exchange and transport systems Flashcards
(269 cards)
1
Q
why do cells need oxygen
A
for aerobic respiration and nutrients
2
Q
what waste products to cells excrete
A
carbon dioxide and urea
3
Q
what needs to be exchanged between organisms
A
heat (as cells need to be kept at roughly the same temperature)
4
Q
surface area to volume ratio
A
smaller animals = bigger SA:V, which means more heat loss
5
Q
what do multicellular organism need
A
exchange organs and mass transport systems (as diffusion is too slow)
6
Q
what is the mass transport system
A
circulatory system, which uses blood to carry hormones, antibodies, waste, glucose and oxygen around the body
7
Q
heat exchange factors
A
size and shape
8
Q
size on heat exchange
A
bigger surface area to volume ratio=faster heat loss, therefore small animals need a high metabolic rate to generate to stay warm
9
Q
shape
A
compact=small SA:V, minimises heat loss
high SA:V =faster heat loss, lose moer water
10
Q
what do small mammals need to eat
A
high energy foods such as seeds and nuts to deal with high metabolic rate
11
Q
gas exchange surfaces adaptations
A
large surface area, thin (short diffusion pathway), maintains concentration gradient
12
Q
single-celled organisms absorbing and releasing gas
A
by diffusion through their outer surface, through large surface area, thin surface
13
Q
oxygen once it enters the cell
A
can take part in biochemical reactions as soon as it diffuses into the cell
14
Q
what system do fish use for gas exchange
A
counter-current system
15
Q
what is the counter-current system
A
water and blood flow in opposite directions which maintains a concentration gradient and means diffusion occurs as long as possible
16
Q
how do fish get oxygen
A
water containing oxygen goes through its mouth and out the gills
17
Q
what are gills made up of
A
thin plates called gill filaments (which gives a big surface area for exchange of gases)
18
Q
what are gill filaments covered in
A
covered in lots of tiny structures called lamellae (which increase surface area further)
19
Q
lamellae structure
A
lots of blood capillaries, thin surface layer of cells (to speed up diffusion)
20
Q
what do insects use to exchange gases
A
tracheae
21
Q
what are tracheae
A
microscopic air-filled pipes used for gas exchange
22
Q
how does air move through the tracheae
A
through pores on the surface called spiracles , down the concentration gradient
23
Q
tracheae branches
A
tracheoles
24
Q
tracheoles adaptations to effective oxygen diffusion
A
have thin, permeable walls and go to individual cells (diffuses directly into respiring cells)
25
how do insects move air in and out of spiracles
rhythmic abdominal movements
26
carbon dioxide removal from insects
down concentration gradients towards the spiracles and released
27
what are dicotyledonous plants
group of flowering plants
28
why do dicotyledonous plants need C02
for photosynthesis
29
why do dicotyledonous plants need 02
respiration (produces CO2 as waste product)
30
what is the main exchange surface of dicotyledonous plants
surface of mesophyll cells in the lead
31
how are mesophyll cells adapted for gas exchange
large surface area
32
how do gases move through the leaf
in through stomata
33
what are stomata
special pores in the epidermis
34
what can stomata do
open to allow gas exchange, and close if the plant is losing too much water
35
what controls the stomata
guard cells
36
how to insects prevent losing too much water
close spiracles using muscles, have waxy cuticle over body, tiny hairs around spiracles (reduce evaporation)
37
how do guard cells control stomata
water enters the cells, making them turgid and opens stomata when plant has lots of water, when plant is dehydrated the guard cells lose water and become flaccid which closes the stomata
38
what are xerophytes
plants that live in warm, dry or windy conditions
39
what are plants that live in warm, dry or windy conditions
xerophytes
40
xerophyte adaptations
```
stomata sunk in pits
layer of hairs
curled leaves
reduced number of stomata
waxy, waterproof cuticles
```
41
stomata sunk in pits adaptation
trap moist air, reducing concentration gradient between leaf and air, and reducing diffusion out of the leaf and reducing evaporation
42
layer of hairs adaptation
traps moist air around stomata
43
curled leaves adaptation
(with stomata inside) protects from wind which reduces rate of evaporation and diffusion
44
reduced number of stomata adaptation
fewer places for water to escape
45
waxy, waterproof cuticle adaptation
reduces evaporation
46
lung structure
trachea, splits into 2 bronchi (one leading to each lung), branches into bronchioles, end in air sacs called alveoli
47
ventilation
breathing in and out - inspiration and expiration
48
inspirtation
air breathing in
49
inspiration sequence
```
active process
external intercostal muscles contract
diaphram muscles contract
