This maintains a concentration gradient across the whole length of the gill so oxygen can diffuse into the blood across the whole length of the gill.
This ensures that maximum possible gas exchange is achieved

Question 24

In fish, what is it called where blood and water flow in opposite directions to maintain a concentration gradient of oxygen across the whole length of the gill

Answer 24

Countercurrent flow

Question 25

Fish have a countercurrent flow where...and...flow in opposite directions

Answer 25

Blood Water

Question 26

In fish the purpose of the countercurrent flow is to maintain a concentration gradient of oxygen across the whole length of the...

Answer 26

Gill

Question 27

In the countercurrent flow in fish, blood and water always flow in opposite directions so... always meets...with a higher concentration of oxygen

Answer 27

Blood Water

Question 28

Which do fish use out of countercurrent flow and parallel flow and why

Answer 28

Countercurrent flow Blood always meets water with a higher concentration of oxygen (as they're flowing in opposite directions) so a concentration gradient is maintained across the whole length of the gill. (In parallel flow water and blood flow in the same direction so equilibrium is reached halfway across the gill so diffusion of oxygen into the blood stops)

Question 29

2 structures of fish gills that increase surface area

Answer 29

Gill filaments Gill lamellae (increase it even further)

Question 30

What are xerophytic plants

Answer 30

Plants that are adapted to live in dry or physiologically dry habitats

Question 31

Plants that are adapted to live in dry or physiologically dry habitats are called...

Answer 31

Xerophytes

Question 32

Physiologically dry habitat meaning (xerophytes are a type of plants that are adapted to live in physiologically dry habitats)

Answer 32

Even though there's lots of water it's hard for the plants to get the water E.g in frozen environments and in salt marshes due to a low water potential

Question 33

How do curled leaves help to prevent water loss on xerophytic plants

Answer 33

Water vapour is trapped inside which reduces the water vapour diffusion gradient between the inside and outside of the leaf

Question 34

How do hairy leaves help prevent water loss in xerophytes

Answer 34

All of the hairs trap water vapour (moisture) close to the stomata which reduces the water vapour diffusion gradient

Question 35

3 key features of xerophytes which helps prevent water loss by reducing the water vapour diffusion gradient between the inside and outside of the leaf

Answer 35

Hairy leaves Rolled up/ curled leaves Sunken stomata

Question 36

How do sunken stomata help prevent water loss in xerophytes

Answer 36

They trap moist air (water vapour) which reduces the water potential diffusion gradient between the inside and outside of the leaf

Question 37

How does a thick waxy cuticle reduce water loss in xerophytes

Answer 37

It creates an increased waterproof barrier which reduces water loss by evapotranspiration

Question 38

A thick...gives leaves a shiny appearance

Answer 38

Waxy cuticle (A thick waxy cuticle creates an increased waterproof barrier so reduces water loss from the leaf by evapotranspiration)

Question 39

How do needle-like leaves reduce water loss in xerophytes

Answer 39

They have a small surface area which decreases the surface area to volume ratio. This reduces the rate of diffusion of water vapour from the leaf into the atmosphere

Question 40

When the rate of photosynthesis is equal to the rate of respiration, there is no net movement of....and all the...produced during photosynthesis is used for respiration

Answer 40

Gases (carbon dioxide and oxygen) Glucose

Question 41

When the rate of ... is greater than the rate of ...., the plant grows (accumulates biomass) as more glucose is produced in photosynthesis than is needed for respiration

Answer 41

Photosynthesis Respiration

Question 42

Another way for saying a plant grows is saying that is accumulates...

Answer 42

Biomass

Question 43

In both plant leafs and insects, the gases that they need enter by ... from the air

Answer 43

Diffusion

Question 44

In both a plant leaf and insect the movement of gases is..... E.g through the spiracles in insects and stomata in plant leaves

Answer 44

Controlled

Question 45

Which out of insects and plant leaves have a smaller surface area to volume ratio

Answer 45

Insects (They have less surface area in proportion to their volume compared with plant leaves)

Question 46

The...density is the number of stomata per area in field of view

Answer 46

Stomatal

Question 48

In xerophytes a thick waxy cuticle reduces water loss by ...(which process of water loss)

Answer 48

Evapotranspiration

Question 49

The gross structures of the human gas exchange system include what 4 things (they are the structures that air travels through)

Answer 49

Trachea, bronchus, bronchioles, alveoli

Question 50

During inspiration the....Intercostal muscles contract

Answer 50

External

Question 51

During expiration the...intercostal muscles contract

Answer 51

Internal

Question 52

During inspiration the external intercostal muscles contract which means that the internal intercostal muscles ...

Answer 52

Relax (The internal intercostal muscles and external intercostal muscles are antagonistic as when one is contracting, the other is relaxing)

Question 53

The internal intercostal muscles and external intercostal muscles are ... as when one is contracting, the other is relaxing

Answer 53

Antagonistic

Question 54

True or false, during inspiration and expiration the diaphragm always does what the external intercostal muscles do

Answer 54

True E.g during inspiration the external intercostal muscles contract so the diaphragm contracts and during expiration the external intercostal muscles relax so the diaphragm relaxes

Question 55

During inspiration the external intercostal muscles contract, the ribs move...and ...and the diaphragm contracts. This ... the volume of the thorax and ... the pressure in the thorax. This causes air to move into the lungs down a pressure gradient

Answer 55

Up and outwards Increases, decreases

Question 56

During expiration the internal intercostal muscles contract, the ribs move...and ...and the diaphragm relaxes. This ... the volume of the thorax and ... the pressure in the thorax. This causes air to move into the lungs down a pressure gradient

Answer 56

Down and inwards Decreases, increases

Question 57

The trachea are made up of....shaped rings of..

Answer 57

C Cartilage

Question 58

When the diaphragm contracts it ...(what happens to its shape)

Answer 58

Flattens

Question 59

When the diaphragm relaxes it....(what happens to its shape)

Answer 59

Domes

Question 60

True or false, ventilation and breathing are the same thing

Answer 60

True Ventilation is just the scientific term for breathing

Question 61

Inspiration and expiration (ventilation) is caused by ....differences between the thorax cavity (thorax) and the atmosphere

Answer 61

Pressure

Question 62

The thin layer of cells that line the alveoli is called the...

Answer 62

Alveolar epithelium

Question 63

What is the thin layer of cells called that line the alveoli

Answer 63

Alveolar epithelium

Question 64

What is the alveolar epithelium

Answer 64

A thin layer of cells that line the alveoli

Question 65

2 adaptations of the alveoli for gas exchange in humans

Answer 65

A large number of alveoli provided a large surface area The alveolar epithelium is one cell thick and contains flattened thin cells (it's a squamous epithelium) which provides a short diffusion pathway

Question 66

Adaptations of the lungs for gas exchange in humans

Answer 66

Ventilation maintains concentration gradients The capillary endothelium is one cell thick to provide a short diffusion pathway Red blood cells are squashed against the capillary endothelium to provide a short diffusion pathway Slow blood flow allows time for diffusion There's lots of alveoli to provide a large surface area The alveolar epithelium is one cell thick and contains flattened thin cells (it's a squamous epithelium) which provides a short diffusion pathway

Question 67

What is a risk factor

Answer 67

Something that increases the chance of developing a disease