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3 exchnage substances Flashcards

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1
Q

why do organisms exchange substances with environment?

A

. cells need oxygen and nutrients
. organisms need to excrete waste
. heat needs to be exchange to maintain internal environment

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2
Q

describe relationship between size and sa:vol ratio

A

. as organism increases in size, sa:vol ratio decreases

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3
Q

why is a small sa:vol ratio bad for large organisms?

A

. diffusion too slow to deep body cells
. large vol has requirements too high for sa
. have changes to body to facilitate for this
. larger animals struggle to lose heat
. smaller animals require more metabolic reactions to maintain heat

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4
Q

explain how small animals are able to maintain constant body temp

A

. smaller so larger sa:vol
. faster heat loss
. faster rate of metabolism releases heat

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5
Q

why do single celled organisms not need specialised exchange systems

A

. have large sa:vol ratio and short diffusion pathway

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6
Q

explain an advantage for larger animals of having a specialised system that facilitates oxygen uptake

A

. large organisms have smaller sa:vol ratio
. overcomes long diffusion pathway

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7
Q

How are insects adapted for gas exchange?

A

. need to exchange gases but must reduce waater loss
. have branched, chitin lined tracheae connected to spiracles
. fast exchange of gases as diffusion distance small at tracheoles
. no transport system as exchange is directly connected to respiring tissues
. body can move by muscles so maintains conc gradient for gases
. fluid in end of tracheoles goes into tissues in excersise so faster diffuision

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8
Q

how is the insects respiratory system adapted for efficient gas exchange?

A

. constant conc grad maintained as direct contact with respiring tissues so o2 always taken away and co2 always pushed out
. tracheae lined with chitin
. tracheoles are very branched to inc sa
. tracheoles are permeable
. shor diffusion distance as tracheoles in direct contact with respiring tissues

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9
Q

explain how terrestrial insects control water loss

A

. insects can close spiracles using muscles
. have waterproof waxy cuticle and hairs around spiracles to reduce evaporation

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10
Q

explain movement of oxygen into gas exchange system of an insect at rest

A

. oxygen used in aerobic respiration
. so oxygen gradient established
. so oxygen diffuses in

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11
Q

explain how fish gills are adapted to take in more oxygen in water

A

. water has lower o2 content than airand diffuion slower in water
. gills have thin filaments with tiny lamellae to inc sa for diffusion
. water containg o2 goes into mouth and out of gills
. gills have lots of blood capillaries and are thin for short diff pathway

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12
Q

what is one directional flow?

A

. system used by fish where water goes in through t he mouth, out gills, into wateri

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13
Q

what is counter current flow

A

. water and blood flow in opposite directions so diffusion gradient between adjacent flows maintained over whole lamellae surface

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14
Q

describe and explain the advantage of counter current principle in gas exchange across a fish gill

A

. water and blood flow in opposite directions
. maintains concentration gradient of oxygen
. diffusion along length of capilary

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15
Q

explain how plamts exchange gases at surface of mesophyll cells

A

. plants need co2 for photosynthesis
. gases enter and leave through stomata in epidermis layer
. gas exchange at surface of mesopyll cells with high surface area
. stomata open and close
two guard cells control open and close of stomata

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16
Q

what adaptations does a plant have

A

. waxy cuticle - impermeable to water but also stops gas exchnage
. air spaces in spongy mesophyll - decreases diffusion distance
. palisade mesopyll cells have most chloroplasts to inc photosynthesis
. mesophyll cells are site of gas exchange
. more stomata on underside of leaf to prevent water loss

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17
Q

explain how plant cells reduce water loss

A

. stomata stay open in day to allow gas exchange
. water enters guard cells and become turgid so open
. if plant gets dehydrated guard cells lose water so go flaccid and close

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18
Q

waht is a xerophyte and how are they adapted?

A

. plants adapted for hot dry conditions
. have rolled leaf shape to trap humid air
. reduced leaf sa for transpiration
. sunken stomata, traps humid air to reduce wp gradient
. no stomata on exosed lower surface
. hairs trap moist air
. thick cuticle, waxy covering reduces evaporation
. shallow roots enable rapid uptake of rainfall
. widespread roots allow collection of more water
. swollen stem for water storage
. small/no leaves

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19
Q

how would you calculate the mean diameter of stomata?