ribcage moves upwards and outwards
diaphram flattens
thoratic cavity volume increased
lung pressure decerases
air flows from high-low pressure, so flows into lungs
```
50
expiration
```
passive process, but can be forced
external intercostal muscles relax
diaphram muscles contract
diaphram becomes curved again
ribcage moves downwards
thoratic cavity volume decreases
```
51
forced expiration
internal intercostal muscles contract which pulls ribcage further down and in , movement of the two sets of intercostal muscles is antagonistic
52
what is antagonistic
opposite
53
where does gas exchange in humans occur
alveoli
54
alveoli adaptations for gas exchange
lots in lungs (big surface area)
surrounded by network of capillaries (short diffusion distance)
thin exchange surface - alveolar epithelium is only one cell thick (short diffusion pathway)
steep concentration gradient
55
O2 across alveoli
diffuses out across alveolar epithelium and capillary endothelium, and into the haemoglobin in the blood
56
CO2 across alveoli
diffuses into the alveoli from the blood and is breathed out
57
lung diseases
pulmonary tuberculosis
fibrosis
asthma
emphysema
58
pulmonary tuberculosis
immune system builds a wall around the bacteria in the lungs forming tubercles (small hard lumps), infected tissue within these die and tidal volume is decreased
symptoms = cough, blood & mucus, chest pains
59
fibrosis
formation of scar tissue in lungs through e.g infection, so lungs can't expand as much and tidal volume is reduced
60
what is tidal volume
volume of air in each breath
61
what is ventilation
number of breaths per minute
62
what is forced expiratory volume
volume of air that can be breathed out in 1 second
63
forced vital capacity
maximum volume of air possible to breathe forcefully out after a deep breath
64
asthma
airways become inflames/irritated, during an attack the smooth muscle lining in bronchioles contracts and mucus is produced, which constricts airways
65
emphysema
caused by smoking or long term exposure to air pollution, inflammation which attracts phagocyes to the area which produce an enzyme that breaks down elastin, so lungs can't recoil, or destruction of alveoli
66
what is elastin
protein found in walls of alveoli
67
during dissection of the lungs
sharp but not too sharp tools, cutting board, cut lengthways along cartlidge
68
what breaks food down into smaller molecules
digestion
69
why are foods broken down
large molecules can't be absorbed as they are too big to cross cell membranes (e.g starch, proteins)
70
what happens during digestion
large molecules are broken down into smaller molecules
71
why does digestion occur
so the molecule can be transported across the cell membrane and transported around the body
72
what are fats broken down into
fatty acids and monoglycerides
73
how are fats broken down
hydrolysis reactions
74
what are proteins broken down into
amino acids
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how are proteins broken down
hydrolysis reactions
76
what breaks down the biological molecules during digestion
digestive enzymes
77
what are digestive enzymes produced by
specialised cells in the digestive system
78
where are digestive enzymes released into
the gut
79
what is amylase
digestive enzyme
80
what does amylase do
catylses conversion of starch into maltose
81
how does amylase do this
hydrolysis, breaks the glycosidic bonds
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what produces amylase
salivary glands and pancreas
83
where is amylase released into
from the salivary glands = the mouth, from pancreas = small intestine
84
what are carbohydrates broken down by
amylase and membrane-bound disaccharides
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what are membrane-bound disaccharides
enzymes attached to the membranes of epithelial cells lining the ileum
86
what is the ileum
final part of small intestine
87
what do membrane-bound disaccharides do
help break down disaccharides (e.g maltose, lactose, sucrose) into monosaccharides (glucose, fructose, galactose)
88
how do membrane-bound disaccharides do this
hydrolysis reactions, breaking gylcosidic bonds
89
how do monosaccharides move across the cell membranes of the ileum
specific transporter proteins
90
how are lipids broken down
lipase and the help of bile salts
91
what is lipase
digestive enzyme
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what do lipase enzymes do
catalyse the breakdown of lipids into monoglycerides and fatty acids
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how do lipases do this
hydrolysis, breaking ester bonds
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where are lipases made
pancreas
95
where does lipase work
small intestine
96
where are bile salts produced
liver
97
what do bile salts do
emulsify lipids
98
why are bile salts important in lipid digestion
