3.3.2 Gas Exchange Flashcards Preview

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Flashcards in 3.3.2 Gas Exchange Deck (34):
1

FISH:
Explain how the gills allow efficient gas exchange

•The lamellae provide a large surface area
•Thin epithelium so a short diffusion pathway
•Counter-current flow maintains the concentration gradient across whole length of lamellae

2

FISH:
Explain how the highly folded structures of the gill (lamellae) increase the efficiency of gas exchange

They increase the surface area over which diffusion can take place

3

FISH:
Describe and explain how the countercurrent system leads to efficient gas exchange across the gills of a fish.

Water and blood flow in opposite directions.
This maintains a concentration gradient across the gill (as there is always a higher concentration of oxygen in the water than blood)

4

Name the process by which carbon dioxide is removed from a single celled organism

Simple diffusion over the body surface

5

INSECTS:
Explain how the tracheal system limits the size of the insect

Because it relies on diffusion to bring oxygen to respiring tissues.
If insects were large it would take too long for oxygen to reach the tissues rapidly enough to supply the insects needs

6

INSECTS:
Give 2 explanations as to why the rate of water loss during gas exchange is very low in most insects.

•Insects have spiracles that can close to reduce water loss
•Insects have sunken spiracles that trap moist air

7

Describe and explain ways in which plants limit water loss.

•Plants have a waxy cuticle which prevents the evaporation of water;
•Plants have hairs on their surface that trap moist air reducing the water potential gradient
•Plants have sunken stomata which again traps moist air reducing the water potential gradient
•The stomata can close which reduces evaporation

8

How can you calculate pulmonary ventilation rate?

= tidal volume (dm3) x breathing rate (min-1)

9

LEAVES:
Explain why less water is lost by a plant when the air is humid.

Humidity reduces the difference in concentration of water between the plant and the air.
Reduced concentration gradient = less water loss

10

During an asthma attack, less oxygen diffuses into the blood from the alveoli.
 Explain why.

Asthma attacks narrow the airways, so not as much oxygen reaches the alveoli.
This means that there is a small concentration gradient (between blood and alveoli) so rate of diffusion is lower

11

What are xerophytes?

Plants that are adapted to living in areas where water is in short supply

12

Give examples of how xerophytes limit water loss

•Thick cuticle
•Waxy cuticle
•Rolled up leaves
•Hairy leaves
•Stomata in pits or grooves
•A reduced surface area to volume ratio
•Deep roots
•Sunken stomata

13

XEROPHYTES:
Explain how having rolled up leaves reduces water loss

-Traps a region of still air within the rolled leaf.
-The trapped region has a high water potential.
-As there is no water potential gradient between the inside and outside of the leaf there is no water loss

14

XEROPHYTES:
Explain how having hairy leaves reduces water loss

-Traps still, moist air next to the leaf surface.
-This reduces the water potential gradient between the inside and outside of the leaf so less water is lost.

15

XEROPHYTES:
Explain how having stomata in pits or grooves reduces water loss

-It traps still, moist air next to the leaf surface.
-This reduces the water potential gradient between the inside and outside of the leaf so less water is lost.

16

Explain why water is always lost from the gas exchange surfaces of terrestrial organisms

-Gas exchange surfaces are permeable.
-As there is a higher concentration of water molecules inside the animal than outside water will diffuse out.

17

Why does every cell inside an insect have a short diffusion distance?

They are only a short distance from the tracheae or the tracheoles

18

INSECTS:
Name the tiny pores on the body surface of insects

Spiracles

19

INSECTS:
For much of the time the spiracles are (open or closed)

Closed, to prevent water loss

20

INSECTS:
Periodically spiracles must open. Why?

To allow gas exchange

21

FISH:
What happens if blood and water flow in parallel?

-Diffusion of oxygen into the blood is less efficient - (only 50%)
-Equilibrium is reached as the conc. gradient cannot be maintained along the whole filament

22

XEROPHYTES:
How can a reduced SA : Vol ratio in leaves be achieved?

eg. Leaves are reduced to pine needles

23

LUNGS:
Starting with nose/mouth, list the structures that air passes through

Trachea - bronchi - bronchioles - alveoli

24

LUNGS:
What prevents the trachea from collapsing?

Rings of cartilage

25

LUNGS:
List the adaptations of the alveoli that make it ideal for gas exchange

Single layer of epithelium cells
Stretch as breathe in
Spring back as breathe out
Huge SA
Moist
Rich blood supply

26

LUNGS:
What happens to the intercostals as we breathe in

External contract
Internal relax

27

LUNGS:
What happens to the rib cage and the diaphragm before we inhale

Ribs - move up and out
Diaphragm - contracts and moves down

28

LUNGS:
What happens to the volume and pressure of the thorax before we inhale air

Volume increases
Pressure decreases

29

LUNGS:
What is the 'tidal volume'?

The volume of air we breath in and out at rest (typically about 0.5dm3)

30

LUNGS:
List the events of
a) Intercostal Muscles
b) ribs
c) Diaphragm
before we inhale

a) Internal contract, external relax
b) Ribs move down and in
c) Diaphragm relaxes, domes up

31

LUNGS:
Typically, what is the normal ventilation rate?

12-20 breaths per min

32

Describe the gross structure of the human gas exchange system

Trachea - Bronchi - Bronchioles - alveoli

33

Describe how we breathe IN

Diaphragm contracts
External intercostal muscles contract
Volume increases and pressure decreases in thorax
Air moves into lungs

34

Describe how we breathe OUT

Diaphragm relaxes
Internal intercostal muscles contract
Volume decreases and pressure increases in thorax
Air moves out of the lungs