Exchange

Question 1

The ___ and _______ rate of an organism affects the rate of exchange.

Answer 1

size, metabolic

Question 2

What happens to the SA:V as a cell increases?

Answer 2

it decreases

Question 3

How do you calculate SA:V ?

Answer 3

SA / V

Question 4

Why do small, inactive organisms not have a specialised gas exchange?

Answer 4

• Large SA to V

- Substances can diffuse in/out quick enough as substances don’t have to travel far to get to cells

Question 5

what are the 3 reasons why large organisms need a specialised circulatory system

Answer 5

• need to meet metabolic requirement
• V increases at a faster rate than SA
• Cells too far away from outer surface, too long for diffusion

Question 6

Name the 4 features of specialised gas exchange

Answer 6

• Large SA:V = increases exchange rate
• Very thin = diffusion pathway short
• selectively permeable = allow selected materials across
• movement of internal (i.e. blood) and environmental medium (i.e. air) = allow diffusion gradient

Question 7

describe gas exchange in a single celled organisms

Answer 7

• no specialised gas exchange
• large SA:V
• short diffusion pathway
• diffusion rapid enough to allow O2 (respiration) in and CO2 out (toxic)

Question 8

name the 3 main parts of the tracheal system of an insect

Answer 8

spiracles, trachea, tracheoles

Question 9

Name the 3 ways gases move in/out of tracheal system

Answer 9

• ends of tracheoles filled with H2O
• mass transport
• Along a diffusion pathway

Question 10

explain how the end of the tracheoles filled with H2O help gases move in/out of insect

Answer 10

1. anaerobic respiration = lactate produced
2. lactate soluble = lowers H2O potential of cells
3. H2O moves into cells (osmosis)
4. volume of H2O in tracheoles reduced
5. air drawn in further
6. liquid diffusion pathway = diffusion rapid

Question 11

explain mass transport of gases in an insect

Answer 11

1. contraction of muscles squeeze trachea
2. mass movement of air in/out
3. speeds up exchange of gases

Question 12

explain how gases in insects move along a diffusion pathway

Answer 12

1. cells respiring, O2 reduced = conc. reduced in tracheoles
2. creates diffusion gradient = O2 diffuses into trachea/tracheoles
3. CO2 produced = creates gradient in opposite direction
4. CO2 leaves

Question 13

Name the components of the specialised gas exchange in fish

Answer 13

gills (covered by operculum), gill filaments, gill arch, blood vessels, lamellae

Question 14

explain countercurrent flow

Answer 14

blood and O2 flow in OPPOSITE directions so:

• conc. of O2 in H2O always slightly more than blood, NEVER REACHES EQUILIBRIUM
• diffusion gradient maintained across whole lamellae
• ventilation (brings O2 to gills) allows mass transport = carrying O2 away: steep conc. gradient
• 80% of O2 diffuses into blood

Question 15

explain why co-current or parallel flow is not used

Answer 15

• diffusion gradient maintained for only half distance across lamellae
• no net diffusion (when conc. equilibrates)
• only 50% of O2 diffuses into blood

Question 16

why are these used in fish: gill filaments, lamellae, epithelium and blood vessels

Answer 16

gill filaments = increase SA
lamellae = increase SA further
epithelium = short diffusion pathway
blood vessels = conc. gradient

Question 17

what processes in plants maintain the diffusion gradients?

Answer 17

• photosynthesis (CO2 diffuses in from external air) and - respiration (O2 diffuses from external air)

Question 18

Adaptation of leaves: In leaves diffusion takes place in ___ phase. Air spaces ______ compared to V of tissue. Many interconnecting __ spaces so gases readily come into contact with ________ cells. Large _____ ____ of _______ cells so there is rapid diffusion. Lots of ______, no cell far from a stoma = _____ diffusion pathway.

Answer 18

1. gas
2. large
3. air
4. mesophyll
5. surface area
6. mesophyll
7. stomata
8. stoma
9. short

Question 19

stomata are surrounded by ______ cells which open/close stomatal ________.

Answer 19

guard cells, aperture

Question 20

an increase in _______ acid can trigger ____ ions to flow into _____ cell, _____ H2O potential. This increases ______ so guard cell ____ stomata.

Answer 20

1. abscisic
2. K+
3. stomata
4. lowering
5. turgor
6. opens

Question 21

How does a thick waxy cuticle reduce H2O loss in xerophytic plants

Answer 21

waterproof so less H2O escapes i.e. holly

Question 22

how does hairy leaves and stomata in pits/grooves reduce H2O loss

Answer 22

traps still/moist air. H2O potential gradient reduced both in/out leaf. Reduces evap. i.e. pine trees

Question 23

how does the rolling up of leaves reduce H2O loss

Answer 23

traps still air. High water potential. No water potential gradient between in/out of cell. No water loss. i.e. marram grass

Question 24

how does reducing SA:V of leaves reduce H2O loss

Answer 24

as a smaller SA:V slower rate of diffusion i.e. pine needles

Question 25

How do insects limit H2O loss (4 ways)

Answer 25

- Small SA:V (minimise area where H2O is lost) - waterproof cuticle covering exoskeleton - spiracles closed majority of time - tiny hairs around spiracles, humid = trap H2O

Question 26

The trachea is supported by what and what 2 cells line the wall of the trachea?