they increase the surface area that lipases can work on, by creating lots of small droplets instead of one big droplet
99
what are micelles
monoglycerides and fatty acids stuck with the bile salts
100
what do monoglycerides and fatty acids with bile salts form
tiny structures called micelles
101
what are proteins broken down by
endopeptidases
102
what are endopeptidases
a form of proteases
103
how do endopeptidases work
hydrolyse the peptide bonds inside a protein to break it down into amino acids
104
endopeptidases examples
trypsin
chymotrypsin
pepsin
105
where is trypsin made
synthesised in the pancreas
106
where is trypsin released
small intestine
107
where is chymotrypsin made
synthesised in the pancreas
108
where is chymotrypsin released
small intestine
109
where is pepsin released into
the stomach
110
where is pepsin released from
stomach lining
111
what conditions does pepsin work in
acidic
112
how are the acidic conditions produced in the stomach
the hydrochloric acid
113
what are proteins broken down into
exopeptidases
114
what do exopeptidases do
hydrolyse peptide bonds at the ends of protein molecules, and remove single amino acids from proteins
115
exopeptidases examples
dipeptidases
116
what do dipeptidases do
seperate the 2 amino acids that make up dipeptides by hydrolysing the peptide bond between them
117
where are dipeptidases found
cell-surface membrane of epithelial cells in the small intestine
118
what are the products of digestion
monosaccharides, monoglycerides and fatty acids, amino acids
119
what are the monosaccharides produced that are absorbed
glucose , galactose, fructose
120
how is glucose absorbed
by active transport with sodium ions via a co-transporter protein
121
how is galactose absorbed
by active transport with sodium ions via a co-transporter protein
122
how is fructose absorbed
by facilitated diffusion through a different co-transporter protein
123
where are the products of digestion transported across
across the ileum epithelial into the bloodstream
124
how are monoglycerides and fatty acids absorbed
diffuse directly across the membrane as they are lipid-soluble
125
what helps monoglycerides and fatty acids move towards the epithelium
micelles
126
how do micelles help move the products
they constantly break up and re-form, so release monoglycerides and fatty acids to be absorbed
127
how are amino acids absorbed
diffusion with sodium ions through a sodium-dependent transporter protein
128
how do sodium ions move into the iluem from epithelial cells
by active transport
129
how is oxygen carried around the body
haemoglobin
130
where is haemoglobin found
red blood cells
131
what do red blood cells contain
haemoglobin
132
what is haemoglobin
large protein with a quaternary structure (made up of 4 polypeptide chains)
133
what does each polypeptide chain contain in haemoglobin
haem group
134
what does the haem group contain
iron ion
135
what does the iron ion in the haem group do
gives haemoglobin its red colour
136
what does haemoglobin have
high affinity for oxygen
137
what does high affinity for oxygen mean
high tendancy to combine with oxygen
138
how many oxygen molecules can each haemoglobin molecule carry
4
139
what is oxyhaemoglobin
haemoglobin in the lungs joined with oxygen
140
how does oxyhaemoglobin form
when oxygen joins to haemoglobin in the red blood cells via a reversible reaction
141
what does oxygen dissociating mean
oxygen leaves oxyhaemoglobin
142
what is the chemical symbol for haemoglobin
Hb
143
what is the chemical symbol for oxyhaemoglobin
HbO8
144
what is the partial pressure of oxygen (pO2)
measure of oxygen concentration, greater concentration of dissolved oxygen in cells = higher partial pressure
145
what is the partial pressure of carbon dioxide (pCO2)
measure of concentration of C02 in a cell
146
what factor affects haemoglobins affinity for oxygen
the partial pressure of oxygen
147
what happens to haemoglobin when there is a high partial pressure of oxygen
oxygen loads onto haemoglobin to form oxyhaemoglobin
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what happens to haemoglobin when there is a low partial pressure of oxygen
oxyhaemoglobin offloads oxygen
149
how does oxygen enter blood capillaries
at the alveoli in the lungs
150
what is the pO2 of alveoli
high
151
what happens to the haemoglobin at the alveoli
oxygen loads onto it to form oxyhaemoglobin due to high pO2
152
what happens to pO2 when cells respire
it lowers, as oxygen is used up (red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen to be used)
153
what happens after oxyhaemoglobin offloads its oxygen to respiring cells
returns to the lungs to collect more oxygen and become oxyhaemoglobin again
154
what does a dissociation curve show
how saturated the haemoglobin is with oxygen at any given partial pressure
155
what does the dissociation curve look like
S shaped
156
what does the first oxygen entering the Hb do to the molecule
