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N Biology A Level > Topic 4 Exhange And Transport > Flashcards

Topic 4 Exhange And Transport Flashcards

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1
Q

what adaptations of respiratory surfaces can be taken to provide sufficient diffusion?

A
  • thinner membrane
  • higher SA (:V ratio)
  • some means of maintaining conc gradient
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2
Q

what are insects’ external called?

A

exoskeleton

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3
Q

what are exoskeletons made up of?

A

chitin

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4
Q

what are some uses of chitin in insects?

A
  • provide strength and flexibility
  • impermeable to oxygen, so barrier to gas exchange
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5
Q

what is the gaseous route in insects?

A

spiracles > tracheae > tracheoles >

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6
Q

in what conditions would insects close their spiracles?

A

hot and dry

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7
Q

what are insect ‘blood’ called?

A

haemolymph

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8
Q

how does fish obtain oxygen?

A

from water using internal gills. they have gill filaments protected by the operculum, in the buccal cavity

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9
Q

how does the gill ventilate?

A

maintained by changes of water pressure.
mouth opens and closes forcing water across gills
when mouth opens, operculum shuts

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10
Q

what is the mechanism used in fish gaseous exchange?

A

counter current flow
to maintain a conc gradient along the whole length of blood-water boundary

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11
Q

where are the lungs of locusts housed in?

A

thorax

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12
Q

what is the thorax?

A

an air tight chamber formed by the rib cage and intercostal muscles, and domed floor (diaphragm)

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13
Q

what happens during a mammal inspiration?

A

external intercostal muscles contract,
ribs move up and out
diaphragm down and contracts

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14
Q

what happens during a mammal expiration?

A

external intercostal muscles relax
ribs move down and inwards,
diaphragm relax

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15
Q

how do stomas close?

A

K+ ions actively transported into guard cells, lowering water potential, and water enters by osmosis. guard cells becomes turgid, swells and closes

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16
Q

what is the definition of osmosis?

A

net movement of water from a higher water potential to a lower water potential through a partially permeable membrane

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17
Q

how do stomas open?

A

K+ ions actively transport out of guard cells, increasing wp in guard cells, so water osmosise out of guard cells from high wp to low wp

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18
Q

what are lenticels?

A

pores on bark/stem of tree

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19
Q

what do lenticels do?

A

allow direct diffusion from air to tissues!
gaseous exchange
prevent water loss

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20
Q

why do small organisms like flatworms not have circulatory systems?

A

They have large SA:V ratio

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21
Q

what does a good circulatory system contain? 3 things

A
  • an effective pump of fluids
  • suitable fluid/medium
  • dense network of tubes/vessels
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22
Q

what is an open circulatory system?

A

where fluids (eg blood) is not contained, flows freely through cavities

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23
Q

what is a closed circulatory system?

A

have vessels that contain the fluids throughout the body

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24
Q

what organisms have open circulatory systems?

A

invertebrates
insects, lobsters, crabs

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25
Q

what organisms have closed circulatory systems?

A

most vertebrates
mammals, fish, birds, reptiles

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26
Q

what are advantages of closed circulatory systems?

A

fast metabolism, blood transported faster due to higher pressure, further distances

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27
Q

what are disads of closed circulatory systems?

A

uses a lot of energy

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28
Q

what are advantages of open circulatory systems?

A

less to transport, less energy needed

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29
Q

what are disads for open circulatory systems?

A

slow metabolic rate

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30
Q

how does gas exchange take place in leaves?

A

Gas exchange occurs in plants through tiny pores called stomata, which are found on the leaves. Carbon dioxide enters the plant through the stomata, and oxygen is released.

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31
Q

what are the components of blood?

A

plasma
erythrocytes
leukocytes
platelets

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32
Q

what is plasma and what does it do?

A
  • transport digested food products, nutrient molecules, excretory products and chemical messages
  • help maintain steady body temp by transferring heat
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33
Q

what are erythrocytes and what do they do?

A

contain haemoglobin
transport oxygen

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34
Q

what are leucocytes and what do they do?

