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A-Level Biology > Module 3:Exchange and Transport > Flashcards

Module 3:Exchange and Transport Flashcards

1
Q

How do microorganisms obtain nutrients and remove waste

A

Exchange via their surface
Nutrients move in via diffusion
Waste moves out via diffusion

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2
Q

Why are microorganisms able to perform exchange via their surface

A

Large surface area to volume ratio
Short diffusion distance
Low demand

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3
Q

Why can’t animals/plants perform exchange via their surface

A

Small surface area to volume ratio
Multicellular (large diffusion distance and high demand)
Impermeable surface (prevent pathogens entering and reduce water loss)
Require exchange and transport systems

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4
Q

Exchange system

A

Increases rate of diffusion of nutrients in and wastes out

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5
Q

Transport system

A

Deliver nutrients and remove waste from all cells

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6
Q

Why do fish have specialised gas exchange systems

A

Multicellular organism so has small surface area to volume ratio, large diffusion distance, high demand and body surface is impermeable
Can’t perform gas exchange via surface
Need transport system

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7
Q

Structure of gills in fish

A

Many Gill filaments and Gill lamellae=large surface area
Gill lamella have a thin wall (shirt diffusion distance) and are permeable
Ventilation brings in pure water with high oxygen and low carbon dioxide
Circulation brings deoxygenated blood low oxygen and high carbon dioxide
Water and blood have countercurrent flow to maintain favorable concentration gradient all the way along Gill lamellae

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8
Q

Why do insects have specialised gas exchange systems

A

Multicellular organism so has a small surface area to volume ratio, large diffusion distance, high demand and body surface made of exoskeleton (impermeable barrier to reduce water loss)
Can’t perform gas exchange via their surface so require tracheal system

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9
Q

Structure of tracheal system in insects

A

Starts with openings on the body called spiracles
Spiracles contain valves which open for gas exchange and close to prevent water loss
Spiracles connected to trachea
Trachea connected to tracheoles
Tracheoles connect directly to respiring cells delivering oxygen and removing carbon dioxide

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10
Q

How does gas exchange occur in the tracheal system of insectx

A

At rest: down a concentration gradient oxygen moves in and carbon dioxide moves out by simple diffusion
When active: by ventilation, air inhaled for mass flow of oxygen in and air exhaled for mass flow of carbon dioxide out

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11
Q

Function of the lungs

A

Site of gas exchange in mammals
Oxygen in blood used in cells for respiration
Carbon dioxide out of the blood toxic waste product of respiration

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12
Q

What are the lungs made up of

A 
Trachea
Bronchi 
Bronchioles 
Alveoli 
Capillaries
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13
Q

Function of trachea, bronchi, bronchioles

A

Transport of air and filter air

Bronchioles also control the amount of air reaching the alveoli

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14
Q

Structure of the trachea and bronchi

A

Wall made of c shaped cartilage
Cartilage is so strong so trachea and bronchi don’t collapse
C shaped to give flexibility
Lining made of goblet cells and ciliates epithelial cells
Goblet cells make mucus which traps pathogens
Ciliated epithelial cells have cilia which pushes mucus up and out of the lungs

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15
Q

Structure of the bronchioles

A

Walls made of smooth muscle
Smooth muscle contracts, lumen narrows and bronchioles constricts
This occurs when surrounded by noxious gases to reduce the amount that reaches the alveoli
Lining made of goblet cells and epithelial cells

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16
Q

Adaptations of the alveoli

A

Millions of alveoli that are folded to increase the surface area
One cell thick/squamous epithelial cells for a short diffusion distance
Elastic tissue in wall (stretches with breathing in to increase surface area,recoils when breathing out to push air out)
Ventilation maintains concentration gradient of high oxygen and low carbon dioxide

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17
Q

Adaptation of capillaries

A

Millions of tiny capillaries for large surface area
One cell thick so short diffusion distance
Narrow lumen to increase diffusion time but decrease diffusion distance
Circulation maintains concentration gradient of low oxygen and high carbon dioxide