it makes it easier
157
how does carbon dioxide concentration affect oxygen offloading
higher partial pressure of carbon dioxide=haemoglobin gives up its oxygen more readily
158
what effect is carbon dioxide affecting oxygen offloading called
Bohr effect
159
why does carbon dioxide concentration affect oxygen offloading
it means cells recieve more oxygen during activity, as when cells respire they produce carbon dioxide which highers pCO2
160
what happens to the dissociation curve when there is high PCO2
it shifts right
161
what is different about haemoglobin in different organisms
different type, with different oxygen transporting capabilities
162
what haemoglobin do organisms in a low oxygen concentration habitat have
haemoglobin with a higher affinity for oxygen than humans, so the dissociation curve is to the left of ours
163
what does a shift left in the dissociation curve mean
haemoglobin with a higher affinity for oxygen
164
what haemoglobin do active organisms with a high oxygen demand have
haemoglobin with a lower affinity for oxygen than humans, so dissociation curve shifts to right
165
what does a shift to the right in the dissociation curve mean
haemoglobin with lots of surrounding oxygen
166
what transport system is the circulatory system
mass transport system
167
where does the circulatory system carry marterials to and from
carries them from specialised exchange organs to their body cells
168
what is the circulatory system made up of
the heart and blood vessels
169
what does the heart do
pumps blood through blood vessels to reach different parts of the body
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what are blood vessels
arteries, veins, capillaries
171
what does blood transport
respiratory gases, products of digestion, metabolic wastes and hormones
172
what are the 2 circuits in the circulartory system
1=takes blood from the heart to the lungs then back to the heart,
2=around the rest of the body from the heart
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how does the heart get its blood supply
left and right coronary arteries
174
what are arteries function
carry oxygenated blood from the heart to the rest of the body (except pulmonary arteries, which take deoxygenated blood to the lungs)
175
what are arteries adaptations
thick and muscular walls with elastic tissue (so can stratch and recoil as the heart beats), which helps maintain high pressure, folded inner lining which allows it to stretch and maintain high pressure
176
what is the inner lining of arteries
endothelium
177
what do arteries divide into
smaller vessels called arterioles
178
what do arterioles do
form a network throughout the body which have muscles inside that carry blood around the body by contracting to restrict blood flow or relaxing to allow full blood flow
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what do veins do
take deoxygenated blood back to the heart under low pressure (except pulmonary veins which take oxygenated blood to the heart from the lungs)
180
what are veins adaptations
wider lumen with very little elastic or muscle tissue, contain valves to stop blood flowing backwards, body muscles surrounding contract to help with blood flow
181
what do arterioles branch into
capillaries
182
what are the smallest blood vessel
capillaries
183
where are capillaries found
near cells in exchange tissues
184
why are capillaries found here
so there's a short diffusion pathway
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how thick are capillary cell walls
one cells thick
186
why are capillary cell walls this thick
so there's a short diffusion pathway
187
how many capillaries are there
a large number
188
why are there this number of capillaries
to increase surface area for exchange
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what are networks of capillaries in tissue called
capillary beds
190
what is tissue fluid
fluid that surrounds cells in tissues
191
what is tissue fluid made from
small molecules that leave the blood pasma, doesn't contain red blood cells or big proteins (too big to be pushed through capillary walls)
192
what gets taken out of tissue fluid by cells
oxygen and nutrients
193
what do cells put into tissue fluid
metabolic waste
194
what is the hydrostatic pressure are the start of the capillary bed
greater than in the tissue fluid
195
what does the difference in hydrostatic pressure mean
it forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid
196
what happens as the fluid leaves
hydrostatic pressure reduces in the capillaries, meaning it is lower than at the venule end
197
what does the fluid loss mean
the concentration plasma proteins also increases, and water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid
198
what does the water potential difference mean
some water re-enters the capillaries from the tissue fluid at the venule end by osmosis
