gas exchange Flashcards
2.40B - 2.50
1
Q
2.40B what is diffusion
A
diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration
2
Q
2.40B what happens in diffusion
A
molecules move down a concentration gradient as a result of their random movement
4
Q
2.40B what does diffusion do in regards to gas exchange
A
diffusion drives the process of gas exchange
5
Q
2.40B what organisms can exchange gases by simple diffusion through the cell membrane
A
single-celled organisms such as amoeba
6
Q
2.40B what can single-celled organisms (amoeba) do through the cell membrane
A
they can exchange gases sufficiently by simple diffusion through the cell membrane
7
Q
2.40B what organisms have exchange surfaces and organ systems that maximise the exchange of materials
A
multicellular organisms
8
Q
2.40B what do multicellular organisms have that maximise the exchange of materials
A
exchange surfaces and organ systems
9
Q
2.40B name examples of gas exchange organs in organisms
A
gills in fish, lungs in humans & leaves / roots in plants
10
Q
2.40B how do gas exchange organs increase the efficiency of exchange
A
they have a large surface area to increase the rate of transport
they have a short diffusion distance for substances to move across
(animals have gas exchange surfaces that are well-ventilated to maintain steep concentration gradients)
11
Q
2.41B what do the processes of respiration and photosynthesis both rely on
A
the exchange of oxygen and carbon dioxide
12
Q
2.41B what do all living cells do in gas exchange during respiration
A
all living cells respire
13
Q
2.41B what does the process of gas exchange during respiration require
A
the uptake of oxygen and the release of carbon dioxide
14
Q
2.41B how does oxygen diffuse in gas exchange during respiration
A
oxygen diffuses down the concentration gradient
from a high concentration (outside the leaf)
to a low concentration (inside the leaf)
15
Q
2.41B what do the cells use in respiration so the concentration is low
A
the cells use oxygen in respiration so the concentration is always low inside the respiring cells
16
Q
2.41B how does carbon dioxide diffuse in gas exchange during respiration
A
the carbon dioxide diffuses down the concentration gradient
from a high concentration (inside the leaf)
to a low concentration (outside the leaf)
17
Q
2.41B when do plant cells photosynthesise during gas exchange during photosynthesis
A
when there is enough sunlight
18
Q
2.41B what does the process of gas exchange during photosynthesis require
A
it requires the uptake of carbon dioxide and the release of oxygen
19
Q
2.41B how does carbon dioxide diffuse in gas exchange during photosynthesis
A
carbon dioxide diffuses down the concentration gradient
from an area of high concentration (outside the leaf)
to an area of low concentration (inside the leaf)
20
Q
2.41B what do the cells use in photosynthesis so the concentration is low
A
the cells use carbon dioxide in photosynthesis so the concentration is always low inside the photosynthesizing cells
21
Q
2.41B how does oxygen diffuse in gas exchange during photosynthesis
A
oxygen diffuses down the concentration gradient
from a high concentration (inside the leaf)
to a low concentration (outside the leaf)
22
Q
2.41B in photosynthesis where do carbon dioxide and oxygen diffuse
A
carbon dioxide diffuses into the leaf
oxygen diffuses out of the leaf
23
Q
2.41B in photosynthesis what diffuses into the leaf and out of the leaf
A
carbon dioxide diffuses into the leaf
oxygen diffuses out of the leaf
24
Q
2.42B the structure of a leaf is adapted for what
A
both photosynthesis and gas exchange
25
Q
2.42B name some things found inside a leaf
A
cuticle
upper epidermis (bricks)
palisade mesophyll (longer rectangles)
xylem & phloem
spongy mesophyll (air bubbles)
lower epidermis (smaller bricks w/ hole)
guard cell (hole in lower epidermis)
cuticle
26
2.41B in respiration what diffuses out of the leaf and what diffuses in
carbon dioxide diffuses out of the leaf and oxygen diffuses into the leaf
27
2.41B in respiration where do carbon dioxide and oxygen diffuse
carbon dioxide diffuses out of the leaf and oxygen diffuses into the leaf
28
2.41B how does gas exchange occur in a single-celled organism
in a single celled organism (like an amoeba) gas exchange occurs through diffusion
29
2.42B what is the leaf specifically adapted to do
to maximise gas exchange
30
2.42B what are the 3 key gases to consider in gas exchange in a leaf
carbon dioxide - released in respiration but used in photosynthesis
oxygen - released in photosynthesis but used in respiration
water vapour - released in respiration and transpiration
31
2.42B where will gases always diffuse in a leaf
they will always diffuse down a concentration gradient
(where there is a high concentration to where there is a low concentration)
32
2.42B what is the pathway of carbon dioxide from the atmosphere to chloroplasts by diffusion
atmosphere -> through the open stoma -> air spaces around spongy mesophyll -> diffuses through cell wall & membrane of mesophyll cells -> dissolves in cytoplasm -> diffuses into chloroplast
33
2.42B what are some adaptations of the whole leaf for gas exchange
thin which gives a short diffusion distance
flat which provides a large surface area to volume ratio
they have many stomata which allow movement of gases in and out of the air spaces by diffusion
34
