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biology mrs champion > Exchange Surfaces P2 > Flashcards

Exchange Surfaces P2 Flashcards

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1
Q

What are adaptions of erythrocytes (RBC’s)

A
  • Biconcave shape maximises SA for gas exchange
  • Small and flexible to pass through narrow capillaries
  • No nucleus, more room to carry respiratory gases
  • Packed with haemoglobin
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2
Q

What is haemoglobin?

A
  • Globular protein
  • 1 polypeptide chain
  • 1 haem group
  • Each haem group has an affinity for oxygen
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3
Q

What is haemoglobin called when it becomes oxygenated?

A
  • Oxyhaemoglobin
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4
Q

What is partial pressure?

A
  • The amount of oxygen in any tissue
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5
Q

Explain foetal haemoglobin

A
  • Higher affinity for oxygen than adult haemoglobin
  • Must be able to associate oxygen from an environment that makes adult haemoglobin release oxygen
  • Foetus gains oxygen from mother at placenta which contains oxygenated blood
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6
Q

How is CO2 removed ?

A
  • 5% dissolves directly into plasma
  • 10% combines with haemoglobin
  • 85% transported as hydrocarbinate ions
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7
Q

How is carbonic acid formed ?

A
  • As Co2 diffuses into blood, some enters RBC’s
  • Combines with water to form weak acid = carbonic acid
  • Reaction is catalysed by enzyme
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8
Q

What is dissociation within carbonic acid?

A
  • Carbonic acid dissociates and releases hydrogen ions and hydrogen carbonate ions
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9
Q

What is the chloride shift?

A
  • Hydrogen carbonate ions diffuse out of RBC’s into plasma by diffusion
  • Change inside cell is maintained by movement of chloride ions from plasma into RBC
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10
Q

Why is haemoglobinic acid produced?

A
  • To removed hydrogen ions and maintain pH of RBC
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11
Q

What is the Bohr effect?

A
  • Hydrogen ions released from dissociation of carbonic acid compete for the space
  • When carbon dioxide is present, the hydrogen ions displace the oxygen on the haemoglobin
  • More oxygen is released from oxyhaemoglobin into tissues
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12
Q

What does the pulmonary vein carry?

A
  • Blood from lungs to heart
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13
Q

What is the aorta?

A
  • The major artery leaving the heart
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14
Q

What do semi-lunar valves do?

A
  • Prevent back flow of blood from arteries into ventricles
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15
Q

What do atrio ventricular valves do?

A
  • Prevent back flow into atria
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16
Q

Which side of heart is thicker and why?

A
  • Left because it pumps blood further
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17
Q

What is blood pressure?

A
  • Pressure circulating blood on the blood vessels, indicates heart pumping ability and elasticity of blood vessels
  • Top number is systolic blood pressure, highest level blood pressure reaches when heart beats
  • Bottom number is systolic blood pressure, lowest level your blood pressure reaches as heart relaxes between beats
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18
Q

What is the cardiac cycle?

A
  • The process of the cardiac muscle contraction and relaxation in one beat
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19
Q

What are the 3 phases of cardiac cycle?

A

1) Filling phase (DIASTOLE)
- Relaxation of both atria and ventricles
- Internal heart vol increases
- Blood flows into atria
- Arterial pressure is low

2) Atrial contraction (ATRIAL SYSTOLE)
- Small contraction pushes all blood into ventricles
- Stretches walls of ventricles ensuring they are full of blood

3) Ventricular contraction (VENTRICULAR SYSTOLE)
- Walls of ventricles contract, increasing pressure fast in up direction
- Semi-lunar valves open allowing blood out of heart
- Ventricle walls relax
- Blood pressure in arteries is high

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20
Q

What can myogenic muscle tissue do?

A
  • Ininiate its own contraction
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21
Q

What is an electrocardiogram (ECG)

A
  • Method of monitoring electrical activity of heart
22
Q

What is made up of a vascular bundle?

A
  • Xylem and phloem
23
Q

What does xylem and phloem do?

A
  • Xylem moves WATER and mineral ions UPWARDS
  • Phloem moves SUGARS UPWARDS or DOWNWARDS
24
Q

Where are vascular bundles located?

A
  • In middle to help plant withstand trudging strains as stems and leaves are blown in wind
25
Q

Is xylem living or dead?

A
  • Dead
26
Q

Is phloem living or dead?

A
  • Living
27
Q

Describe xylem

A
  • Made up of several types of cells
  • Long, hollow structures
28
Q

Describe phloem

A
  • Main transporting vessels are sieve tube elements
  • Made of many cells joined end to end to form long, hollow structure
29
Q

What is the water potential?