A

defend body against infections

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35
Q

what is a P wave?

A

wave from SAN

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36
Q

what is the QRS wave?

A

w.o.e from AVN -> bundle of His -> apex -> purkinje fibres
(Ventricular systole)

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37
Q

what is the T wave?

A

ventricles recover, back to normal

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38
Q

what is the QT interval?

A

contraction time

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39
Q

What is the TP interval?

A

diastole

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40
Q

What is the name of the heart arrhythmia when HR is higher than normal?

A

Tachycardia

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41
Q

What is the name of the heart arrhythmia when HR is lower than normal?

A

Bradycardia

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42
Q

What happens during diastole?

A

AV valve open
SL valve close
blood trickle down ventricles

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43
Q

what happens during atrial systole?

A

atrium walls contract ; ventricles relax
AV valves open ; SL valve close

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44
Q

what happens during ventricular systole?

A

atrial walls relax ; ventricular walls contract
SL valve open, AV valve close

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45
Q

what route does the wave of excitation (w.o.e) take?

A

SAN (in right atrium) -> atrial walls -> AVN -> delay -> bundle of His in septum -> apex -> purkinje fibres -> ventricular walls

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46
Q

why is there a delay of w.o.e when travelling across chambers?

A

to make sure all blood are pumped out, so the chambers woulnd’t both be pumping blood simultaneously

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47
Q

what are 4 things needed for clotting to occur?

A
  • clotting factors
  • fibrin
  • platelets
  • erythrocytes & leucocytes
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48
Q

what are the 4 stages of the clotting process?

A
  1. nearby platelets activated
  2. clotting factors reinforce platelets
  3. fibrin acts like glue
  4. erythrocytes/leucocytes reinforce clots
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49
Q

how is the clot removed by the body when no longer needed?

A

dissolves it

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50
Q

what are the stages that lead to atherosclerosis

A
  • arterial endothelium (a.e.) is damaged
  • cholesterol deposited onto wall, forming atheroma
  • may rupture (a.e.)
  • trigger blood clotting process, forming blood clot
  • lumen narrow
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51
Q

how are endothelium damaged in terms of atherosclerosis?

A

from high pressures

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52
Q

why do blood clots in lumen increase blood pressure?

A

lumen becomes more narrow, loses elasticity in arterial wall so blood pressure increases
and block blood flow

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53
Q

why is it lethal for atherosclerosis to occur?

A

thrombus(blood clot) increases blood pressure, and block blood flow, affecting oxygen supply to the heart. failure to respire results in death

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54
Q

What is tissue fluid formed from?

A

Plasma, components of blood that diffused out from hydrostatic pressure
Pass between the cells in most tissues of the body

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55
Q

What is hydrostatic pressure generated from?

A

Heartbeats

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56
Q

What does not transport out of capillaries?

A

Erythrocytes and proteins

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57
Q

How is lymph formed?

A

Some tissue fluids return to capillaries, those that don’t, goes to lymph capillaries
Molecules too large to enter blood capillaries can pass into lymph system

And drains back into blood circulation

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58
Q

Where are lymphocytes produced?

A

Lymph nodes

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59
Q

The lymph system is a pathway for _____ to be transported from _______ to the ________ following digestion

A

Lipids
Intestines
Bloodstream

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60
Q

Why is water potential more negative near the venule end than tissue fluid?

A

Because water diffuses out via osmosis from oncotic pressure
Loss of fluids but same concentration of proteins

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61
Q

what are 2 pathways for water to transport through root hair cells?

A
  • apoplastic
  • symplastic
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62
Q

what is the apoplastic pathway?

A

water travels through cell wall, non-living cells of root hair cells via diffusion

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63
Q

what is the symplastic pathway?

A

water travels through cytoplasm, living cells of root hair cells via osmosis

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64
Q

why do water molecules often choose apoplastic pathway > symplastic?

A

faster with less resistance

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65
Q

what does the casparian strip cause

A

apoplastic pathway joins symplastic pathway as it blocks water

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66
Q

what do xylem tissues transport?

