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biology > Topic 4- exchange and transport > Flashcards

Topic 4- exchange and transport Flashcards

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1
Q

explain what these components within the fluid mosaic model do:

-glycoproteins
-peripheral proteins
-integral proteins
-cholesterol

A

glycoproteins- important for cell recognition or as receptors for hormones/neurotransmitters

peripheral proteins- may be enzymes, involved in regulating transport (eg cell signalling)

integral proteins- main transport system of the membrane (form either permanent pores or other transport mechanisms like carrier proteins)

cholesterol- controls fluidity of membrane

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2
Q

explain what happens to the fluidity of membrane at:

high temp
low temp

A

high temp- fluidity increases
low temp- solidifies

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3
Q

define diffusion

A

passive movement of particles from an area of high concentration, to an area of low concentration, down a concentration gradient in order to establish equilibrium

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4
Q

In what circumstances does facilitated diffusion take place?

What happens in facilitated diffusion?

A

when molecules can not cross cell membranes (strong charge/size)

takes place through carrier proteins/protein channels

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5
Q

explain what a gated channel is ( used in facilitated diffusion)

channels that only open when a specific m… or c… is detected

A

channels that only open when a specific molecule/charge is detected

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6
Q

explain what a protein carrier is (used in facilitated diffusion)

s… to particulare substances/molecules

picks up molecule, c… s… and moves molecules through m… before r…. it

A

carrier molecules are on cell surface membrane

they are specific for particular substances/molecules

carrier protein picks up molecule and changes shape, this moves molecule through the membrane and then releases it

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7
Q

name factors which affect diffusion across a membrane

A

molecule size, solubility and charge

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8
Q

define osmosis

A

movement of water molecules from a region of high water potential to a region of low water potential, through a partially permeable membrane

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9
Q

explain what turgor pressure is

i..f… exerted by the c… w… as the p… swells

A

turgor pressure is the inward force exerted by the cell wall as the protoplasm swells.
this is generated because water moves in by osmosis, generating hydrostatic pressure- this generates a reactive force pushing inwards.

both these forces prevent more water moving into the cell.

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10
Q

define active transport

A

movement of molecules through carrier proteins from an area of high concentration to an area of low concentration

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11
Q

active transport uses a carrier protein so therefore requires

A

energy

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12
Q

explain how ATP becomes ADP

A

ATP is hydrolysed
one phosphate breaks off, forming ADP and pi

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13
Q

Explain evidence for active transport.

A

Only takes place in living, respiring cells

Rate depends on temp and oxygen
(this affects respiration rate and therefore rate of ATP production)

Cells that are known to do a lot of active transport have many mitochondria

Poisons that stop ATPase also stop active transport (for example cyanide)

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14
Q

What is endocytosis?

A

Membranes taken up and surrounded by vesicles.

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15
Q

What is exocytosis?

A

The emptying of membrane bound vesicles.

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16
Q

What is:

Phagocytosis
Pinocytosis

A

Both forms of endocytosis, membranes being taken up and surrounded by a vesicle.

Phago- large molecules (bacteria)
Pino- small molecules

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17
Q

explain why fish need to be able to do efficient gas exchange

A

they are waterproof
small SA:VOL
low oxygen content in water (0.8)

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18
Q

where is the site for gas exchange in fish?

explain how they are well adapted for this

A

gills

high SA
rich blood supply, maintains concentration gradient
thin walls for short diffusion distance
occur in large stacks

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19
Q

what is the operculum and its function?

A

the operculum is a protective bony flap which maintains water flow even when the fish is stationary

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20
Q

describe the parts of an insect

A

3 pairs of legs
3 body sections (head/thorax/abdomen)
1 pair of antenna
(usually wings)

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21
Q

describe the exoskeleton of an insect

A

insects have a hard exoskeleton made up of the polysaccharide chitin, meaning it is impermeable and gases can not get in

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22
Q

what are spiracles?

A

small pores on the exoskeleton of an insect, allow gases to diffuse in

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23
Q

where do spiracles lead to? describe these

A

gases enter spiracles and lead to trachea

trachea contain chitin to stop the walls collapsing

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24
Q

where do trachea lead to?

A

tracheoles

these are finer tubes which extend down, no chitin as they are the surface for gas exchange

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25
Q

explain how tracheoles are efficient

A

Large number

Thin permeable walls

Tips of tracheoles have water (gases can dissolve into)

Direct contact with tissues/organs

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26
Q

what is a disadvantage of spiracles?

A

Spiracles allow water loss and can cause insect to dry out

Insects close spiracles and use air sacs

Insects use abdomen to compress internal organs and force air out of spiracles

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27
Q

what is the role of the waxy cuticle?

A

prevent water loss

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28
Q

what is the role of the upper epidermis?