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18
Q

How does oxygen move from the alveoli to the capillaries

A

Simple diffusion

Passing through alveolar epithelium and capillary epithelium

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19
Q

How does carbon dioxide move from the capillaries to the alveoli

A

Simple diffusion

Capillary epithelium and alveoli epithelium

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20
Q

Inhalation

A 
External intercostal muscles contract, internal relax
Rib cage moves up and out 
Diaphragm contacts and flattens 
Increase in thoracic volume 
Decreased thoracic pressure
Increased atmospheric pressure
Air drawn into lungs
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21
Q

Exhalation

A

External intercostal relax, internal contract
Rib cage moves down and in
Diaphragm relaxes, dome shape
Decrease thoracic volume
Increased thoracic pressure, decrease atmospheric pressure
Air forced out
Aided by elastic recoil in alveoli

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22
Q

Formula for pulmonary ventilation

A

Tidal volume x ventilation rate

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23
Q

Tidal volume definition

A

Volume of air breathed in/out in one breath

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24
Q

Ventilation rate definition

A

Number of breaths per minute

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25
Q

Pulmonary ventilation definition

A

Volume of air breathed in/out in one minute

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26
Q

Function of intestines

A

Site of exchange of digested nutrients in mammals

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27
Q

Digestion definition

A

Hydrolysis of large insoluble molecules into small soluble molecules so they can move into the blood and into the body cells

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28
Q

Digestion of starch/glycogen

A

Into glucose by Amylase (salivary in mouth,pancreatic in small intestine)
And maltase/lactase/sucrase (lining of small intestine)

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29
Q

Digestion of proteins

A

Amino acids by endopeptidases, exopeptidases,dipeptidases
In stomach, small intestine, lining of small intestine
(In that order relating to enzyme above)

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30
Q

Lipids digestion

A

Into monoglycerides and two fatty acids by lipase found in small intestine

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31
Q

What do intestines absorb

A

Small intestine absorbs small soluble nutrients (glucose, amino acids,monoglycerides and fatty acids, vitamins and minerals)
Large intestine absorbs water

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32
Q

Why do humans/mammals require a specialised transport system

A

Multicellular so have large diffusion distance and high demands
Needs transport system to deliver nutrients and remove waste
Circulatory system

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33
Q

What is the circulatory system made of

A

Heart
Blood vessels
Blood

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34
Q

Why double circulatory system?

A

Heart pumps twice
Blood goes through heart twice in one cycle
Two separate blood flows

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35
Q

Why is the transport system in mammals called a closed circulatory system

A

Blood is transported in blood vessels

Helps to maintain blood pressure and redirect blood flow

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36
Q

Layout of circulatory system

A 
Heart 
Arteries
Arterioles
Capillaries
Venues
Veins
Heart
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37
Q

Artery/aterioles

A

Blood away from heart

Arterioles are small arteries

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38
Q

Capillaries

A

Site of exchange
Nutrients out
Waste in

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39
Q

Veins/venules

A

Return blood back to the heart

Venules are small veins

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40
Q

Brief blood flow in heart

A 
Vena cava
Right atrium 
Right ventricles
Pulmonary artery
Lungs
Pulmonary vein 
Left atrium 
Left ventricle
Aorta 
Body
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41
Q

Which ventricle wall is thicker

A

Left
Pumps blood to rest of the body
At higher pressure
Stronger contractions

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42
Q

Valves in the heart

A

Tricuspid= right AV
Bicuspid= left AV
two semi lunar

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43
Q

When are AV valves open or closed

A

Open=pressure in atria is greater than pressure in the ventricles
Closed=pressure in ventricles greater than pressure in the atria

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44
Q

When are SL valves open or closed

A

Open= pressure in ventricles greater than pressure in arteries
Closed=pressure in arteries greater than pressure in ventricles

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45
Q

Describe the process of the cardiac cycle

A

Filling stage:atria relaxed, ventricles relaxed, AV valves open,SL valve closed
Atrial systole:SAN in right atrium initiates heart beat and sends impulse across both atria so they contract and pushes all remaining blood into the ventricles
Ventricular systole:AVN picks up impulse, delays it so ventricles can fill and sends impulse down non conductive septum down the bundle of His, at apex the impulse goes up both walls of ventricles in purkinje fibres so ventricles contract from base upwards, when ventricles contract the AV valve closes and SL valve opens and blood leaves the heart
Ventricular diastole: SL valve closes Then the AV valve opens and filling starts again