A

. measure with eyepiece graticule
. calibrate eyepiece graticule against stage micrometre
. take number of measurements
. calculate mean by adding and dividing by number of measurements made

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20
Q

how do you calculate stomatal density

A

. first calculate area of fov
. count no stomata
. calculate no in 1mm

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21
Q

explain gas exchange in humans

A

. humans require o2 in blood and to remove co2
. air in trachea, splits into bronchi, then many brnchioles, then alveoli where gas exchange occurs

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22
Q

explain adaptations of the alveoli

A

. many alveoli - inc sa
. alveolar epithelium and capillary endothelium one cell thick, short diff path
. many capillaries close to alveoli - maintains conc grad
. iwell ventilated - brings o2 and takes co2 to maintain steep conc grad

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23
Q

describe the pathway of oxygen in a human

A

air in atmos > trachea > bronchus > bronchioles > alveoli > alveolar epithelium > capillary endothelium > blood

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24
Q

explain how all ventilation happens in the lungs

A

. diaphragm and internal/external intercostal muscles contract to change vol of thorax so air pressure changes and moves down conc gradient

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25
Q

explain inspiration in the lungs

A

. external intercostal - contract
. internal intercostal - relax
. diaphragm - contracts
. rib movement - up and out
. thorax vol - inc
. air p in thoracic cavity - dec below atmos p
. air - moves in down p grad

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26
Q

explain expiration in lungs

A

. external intercostal - relax
. internal intercostal - contract
. diaphragm - relaxes to dome shape
. rib movement - down and in
. thorax vol - dec
. air p in thoracic cavity - inc past atmos p
. air - moves out down p grad

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27
Q

describe and explain the mechanism that cause sthe lungs to fill with air

A

. diapragmh contracts and external intercostal muscles contract
. pressure decreases
. air movesodwn pressure gradient

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28
Q

what are tidal volume, ventilation rate, forced expiratory volume, and forced vital cappacity

A

. lung diseases can affect lung function and gas exchange
. tidal volume - vol of air in each breath
. ventilation rate - breaths per minute
. forced expiratory volume - max vol air breathed out in 1 sec, measures bronchiole function
. forced vital capacity - max vol air breathed out forcefully after deep breath

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29
Q

what is digestion

A

during digestion, large insoluble biological molecules are hydrolysed to smaller soluble molecules that can be absorbed across cell membranes

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30
Q

name the sites of chemical digestion

A

. mouth, stomach, small intestine

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31
Q

name the sites that produce enzymes

A

. salvary glands, stomach, small intestine

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32
Q

explain carbohydrate digestion

A

. starch hydrolysed to maltose
. amylase produced by salivary gland which release into mouth
. amy also produced by pancreas and released into small intestine
. membrane bound disaccs attached to membrane epithelial cells in ileum, break down disaccs into monosaccs

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33
Q

where in the body produces what digestive enzymes?

A

. mouth - salivary amylase hydrolyses glycosydic bonds in starach to form maltose
. salivary glands - produce enzyme amylase
. small intestine - pancreatic amylase hydrolyses glyc bonds in starch forming maltose
. pancreas - produces pancreatic amylase
. small intestine - disaccharides attatched to epithelial cells on ileum hydrolyse glyc bond in disaccs to make monosaccs

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34
Q

explain lipid digestion

A

. lipdids hydrolysed to monoglyc and fatty acids catalysed by lipase
.lipases are made in the pancreas and work in small intestine
. bile salts produced by liver, emulsify big shit into little shit = bjg sa
. monoglyc and fat acid form micelles with bile salts

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35
Q

how can you measure lipid digestion

A

. seen by measuring pH
. as lipids hydrolysed fatty acids make solution more acidic
. faster change in ph = faster hydrolysis of lipids
. measure with a ph meter not a buffer as this would keep ph constant

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36
Q

whatis invloved in protein digestion

A

. proteins hydrolysed by 3 protease enzymes: endo, exo and dipeptidases into amino acids
. endo hydrolyse bonds within the aa chain, produced by the stomach cells or pancreas secreted into small intestine
. exo - produced by pancreas go into small intestine , hydrolyse aa ends and remove single aa
. dipep - located on cell surface membrane of epithelial in s intestoine and separate dipeps into 2 aa