A

transparent and allows max light into chloroplasts

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29
Q

what is the role of the palisade mesophyll?

A

vertically stacked, contains chloroplasts

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30
Q

what is the role of the spongy mesophyll?

A

provide an increased SA for gas exchange

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31
Q

what is the role of guard cells?

A

open and close stomata

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32
Q

How is the structure of a leaf adapted for efficient gas exchange?

A

LARGE SA – cells in spongy mesophyll are irregular shape

MOIST – allows gases to dissolve (moist spongy mesophyll)

THIN BARRIER- single cell membrane so short diffusion distance

HIGH CONC GRADIENT- gases move freely between the air spaces in leaf out through stomata to gas surrounding leaf

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33
Q

How do stomata open/close?

A

Stomata open during the day when conditions are favourable – carbon dioxide diffuses in and oxygen diffuses out

Stomata open by ions (mainly K+) moving into guard cells by active transport. This means water moves into cell by osmosis (as water potential decreased) and so guard cells become turgid. (swell and they open)

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34
Q

describe the route blood takes

A

vena cava
R atrium
R ventricle
pulmonary artery
lungs
pulmonary vein
L atrium
L ventricle
aorta
body

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35
Q

What are lenticles?

A

Lenticles are loosely arranged cells which act as a pore to allow gas exchange in lignified (woody) plants

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36
Q

describe an ‘open’ system

A

Blood enters ‘heart’ through tiny holes

Blood is pumped into body cavity and circulated

Eg: insects

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37
Q

describe a ‘closed’ system

A

Always in vessels

Travels further

Blood under more pressure

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38
Q

describe features of a mass transport system

A

A system of vessels that carries substances (closed system)

A way of making substances move in correct direction (a one way vessel system)

Means of moving substances fast enough to supply the needs of organism

Suitable transport medium

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39
Q

as animals increase in size , what happens to their SA : VOL ratio?

A

as animals increase in size , their SA:VOL ration decreases

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40
Q

Double circulatory system consists of two parts - what are these?

A

pulmonary circulatory system
systemic circulatory system

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41
Q

Double circulatory system consists of two parts- explain the pulmonary system

A

carries deoxygenated blood from heart to the lungs and oxygenated blood back to the heart

(slow delivery through lungs, increasing time for diffusion)

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42
Q

Double circulatory system consists of two parts- explain the systemic system

A

carries oxygenated blood from heart to body cells (oxygen used) back to heart (deoxygenated)

(fast delivery to maintain metabolic rate as animals with a double circulatory system have to maintain their own body temp)

43
Q

what is happening in ‘diastole’ stage of the cardiac cycle?

A

ventricles relaxing (finishing contraction) atria are relaxed

blood is entering heart from pulmonary vein/vena cava

SL valves closed
AV valves opening

44
Q

what is happening during the ‘atrial systole’ stage of the cardiac cycle?

A

atria contracted
ventricles relaxed

blood moving from atria to ventricles

SL valves shut
AV valves open

45
Q

what is happening during the ‘ventricular systole’ stage of the cardiac cycle?

A

atria relaxed
ventricles contracted

blood moves from ventricles out of heart via pulmonary artery and aorta

SL valves open
AV valves shut

46
Q

The heart can beat without any input from the nervous system as long as….

A

the cells stay alive

(uses myogenic contraction)

47
Q

How is the cardiac cycle initiated?

A

sino-atrial node
(pacemaker)

48
Q

Where is SAN (pacemaker) located?

A

top of right atrium

49
Q

What do the cells in the SAN (pacemaker) do?

A

control the rhythm and pattern of all cardiac cells

50
Q

describe the stages occurring in electrical stimulation of the heart

Blood enters ?

SAN sends impulse across walls of ? , causing them to ? (atria systole)

Impulse reaches AV ?

Slight delay, impulse passed onto b… of H…

Impulse passed onto both branches of the ? tissue

Impulse passes through ? walls and causes contraction (? systole)

Blood leaves heart

? signal dissipates

A

Blood enters heart

SAN sends impulse across walls of atria, causing them to contract (atria systole)

Impulse reaches AV node

Slight delay, impulse passed onto bundle of His

Impulse passed onto both branches of the purkyne tissue

Impulse passes through ventricle walls and causes contraction (ventricular systole)

Blood leaves heart electrical signal dissipates

51
Q

draw an ECG graph for a heartbeat

A

look at notes app

52
Q

arteries

  1. In what direction do arteries carry blood?
  2. Describe the different layers of an artery
A

1.Arteries carry blood away from the heart
2.External layer of tough tissue, middle layer (elastic fibres and smooth muscle), smooth lining, lumen

53
Q

explain the reason for these features of an artery

Walls contain elastic fibres

Muscle fibres in walls

Collagen fibres in walls

Smooth lining (endothelium)

A

Walls contain elastic fibres -Allow muscle to stretch and recoil

Muscle fibres in walls -Maintain pressure

Collagen fibres in walls -String, prevents bursting

Smooth lining (endothelium) -Prevents friction therefore allowing blood to flow easily

54
Q

What direction do veins carry blood?

state and explain (why they have these features) two features of veins

A

towards the heart

semi-lunar valves- prevents blood backflow
often situated between muscles- as muscles contract, they squeeze against the veins and push the blood through

55
Q

capillaries

site of …..

what are walls made from?

