Gas Exchange Essay Research Paper Gas Exchange

9 September 2017

Gas Exchange Essay, Research Paper

Gas Exchange 3.1 & # 216 ; Surface

country to volume ratio & # 216 ; Exchange

of gases occurs by diffusion at surface Whereas & # 216 ; Production

of wastes and usage of resources occurs in the volume & # 216 ; Therefore,

as organisms addition in size they have proportionally less surface country compared

to volume & # 216 ; Adaptations

? level, thin, ribbed organic structures increase exchange surfaces 3.2 & # 216 ; As

beings get larger? they must hold exchange surfaces within them & # 216 ; all

are damp, thin permeable, big surface country Plants Spongy/Palisade Mesophyll Air straight contacts cells Insects Ends of tracheoles Air straight contacts cells Fish Gill Lamellae O2 absorbed by blood pigments so delivered to

cells Mammals Alveoli O2 absorbed by blood pigments so delivered to

cells Ventilation & # 216 ; Aim

? maintain concentration gradient & # 216 ; Remove

CO2 rich O2 hapless air & # 216 ; Supply

O2 rich CO2 hapless air & # 216 ; Move

respiratory medium over exchange surface & # 216 ; Insects

? larger insects make pumping motions of the venters, which crushes the air

pouch and helps to travel air & # 216 ; Fish

? travel operculum out, buccal pit up? hence one manner flow of H2O over

the gill gill? counter current flow of H2O against the way of

blood flow & # 216 ; Mammal

? Tidal flow of air? motion of stop and ribs Control of Breathing & # 216 ; Involuntary & # 216 ; Respiratory

Centre is bundle of nervousnesss in myelin oblongata & # 216 ; Urges

are sent to the stop and external intercostal musculuss doing them to

contract & # 216 ; As

lungs expand stretch receptors in airway sense and direct back info & # 216 ; Meeting Demand & # 216 ; CO2

degrees vary harmonizing to exercising & # 216 ; As

Carbon dioxide goes up? pH goes down & # 216 ; Chemoreceptors

sense this & # 216 ;

Receptors in the myelin oblongata & # 216 ;

Carotid organic structures in the carotid arteries & # 216 ;

Aortal organic structures in the aortal arch & # 216 ;

As chemoreceptors sense addition in CO2 or lessening in

pH, urges are sent to the respiratory Centre, this sends impulses to the

stop and intercostal musculuss increase the rate of airing. Oxygen/Haemoglobin

Dissociation Curves 3.7 ( portion ) & # 183 ;

Red blood cells contain hemoglobin ( Hb ) which transports all of the O around your organic structure

and most of the CO2 & # 183 ;

Each Hb molecule can transport up to four O2 molecules.However, & # 183 ;

The relationship between O2? concentration ( partial force per unit area of O2

– P O2 ) and how much is taken up by Hb ( % impregnation ) is non additive, it is & # 8216 ; S & # 8217 ; shaped ( sigmoid ) & # 183 ;

This is because a wholly & # 8216 ; empty & # 8217 ; Hb molecule takes

up the first O2 instead & # 8216 ; reluctantly & # 8217 ; , so takes up the staying

three quickly, and eventually it is & # 8216 ; full & # 8217 ; and won & # 8217 ; Ts take up any more. & # 183 ;

Loading: In

the lungs the pO2 is really

high, so Hb is & # 8216 ; filled up & # 8217 ; ( saturated ) with O2, represented by the

level & # 8216 ; top & # 8217 ; of the curve & # 183 ;

Transporting: As

the Hb travels through arterias and arteriolas, pO2 beads, but non

plenty for the Hb to give up any O, we are still in the level part at the top. & # 183 ;

Droping: When

the Hb reaches capillaries which are following to actively respiring cells, pO2 is much lower, due to

O being consumed to do ATP. Here, Hb is & # 8216 ; emptied & # 8217 ; of its O, which

diffuses to the cells. This is represented by the steep portion of the curve in

the center of the & # 8216 ; S & # 8217 ; . & # 183 ;

The relationship between P O2 and Hb

impregnation is non fixed, the form of the curve alters in response to assorted

conditions: Condition Effect on curve Overall consequence Increased pCO2 Shifts to the right