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46
Q

What causes the heart sounds

A

When the valves close
1st when AV closes
2nd when SL closes

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47
Q

Formula for cardiac output

A

Stroke volume x heart rate

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48
Q

Stroke volume definition

A

Volume of blood pumped out of the heart in one beat

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49
Q

Heart rate definition

A

Number of beats per minute

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50
Q

Cardiac output definition

A

Volume of blood pumped out of the heart in one minute

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51
Q

Coronary heart disease and myocardial infarction

A

High blood pressure damages lining of coronary artery
Cholesterol builds up beneath the lining=atheroma
Atheroma breaks through lining and forms atheromaous plaque on lining in the lumen
Causes turbulent blood flow
Blood clot (thrombus) forms
Blocks coronary artery
Less blood flow to artery
Less glucose and oxygen delivered
Heart muscle cant respire
So it dies (myocardial infarction)

52
Q

Risk factors of CHD

A

Age gender ethnicity
Saturated fats (increases LDL, deposits cholesterol in arteries to form atheroma)
Salts (increase blood pressure, lowers water potential of blood so it holds the water)
Smoking (nicotine increases heart rate and makes platelets more sticky,blood clot. Carbon monoxide permanently blocks haemoglobin)
Obesity and lack of exercise

53
Q

Atheroma and aneurysm

A

Atheroma weakens wall of artery
Blood builds up in the wall
Wall swells then bursts=aneurysm

54
Q

Role of arteries/arterioles

A

Generally carry oxygenated blood away from the heart

Exception is the pulmonary artery that carries deoxygenated blood to the lungs

55
Q

Roles of veins/venules

A

Generally carry deoxygenated blood back to the heart
Exception pulmonary vein carries oxygenated blood back to the heart, hepatic portal vein carries deoxygenated blood from digestive system to liver for filtering

56
Q

Function of arteries/arterioles

A

Carry blood away from the heart so need to withstand high pressure and maintain high pressure

57
Q

Structure of arteries/arterioles

A

Narrow lumen=maintains pressure
Squamous epithelial cells=smooth lining to reduce friction
Thick wall=withstand pressure
Elastic tissue=stretches and recoils
Smooth muscle in wall (particularly arterioles)=contracts an relaxes to control blood flow, construction and dilation
Collagen in wall=prevents artery from tearing

58
Q

Function of veins and venules

A

Returns blood back to the heart under low pressure

59
Q

Structure of veins/venules

A

Wide lumen=ease of blood flow
Squamous epithelial cells=smooth lining to reduce friction
Thin wall=veins can be squashed by skeletal muscle pushing blood back to the heart
Valves in lumen=prevents backflow of blood

60
Q

Function of capillaries

A

Site of exchange
3 locations:
alveoli (takes in oxygen, removes carbon dioxide)
microvilli (takes in glucose/amino acids)
all cells (deliver nutrients and remove waste)

61
Q

Adaptation of capillaries

A

Many small capillaries=large surface area
Squamous epithelial cells=short diffusion distance
Pores between cells= fluid can move in and out
Narrow lumen= increase diffusion time and decrease diffusion distance

62
Q

Content of blood

A 
Plasma which carries 
Red blood cells
White blood cells
Platelets 
Nutrients
Waste 
Proteins
63
Q

How does exchange occur between capillaries and all cells

A

By mass flow
Fluid moves out of blood in capillaries carrying the nutrients
Fluid moves back into the blood in the capillaries carrying waste

64
Q

Fluids in the body and their names

A

Blood= plasma
Surrounding cells=tissue fluid
Lymph system=lymph

65
Q

How is tissue fluid formed and returned to the circulatory system

A

Arterial end there is a build up of hydrostatic pressure
Pushes fluid out of the capillary via pores
Fluid carries nutrients with it
Fluid surrounds cell, called tissue fluid
Venule end the fluid moves back in by osmosis
Capillary has low water potential due to the presence of proteins (too large to move out of the capillaries)
Any excess tissue fluid is picked up by the lymph system and deposited in the vena cava