199
what happens to excess tissue fluid
it is drained into the lymphatic system
200
what does the right hand side of the heart do
pumps deoxygenated to the lungs
201
what does the left hand side of the heart do
pumps oxygenated blood to the whole body
202
what is the thickness of the left ventricle muscular wall
thicker
203
why is the left ventricle this thickness
so that it can powerfully contract to pump blood all
204
why are the ventricle walls thicker than the atria
because they have to push the blood out of the heart around the body
205
what do the atrioventricular valves do
link the atria to the ventricles and stop blood flowing backwards
206
what do the semilunar valves do
link the ventricles to the pulmonary artery and aorta and stops blood flowing back into the heart
207
what do the cords between the atrioventricular valves do
connect the valves, and stops them from being forced up into the atria when the ventricles contract
208
what opens and closes the valves
the pressure in the heart chamber, higher pressure behind the valves forces the opens but high pressure infront forces it shut
209
what does the cardiac cycle do
pumps blood around the body
210
first stage of the cardiac cycle
ventricles relax, atria contract which decreases the chamber volume and increases the pressure which pushes blood into the ventricles increasing pressure and volume which ejects the blood
211
second stage of the cardiac cycle
atria relax, ventricles contract which decreases their pressure and increases their pressure, which forces the AV valves shut stopping back flow. pressure in ventricles is higher than in the aorta and pulmonary which forces the SL valves open
212
third stage of the cardiac cycle
ventricles and atria relax, blood returns to the heart and pressure starts to increase again
213
what do most cardiovascular diseases start with
atheroma formation
214
what is atheroma
when the inner lining of an artery is damaged, which causes white blood cells and lipids from the blood to clump together under the lining and form fatty streaks. overtime they build up and harden to form a fibrous plaque called atheroma
215
what does an atheroma do
blocks the lumen which restricts blood flow and increases blood pressure
216
example of cardiovascular disease
coronary heart disease, which occurs when artieries have lots of atheromas
217
what do atheromas do
increase the risk of aneurysms and thrombosis
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what is an aneurysm
baloon-like swelling of the artery
219
how do atheromas increase the risk of aneurysms
they damage and weaken the arteries and narrow them (increasing blood pressure), and so when blood flows through the weakened artery at a high pressure it can push out the inner layers through the outer elastic layer and cause an aneurysm
220
what is caused if an aneurysm busts
haemorrhage
221
what is a haemorrhage
bleedin
222
what is thrombosis
formation of a blood clot
223
how can atheromas increase the risk of thrombosis
ruptures the endothelium, which damages the artery and leaves a rough surface where platelets and fibrin accumulate and form a blood clot, and debris from the rupture can cause another blood clot to form further down the artery
224
what can happen to the blood clot in arteries
can cause a blockage or become dislodged and block a blood vessel in another place
225
what causes a myocardial infarction
interrupted blood flow to the heart
226
what is a myocardial infarctions other name
heart attack
227
what are the symptoms of myocardial infarctions
pain in chest, shortness of breath, sweating
228
factors that increase risk of cardiovascular disease
high cholesterol and poor diet, cigarette smoking, high blood pressure, age, sex
229
how does high cholesterol and poor diet increase risk of cardiovascular disease
cholesterol is main consistuent of fatty deposits that form atheromas, diet high in fat increaes cholesterol, diet high in salts increases risk of high blood perssure
230
how does cigarette smoking increase risk of cardiovascular disease
because it contains nicotine and carbon monoxide, and decreases the amount of antioxidants in the blood, important for protecting cells
231
how does nicotine increase risk of cardiovascular disease
increases risk of high blood pressure
232
how does carbon monoxide increase risk of cardiovascular disease
combines with haemoglobin and reduces the amount of oxygen transported by the blood to tissues, so the heart doesn't recieve enough oxygen
233
how does high blood pressure increase risk of cardiovascular disease
increases risk of damage to artery walls and so increases risk of atheroma formation
234
interpreting data on risk factors
describe data, draw conclusions, check any conclusions are valid, sample size
235
tissues involved in transport in plants
xylem and phloem
236
what does the xylem transport
water and mineral ions in solution