( Bohr displacement ) At any given pO2, Hb will be less concentrated, so O will be

given up more easy Increased temperature Shifts to the right At any given pO2, Hb will be less concentrated, so O will be

given up more easy Increased pH ( alkaline ) Shifts to the left At any given pO2, Hb will be more concentrated, so O will be

given up less easy & # 183 ;

This makes good sense, if cells are actively respiring

they produce CO2, heat up and go more acidic ( due to fade out

CO2, and production of lactic acid ) , all these things cause the

curve to travel to the right, so

O is given up easy. This O is exactly what actively respiring

cells need! & # 183 ;

Other illustrations: Foetal Hb is to the left of its female parent & # 8217 ; s ( so it can & # 8217 ; steal & # 8217 ;

O from her blood via the placenta ) . Myoglobin, in musculuss has a curve to

the left of Hb ( it besides & # 8217 ; bargains & # 8217 ;

O from Hb, and retains it as a shop and merely gives it up at really low pO2 ) . & # 183 ;

Finally, Hb carries CO2 by agencies of a series

of reactions ( catalysed by carbonaceous anhydrase ) which consequence in the production

of H ions and hydrogencarbonate ions. The H ions are taken up by

Hb, intending that Hb acts as a buffer,

absorbing extra acid. The hydrogencarbonate diffuses into the plasma, in

exchange for chloride ions ( the chloride displacement ) .CARDIAC CYCLE AND ITS CONTROL & # 183 ;

The bosom musculus is?

myogenic ( contracts without stimulation ) & # 183 ;

The sino-atrial node coordinates the bosom round so that

the musculus cells contract together. & # 183 ;

The SAN is in the right atrium next to the vein cava & # 183 ;

Specialised musculus ( Purkinje ) fibres radiate out from

the node and do atrial contracton ( systole ) & # 183 ;

These stimulate the AVN, on the septum at the junction

of the atria & A ; ventricles & # 183 ;

The AVN causes a clip hold which ensures the ventricle

contracts after the atria & # 183 ;

The package of His ( Purkinje fibres ) pass down the

septum to the vertex of the ventricles & # 183 ;

These first cause contraction of the papillose musculuss

which tenseness the cuspid valves & # 183 ;

Ventricular systole radiates upwards from the vertex & # 183 ;

Once the electrical stimulation has died away the bosom

Chamberss relax ( diastole ) CONTROL OF HEART RATE & # 183 ;

The SAN sets a resting bosom rate & # 183 ;

Blood O2 & A ; CO2 degrees are

detected by chemoreceptors of the Aortic & A ; Carotid bodies & # 183 ;

These send nervus urges to the cardiovascular Centre

of the myelin & # 183 ;

The myelin has chemoreceptors which besides detect CO2 & # 183 ;

If CO2 drops the CV Centre sends nerve

urges along parasympathetic nervousnesss to the SAN, which reduces bosom rate

( vagus nervus ) & # 183 ;

If CO2 goes up the CV Centre sends nerve

urges along sympathetic nervousnesss to the SAN, which increases bosom rate

( gas pedal nervus ) & # 183 ;

Epinephrine can besides move straight on the SAN, mirroring

the consequence of sympathetic nervousnesss & # 183 ;

CO2? dissolves

in H2O to let go of H ions which decrease the pH and increase the

sourness & # 183 ;

The bosom rate is controlled so that the demands of the

organic structure are met with the minimal cardiac end product. ? PRESSURE & A ;


Valves stop the backflow of blood within the bosom and

as blood exits the bosom & # 183 ;

Muscular contraction ( systole ) causes an addition in

hydrosatic force per unit area in the bosom. & # 183 ;

When the valves open the volume of the bosom chamber

lessenings & # 183 ;

Blood ever attempts to flux from high to low force per unit area

unless valves stop it & # 183 ;

Valves open or

near when force per unit area lines cross ( on graph ) & # 183 ;

The bosom empties from the underside up. ELECTRICAL ACTIVITY & # 183 ;

P is the hint produced by stimulation of atrial

systole & # 183 ;

QRS is the hint produced by venricular systole CIRCULATION AND BLOOD VESSELS & # 183 ;

Blood leaves the bosom in jets when the ventricle

contacts & # 183 ;

In arterias, this is foremost pushed along by snap

and so by a peristaltic pulsation & # 183 ;