66
Q

Why does high blood pressure cause accumulation of tissue fluid

A

Increases hydrostatic pressure
Causes more tissue fluid to form
Not as much can be returned by the circulatory system

67
Q

Why does diet low in protein cause an accumulation of tissue fluid

A

Water potential isn’t as low as normal

Not as much fluid can move back into capillary by osmosis

68
Q

Pressure in arteries

A

Highest pressure as they connect directly with the heart
Pressured fluctuates (increases when ventricles contract so elastic tissue stretches, decreases when ventricles relax so elastic tissue recoils)
Overall decrease in pressure due to friction

69
Q

Pressure in arterioles

A

Large decrease in pressure due to increase in total cross sectional area
Ensures pressure isn’t too high to damage capillaries

70
Q

Pressure in capillaries

A

Hydrostatic pressure

Decreases due to a loss of fluid

71
Q

Pressure venules/veins

A

Blood under low pressure

72
Q

Function of red blood cells

A

Carry haemoglobin

Haemoglobin carries oxygen

73
Q

Structure of haemoglobin

A 
Globular protein (soluble and 3D shape) 
Quaternary structure made of 4 polypeptide chains 
Each chain carries a haem group 
Each haem group carries ferrous ion 
Each Fe2+ carries O2
Haemoglobin carries 4 x O2
74
Q

Affinity definition

A

The level of attraction haemoglobin has to oxygen

High affinity= strong attraction

75
Q

Role of haemoglobin

A

Load oxygen in the lungs and deliver it to the respiring tissues

76
Q

Role of haemoglobin in oxygen transport

A

Haemoglobin has high affinity in the lungs due to high partial pressure of oxygen and low partial pressure of carbon dioxide, haemoglobin loads oxygen in the lungs and becomes saturated

Transported in the blood in red blood cell

At the respiring tissues haemoglobin has low affinity due to low partial pressure of oxygen and high partial pressure of carbon dioxide so oxygen is unloaded and haemoglobin becomes unsaturated

77
Q

Relationship between oxygen partial pressure and affinity of haemoglobin

A

Positive correlation
As oxygen partial pressure increases affinity of haemoglobin increases
Produces s shaped sigmoid curve called oxygen dissociation curve
Middle portion of curve has a steep gradient so when respiring tissues change from resting to active and partial pressure falls there is a large drop in affinity so more O2 delivered to respiring tissues

78
Q

Relationship between carbon dioxide partial pressure and affinity of haemoglobin

A

Negative correlation
CO2 partial pressure increases then saturation of haemoglobin decreases
Occurs at site of respiring tissues means carbon dioxide lowers ph of blood
Haemoglobin changes shape so oxygen is released, lowering affinity, curve shifts to right
Bohr shift
More oxygen delivered to respiring cells

79
Q

How does a foetus receive oxygen

A

From mothers blood oxygen dissociates from mothers haemoglobin and associates with foetal haemoglobin in the placenta
Foetal haemoglobin has a higher affinity than mothers

80
Q

Benefit of foetal haemoglobin having high affinity

A

ODC will shift to left as it has high affinity
Oxygen will dissociate from mothers haemoglobin and associate with fetal haemoglobin at the low partial pressure of oxygen so has enough oxygen for its needs

81
Q

Hey do adults not keep foetal haemoglobin

A

The high affinity will mean less oxygen will be unloaded at the respiring tissues

82
Q

Affinity of organisms in a low oxygen environment

A

High affinity

Curve to the left so it can readily associate oxygen at the low oxygen partial pressures

83
Q

Affinity of active organisms

A

Low affinity
Curve to the right
More oxygen unloaded to meet cells demand for respiration