A
  • water
  • mineral ions
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67
Q

what factors increases the rate of transpiration? And why?

A
  • ↑temp (increase KE)
  • ↑wind (moving air maintains concentration gradient)
  • ↑light intensity (stomata open in light)
  • ↓humidity (increase concentration gradient)
    diffusion
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68
Q

what bond is formed between water molecules for cohesion?

A

Hydrogen bonds

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69
Q

why are xylems dead, hollow cells with no end walls?

A

without cytoplasm or nucleus
to reduce resistance for water to move up xylem for cohesion and adhesion

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70
Q

why are xylems lignified?

A

give structure
waterproofing
strengthen

71
Q

why do xylems have pits?

A

holes in water to let water in and out

72
Q

What is the casparian strip and what is it made up of?

A

Waterproof block blocking water through the cell wall in apoplastic pathway
Made up of lignin and suberin

73
Q

How does water move up the stem?

A

Cohesion and adhesion in xylem

74
Q

How is water transported in xylem to leaves? 3 marks

A
  • cohesion between water molecules via hydrogen bonds
  • adhesion to xylem walls
  • from higher to lower wp: lower in leaves bcs water transpired out from leaves/stomata
75
Q

Is apoplastic pathway diffusion or osmosis?

A

Diffusion
Bcs no need to travel through partially permeable membranes

76
Q

Where does translocation occur?

A

Phloem

77
Q

What is the source cell

A

Produce glucose and convert to sucrose , Supply of carbs

78
Q

What do sink cells do

A

Store carbs and uses them (eg for growing shoot tip, fruit, seed)

79
Q

What direction does translocation take place

A

Bidirectional

80
Q

What adaptations does phloem have

A
  • sieve tube elements: little cytoplasm, no nucleus. Thin sieve plates
  • companion cells: large nucleus, many mitochondria to produce ATP for active processes.
81
Q

Plasmodesmata allows…

A

Communication and flow of minerals in companion cells

82
Q

What are plasmodesmatas?

A

Channel in between cells where cytoplasm joins

83
Q

Proofs for acidic companion cells/phloem and use of H+ ions in translocation and phloem uses living cells?

A
  • radioactive isotopes
  • pH is low in companion cells
  • ringing experiments
  • Aphid Stylet analysis (cutting off their heads to find sucrose)
  • metabolic poisons (using cyanide to kill phloem but xylem still working)
84
Q

What’s the difference between dead cells and non-living cells?

A

Dead cells were once living
Non-living never lived

85
Q

how do small simple organisms respire?

A

small diffusion distance
large SA:V ratio
low metabolic demands

86
Q

how do large complex organisms respire?

A

substances need to travel long distance to reach cells/tissues from external surface
small SA:V ratio
high metabolic rate
specialised gas system required

87
Q

what is fick’s law?

A

rate of diffusion is proportional to:
SA x diff in conc / diffusion distance

88
Q

how do spiracles open and close?

A

by small sphincters

89
Q

what are insect exoskeleton made up of?

A

chitin

90
Q

Describe the structure of a cell membrane. (3 marks)

A

phospholipid bilayer - hydrophilic heads and hydrophobic tails
channel proteins and proteins to transport molecules

91
Q

what are features of ATP?

A

can move easily across intracellular membranes
used in metabolic reactions
small but sufficient

92
Q

what are 3 mechanisms used to transport?

A
  1. passive transport (diffusion, (facilitated) osmosis)
  2. endocytosis & exocytosis
  3. active transport
93
Q

what could rate of transport across membranes be affected by?

A
  • molecule size
  • solubility
  • charged particles
94
Q

facilitated diffusion transports molecules …. the conc gradient

A

down!

95
Q

compare carrier vs channel proteins??

A

ca: both active and passive transport, can move across membrane, can transport both water solu/insoluble substances
ch: only passive, cannot move, only pass water soluble substances

96
Q

what is endocytosis?

A

infolding or extension of the plasma membrane to form vesicle or vacuole

97
Q

is phagocytosis active or passive?