A
  • Measure of tendency of water molecules to move from one place to another
  • Moves from a region of higher WP to area of lower WP down conc gradient by osmosis
30
Q

Explain a turgid plant

A
  • Cell has strong cellulose wall so can’t burst but once full the cell is turgid as water inside cell starts to exert pressure onto wall
  • As pressure builds it reduces intake of water molecules
31
Q

Explain plasmolysis

A
  • Cell looses turgidity if WP of cell is higher than WP of solution
  • Cytoplasm and vacuole shrinks
  • Plasma membrane will loose contact with wall
32
Q

How is water uptaken from soil in 3 steps?

A

1) Epidermal root hair absorbs soil minerals using active transport
2) New minerals lower the water potential of the cytoplasm
3) Water is taken up by the cell using osmosis down WP gradient

33
Q

Explain transportation in steps

A

1) Water enters root via osmosis
2) Symplast pathway into xylem
3) Osmosis from xylem into leaf mesophyll cells
4) Water evaporates from mesophyll cell surface into leaf air spaces
5) Water vapour moves through intercellular spaces and out through stomata due to diffusion gradient

34
Q

What does waxy cuticle do?

A
  • Makes lead waterproof to prevent cells from loosing water rapidly
35
Q

What does diffusion allow?

A
  • CO2 to move from air to lead and oxygen to move out the leaf down conc graident
36
Q

What does stomata do?

A
  • Open and close to control amount of water lost
  • Allows gas exchange to take place
37
Q

What do guard cells do in water favourable situations?

A
  • Become turgid
  • Hole is created
38
Q

What do air spaces in leaf provide ?

A
  • Large surface area for gas exchange that substances can diffuse
39
Q

What can a potometer be used for?

A
  • Show the uptake of water by a plant in different conditions
  • Air bubble moves as plant loses water from leaves
40
Q

How does water move across the root?

A

1) ENDOdermis is made of cells with waterproof casparian strip surrounding them
2) Casparian strip blocks the apoplast pathway so symplast pathway is used
3) Minerals pumped into xylem by active transport into xylem
4) Water follows into xylem using osmosis again down water potential gradient

41
Q

What is the casparian strip?

A
  • Waterproof by Suberin
  • Located on edged of cells which blocks water from apoplast pathway
42
Q

What 3 processes helps move water up plants?

A
  • Root pressure
  • Transpiration pull
  • Capillary action
43
Q

Describe root pressure

A
  • Minerals move into xylem vessel through active transport
  • Means water molecules move into xylem vessel using newly created water potential gradient via osmosis
44
Q

Describe transpirational pull

A
  • Water molecules attracted together by cohesion forming chain
  • Water molecules lost from leaves in transpiration pull the rest of water column attached to them up the stream
  • Pulling action creates tension in water chain
  • Xylem made with lignin to ensure vessel doesn’t collapse = cohesion tension theory
45
Q

What is capillary action?

A
  • Water molecules are attracted to the side of the xylem vessels using adhesion
  • Xylem are narrower so forces water up tubes
46
Q

What are sieve tubes?

A
  • Make up tube of phloem by stacking on eachother
  • No nucleus
  • Contain cross walls with pores in
47
Q

What are companion cells?

A
  • In between sieve tubes
  • Lots of mitochondria for ATP
  • ATP loads sucrose into tubes
48
Q

What is translocation?

A
  • Movement of assimilates
  • Occurs in phloem
  • Parts of plants that release sugar into phloem are sources
  • Parts of p;ants that removed sugar from phloem are sinks
49
Q

How is sucrose entered into phloem?

A
  • Companion cells uses ATP to pump hydrogen ions into surrounding leaf tissue
  • Hydrogen ions diffuse back in using cotransporter proteins
  • H+ ions carry (cotransport) sucrose back in with them
  • Sucrose then use their concentration gradient to diffuse into sieve tube elements in phloem through plasmodesmata
50
Q

What is the movement at the source

A

Sucrose enters sieve tube and makes the water potential within it more negative.
- This means water moves in to sieve tube by
osmosis from surrounding tissues.
-This increases the hydrostatic pressure at the source, pushing the sucrose along the tube (down pressure gradient)
- This is mass flow.

51
Q

What is the movement at the sink?

A

Sucrose is stored or used at the sink by surrounding cells.
-More sucrose molecules enter tissues as old ones are
used.
- Sucrose moves by diffusion or active transoort
- This causes the water potential in sieve tube to become less negative in these areas
- Water moves out of sieve tubes into surrounding cells by osmosis
Hydrostatic pressure is lowered at the sink (therefore
maintaining pressure gradient)

biology mrs champion (5 decks)

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