2.42B what are some adaptations of the internal leaf structures / tissues for gas exchange
air spaces to allow gas movement around the loosely packed mesophyll cells
many stomata in the lower epidermis open in sunlight to allow gas movement in and out of the leaf
thin cell walls allow gases to move into the cells easily
moist air which gases can dissolve into for easier movement into and out of cells
close contact between the cells and the air spaces allows efficient gas exchange for photosynthesis and respiration
35
2.43B where are the stomata
they are found between two guard cells predominantly on the lower epidermis of the leaf
36
2.43B what are the guard cells responsible for
for the opening and closing of the stomatal pore which controls gas exchange and water loss
37
2.43B what does the stomatal pore do
it controls the gas exchange and water loss
38
2.43B how does water move in regards to the stomata
the stomata opens when water moves by osmosis into the guard cells
39
2.43B when water moves into the guard cells this makes them
turgid
40
2.43B when guard cells are turgid this allows
gases to diffuse in and out of the leaf through the stomatal pore
41
2.43B when do stomata tend to open
stomata tend to open when there is plenty of water and sunlight
42
2.43B when do the stomata close
they close when the guard cells lose water by osmosis
43
2.43B where does the water move to when the stomata close
it moves to the neighbouring epidermal cells and they become flaccid
44
2.43B what do the epidermal cells become when water enters them
flaccid
45
2.43B what does flaccid prevent
it prevents any diffusion in or out of leaf
46
2.43B when do stomata tend to close
they tend to close due to low water availability or low sunlight
47
2.43B what do the guard cells do
the guard cells control the opening and closing of the stomata
48
2.44B when do plants photosynthesise
they photosynthesise when they have access to light however cells respire all the time
49
2.44B what does this mean for gas exchange during a 24 hour period
gas exchange in plants varies throughout a 24 hour period
50
2.44B what happens during the daytime with plants
during the daytime they both respire and photosynthesise
51
2.44B in the day which rate is higher photosynthesis or respiration
photosynthesis tend to be higher - unless there is a low light intensity
52
2.44B in the daytime what does this mean for carbon dioxide and oxygen in the plant
there is a net diffusion of carbon dioxide into the plant and a net diffusion of oxygen out of the plant during the day
53
2.44B during the night time what do plants do
they only respire
54
2.44B in the nighttime what does this mean for carbon dioxide and oxygen in the plant
this means that there is a net movement of oxygen into the plant and a net diffusion of carbon dioxide out of the plant during the nighttime
55
2.44B what happens at low light intensities
the rate of photosynthesis is equal to the rate of respiration
56
2.44B at low light intensities what does this mean for carbon dioxide and oxygen
this means that there is no net movement of oxygen or carbon dioxide in either direction
57
2.44B what do plants do in the day and night
plants photosynthesise and respire during the day but only respire at night time
58
2.45B practical: what apparatus do you need for the effect of light on gas exchange in plants
Boiling tubes
Cotton wool
Aluminium foil
Gauze
Rubber bungs
Hydrogencarbonate indicator
Leaves
59
2.45B practical: method for the effect of light on gas exchange in plants
measure out 20cm3 of hydrogencarbonate indicator into 4 boiling tubes
place cotton wool in the tubes
label the boiling tubes A-D
tube a - no leaf (control tube)
tube b - place a leaf in tube and leave in the light
tube c - place a leaf in the tube and wrap it in aluminium foil to block out the light
tube d - place a leaf in then tube and wrap it in gauze
place a bung on the top of each tube
leave all 4 tubes in the light for 30 mins
60
2.45B practical: what can hydrogencarbonate indicator be used for
it can be used to study gas exchange in different light conditions
61
2.45B practical: results for the effect of light on gas exchange in plants
after 30 mins
tube a - control tube should remain an orange / red colour as it is at atmospheric levels
no net movement
tube b - the leaf is photosynthesising and respiring
because the rate of photosynthesis is greater than the rate of respiration the indicator will turn purple as there is less carbon dioxide than atmospheric levels
tube c - no sunlight reached the leaf
no light - leaf not photosynthesise but will respire producing carbon dioxide
indicator turns yellow as carbon dioxide levels increase above atmospheric levels
tube d - gauze allowed partial light
rate of photosynthesis equals the rate of respiration so there was no net change in carbon dioxide levels
indicator remains orange / red
62
2.45B practical: what does hydrogencarbonate indicator change
it will change from orange / red to yellow with increasing carbon dioxide or purple with decreasing carbon dioxide
63
2.45B practical: CORMS practical
- change
- we will change the availability of light for each boiling tube (not wrapped, wrapped in foil, wrapped in gauze)
- organisms
- The leaves should be from the same species/age of the plant, they should be approximately the same size
- repeat