A

site of gaseous exchange

walls are made of one layer of epithelium cells

56
Q

explain these features of capillaries

Diameter is one RBC

Squamous epithelial cells

‘leaky’ walls

No muscle, elastic fibres or collagen in walls

A

Diameter is one RBC -Slows blood, increases time for exchange of substances

Squamous epithelial cells -Prevents friction

‘leaky’ walls -Substances can be exchanged

No muscle, elastic fibres or collagen in walls- Allows exchange of substances

57
Q

describe the features of an erythrocyte (RBC)

A

Haemoglobin to carry oxygen

No nucleus (more space)

High SA:VOL

Biconcave disc

Flexible

58
Q

what is the role of a leucocyte? (WBC)

what are the immune-specific and non-specific types of WBC?

A

immune response, defend the body against infection

Non-specific immune response (granular)- neutrophil/basophil/eosinophil

Specific immune response (agranular) - lymphocyte/monocyte

59
Q

What is the role of plasma?

A

carries dissolved substances such as:
- digested food products (glucose/amino acids)
-excretory products (carbon dioxide/urea)
-chemical messages (hormones)

also maintains stable body temperature

60
Q

What is the role of platelets?

A

begin a blood clotting cascade

61
Q

describe the process of forming a blood clot

A

damaged tissue
|
activated platelets
|
(thromboplastin)
prothrombin -> (thrombin)
|
fibrinogen-> fibrin

fibrin + blood cells and platelets = clot

-one in brackets are enzymes
-fibrinogen is soluble , fibrin is insoluble

62
Q

describe the stages of atherosclerosis

A

damage to endothelium

causes cholesterol to build

body recognises damage, inflammatory response

further build up of cholesterol , creates plaque called atheroma

calcium salts and fibrous tissues build up around atheroma, hardening it

reduces elasticity of artery walls and narrows lumen

increases blood pressure - lead to more plaques or rupture to endothelium

results in a blood clotting cascade which may block blood flow entirely

63
Q

what is an aneurysm?

A

damage that the atheroma does to the artery wall

64
Q

what is meant that atherosclerosis is a multi factorial disease?

A

many factors influence the likelihood of you developing the disease

65
Q

what are modifiable risk factors?

A

generally lifestyle factors which you have the ability to control such as diet and exercise

66
Q

what are non-modifiable risk factors?

A

factors such as age and genetics

67
Q

describe the two types of cholesterol

A

LDLs
low density lipid proteins
bad
bind to membrane of cells
left in blood of in too high conc

HDLs
high density lipid proteins
good
take fatty acids to the liver to be broken down

68
Q

describe three ways carbon dioxide can leave the body

A

plasma

combine with haemoglobin to form carbaminohaemoglobin

form hydrogen carbonate ions (HCO3-)

69
Q

describe the stages of carbon dioxide leaving the body through the formation of hydrogen carbonate ions

A

carbon dioxide produced by cell

this diffuses into RBC

CO2 + H2O (from cytoplasm) = H2CO3

H2CO3 (carbonic acid) dissociates into H+ and HCO3-

HCO3- diffuses out of cell and Cl- enters cell as minus was lost

meanwhile , haemoglobin drops off oxygen
HbO8 ——> Hb + 4O2

the Hb and the H+ (from above) join to make HHb (haemoglobinic acid)

70
Q

what is the equation for oxygen movement in the body?

A

oxygen+haemoglobin->oxygaemoglobin

71
Q

label the equation:

hb + 4o2 -> HbO8

-high/low partial pressure
-association
-disassociation

A

consult notes app

(number 4)

72
Q

haemoglobin
has a high affinity for ….
has ? haem groups
can carry ? oxygen atoms

A

haemoglobin
has a high affinity for oxygen
4 haem groups
each can hold an O2 , so can carry 8 oxygen atoms

73
Q

draw and label the oxygen disassociation curve of haemoglobin

A

notes app, number 5

74
Q

explain the difference in affinity for oxygen between adults and fetal haemoglobin

A

fetal haemoglobin has a higher affinity for haemoglobin as there is lower oxygen tension in the fetal blood

maternal blood releases oxygen from the haemoglobin

the fetal curve is above / to the left of the adult curve

75
Q

what is myoglobin?