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37
Q

tha action of endopeptidases and exopeptidases can increasethe rate of protein digestion. describe how

A

. exopeps hydrolyse petide bonds at end of polypep and endopeps hydrolyse internal pep bond within polypep
. more ends/ surface area

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38
Q

how are the products of digestion absorbed

A

. after hydrolysis, small soluble products absorbed from ileum

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39
Q

hoe are the ileum adapted for absorption

A

. very long and folded into villi, inc sa for absorption
. villus have good capillary networks of tubes called lacteals which is part of lymph system
. both remove absorbed molecules, maintains conc grad
. lining of ileum made of one layer of epithelial cells, capillaries one cell of endothelial cells, short absorption pathway

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40
Q

what are the adaptations of epithelial cells
in the small intestine

A

. cells have microvilli, inc sa
. membrane has more protein channels and carriers for more a transport, fac diff, co transport
. has more mitochondria for atp more transport
. more ribosomes, RER and golgi for protein synth and modification to produce more membrane proteins

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41
Q

how are the products of digestion absorbed

A

. monosaccharide such as glucose and aa are taken up by co transport
. na+ actively transported out of ileum into blood, lowers conc in cell.
. NA+ diffuses down gradient through protein, brings glucose iwth by co transport
. glucose moves out of cell by facillitated diffusion due to conc grad, diffuses into capillary
. respiratory inhibitors stop active processes due to no atp

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42
Q

what would happen to digestion if there was no respiration?

A

. without atp NA ions dont move by act tran
. this increases conc of NA in cell and reduce conc grad between ileum and cell
. without conc grad NA wont be drawn
down grad so decreas absorption of glucose

43
Q

the movement of na out of the cell allows absorption of glucose into the cell lining teh ileum explain how

A

. conc grad for NA+
. NA+ moving in facilitated diffusion/ co transport brings glucose with it

44
Q

where are chylomicrons formed

A

. golgi produces chylomicrons from triglycerides and proteins
. the chylomicrons are exported by exositosis
. chylomicrons absorbed into lacteals in the villi

45
Q

describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels

A

. micelles contain bile salts and fatty acids
. make fatty acids/ monoglycerides
. fatty acids monoglyceridees absorbed by diffusion
. triglyycerieds formed in cells
. vesicles moved to cell membranes

46
Q

what is haemoglobin and oxyhaemoglobin

A

. hb is a quarternary protein that carries o2 around teh body
. oxyhaemoglobin is when o2 has bound to hb

47
Q

what is associate and dissociate relating ot haemoglobin

A

. ass - when O2 binds to HB
. dissass - when o2 leaves the oxyhaemoglobin

48
Q

what is partial pressure

A

. the pressure created by a gas in a specific shape

49
Q

what is the bohr effect

A

. the effectn of co2 on the affinity of hb, the more co2 the lower the affinity of haemoglobin for oxygen

50
Q

what is the equation for the creation of oxyheamoglobin

A

. oxygen + hb <> oxyhaemoglobin

51
Q

what is haemoglobin

A

. found in red blood cells
. protein with quaternary structure
.each of 4 chains has Fe group, binds to o molecule
. first molecule that binds causes shape change, uncovers other binding sites making further binding easier

52
Q

. explain the oxygen dissociation curve

A

. the amount of o2 carried depends on the partial pressure of o2 (Po2)
. at high po2 o2 is loaded (in lungs)
. o2 dissociation graph is s shape
. steep o2 uptake in middle due to little change in po2
. o2 lozded at high po2, unloaded at low po2

53
Q

what causes different shaped hb molecules and what do they do differently

A

. different shapes casued by different genes
. different shapes foudn in animals and foetuses
. different shapes have different affinities for oxygen

54
Q

what does it mean if the curve is to the left of the normal on an oxygen dissociation graph?