In the tissue capillaries this is smoothed out to a

changeless flow by the arteriolas, in the lungs, the blood continues to flux in

pulsations & # 183 ;

Throughout circulation there is a force per unit area bead & # 183 ;

Fluid leaves the arteriolas and bathes the tissues,

because the hydrostatic force per unit area outwards exceeds the difference in H2O

possible ( osmotic force per unit area ) & # 183 ;

Most is drawn back into the venulas by the solute

potency of the blood proteins ( osmotic potency ) , some returns via the lymph & # 183 ;

Blood flow is the fastest where the entire cross

sectional country is least. & # 183 ;

The same volume of blood must come in and go forth the bosom

per minute but the force per unit area is different Digestion Q

Mammals have a intestine to digest so absorb nutrient Q

The generalized construction of the mammalian intestine wall Q

Epithelium Q

Lumens? ? Q

Muscle beds? ? Q

How different parts of alimental canal are adapted for

their functionq

Motion of nutrient through vermiculation Q

How? ? Q

Sites of production and action of Amylases? Mouth Starch to Maltose Endopeptidases Stomach/Pancreas? Pepsin/Trypsin Polypeptides into smaller ironss Exopeptidases Pancreas and intracellular ( little intestine epithelial

cells ) Cuts di and tripeptides into single amino acids Lipase Pancreas Fats into monoglycerides and fatty acids Maltase intracellular ( little intestine epithelial cells ) Breaks maltose into glucose Bile Liver Not an enzyme? emulsifies fats into smaller droplets q

Mechanisms for soaking up in the ileumq

Structure of a liver lobuleq

Control of Digestive Secretions Q

Nervous? sight odor Q

Hormonal Gastrin Presence of nutrient in the tummy Stomach secretes pepsin and hydrochloric acid? Begins

muscular motion of tummy Cholecystokinin Presence of acidified chyme in duodenum causes cells in

the mucous membrane of duodenum to release endocrine into blood stream Pancreas secretes enzymes? Gall vesica secretes bile Secretin Presence of acidified chyme in duodenum causes cells in

the mucous membrane of duodenum to release endocrine into blood stream Effectss liver ( gall ) and Pancreas? fluid? non? enzymic constituents of pancreatic

juice Q

Liver Q

Blood sugar Q

Glycogenesis doing animal starch from glucose Qs

Glycogenolysis interrupting up animal starch into glucose Q

Gluconeogenesis? doing glucose from non-carbohydrate

beginnings ( fats and proteins ) q

Functions of insulin ( traveling down ) and glucagon ( traveling up ) in commanding blood sugar levelsq Transamination? altering one amino acid into another

? non possible to synthesis indispensable amino acids ( must be obtained from diet3.8? ? ? ? ? ? ? ? ? Elimination and OsmoregulationMost

inquiries in the test ask about some, or all, of the followers: & # 183 ;

The kidney, specifically: & # 183 ;

which substances

move, & # 183 ;

in which way

and why, & # 183 ;

how this is controlled. & # 183 ;

What other

animate beings do, peculiarly one-celled?

animate beings, fish ( which both excrete ammonium hydroxide

straight into H2O ) and insects ( which excrete solid uric acid ) and why. & # 183 ;

Deamination and the ornithine rhythm ( learn and

regurgitate! ) . The Kidney & # 183 ;

Everything the kidney does is done in the uriniferous tubules ( about a million per kidney ) & # 183 ;

First, the blood is filtered

at the glomerulus. All the constituents of the blood are squeezed through the

filter into Bowman & # 8217 ; s capsule, except proteins

and cells. Reabsorption & # 183 ;

Glucose, aminic acids and mineral ions are actively

reabsorbed into the blood in the proximal

convoluted tubule. & # 183 ;

Water, by osmosis is besides reabsorbed to equilibrate the

concentration. & # 183 ;

Changing sums of salts and H2O are reabsorbed from

the distal convoluted tubule. & # 183 ;

Changing sums of H2O are reabsorbed from the roll uping canals. & # 183 ;

Some toxicant substances are secreted, actively, into

the proximal convoluted tubule.Generating

Concentrated Urine & # 183 ; go uping limb impermeable to H2O but actively pumps out Na chloride