- We will repeat the investigation several times to ensure our results are reliable
- measurement 1
- we will observe the change in the hydrogen carbonate indicator
- measurement 2
- after 30 minutes
- same
- control the volume of hydrogen carbonate indicator, the number of leaves, the temperature of the environment
64
65
2.46 what is the thorax
the human chest cavity
66
2.46 what does the thorax consist of
the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes
67
2.46 in the thorax describe the structure of the ribs
bone structure that protects internal organs such as the lungs
68
2.46 in the thorax describe the structure of the intercostal muscles
muscles between the ribs which control their movement causing inhalation & exhalation
69
2.46 in the thorax describe the structure of the diaphragm
sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation & exhalation
70
2.46 in the thorax describe the structure of the trachea
windpipe that connects the mouth and nose to the lungs
71
2.46 in the thorax describe the structure of the larynx
also known as the voice box, when air passes across here we are able to make sounds
72
2.46 in the thorax describe the structure of the bronchi (plural)
large tubes branching off the trachea with one bronchus (singular) for each lung
73
2.46 in the thorax describe the structure of the bronchioles
bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli
74
2.46 in the thorax describe the structure of the alveoli
tiny air sacs where gas exchange take place
75
2.46 in the thorax describe the structure of the pleural cavity
the fluid filled space between the pleural membranes which reduces friction and allows the lungs to move freely
76
2.46 the lungs are the ... surface in humans
gas exchange
77
2.46 what features do all gas exchange surfaces have in common
large surface area for faster diffusion of gases across the surface
thin walls to ensure diffusion distances remain short
good ventilation with air so diffusion gradients can be maintained
good blood supply to maintain a high concentration gradient so diffusion occurs faster
78
2.47 muscles are only able to pull on bones not push them meaning
there must be two sets of intercostal muscles to work antagonistically to facilitate breathing
79
2.47 what do the external intercostal muscles do
pull the ribcage up
80
2.47 what do the internal intercostal muscles do
pull the ribcage down
81
2.47 which intercostal muscles pull the ribcage up
the external intercostal muscles
82
2.47 which intercostal muscles pull the ribcage down
the internal intercostal muscles
83
2.47 what is the diaphragm
a thin sheet of muscle that separates the chest cavity from the abdomen
84
2.47 during inhalation describe the diaphragm & intercostal muscles
external intercostal muscles contract
ribcage moves up and out
diaphragm contracts & flattens
volume of thorax increases
pressure inside thorax decreases
- relative to the outside body -
air is drawn in
85
2.47 during exhalation describe the diaphragm & intercostal muscles
external intercostal muscles relax
ribcage moves down and in
diaphragm relaxes & becomes dome-shaped
volume of thorax decreases
pressure inside thorax increases
- relative to the outside body -
air is forced out
86
2.48 how are alveoli highly adapted for gas exchange
large surface area to volume ratio:
there are many rounded alveolar sacs
minimise / short diffusion distance:
alveoli have thin, single layers of cells
steep concentration gradient:
ventilation maintains high levels of oxygen & low levels of carbon dioxide
good bloody supply & maintains concentration gradients:
ensures a constant supply of blood high in carbon dioxide & low in oxygen
a layer of moisture on the surface of the alveoli helps diffusion as gases dissolve
87
2.49 smoking cigarettes has been linked to
disease in the lungs and is a risk factor in coronary heart disease
88
2.49 what does nicotine in cigarettes do
narrows blood vessels and increases heart rate, leading to increased blood pressure
causes high blood pressure that leads to blood clots forming in the arteries potentially resulting in heart attack or stroke
89
2.49 what does carbon monoxide in cigarettes do
binds irreversibly to haemoglobin reducing the capacity of blood to carry oxygen
breathing frequency & depth need to increase putting more strain on the breathing system
circulatory system needs to pump blood faster
- raising blood pressure & increasing risk of coronary heart disease & stroke
90
2.49 what does tar in cigarettes do
it's a carcinogen linked to increased chances of cancerous cells developing in the lungs
contributes to COPD which occurs when chronic bronchitis and emphysema occur together
91
2.49 what happens in chronic bronchitis
tar stimulates goblet cells & mucus glands to enlarge and produce more mucus
mucus builds up blocking the smallest bronchioles
leading to infections
build up of mucus can result in damage to the cilia preventing them from beating & removing the mucus
a smokers cough is the attempt to move the mucus
92
2.49 what happens in emphysema
phagocytes that enter the lungs release elastase an enzyme that breaks down the elastic fibres in the alveoli
alveoli become less elastic & cannot stretch so many burst
the breakdown of alveoli reduces the surface area for gas exchange
patients become breathless & wheezy
93
2.49 smoking can cause ... and several types of cancer including ...