A

. hb has a higher affinity for oxygen
. hb loads oxygen more readily and saturated easier at lower po2
. unloads only at low po2 (ensures diving animals stay under for time)
. o2 supplied to respiring tissues even in low o2 environments

55
Q

why is foetal hb shaped differently

A

. has a higher affinity for oxygen
. attracts o2 away from adult maternal hb across placenta to foetal hb

56
Q

explain teh advantage of a lugworm having hb with a dissociation curve in the position shown? (left)

A

. hb has a higher affinity for o2
. ayt lower partial pressure of o2

57
Q

what is the bohr effect in a more upsettingly scientific way

A

. respiring casues co2
. dissolves to make carbonic acid and H+
. as co2 inc, ph dec
. causes change in hb shape and reduces affinity
. more co2 = lower o2 affinity

58
Q

what is the effect of co2 on o2 dissociation curve and what does it show

A

. curve shifts to right
. hb o2 affinity dec
. o2 dissociates from hb more readily
. more o2 inloaded to tissues for aerobic respiration

59
Q

what is mass flow

A

. used for substances tomove long distances
. in living animals substances like water, solutes and suspended objects
. fluid moves in a direction due to a force
. requires energy source to pump fluid
. faster than diffusion
. used in circulatory system, xylem, phloem

60
Q

why is mass flow used in large organisms

A

. sa:vol too small
. diff distance too long
. mass flow takes gases and nutrients close to all cells

61
Q

what do closed and double circulatory system mean

A

. closed - blood enclosed wiyhin blood vessels and pumped around by the heart
. double- blood passes throyugh the heart twice in one cycle
. enables lungs to maintain higher pressure than rest of body

62
Q

name the features of an artery

A

. Artetry - Away
. thick walls to resist p and prevent rupture
. folded endothelium
. narrow lumen to maintain p
. high elastic content
. no valves
. p drops when ventricle relaxes but stays overall high due to elastic content
. p decreases with distance fom the heart

63
Q

name the features of veins

A

. veIN = IN to heart
. thin walls so low pressure
. blood moves with breathing
. wide lumen so fits large vol blood w lower resistance
. . unfolded endothelium
. low elastic content
. valves to prevent backflow
. pressure always low

64
Q

what are the features of capillaries

A

. small diameter but v frequent so goes close to all cells
. thin one cell thick endothelium
. narrow lumen reduces diffusion distance
. capillary pores allow pout water and white blood cells so reduces pressure

65
Q

what substances does tissue fluid have?

A

. water
. dissolved ions
. dissolved monomers
. dissolved gasses
. hormones
. white blood cells
. has NO: red blood cells/larege plasma proteins

66
Q

how is tissue fluid formed?

A

. hydrostatic pressure of blood high at arteriole end due to contraction of left ventricle
. reduces vol. and therefore p in capillary

67
Q

how is tissue fluid returned to circulatory system?

A

. plasma proteins and large molecules remain
. this lowers the water potential of b
. water moves back into venous end of capillary by osmosis
. lymph system collects any excess tissue fluid returned to blood

68
Q

explain how water from tissue fluid is returned to the circulatory system

A

. proteins remain
. reduces water potential of blood
. water moves by osmosis
returns to blood by lymphatic system

69
Q

what is the way to remember movement of blood in the body

A

. Rvava(lung)vavaL
. right vena cava, atrium, ventricle, artery (pulm) (lung) veins (pulm) atrium, ventricle, aorta

70
Q

where does the heart recieve its blood supply from?

A

. the coronary artery

71
Q

which side of the heart has oxygentaed and which has deoxygenated

A

. right deox left ox

72
Q

why is there thicker walls in ventricles than atriums

A

. vent made of thicker muscle rcause blood pumped away further so higher p needed
. atria only pump b to arteries

73
Q

why is the left side of the heart thicker

A

.. blood is pumped to all body sytems from l side so higher p demand
. right pumps only to lungs so less resistance

74
Q

what are the internal structures of the heart and whta are there functions

A

. atrium - contracts to force blood inot the ventricle
. ventricle - contracts to force blood inot aorta/ pa rtery
. bicuspid valve - prevents backflow
. tricuspid valve - prevents backflow from r vent to r atri
. semilunar valces - prevents backflow of b from artery to ventri
. cords - prevent valve from inverting

75
Q

what happens if the coronary arteries are blocked

A

. less/ no O2 to coranary muscle
. npo/ less aerobic respi
. no/less atp
. cardiac muscle cells die/ contract less
. leads to heart attack

76
Q

what happens in ventricular diastole

A

. diastole - relaxes
. heart relaxes, pressure drops
. blood fills atria from veins