( salt ) so the fluid in the go uping limb gets more and more dilute. & # 183 ;

tissue fluid

environing cringle has sodium chloride pumped into it from go uping cringle and

hence becomes more concentrated. & # 183 ; falling limb loses H2O to the

environing tissue fluid, passively,

by osmosis, but is impermeable to sodium chloride, so salt doesn & # 8217 ; t follow. & # 183 ;

The high Na chloride concentration in the tissue

fluid around the cringle draws H2O out of the nearby collection canal, by osmosis.Antidiuretic

Hormone ( ADH ) controls the volume and H2O potency of the blood & # 183 ;

Osmoreceptors in hypothalamus are sensitive to H2O

potency of the blood & # 183 ; Drop

in H2O potency ( more concentrated ) consequences in release of ADH from pituitary secretory organ & # 183 ;

ADH causes the usually impermeable roll uping canal and distal

tubule walls to go more permeable ensuing in more H2O being

reabsorbed into the blood and the urine going more concentrated and of a

& gt ; smaller volume Aldosterone controls

the volume and Na ( Na+ ) content

of the blood & # 183 ;

Drop in blood volume detected by cells in the kidney

( juxtaglomerular cells ) , which is by and large associated with low blood Na+ . & # 183 ;

A complex concatenation of events causes aldosterone to be released from the cerebral mantle of the adrenal secretory organ. & # 183 ;

Aldosterone causes the distal tubule to resorb more

Na+ , which increases blood Na+ and volume. & # 183 ;

Finally, the kidney helps to command blood pH, by releasing extra acid or base into the

distal convoluted tubule ( so the pH of piss can change, but blood pH remains the

same ) .Revision notes on Xylem and Phloem ( 3.7?

portion ) Root construction Angstrom

cross subdivision of a root shows that the vascular tissues occur in packages

at regular intervals around the outer portion of the root. The Centre of a root is

filled with pith. The outermost bed of the root is rainproof with lenticels

for gas exchange. Each package consists

of bast on the outside and xylem on the interior with the cambium in

between. ? There may besides be sclerenchyma

fibers exterior to the bast to give excess strength. ? The cambium is meristematic bring forthing new xylem and bast as the

root additions in girth. At the nodes of the root subdivisions in the vascular

packages occur so that the vascular packages enter the leafstalks of foliages as good

as go oning up the root. In woody workss the vascular tissue forms a complete ring

around the root and the Centre of the root becomes filled with xylem ( wood ) as

the works gets bigger. Xylem structureXylem consists of xylem

vass and tracheids every bit good as parenchyma tissue. ? The vass are made from columns of cells in which the terminal walls

hold broken down to go forth a long tubing. ?

These cells die as they become specialized because their walls become

impregnated with lignin which is non permeable. The net consequence is a tubing of

xylem elements in which there is no cytol. ?

Xylem vass remain in contact via cavities in their sidelong ( side )

walls. ? Tracheids are besides dead but each

tracheid has a pointed terminal and overlaps the 1s above and below, the tracheids

besides have connexions via cavities. Between the vass and tracheids is xylem

parenchyma. Xylem functionXylem carries H2O and

ions from the roots to the root, leaves, flowers and fruits. Water travels upwards in

the xylem because of the transpiration pull caused by vaporization of H2O from

the cells of the foliage followed by diffusion of H2O vapor through the pore

i.e. transpiration ( besides acquire some transpiration through the cuticle ) . The uninterrupted column of H2O in the xylem does non

separate due to forces of coherence between the H2O molecules. ? These forces are made possible because H2O

is a polar molecule and H2O molecule have hydrogen bonds between them and

they besides adhere to the walls of the xylem vessel. ? This is known as the COHESION TENSION THEORY of H2O motion. Conveyance in the xylem is an illustration

of MASS FLOW. Because

the cytol has gone from the xylem and the terminal walls of the vass have

disintegrated so there is no barrier to the flow of H2O up the xylem. ? Water can go forth the xylem through the cavities

to travel into next tissues. Ions absorbed in the roots besides move upward in

the xylem dissolved in the H2O Water

enters the xylem after it has been absorbed and has travelled across the root

to the cardinal vascular package of the root. ?

Capillarity and Root force per unit area besides play a portion in H2O motion in

works but neither can explicate how H2O can go to the top of trees. EvidenceEvidence

for the coherence tenseness theory of H2O motion comes from the fact that

H2O in the xylem is under tenseness so air enters the xylem if the xylem is

damaged and by the fluctuation in the girth of trees at different times of the

day. ? Water can be shown to travel up the

xylem by leting a root to take up dye. ?