A

active
requires energy

98
Q

what is exocytosis?

A

reverse of endocytosis
- release plasma membrane
- release molecules synthesised by the cell

99
Q

what is endocytosis?

A

plasma membrane forms a pit and move inwards

100
Q

what are channel proteins for water called?

A

aquaporins

101
Q

what does hypertonic mean? what would happen to animal cells?

A

concentrated solution
so animal cells lose water molecules, becomes crenated

102
Q

what does hypotonic mean? what happens to animal cells when placed in it?

A

pure water solution
cell gains water, membrane bursts aka haemolysis bcs no cell wall

103
Q

what is water potential and what is the unit?

A

measure of tendency for water to pass into or out of cell
kPa

104
Q

what is the water potential equation for plant cells?

A

water potential = turgor pressure + osmotic potential

105
Q

what is turgor pressure?

A

pressure inside plant cells caused by water entering the cell

106
Q

what is osmotic potential?

A

water potential of solution caused by solutes dissolved in it
(ALWAYS NEGATIVE)

107
Q

what is the unit for partial pressure of oxygen and what does it mean?

A

kPa
concentration of oxygen basically

108
Q

what is Hb short for?

A

haemoglobin

109
Q

Hb + 4O2 <->

A

HbO8

110
Q

when does Hb become saturated?

A

at high partial pressure (pp) of oxygen, and low pp of CO2

111
Q

when does Hb dissociate with oxygen?

A

at low pp of O2, high pp of CO2

112
Q

what is the relationship between partial pressure (pp) of O2 and % saturation of Hb?

A

oxygen dissociation curve
sigmoid curve

113
Q

what is the explanation for Hb’s sigmoid curve?

A

Hb finds it difficult to bind to the first O2 molecule.
When it does bind, it changes the tertiary structure of Hb (via cooperative binding), making it easier for O2 molecules to bind to

114
Q

why does Hb’s tertiary structure change after binding to the first O2?

A

cooperative binding

115
Q

what do curves on the left of the normal sigmoid curve mean?

A

Hb has higher affinity for O2,

116
Q

what does affinity in terms of Hb mean?

A

becoming saturated with O2 at lower pp of O2
(higher affinity = gives up oxygen less readily)

117
Q

what are 2 exemplar organisms that have S-curves to the left?

A

llama (live in higher altitude, pp of O2 lower)
lugworms (in waterlogged burrows, pp of O2 lower in air than water)

118
Q

what are 2 exemplar organisms that have S-curves to the right?

A

mice
birds

119
Q

why do mice’s Hb have lower affinity for O2?

A

small, so high SA:V ratio
high metabolic rate
lose lots of energy as heat
so more O2 is supplied to cells for more aerobic respiration to compensate for heat loss

120
Q

why do birds’ Hb have lower affinity for O2?

A

they fly, so use up lots of energy for muscle contraction
Hb has lower affinity by giving up O2 at higher pp of O2 to supply O2 to muslces

121
Q

what are myoglobins?

A

oxygen store in muscles

122
Q

where are myoglobin curves found relative to normal adult Hb? Why?

A

Left
only gives up O2 at v low pp of O2, eg during vigorous exercise

123
Q

where is the foetal Hb curve found relative to the adult (maternal) Hb? Why?

A

Left
greater affinity for O2, becomes saturated w O2 at lower pps of O2
- allow foetus to take O2 from mother’s blood in placenta where pp of O2 is low

124
Q

what is the Bohr effect?

A

the greater the CO2 conc, the greater shift to right (low pH changes quaternary structure of Hb)

125
Q

In terms of oxidation dissociation curves:
there is a ____ correlation between high temperatures and low pHs and shift to the ____. Because it reduces _______

A

positive
right
rate of respiration for O2 dissociation

126
Q

what is the sequence of events for blood clotting?

A
  • platelets form a plug and release clotting factors, including thromboplastin
  • prothrombin → thrombin
  • which activates fibrinogen→fibrin
127
Q

what are neutrophils?