77
Q

what happens in atrial systole

A

. systole - contracts
.  Pressure in atria increases
. Higher pressure in atria and ventricles opening the atrioventricular valve
. Blood forced into ventricles
.  valves in veins stop blood going backwards

78
Q

What is ventricular systole

A

. Ventricles contract from base up, increases blood pressure
. Ventricular pressure higher than atrial pressure shutting AV valve, prevents backflow into atria
. Ventricular pressure higher than aortic pressure, open semi lunar valve
. Be forced through semi lunar valve into artery

79
Q

What happens to the heart when there is an atheroma

A

. Atheroma is term for buildup of materials in arteries
. Damages endothelial cells, macrophages and lipids from blood clumped together and form fatty streaks
. White blood cells, lipids and connective tissues build up and harden develop into atheroma
. Blood flow is restricted increasing blood pressure causing aneurysms or blood clots

80
Q

What are aneurysms and thrombosis

A

. Aneurysm-swelling of artery, blocks artery increase in blood pressure, high-pressure blood travels through weekend and damaged blood vessel, starts to push into layers of blood vessel through elastic layers, from swelling, if bursts results in haemorrhage
. Thrombosis-blood clot, damages artery wall causing rough surface, causes blood platelets and Febrian to build up damage site, formed blood clot, could cause blockage of artery or could break away and black blood vessel elsewhere

81
Q

What happens in coronary heart disease

A

.build up of fat in the coronary arteries causing less blood to be able to flow through
. May result in heart attack
. Heart muscle no longer supply with sufficient blood
. Muscle requires oxygen and glucose from the blood for respiration ATP production
. Prevention of respiration causes heart muscle to become damaged and possibly die

82
Q

What are cardiac output, stroke volume, and heart rate

A

. Cardiac output-total volume of blood pumped out by heart in one minute
. Stroke volume – total volume of blood pumped out of the heart in one for cardiac cycle
. Heart rate – number for cardiac cycles (Heartbeat) in a minute

83
Q

What equation is used to measure cardiac output

A

. Cardiac output (cm3min-1) = heart rate (bpm) ×/volume (cm3)

84
Q

What causes cohesion in water molecules

A

. Water is a polar molecule shadow electrons attract oxygen making it more negative and hydrogen slightly more positive
. Causes water to interact with each other negative charge attracts positive charge of all the molecules
. Attraction is caused by hydrogen bonding called cohesion

85
Q

What are the features of the xylem and what did they do

A

. Consist of dead cells - walls contain lignin which water adheres to providing strength to xylem to prevent inward collapse
. No cytoplasm or organelles or no impeded flow (Hollow)
. No end walls forming continue a system of tubes for water transport
. Pits (small gaps in xylem wall) allows horizontal movement of water

86
Q

What does water need to pass through the xylem

A

. Adhesion-forces between water molecules and hydrophilic lining of xylem walls
. Cohesion-force between water molecules forming columns in xylem
. Tension-Paul generated by water evaporation create negative pressure in xylem
. Transpiration-evaporation of water as water vapour from the leaves on a sheet of plans usually through the stomata

87
Q

Explain the movement of water in the transpiration stream

A

. Transpiration-diffusion of water vapour through stomata, lowers water potential of leaf cells so H2O moves from higher water potential in xylem to leaf cells by osmosis
. What are drawn up xylem creating tension
. H2O molecules cohere together forming column of water
. H2O molecules stick to xylem cell walls by adhesion
. Water enters routes from the soil by osmosis travelling across the route contacts into xylem

88
Q

What is the relationship between transpiration and tension in the xylem

A

. As transpiration increases tension increases in xylem due to upward pull a column of water causing a lower diameter of the xylem

89
Q

Describe the cohesion tension theory of water transport in the xylem

A

. Water lost from leaves because of transpiration/evaporation of water
. Lowers water potential of mesophyll
. water pulled up xylem creating tension
.water molecules cohere by hydrogen bonds
. Forming continuos water column
.  adhesion of water to the walls of xylem 

90
Q

What four factors affect the rate of transpiration

A

. Temperature-more kinetic energy, more of operation for Mesa cell cells, more diffusion of vapour through stomata
. Humidity-Erin side with a saturated, where is external air has low water potential increases in external humidity loweris the gradient
. Movement-1 removes layer of saturated outside is tomato reducing water potential so gradient steeper
. Light intensity iPhone increase light open system and more to allow CO2 into photosynthesis causing increased transpiration

