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biology > Topic 4- exchange and transport > Flashcards

Topic 4- exchange and transport Flashcards

(103 cards)

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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
explain how tracheoles are efficient
Large number Thin permeable walls Tips of tracheoles have water (gases can dissolve into) Direct contact with tissues/organs
26
what is a disadvantage of spiracles?
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
27
what is the role of the waxy cuticle?
prevent water loss
28
what is the role of the upper epidermis?
transparent and allows max light into chloroplasts
29
what is the role of the palisade mesophyll?
vertically stacked, contains chloroplasts
30
what is the role of the spongy mesophyll?
provide an increased SA for gas exchange
31
what is the role of guard cells?
open and close stomata
32
How is the structure of a leaf adapted for efficient gas exchange?
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
33
How do stomata open/close?
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)
34
describe the route blood takes
vena cava R atrium R ventricle pulmonary artery lungs pulmonary vein L atrium L ventricle aorta body
35
What are lenticles?
Lenticles are loosely arranged cells which act as a pore to allow gas exchange in lignified (woody) plants
36
describe an 'open' system
Blood enters 'heart' through tiny holes Blood is pumped into body cavity and circulated Eg: insects
37
describe a 'closed' system
Always in vessels Travels further Blood under more pressure
38
describe features of a mass transport system
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
39
as animals increase in size , what happens to their SA : VOL ratio?
as animals increase in size , their SA:VOL ration decreases
40
Double circulatory system consists of two parts - what are these?
pulmonary circulatory system systemic circulatory system
41
Double circulatory system consists of two parts- explain the pulmonary system
carries deoxygenated blood from heart to the lungs and oxygenated blood back to the heart (slow delivery through lungs, increasing time for diffusion)
42
Double circulatory system consists of two parts- explain the systemic system
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
what is happening in 'diastole' stage of the cardiac cycle?
ventricles relaxing (finishing contraction) atria are relaxed blood is entering heart from pulmonary vein/vena cava SL valves closed AV valves opening
44
what is happening during the 'atrial systole' stage of the cardiac cycle?
atria contracted ventricles relaxed blood moving from atria to ventricles SL valves shut AV valves open
45
what is happening during the 'ventricular systole' stage of the cardiac cycle?
atria relaxed ventricles contracted blood moves from ventricles out of heart via pulmonary artery and aorta SL valves open AV valves shut
46
The heart can beat without any input from the nervous system as long as....
the cells stay alive (uses myogenic contraction)
47
How is the cardiac cycle initiated?
sino-atrial node (pacemaker)
48
Where is SAN (pacemaker) located?
top of right atrium
49
What do the cells in the SAN (pacemaker) do?
control the rhythm and pattern of all cardiac cells
50
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
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
draw an ECG graph for a heartbeat
look at notes app
52
arteries 1. In what direction do arteries carry blood? 2. Describe the different layers of an artery
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
explain the reason for these features of an artery Walls contain elastic fibres Muscle fibres in walls Collagen fibres in walls Smooth lining (endothelium)
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
What direction do veins carry blood? state and explain (why they have these features) two features of veins
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
capillaries site of ..... what are walls made from?
site of gaseous exchange walls are made of one layer of epithelium cells
56
explain these features of capillaries Diameter is one RBC Squamous epithelial cells 'leaky' walls No muscle, elastic fibres or collagen in walls
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
describe the features of an erythrocyte (RBC)
Haemoglobin to carry oxygen No nucleus (more space) High SA:VOL Biconcave disc Flexible
58
what is the role of a leucocyte? (WBC) what are the immune-specific and non-specific types of WBC?
immune response, defend the body against infection Non-specific immune response (granular)- neutrophil/basophil/eosinophil Specific immune response (agranular) - lymphocyte/monocyte
59
What is the role of plasma?
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
What is the role of platelets?
begin a blood clotting cascade
61
describe the process of forming a blood clot
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
describe the stages of atherosclerosis