A

leucocyte to fight infection
Phagocytosis by digesting pathogens

128
Q

what are eosinophils?

A

leucocyte in the immune system that fights against germs, such as parasites and bacteria

129
Q

what are monocytes?

A

type of leucocyte: inflammatory and anti-inflammatory processes that take place during an immune response

130
Q

why is bipolar lipids suitable molecules to form cell membrane? 2 marks

A
  • hydrophilic layer interacts with aqueous environment
  • hydrophobic barrier inside
131
Q

how are mineral ions taken up by active transport? (3 marks)

A
  • using ATP
  • against conc. gradient
  • using carrier proteins across membrane
132
Q

describe structure of phospholipid (2 marks)

A

glycerol head
2 fatty acid tails
bonded via ester bonds

133
Q

what is the description of exocytosis?

A

form of active transport where large particles move out of cells

134
Q

how is tissue fluids formed?

A

hydrostatic pressure forcing fluids out of capillaries

135
Q

how is tissue fluids returned to capillaries? (3 marks)

A

oncotic pressure > hydrostatic pressure
generated by proteins that are too large to pass out of capillary
more proteins in plasma than tissue fluids

136
Q

why is there more proteins in plasma than tissue fluids?

A

proteins are too large to pass out of capillaries to tissue fluids

137
Q

compare and contrast the transport of fluids in veins vs lymph vessels (2 marks)

A

both have valves
both are low pressure

faster in vein
heart causes mass flow in vein

138
Q

why is production of tissue fluids essential in the human body? (2 marks)

A
  • supply O2
  • remove CO2/urea
  • so respiration can take place
139
Q

what happens to tissue fluids that aren’t reabsorbed into the blood capillary? (2 marks)

A
  • enters lymphatic system
  • lymph returns to veins/blood
140
Q

what are hydrostatic and oncotic pressures generated by? respectively

A

heart pumping/contraction
(plasma) proteins

141
Q

how does blockage of lymphatic duct lead to lymphoedema? (2 marks)

A
  • proteins accumulate in tissue fluid / less protein in blood plasma
  • lowering oncotic pressure
  • less fluids removed by blood capillary/more fluids drawn out of blood
142
Q

how is tissue fluid formed by the capillary? (3 marks)

A
  • when hydrstatic pressure > oncotic pressure (???)
  • leaves capillaries through pores
  • plasma proteins are too large to leave capillary
  • more plasma proteins in plasma than tissue fluid
143
Q

Why is it difficult to determine osmotic potential than water potential of plant cells? 2 marks

A
  • can only be measured by incipient plasmolysis
  • cannot measure directly
144
Q

Why is it difficult to determine osmotic potential than water potential of plant cells? 2 marks

A
  • can only be measured by incipient plasmolysis
  • cannot measure directly
145
Q

What is myogenic and where is it found?

A

Impulse originating on its own, not nerve impulse
In the heart initiating SAN pacemaker w.o.e.

146
Q

What are the 3 features of alveoli to increase efficiency of diffusion in lungs?

A
  • moist surface, allow gases to dissolve
  • one cell thick, thin membrane
  • high SA:V ratio
  • maintains steep conc gradient
147
Q

Why does mucus in bronchi and bronchioles for cystic fibrosis patients affect them? 2 marks

A

Airways are blocked
So less gaseous exchange since less oxygen to alveoli

148
Q

What are the 2 active enzymes involved in blood clotting process?

A

Thrombin and thromboplastin

149
Q

Why does rate of calcium ion uptake in pancreatic cells increase and level off as calcium ion concentration increases? (2 marks)

A
  • Rate of diffusion increases due to increased concentration gradient
  • rate levels off since transport proteins limit rate
  • bcs calcium ions enter by facilitated diffusion
150
Q

What is the net movement of gaseous exchange in roots of a plant?

A

Only ‘in’ of oxygen
Only ‘out’ of carbon dioxide

151
Q

Describe how the events of the cardiac cycle change when the demand of body cells for oxygen increases. (2 marks)

A
  • cardiac cycle happens more frequently
  • ventricles contract more forcefully
152
Q

How does translocation take place?