Answer 26

+ supported by C-shaped rings of cartilage - goblet cells = secrete mucus - ciliated epithelial cells = moves mucus up to pharynx where it goes down oesophagus to stomach

Question 27

describe the bronchi

Answer 27

- 2 divisions of trachea - have muscle and ciliated cells. - Have cartilage but amount decreases as bronchi gets smaller

Question 28

What 3 part make up the alveoli?

Answer 28

- collagen - elastic fibres - epithelial cells

Question 29

why do alveoli contain elastic fibres

Answer 29

so they can stretch when filled and recoil so CO2 can be expelled

Question 30

Is this true or false: gases move from an area of low pressure to high pressure

Answer 30

false: gases move from an area of high to low pressure

Question 31

describe what happens during inspiration/inhalation

Answer 31

1. external intercostal muscles contract 2. diaphragm contracts/flattens 3. volume of thorax increases 4. atmospheric pressure is greater than inside lungs 5. air moves down a concentration gradient into lungs

Question 32

describe what happens during expiration/exhalation

Answer 32

1. internal intercostal muscles contract 2. diaphragm relaxes 3. volume of thorax decreases 4. atmospheric pressure lower than inside lungs 5. air moves down concentration gradient out of lungs

Question 33

define tidal volume and its units

Answer 33

volume of air inspired with each breath at rest - dm3

Question 34

define ventilation rate and its units

Answer 34

no. of breaths in 1 min. min-1

Question 35

define pulmonary ventilation rate and its units

Answer 35

total volume of air moved into lungs in 1 min. dm3 min-3

Question 36

define total lung capacity

Answer 36

total volume of air contained in the lung at the end of max. inhalation

Question 37

define vital capacity

Answer 37

max. volume of air a person can expel after max. inhalation in 1 breath

Question 38

define residual volume

Answer 38

volume of gas remaining in lung at end of max. exhalation

Question 39

define the equation for pulmonary ventilation

Answer 39

tidal volume x ventilation rate

Question 40

define the equation for cardiac output

Answer 40

stroke volume x heart rate

Question 41

Alveoli have a single layer of _________ cells whereas blood capillaries have a single layer of ________ cells

Answer 41

1. epithelium | 2. endothelium

Question 42

- Red blood cells pass ______ through capillaries = ______ time for ______. - Red blood cells _______ against capillary wall and walls are very ___ = diffusion pathway _______ - Alveoli and pulmonary capillaries have large ______ ____. - ______ flow thru capillaries = maintains ______ - breathing and ______ of the heart = ________ and circulating the blood keeps ____ conc. gradient

Answer 42

1. slowly, more, diffusion 2. flatten, thin, short 3. surface area 4. blood, gradient 5. pumping, ventilating, steep

Question 43

define Ficks law and what does it mean

Answer 43

diffusion = SA x Difference in conc. gradient / length of diffusion pathway - diffusion is directly proportional to SA and difference in conc. - inversely proportional to length of pathway

Question 44

What does pulmonary fibrosis do and why does it make it harder to take in O2?

Answer 44

- reduces elasticity in lungs = lung recoil decreases + alveoli can't expand/contract/recoil + smaller SA = less O2/CO2 exchanged, conc. gradient decreases

Question 45

What does asthma do and why does it make it harder to take in O2?

Answer 45

- inflammation of bronchi/bronchioles, more mucus produced + increased resistance to air flow = smaller volume of air into lungs/alveoli + so decrease in O2 conc. diffusion of O2 decreases

Question 46

What does emphysema do and why does it make it harder to take in O2?

Answer 46

- elastin protein in lungs damaged = reduces elasticity + alveoli unable to expand/recoil/stretch + less O2 enters/less CO2 leaves = decrease in CO2/O2 conc. gradient + SA for diffusion decreases, less diffusion

Question 47

name the 5 main risk factors for lung disease

Answer 47

smoking, pollution, genetic makeup, infections, occupation i.e. miner

Question 48

When analysing data: just because there is a _______ does not imply _______. Does not show a specific variable ____ the other due to the fact that there are other ______. Also there is normally a delay between cause and ______.

Answer 48

1. correlation 2. causation 3. causes 4. factors 5. effect

Question 49

what are the 2 things you need to do to prove a specific factor causes an outcome

Answer 49

1. a hypothesis to explain current correlation | 2. perform experiments to prove causal relationships

Question 50

Name at least 3 restrictions on the sources of smoking

Answer 50

- reducing tobacco products - health warnings on packaging - ban on advertising smoking - minimum age of smoking - smoking banned in areas/places

Question 51

____ transport maintains the final ______ gradients that bring substances to/from the cell membranes of individual cells. Also maintains a stable environment (____ fluid)

Answer 51

mass, diffusion, tissue

Question 52

What 2 cells is the bronchioles made up of?

Answer 52

muscle cells lined with epithelial cells | muscle constrict = control air flow

Question 53

where does gas exchange take place?

Answer 53

the alveolar epithelium

Question 54

why do alveoli have a large SA and very thin walls?

Answer 54

increase rate of diffusion