3.1 Exchange surfaces and breathing

Question 1

3 features of a good exchange surface

Answer 1

large SA- more space for molecules to pass through
thin barrier- reduce diffusion distance
good blood supply- keep steep concentration gradient

Question 2

3 factors that affect the need for a transport system

Answer 2

size
sa:v
activity levels

Question 3

Adaptations of the mammalian gaseous exchange system (3)

Answer 3

alveoli small but numerous
thin barrier alveolus wall 1 squamous cell thick
good blood supply large capillary network over alveoli

Question 4

5 steps to inspiration

Answer 4

1. diaphragm contracts
2. external intercostal muscles contract, raising ribs
3. volume of chest cavity is increased
4. pressure drops below atmospheric pressure
5. air is moved into lungs down pressure gradient

Question 5

total lung capacity= x + y

Answer 5

vital capacity

residual volume

Question 6

describe the tracheal system of an insect (5)

Answer 6

spiracles
tracheae
tracheoles
tracheal fluid withdraws to allow bigger sa for exchange

Question 7

What is tidal volume?(3)

Answer 7

volume of air, inhaled / exhaled ;
in, one / each, breath ;
during, steady / regular, breathing

Question 8

What is vital capactiy?(2)

Answer 8

the maximum volume of air ;

inhaled / exhaled, in one breath

Question 9

Explain significance of relationship between SA:V and rate of diffusion in large plants.(5)

Answer 9

have a, small / low, SA : VOL ratio ;
idea of diffusion too slow (to supply requirements) ;
idea of need transport system (for water / minerals /
assimilates) ;
idea of need (special) surface area for, gaseous exchange
/ uptake of minerals ;

Question 10

Why would a large mammal need a specialised exchange system?(3)

Answer 10

low / small, surface area to volume ratio ;
diffusion, too slow / distance too great ;
to supply enough, oxygen / (named) nutrients ;

Question 11

Do small animals have a small or large SA:V?

Answer 11

large

Question 12

Why do multicellular oranisms need good exchange surfaces?

Answer 12

diffusion is too slow

Small SA:V

Question 13

Explain expiration (5)

Answer 13

intercoatal and diaphragm musles relax
ribcage moves downwards and inwards, diaphram relaxes
thorax volume decreases causing pressure to increase above atmospheric pressure
air is forced out of the lungs
this is passive process/ doesnt require energy

Question 14

What 3 things do the lungs have and need for efficient gaseous exchange?

Answer 14

large surface area- increase diffusion rate- e.g. many alveoli
thin-short diffusion distance to increase diffusion rate- e.g. alveoli good blood supply

Question 15

Which of the following contain cartiledge:
trachea
bronchi
bronchioles
alvioli?

Answer 15

trachea and bronchi

Question 16

what do goblet cells do?

Answer 16

secrete mucus to trap microoranisms stopping them reaching alvioli

Question 17

what do cilia do?

Answer 17

beat mucus upwards toward throat

Question 18

what is the purpose of smooth muscle in the walls of the trachea, bronchi and bronchioles?]
what happens to it during exercise?

Answer 18

diameter to be controlled- in exersise it relaxes making tubes wider so theres less resistance and air can move in more easily

Question 19

explain how a spirometer works 4

Answer 19

breathe into tube connected to oxygen chamber
as person breathes in and out lid moves up and down
which moves a pen creating a spirometer trace
soda lime absorbs carbon dioxide