A
  • assimilates in phloem transport substances
  • sucrose transported from source to sink
  • bidirectionally
153
Q

how does sucrose get transported in the phloem?

A
  • from source
  • into companion cells via active transport
  • into sieve tubes
154
Q

What is the mechanism of translocation from source to sink?

A

Mass flow hypothesis

155
Q

Describe the mass flow hypothesis of translocation from source to sink.

A
  • sucrose is loaded into sieve tubes at source
  • lowers wp in sieve tubes
  • water enters via osmosis from xylem and companion cells
  • increasing hydrostatic pressure
  • sucrose content lowers due to sink cell
  • so wp lowered, water osmosise in
  • lower volume of sieve tubes
  • lower hydrostatic pressure at sink than source, so diffusion
156
Q

what happens in sink cells?

A

use sucrose in respiration or converted to starch for storage

157
Q

How are companion cells adapted?

A
  • lots of mitochondria -> ATP for active transport of sucrose into sieve tubes
158
Q

How are sieve tube elements adapted?

A
  • stacked on top of each other, allow uninterrupted flow of sucrose
  • sieve pores allow solutes flow through phloem
  • no nucleus, little cytoplasm and organelles - no obstruction of flow
  • fewer sieve plates from elongation, less resistance
  • many plasmodesmata, allow flow
159
Q

what are strengths of the mass flow hypothesis of translocation?

A
  • explains why contents of phloem are under pressure
  • explains conc gradient between source and sink
160
Q

Weaknesses of the mass flow hypothesis in translocation?

A

does not explain
- bidirectional movement
- why assimilates travel at different rates

161
Q

what are adaptations of root hair cells?

A
  • stick out, increase SA
  • lots of mitochondria, release ATP for active transport
  • lots of ribosomes to make carrier proteins
  • thin cell walls, decrease diffusion distance
162
Q

compare the apoplastic and symplastic pathways.

A
  • non living / living
  • via cell walls / cytoplasm and plasmodesmata
  • diffusion / osmosis
  • faster / slower
  • blocked by Casparian strip / not
163
Q

does water usually travel via apoplastic or symplastic pathway?

A

apoplastic
- faster
- due to less resistance to flow

164
Q

Draw + Label a transverse diagram of a stem

A

(Check photo!)

165
Q

Adaptation of xylems (5 total, give 3 at least)

A
  • no end walls, ensure continuous flow of water
  • dead cells so little resistance to water flow
  • lignified walls, give strength and prevent water leak
  • diff lignin patterns allow stretch
  • pits in walls allow lateral movement of water
166
Q

What is the evidence for cohesion tension theory?

A
  • lignin walls can withstand tension
  • diameter of trees reduced in daytime (due to tension pulling xylem vessels inwards)
167
Q

What is the perfect definition for transpiration?

A

Diffusion of evaporated water vapour from aerial parts of plant through stomata

168
Q

Why is transpiration important?

A
  • brings water to leaves for p/s
  • cools leaves
  • pulling water up keeps plant cell turgid and upright
  • make nitrates and chlorophyll as water contains mineral ions
169
Q

What are similarities between xylem and phloem?

A

Both
- contain vertical arrangement of cells to form tubes
- cells walls made of cellulose
- contain parenchyma cells

170
Q

What are structural differences between xylem and phloem?

A

X / P
- has lignified walls / does not
- no end walls / have sieve plates
- none / has companion cells
- none / has cytoplasm and organelles
- has pits in walls / doesn’t

171
Q

What are general non-structural differences between xylem and phloem?

A

X / P
- dead / living
- one direction / bidirectional
- transports water + mineral ions / organic molecules
- down water gradient / pressure gradient

172
Q

What are 2 types of photometers to measure rate of transpiration?

A
  • bubble photometer
  • mass photometer
173
Q

What does a photometer do?

A

Measure rate of water uptake

N Biology A Level (18 decks)

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