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
what is an aneurysm?
damage that the atheroma does to the artery wall
64
what is meant that atherosclerosis is a multi factorial disease?
many factors influence the likelihood of you developing the disease
65
what are modifiable risk factors?
generally lifestyle factors which you have the ability to control such as diet and exercise
66
what are non-modifiable risk factors?
factors such as age and genetics
67
describe the two types of cholesterol
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
describe three ways carbon dioxide can leave the body
plasma combine with haemoglobin to form carbaminohaemoglobin form hydrogen carbonate ions (HCO3-)
69
describe the stages of carbon dioxide leaving the body through the formation of hydrogen carbonate ions
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
what is the equation for oxygen movement in the body?
oxygen+haemoglobin->oxygaemoglobin
71
label the equation: hb + 4o2 -> HbO8 -high/low partial pressure -association -disassociation
consult notes app (number 4)
72
haemoglobin has a high affinity for …. has ? haem groups can carry ? oxygen atoms
haemoglobin has a high affinity for oxygen 4 haem groups each can hold an O2 , so can carry 8 oxygen atoms
73
draw and label the oxygen disassociation curve of haemoglobin
notes app, number 5
74
explain the difference in affinity for oxygen between adults and fetal haemoglobin
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
what is myoglobin? what is the structure of it? draw myoglobin affinity on a graph compared to haemoglobin use of myoglobin
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
draw a graph with adult hB , fetal hB and myoglobin
myoglobin highest, then fetal, then adult y axis - % saturation of haemoglobin x axis- partial pressure of oxygen
77
explain what the Bohr shift is
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
what is tissue fluid?
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
what is a lymph vessel used for? what does it do with it?
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
how is hydrostatic pressure generated?
hydrostatic pressure is generated due to contractions of the heart
81
why is the hydrostatic pressure lower at the vein (venule) end compared to the artery end?
it is further away from the heart so the pulse is felt less less tissue fluid as a lot has already been lost
82
what does a vascular bundle consist of?
phloem vascular cambium xylem
83
what is a vascular cambium?
unspecialised cells which have the ability to develop into xylem or phloem
84
what is the role of lignin within the xylem?
spirals of lignin waterproof cell, kills cells, allows xylem to maintain structure
85
explain the total net movement in regards to tissue fluid at both the artery and venule end
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
what does a vascular bundle comprise of?
phloem vascular cambium xylem
87
describe the xylem
dead , continuous tube carries sugars one way (up)
88
describe the phloem
carries water both ways
89
describe the vascular cambium
unspecialised cells which can become xylem or phloem
90
define transpiration
loss of water from the leaves by evaporation
91
why is transpiration needed?
evaporation of water cools plant loss of water from top pulls water up, providing plants with water and minerals
92
explain cohesion tension theory
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
explain root pressure
active transport actively moves minerals into the cell this lowers water potential causes water to move in by osmosis
94
describe the apoplast pathway
water travels through cell walls (has casparian strip)
95
describe the symplast pathway
water travels through cytoplasm and plasmodesmata
96
explain casparian strip
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
what affect does temperature have on the rate of transpiration?
temperature increases the rate of transpiration as the water molecules have more KE so more movement, more water used
98
what affect does light intensity have on the rate of transpiration?
light intensity increases the rate of transpiration as more stomata are open, more co2 in, more photosynthesis
99
what affect does humidity have on the rate of transpiration?
higher humidity decreases rate of transpiration higher humidity means there is a higher water potential in the air, steeper conc gradient = more diffusion
100
what affect does air movement have on the rate of transpiration?
air movement increases rate of transpiration Removes water vapour from leaf surfaces; more water diffuses from the leaf
101
define translocation
movement of sucrose throughout the plant where it is needed
102
Describe how sugars are transported through the phloem. describe the stages of translocation : including active loading and mass flow
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
what is translocation?
translocation is the movement of sucrose up and down the plant, from source to sink

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