84
Q

Affinity of small organisms

A 
Large surface area to volume ratio 
Lose a lot of heat
Need to respire to generate heat 
Low affinity 
Curve to right 
Unloads enough oxygen for cells demand of respiration
85
Q

exchange systems in plants

A

leaf and root
leaf absorbs light and carbon dioxide for photosynthesis
root absorbs water and minerals

86
Q

transport systems in plants

A

xylem and phloem
xylem transports water and minerals
phloem transports glucose/sugars
xylem transports one direction from roots to leaves but phloem travels in both directions

87
Q

role of the roots

A

absorbs water and minerals

water by osmosis and minerals by active transport

88
Q

what do plants need water for

A

photosynthesis
cytoplasm hydration
turgidity of cells

89
Q

why do plants need minerals

A

magnesium- chlorophyll
nitrate-make amino acids
phosphate-make phospholipids/ATP/DNA

90
Q

function of the xylem

A

transport water and minerals from roots up the plant to the leaves

91
Q

structure of the xylem

A

long continuous hollow tube (no resistance to water flow)
narrow lumen
walls made out of lignin which is strong, waterproof and adhesive
walls contain pits/pores so water and minerals can leave
xylem cells are dead

92
Q

how does water move up the xylem

A

loss of water at leaves (transpiration)
water move from the top of the xylem into the leaf by osmosis (transpirational pull)
applies tension to the column of water in the xylem
column of water moves up as one as the water particles stick together, cohesion
cohesion-tension theory

93
Q

what is the process that allows water to move up the xylem

A

cohesion-tension theory

94
Q

what supports the cohesion-tension theory

A

capillary action
adhesion
root pressure

95
Q

definition capillary action

A

water automatically move up the narrow lumen of the xylem

96
Q

adhesion definition

A

water particles stick to the lignin in the walls of the xylem

97
Q

cohesion definition

A

water molecules stick together due to the hydrogen bonds that form between the slightly positive hydrogen atoms and slightly negative oxygen atoms

98
Q

why does the diameter of a tree decrease during the

A

more light and higher temperature
increased rate of transpiration
increased transpirational pull
water pulled up the xylem by cohesion-tension
because the water has adhesion to the wall of the xylem the xylem walls are pulled inwards

99
Q

structure of leaves

A 
waxy cuticle (reduce water loss)
upper epidermis
palisade cells  (photosynthesis)
spongy mesophyll cells which contains air spaces (allows gas exchange)
lower epidermis 
stomata and guard cells
100
Q

adaptation of palisade cells for photosynthesis

A

located near top of the leaf so they are closer to light
large in size so there is a large surface area for light
thin cell wall, short diffusion distance of carbon dioxide
many chloroplasts for photosynthesis
large vacuole, pushes chloroplasts to the edge of the cell closer to light

101
Q

structure of chloroplast

A 
organelle for photosynthesis
double membrane 
thylakoid discs
stacks of thylakoids are called granum 
thylakoids contain chlorophyll 
thylakoids surrounded by fluid called stroma 
stacks are linked by lamella
102
Q

how does exchange occur in leaves

A

lower epidermis containing guard cells
when turgid the guard cells form stomata
gas exchange occurs via stomata
in day: plant photosynthesises and respires, co2 moves in for photosynthesis and o2 moves out (some used in respiration)
at night: plant only respires, o2 moves in and co2 moves out

103
Q

transpiration definition

A

loss of water vapour from the leaf via the stomata

104
Q

process of transpiration

A

moist lining of spongy meosphyll cells evaporate forming water vapour
water vapour builds up in air spaces
if water vapour concentration is high enough and he stomata are open the water vapour diffuses out

105
Q

what are the factors that affect the rate of transpiration

A

light
temperature
wind
humidity

106
Q

how does light affect the rate of transpiration

A

more light
more stomata open
increase surface area for transpiration

107
Q

how does temperature affect the rate of transpiration

A

increased temperature
increased evaporation
increases water vapour concentration
more kinetic energy

108
Q

how does wind affect the rate of transpiration

A

more wind
maintains concentration gradient
disperses humid layer

109
Q

how does humidity affect the rate of transpiration

A

less humid
less water vapour in the surrounding air
increase in water vapour
concentration gradient