coronary heart disease and lung cancer
94
2.49 what does nicotine do
it narrows blood vessels - increased blood pressure
increased heart rate
95
2.49 what does carbon monoxide do
binds irreversibly to haemoglobin
breathing frequency has to increase
increases risk of coronary heart disease & strokes
96
2.49 emphysema does what
makes the alveoli less elastic & cannot stretch
the breakdown of alveoli reduces the surface area for gas exchange
97
2.49 smoking increases the risk of cancer which is
the rapid uncontrolled cell growth
98
2.49 tobacco smoke contains ______ ________ which permanently binds to the haemoglobin forming __________________ reducing the amount of oxygen being transported by the blood
carbon monoxide
carboxyhaemoglobin
99
2.49 in healthy lungs the linings of the trachea and bronchi are
specialised to prevent dirt and bacteria entering the lungs
100
2.49 the cilia of the lining cells move transporting the mucus
up the airways where it is then swallowed
101
2.49 chemicals in tobacco smoke destroy _____ reducing their number, at the same time mucus production will increase. the mucus cannot be moved out of the airways quickly so it ______ __ causing _______ _____ and increases the risk of infection
cilia
builds up
smokers cough
102
2.49 __________ is a disease resulting from the build up of in refuted mucus in the bronchi and bronchioles
bronchitis
103
2.49 smoke can also reach the alveoli damaging them: the alveoli walls break down in places and fuse together forming larger irregular air spaces this ___ the surface area for gas exchange so ____ oxygen diffuses into the blood, this disease is called _________ and kills around 20k people in Britain per year
decreases
less
emphysema
104
2.49 chemicals in cigarettes include:
tar - a carcinogen (a substance that causes cancer)
nicotine - an addictive substance which also narrows blood vessels
carbon monoxide - reduces the oxygen-carrying capacity of the blood
105
2.50 practical: the effect of excerise on breathing method
work out student A's breathing rate at rest
count their number breaths for 15 seconds and multiply by 4
repeat to calculate an average
student A should then exercise for a set time (at least 4 minutes)
count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute
compare the result to the breathing rate at rest in order to work out the change in breathing rate as a result of exercise
repeat this last step every minute after exercise for 5 minutes
repeat the process for student B
finally, repeat the whole investigation for each student after a period of rest
106
2.50 practical: the effect of exercise on breathing results
frequency of breathing increases when exercising
this is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
if they cannot meet the energy demand they will also respire anaerobically, producing lactic acid
107
2.50 practical: the effect of exercise on breathing analysis
after exercise has finished, the breathing rate remained elevated for a period of time
this is because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
it can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
this can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid
108
2.50 practical: what might an unfit individual have
higher breathing rate while resting
more rapid increase in breathing rate during exercise
longer recovery period for their breathing rate to return back to a normal resting rate
109
2.50 practical: how do you control all variables
ensure students are similar size, general fitness, age, gender and provide each with the same meal before exercise
110
2.50 practical: CORMS evaluation
change - We will change whether the student has exercised or not
organisms - The students should be of the same age, gender, size and general fitness
repeat - We will repeat the investigation several times to ensure our results are reliable
measurement 1 - We will measure the change in breathing rate
measurement 2 - ...immediately after exercise and each minute for the subsequent 5 minutes
same - We will control the type of exercise carried out, the temperature of the environment, the food intake of the students prior to the investigation
111
2.50 practical: exercise causes the frequency
exercise causes the frequency of breathing to increase in order to provide more oxygen for respiration and to pay off any subsequent oxygen debt
112
2.50 practical: apparatus needed for the effect of exercise
a stop watch
2 students