237
what does the phloem transport
organic substances (e.g sugars) both up and down the plant
238
what are the xylem vessels
long, tube-like formed from dead cells, no end walls, the part if the xylem tissue that trasnports the water and ions
239
how does water move up the xylem
cohesion and tension, the cohesion-tension theory
240
what is the cohesion-tension theory
water evaporated from the leaves (transpiration) which creates tension and pulls more water into the leaf and due to water molecules being cohesive and sticking together it means the whole column moves upwards, water enters through the roots
241
what is transpiration
the loss of water from a plants surface through evaporation
242
how does transpiration occur
water evaporates from the moist cell walls and accumulates in the spaces between cells in the leaf which moves down the concentration out of the cell when the stomata open
243
what factors affect transpiration rate
light, temperature, humidity, wind
244
how does light affect transpiration rate
lighter = faster transpiation rate as the stomata open for photosynthesis
245
how does temperature affect transpiration rate
higher temperature = faster rate as warmer molecules have more energy so evaporate faster, concentration gradient increases so water diffuses out faster
246
how does humidity affect transpiration rate
lower humidity = faster transpiration rate as concentration gradient increased
247
how does wind affect transpiration rate
windier = faster rate as concentration gradient decreased (water molecules moved away from the stomata)
248
what can a potometer be used for
estimate transpiration rate
249
how to use a potometer
cut it sideways, count bubbles
250
how to dissect plants
use tweezers and dissect them in water, transfer to dish containing stain and leave for a minute, rinse off in water and mount each onto a slide
251
how is phloem tissue adapted for transporting solutes
they have sieve tube elements and companion cells
252
what are solutes
dissolved substances
253
what are sieve tube elements
living cells that form the tube for transporting solutes, they have no nucleus and few organelles
254
what are companion cells
cells surrounding the phloem that carry out living functions for sieve cells (e.g providing energy needed for active transport of the solutes)
255
what is translocation
energy requiring movement of solutes to where theyre needed in plants through the phloem
256
whats another name for solutes
assimilates
257
where does translocation move to and from
from the source to the sink
258
what is the source
where its made (high concentration)
259
what is the sink
where its used up (low concentration)
260
how does the source and sink maintain a concentration gradient
through enzymes
261
how do enzymes maintain a concentration gradient between the source and sink
by breaking down the solutes at the sink into something else, which ensures a lower concentration
262
what explains phloem transport
mass flow hypothesis
263
first step of mass flow hypothesis
active transport is used to actively load the solutes from companion cells into the sieve tubes of the phloem at the source which lowers the water potential inside sieve tubes so water enters by osmosis from xylen to companion cells, which creates a high pressure inside the sieve tubes at the source end of the phloem
264
second step of mass flow theory
at the sink end, solutes are removed from phloem to be used up which increases the water potential and means water leaves the tubes by osmosis, which lowers pressure inside sieve tubes
265
third step of mass flow theory
result is a pressure gradient from the source to the sink which pushes solutes along the sieve tubes towards the sink to be used or stored
266
evidence for mass flow (4)
radioactive tracer can be used to track movement of organic substances, pressure in the phloem can be investigated using aphids (where sap flows out quicker nearer leaves), metabolic inhibitor stops translocation (active transport is involved), ring of bark removed = bulge above the ring (shows it flows downwards)
267
evidence against mass flow (2)
sugar travels to many different sinks not the one with highest water potential, sieve plates would create a barrier to mass flow (lots of pressure required to get through them at a reasonable rate)
268
how can the translocation of solutes be demonstrated experimentally
using radioactive tracers
269
method of translocation of solutes being demonstrated experimentally
supplying part of plant with an organic substance that has a radioactive label which will then be incorporated into organic substances produced and moved by translocation, and can be tracket using autoradiography to see which part of the plant its been spread to (by freezing the plant, then placed on photographic film where the plant that contains radioctive material will turn black)