Motion of H2O in the xylem is wholly inactive ( it continues if the

works is poisoned so that it can non do ATP ) , that means that no chemical

energy is expended in H2O motion through the xylem.Phloem StructureThe

bast in a works forms merely a really this bed about the same thickness as a

piece of paper. Phloem tissue consists of screen tubings, comrades cells and

bast parenchyma. ? All phloem tissue is

life ( unlike xylem ) although the cytol of the screen tubing is extremely

specialised and has a decreased figure of cell cell organs. The screen tubing

consist of a column of cells formed end to end. ? Between each cell the cell wall has a figure of holes so that it

has the visual aspect of a screen and this is known as the screen plate. ? The cytol of the screen tubing is modified

and contains no mitochondria. ? Adjacent

to each screen tubing is a comrade cell which has a really heavy cytol and

which supplies energy for the screen tubing. The sieve tubing carry

sugar up and down the plant. ? They are

loaded with sugars in the foliages and so the sugar moves in solution either up

or down the works to where it is needed.Theories of Phloem Transport1. Pressure flow 2. Cytoplasmic streaming 3. Electro-osmotic flowNo one theory provides a wholly satisfactory account to

flow. The most recognized theory is the force per unit area flow theory that

provinces that sugars are loaded into the bast in an country of high concentration,

the beginning, and are so transported by mass flow to an country of low

concentration, the sink, where they are unloaded. ? This theory allows for substances to travel both up and down the

plant. ? Movement of substances in the

bast is an active procedure necessitating ATP.Evidence for1.

The contents of the bast have a positive pressure- they

exude fluid when cut and aphid stylets exude fluid when they penetrate the

bast. 2.

Experiments have shown a concentration in the bast contents

with the highest concentration near the source-analysis of exudations from aphid

stylets 3.

A physical theoretical account of this theory maps 4.

Viruss can be moved in the phloem. ? This must be mass flow as they are nor in solution and are

hence non able to travel by diffusion.Evidence against1.Sugars

and amino acids have been found to travel in different waies in the same

vascular package. 2.

Phloem conveyance may non happen in the way of the deepest sink. 3.

The screen home base is an hindrance to mass flowExperiments used to look into mass flowRadioactive tracers. ? These

are introduced via radioactive C dioxide and photosynthesis and the way

traced by autoradiography.Ringing experiments. ?


bast is removed in a ring around the root and this stops flow in the bast. ? Shows that sugars, aminic acids and salts are

transported in the phloem.Use of Aphids for sampling3.6? ? ? ? ? ? ? ? ? Exchange of Water and Ions in PlantsMost

inquiries in the test ask about some, or all, of the followers: & # 183 ;

Root construction and map ( peculiarly mineral

soaking up ) & # 183 ;

Stomata and transpiration ( and factors impacting

transpiration ) & # 183 ;

Features of desert plants ( workss that live in really dry

conditions ) Root

construction and map: & # 183 ;

Root construction? learn

the typical layout of tissues in roots ( Support Booklet p.20 ) and how it

differs from stems. & # 183 ;

Root map: & # 183 ;

Water and minerals are absorbed through root hairs and base on balls

through the cells of the cerebral mantle. & # 183 ;

These substances can travel through the porous cell walls in

the cerebral mantle, instead like H2O soaking through paper, this is called the apoplast

tract. & # 183 ;

Water and minerals can besides go through through the living portion of

these cells ( cell membrane, cytol etc. ) ? the symplast

tract. & # 183 ;

The cells of the cerebral mantle besides contain big vacuoles, and

substances can go through through these ( every bit good as the cytol etc. ) ? the vacuolar

tract. & # 183 ;

Between the cells of the cerebral mantle and the xylem and bast is

a bed of cells called the endodermis. These cells have a particular waterproof

bed in portion of their cell walls, organizing the Casparian strip.