what is the structure of it?

draw myoglobin affinity on a graph compared to haemoglobin

use of myoglobin

A

respiratory pigment found in muscles , makes it red

made from one polypeptide chain

myoglobin above adult on graph / to the left as it has a higher affinity for oxygen

becomes saturated at very low oxygen partial pressure so acts as an oxygen store for muscles , only releases oxygen at very low partial pressure

76
Q

draw a graph with adult hB , fetal hB and myoglobin

A

myoglobin highest, then fetal, then adult

y axis - % saturation of haemoglobin

x axis- partial pressure of oxygen

77
Q

explain what the Bohr shift is

A

when there is more CO2 , oxygen saturation is lower
oxyhaemoglobin dissociates, releasing O2 and lower partial pressure

this means the graph shifts right and down

78
Q

what is tissue fluid?

A

tissue fluid is the same as blood but without the cells and proteins

its job is to transfer oxygen and nutrients to the tissue

79
Q

what is a lymph vessel used for?

what does it do with it?

A

takes anything that is unwanted (carbon dioxide and urea)

takes it to glands and eventually heart which distributes it where it is going to be broken down

80
Q

how is hydrostatic pressure generated?

A

hydrostatic pressure is generated due to contractions of the heart

81
Q

why is the hydrostatic pressure lower at the vein (venule) end compared to the artery end?

A

it is further away from the heart so the pulse is felt less

less tissue fluid as a lot has already been lost

82
Q

what does a vascular bundle consist of?

A

phloem
vascular cambium
xylem

83
Q

what is a vascular cambium?

A

unspecialised cells which have the ability to develop into xylem or phloem

84
Q

what is the role of lignin within the xylem?

A

spirals of lignin waterproof cell, kills cells, allows xylem to maintain structure

85
Q

explain the total net movement in regards to tissue fluid at both the artery and venule end

A

artery end:
total net movement OUT of capillary as hydrostatic pressure out is larger than oncotic pressure in

venule end:
total net movement INTO capillary as hydrostatic pressure is lower so oncotic pressure is bigger than this

oncotic pressure remains the same across the entire capillary

86
Q

what does a vascular bundle comprise of?

A

phloem
vascular cambium
xylem

87
Q

describe the xylem

A

dead , continuous tube
carries sugars
one way (up)

88
Q

describe the phloem

A

carries water
both ways

89
Q

describe the vascular cambium

A

unspecialised cells which can become xylem or phloem

90
Q

define transpiration

A

loss of water from the leaves by evaporation

91
Q

why is transpiration needed?

A

evaporation of water cools plant
loss of water from top pulls water up, providing plants with water and minerals

92
Q

explain cohesion tension theory

A

due to cohesion (h bonds between water molecules)
water from the top of the plant causes tension which pulls water molecules up from the roots to replace water which has been lost

93
Q

explain root pressure

A

active transport actively moves minerals into the cell

this lowers water potential

causes water to move in by osmosis

94
Q

describe the apoplast pathway

A

water travels through cell walls
(has casparian strip)

95
Q

describe the symplast pathway

A

water travels through cytoplasm and plasmodesmata

96
Q

explain casparian strip

A

blocks apoplast pathway
nitrates and other ions have to pass through the cells cytoplasm

decreases water potential in xylem so water follows

actively transported from cytoplasm to xylem

once water is in xylem, apoplast pathway is blocked so it can not get out

97
Q

what affect does temperature have on the rate of transpiration?

A

temperature increases the rate of transpiration as the water molecules have more KE so more movement, more water used

98
Q

what affect does light intensity have on the rate of transpiration?

A

light intensity increases the rate of transpiration as more stomata are open, more co2 in, more photosynthesis

99
Q

what affect does humidity have on the rate of transpiration?

A

higher humidity decreases rate of transpiration
higher humidity means there is a higher water potential in the air, steeper conc gradient = more diffusion

100
Q

what affect does air movement have on the rate of transpiration?

A

air movement increases rate of transpiration
Removes water vapour from leaf surfaces; more water diffuses from the leaf

101
Q

define translocation

A

movement of sucrose throughout the plant where it is needed

102
Q

describe the stages of translocation : including active loading and mass flow

A

active loading:
H+ ions actively pumped into leaf cell

passively diffuse back, taking sucrose with it (this is done by a co transport protein)

water potential in sieve tube element lower (due to sucrose)

water flows in from companion cell and xylem

mass flow:
lots of contents in cell, high pressure
cells without the leaf have a lower pressure
sap delivered to cells that need sucrose
higher to lower hydrostatic pressure

103
Q

what is translocation?

A

translocation is the movement of sucrose up and down the plant, from source to sink

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