110
Q

what is a potometer

A

apparatus used to measure the rate of transpiration

111
Q

principle of a potometer

A

as transpiration occurs from the leaves the plant will pull up more water from the potometer by cohesion-tension causing the bubble to move more towards the plant
more water lost by transpiration the more water taken up the further the bubble moves

112
Q

measuring rate of transpiration

A

rate=transpiration volume/ time

transpiration volume= distance bubble moves x cross sectional area of tube (pi r ^2)

113
Q

how to set up a potometer

A

choose healthy leaf and shoot
cut shoot underwater and connect to potometer underwater (prevents air bubbles entering/blocking the xylem)
ensure potometer is air tight and water tight

114
Q

what does a potometer actually measure

A

rate of water uptake as a result of water loss from the plant
water loss due to: transpiration, photosynthesis, making cells turgid, loss from potometer

115
Q

xerophyte definition

A

a plant adapted to reduce water loss (reduce transpiration)

116
Q

adaptations of a xerophyte

A

spiky needle like leaves= reduce surface area
thick waxy cuticle= waterproof, impermeable barrier
densely packed spongy mesophyll= less air spaces, less water vapour build up
sunken stomata/hairy leaves/rolled up leaves= traps moist layer of air, reduces concentration gradient

117
Q

function of phloem

A

transport organic material (sucrose) up and down a plant

118
Q

structure of phloem

A

made of sieve tube with companion cells alongside

119
Q

how does the phloem transport an organic material like sucrose

A

mass flow theory
sucrose loaded into the phloem at source
H+ actively transported from companion cells into the source
H+ diffuses back into the companion cells from the source
as they do they pull sucrose with them by co-transport
sucrose diffuses down the sieve tubes
lowers water potential of sieve tube so water follows by osmosis
water carries the sucrose by hydrostatic pressure (mass flow)
sucrose unloaded from phloem at sink
sucrose moves out of phloem into sink by diffusion
water follows by osmosis

120
Q

enzymes of carbohydrate digestion

A

starch/glycogen: (salivary amylase in mouth, pancreatic amylase in small intestine) into maltose

maltose: (maltase on lining of small intestine) into glucose
lactose: (lactase on lining of small intestine) into galactose and glucose
sucrose: (sucrase on lining of small intestine) into glucose and fructose

121
Q

enzymes forprotein digestion

A

endopeptidases: (in stomach) hydrolyse peptide bonds in the middle of the polypeptide chains into many smaller chains
exopeptidases: (in small intestine) hydrolyses peptide bonds at the end of the chains to leave dipeptidases
dipeptidases: (on lining of small intestine) hydrolyse dipeptides into amino acids

122
Q

enzymes for lipid digestion

A

lipase in small intestine leaves monoglyceride and 2 fatty acids

123
Q

adaptations of small intestine for absorption

A

folded to form villus= large surface area
cells lining small intestine have microvilli=large surface area
walls of small intestine are thin= short diffusion distance
rich blood supply= maintains concentration gradient
cells lining small intestine have transport proteins, enzymes and many mitochondria

124
Q

absorption of glucose and amino acids in small intestine

A

sodium ions are actively transported from the cells lining the small intestine into the blood
lowers sodium ion concentration in the cell
sodium ions move from the lumen of the small intestine into the cell
pulls in glucose and amino acids via a cotransport protein
glucose and amino acids build up in the cell and move into the blood via diffusion

125
Q

absorption of monoglyceride and fatty acids

A

lipids initially emulsified by bile into micelles
micelles digested by lipase into monoglycerides and 2 fatty acids
monoglycerides and fatty acids absorbed by cells lining the small intestine by simple diffusion
forms a chylomicron (lipid+cholesterol+lipoprotein)
enters lymph as lacteal then enters blood

126
Q

what is lactose intolerance

A

person doesn’t make lactase enzyme
lactose remains undigested
undigested lactose in lumen of intestine lowers its water potential, water enters lumen by osmosis leading to water faeces
undigested breakdown of lactose by micro-organisms in large intestine gives off gas

A-Level Biology (14 decks)

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