This forces H2O and minerals to

take the symplast tract through the endodermis. & # 183 ;

Because all cell membranes are selectively permeable, this

allows the cells of the endodermis to command

the sum of each mineral taken into the xylem: Substance Method of conveyance across endodermis Reason Water Osmosis Water is drawn up xylem in transpiration watercourse ( see 3.7 ) Minerals at a higher

concentration in dirt than works cells Facilitated diffusion These can flux down

their concentration gradient into the works Minerals at a lower concentration

in dirt than works cells Active conveyance ( requires ATP ) These must be moved against

their concentration gradient into the works Toxins Transport blocked or inhibited Mechanism unknown ( Water and minerals so pass

up the root in the xylem & # 8211 ; see 3.7? and enter the foliages ) Stomata

and transpiration & # 183 ;

99 % of the H2O that goes up the xylem evaporates into air

infinites in the foliages, and diffuses out through the pore as

H2O vapor, this is transpiration. & # 183 ;

Anything that affects the concentration gradient of H2O vapor from works to air will

hence affect the rate of transpiration: Factor Effect on rate of transpiration Reason Increased light strength Increases Stomata unfastened wider in visible radiation ( see below ) Increased humidness Decreases Decreased concentration gradient ( humid air around foliages ) Increased air motion Additions Increased concentration gradient ( humid air around foliages

blown off ) Increased temperature Increases More rapid vaporization from leaves Dry dirt around roots or high salt

concentration ( e.g. sea H2O ) Decreases Decreased consumption of H2O into roots, hence less

available in foliages ( The rate of transpiration can be measured with a potometer ) . & # 183 ;

Clearly, pores are really of import in transpiration, as

most of the H2O vapor base on ballss through them. They normally open in the visible radiation and shut

in the dark ; they besides close when H2O supply to the roots is really poor. & # 183 ;

Stomatal gap is controlled by the two guard cells

which surround each pore. The cell wall on the interior surface is much thicker

than on the outer surface. As these cells become bombastic ( crestless wave ) they bend outwards,

doing the pore to open ( you can show this by lodging cellulose tape on

one side of a allantoid balloon so blowing it up, it bends off from the cellulose tape ) . & # 183 ;

There are two hypotheses to explicate how guard cells change their form: & # 183 ;

The K

motion hypothesis provinces that K ions ( K+ ) are

pumped into the guard cells, by active

conveyance. This lowers their H2O potency, H2O flows in by osmosis,

the guard cells become bombastic and stomata unfastened. The contrary procedure stopping points

pore. This hypothesis is the most widely accepted. & # 183 ;

The starch-sugar

hypothesis provinces that there is a balance between sugars ( soluble ) and amylum

( indissoluble ) controlled by two enzymes with different optimal pH & # 8217 ; s. The enzyme

which converts amylum into sugar has a high

optimal pH ( alkaline ) , which is produced in the twenty-four hours, because acidic CO2

is used up in photosynthesis. Therefore, sugar accumulates, H2O potency

beads, H2O enters, cells become bombastic, stomata unfastened. The enzyme which

converts sugar to amylum has a low

optimal pH ( acidic ) , which is produced at dark, because CO2 is

produced by respiration ( no photosynthesis ) . Starch accumulates, but because

amylum is indissoluble H2O potency rises, H2O foliages, guard cells lose

turgidness, pore near. This hypothesis is non widely accepted.Xerophytes & # 183 ;

These are workss that are adapted to populate in really dry

conditions by holding some, or all, of the undermentioned characteristics: & # 183 ;

A really thick, waxen cuticle to cut down vaporization of H2O

through this portion of the foliage ( epidermal transpiration ) . & # 183 ;

Stomata sunk into cavities, which trap a bed of humid

around them, so cut downing transpiration. & # 183 ;


around pores, once more pin downing a bed of humid air. & # 183 ;

Few, little foliages ; frequently rolled into a tubing. This reduces surface country for

transpiration, and humid air is besides trapped inside the inrolled foliage. & # 183 ;


pore in the twenty-four hours, when it is hot, and opening them at dark,

cut downing vaporization. ( such workss take in CO2 at dark, shop

it? as an organic acid and so interrupt

the acid down in the twenty-four hours to let go of the CO2, internally, for

photosynthesis. This is called CAM

photosynthesis ) . & # 183 ;


of H2O in thick roots and foliages ( these workss are called succulents ) . & # 183 ;

Deep, tap roots to pull up H2O from deep dirt beds. & # 183 ;

Roots really near to the dirt surface, to absorb

condensation which forms at dark.

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