91
Q

What assumptions does a Potometer make

A

. Assumes water loss by transpiration is approximately the same as water uptake by roots
. Some water might be used in photosynthesis and some taken into maintain cell turgidity, measurements may also be affected by water made in respiration

92
Q

What does a petometer do

A

. Creates a sealed environment with water used to measure water uptake based on distance in air bubble moves over time

93
Q

How do you set up a potometer

A

. Choose a leafy stem and cut it underwater to prevent air from entering the xyle
. Fit the cut stem into the rubber tubing or opening of the potometer, ensuring it’s airtight.
. seaal the joints using vaseline
. Fill the potometer tube with water completely, avoiding air bubbles
. Place a small air bubble at the start of the capillary tube to measure water uptake
. Track the bubble’s movement over time to measure water uptake, which is correlated to transpiration rates

94
Q

How do you measure the rate of water uptake

A

. Calculated by pi R squared H where are is radius of capillary tube and H is the distance air bubble moves
. rate is the time in by dividing by time taken for bubble to move

95
Q

What is translocation

A

. Movement of organic molecules from source to sink

96
Q

What are the features of the phloem

A

. Made up of living cells allowing them to produce ATP for sucrose transport
. Sieve tube elements-living cells have no nucleus and just a few organelles Create resistance to flow, and so walls have perforations called sieve plates
. Companion cells – Active cells in excessive tubes, connected to sieve tubes by plasmodesmata (small hole), lots of mitochondria – provide energy for ATP to sieve tubes for active movement of sucrose

97
Q

Explain the mass flow hypothesis

A

. Source produces glucose, converted to sucrose by photosynthesis
. sucrose solution actively loaded into phloem
. phloem water potential decreases, water moves in from xylem by osmosis
. Hydrostatic pressure builds up, forces sucrose solution along phloem by mass flow to sink
. At sink sucrose moves from phloem into sink cell, lowers sink water potential so water moves down gradient in to sink
. Water re-enters xylem by osmosis sucrose used in respiration are stored

98
Q

Describe the process is involved in transport of sugar is in plant stems

A

. Sucrose actively transported into phloem by companion cells
. Lower water potential in phloem and water enters by osmosis
. Produces high hydrostatic pressure
. Mass flow towards sink
. At sink sugars are removed used in respiration

99
Q

What are the features needed for mass flow hypothesis to be correct

A

. Download Uni directional flow
. Higher to lower pressure
. Sucrose moves from source the sink
. Process is active

100
Q

Explain the ringing experiment for the mass flow hypothesis

A

. Bark containing phloem removed from stems to prevent movement of organic substances
. Bored forms above ring fluid above has higher concentration of sugar is the below indicates gradient
. Swelling caused by a buildup of sugar solution, can’t go further because flow blocked and bark has been removed
. swelling above ring due to downward flow of sugar solution
. swelling on one side of ring not both suggest the flow of so use is unidirectional

101
Q

Explain the use of aphids for Proving the mass flow hypothesis

A

. use aphids to pierce top and bottom of stem
. remove aphids body
. sap flows faster at top of phloem indicating pressure gradient
. flows at same rate evrywhere in xylem so no gradient
. suggests high hydrostatic pressure neede for mass flow

102
Q

Explain the use of autoradiography in proving the mass flow hypothesis

A

. Radioactive tracer used to track organic substances
. Uses 14 CO2 which gives converted into sugars
. Detectable using photographic film
. Radioactive carbon in CO2 is incorporated into sucrose
. This occurs at the leaves (source) from here sucrose transported towards roots (Sink)
. Proves movement from source to sink

103
Q

Explain the use of metabolic inhibitors in proving the mass flow hypothesis

A

. If respiratory inhibitors are put in phloem, translocation stops
. Indicates ATP needed for loading of organic molecules into phloem by active transport

104
Q

What evidence contradicts the mass flow hypothesis

A

. Different substances travel at different rates in flower, if only mass flow molecules will be forced at same rate as fluid is pushed from higher to lower pressure
. Different substances move in opposite directions in tube showing bidirectional flow
. Sieve plates would create barrier to mass flow, lots of pressure will be needed for the solution to get through with a reasonable rate

Biology (6 decks)

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