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Biology Paper 1 > Mass Transport > Flashcards

Mass Transport Flashcards

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1
Q

Properties of the xylem

A
  • long
  • dead cells
  • no cell walls
  • contain lignin
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2
Q

Cohesion-Tension theory

A
  • Some water in the leaves is used during photosynthesis
  • Most leaves through transpiration
  • The loss of water causes tension
  • Water is pulled up due to the formation of the hydrogen bonds between water molecules and xylem vessel
  • Hydrogen bonds also form between just water molecules(cohesion) so they all get pulled up together
  • This replaces the lost water
  • Due to this the Ψ in the roots is low, so water diffuses via osmosis down the Ψ gradient
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3
Q

Properties of the phloem

A
  • living cells
  • sieve tube walls made of cellulose
  • Plasmodesmata allows the cytoplasm to be shared between the sieve tube and companion cells
  • sieve plates have pores to allow sap to move through. Sugars are transported through
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4
Q

Process of translocation

A
  • Sucrose is actively transported into the sieve tube elements(STE) so Ψ in the tube decreases
  • Water in the xylem moves in via osmosis into the STE, increasing the Pa at the top of the phloem
  • Sucrose diffuses out of the phloem into the sink cell so Ψ at the bottom increases
  • Water moves out via osmosis back into the xylem and the Pa decreases
  • A Pa gradient is established so particles move from top to bottom
  • Sucrose is then converted back to glucose for respiration + starch
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5
Q

Using ringing to investigate mass transport

A
  • If a ring is cut outside the stem, this halts transport in the phloem but not the xylem as the phloem is located on the outside
  • The tissue above will the ring starts to swell and growth below stops as sucrose cannot be transported
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6
Q

Using tracing to investigate mass transport

A
  • The leaves are exposed to radioactive carbon
  • The plant is frozen very quickly in liquid nitrogen and placed on photographic film
  • The pathway of radioactive sucrose down the phloem can be traced
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7
Q

Evidence for mass flow

A
  • Tracing and ringing provide evidence for mass flow theory

- Both show a casual link between the phloem and sucrose

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8
Q

Evidence against mass flow

A
  • Sap can move up and down the phloem. Hydrostatic Pa gradient is by the movement water from to source to the sink but does not explain the sap’s movement
  • Increased hydrostatic Pa is required for water to flow through the pores, so sieve plates should be a problem
  • The purpose why the phloem has living cells is unclear
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9
Q

Why is the oxygen dissociation curve S-shaped?

A
  • 1st oxygen binds easily
  • 2nd + 3rd bind easily as well due to the 1st one
  • 4th binds with difficulty
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10
Q

What does the curve being further right mean?

A

That they have a higher affinity for oxygen

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11
Q

What happens when the partial pressure of oxygen is high?

A

The affinity for oxygen increases so oxygen binds to haemoglobin

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12
Q

What happens when the partial pressure of oxygen is low?

A

The affinity for O₂ decreases so O₂ dissociates from haemoglobin

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13
Q

The properties of haemoglobin at high altitude

A
  • High affinity for O₂ as there is low PO₂
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14
Q

What happens when partial is low?

A
  • Low affinity for oxygen

- Saturation of haemoglobin is low

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15
Q

What happens when partial pressure is high?

A
  • High affinity for oxygen

- Saturation increases quickly

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16
Q

What is the Bohr effect?

A
  • That the increased dissociation of O₂will cause a shift to the right in the oxyhaemoglobin dissociation
  • This means that O₂ will dissociate at lower partial pressures than normal
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17
Q

What does a double circulatory system mean?

A

Blood travels through the heart twice in one circuit

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18
Q

Function of coronary arteries

A

Supply blood to the heart

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19
Q

Function of pulmonary artery

A

Pumps deoxygenated blood away from the heart to the lungs

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20
Q

Function of pulmonary vein

A

Pumps oxygenated blood to the heart

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21
Q

Why is pressure the aorta high?

A

To ensure that the blood is pumped to all tissues of the body

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22
Q

Function of the vena cava

A

To pump deoxygenated blood from the body back to the heart

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23
Q

Function of renal artery

A

To pump oxygenated blood to the kidneys

24
Q

Function of renal vein

A

To pump deoxygenated blood out of the kidneys

25
Q

What occurs in the right atrium?

A

Deoxygenated blood from body flows into the heart via the vena cava

26
Q

What occurs in the right ventricle?

A
  • Atrioventricular (AV) valves open
  • Deoxygenated blood flows in from the right atrium
  • AV valves close
  • The walls of the ventricle contract forcing the semi-lunar (SL) valves
  • Blood is pumped of the heart into the lungs via the pulmonary artery
27
Q

What occurs in the left atrium

A

Oxygenated blood flows into the left atrium via the pulmonary vein from the lungs

28
Q

What occurs in the left ventricle

A
  • AV valves open
  • Oxygenated blood flows into the ventricle from the left atrium
  • AV valves close and SL valves open
  • Oxygenated blood is pumped out of the heart via the aorta
  • SL valves close
29
Q

Why are the walls of the left ventricle thicker than the right ventricle?

A
  • The left ventricle has to pump blood to the rest of the body whereas the right ventricle only pumps blood to the lungs which is a shorter distance
  • It has more muscle
30
Q

Why are the walls of the ventricles thicker than that of the atria?

A
  • Ventricles pump blood a further distance, so contract with greater force with higher Pa
31
Q

What happens at atrial contraction?

A
  • Blood from the lungs flows into the left atrium while the blood from the body flows into the right atrium
  • The atria contracts, increasing the Pa, vol decreases
  • Blood is forced into the ventricles
  • Ventricles relax as they fill with blood
  • Slight increase in Pa + vol of ventricles
32
Q

What happens at ventricular contraction?

A
  • Atria relax + ventricles begin to contract
  • This causes Pa in the ventricles to increase + vol decreases
  • This shuts the AV valves as Pa in the ventricles is higher than the atria
  • The blood in the ventricles are forced out through the pulmonary vein or aorta
33
Q

What happens during relaxation of the cardiac cycle?

A
  • The blood in the pulmonary artery + aorta are at high Pa
  • Causing the SL valves to close as there is more Pa in the arteries than the ventricles
  • Both the ventricles + artria relax and AV valves open
34
Q

What are arterioles?

A
  • Smaller vessels that stem from arteries that are connected to organs
35
Q

What are veins and their properties?

A
  • They transport blood back to the heart
  • Wide lumen; allows blood to flow at low pressure
  • Thin muscle wall
  • Elastic tissue
  • Has valves; to prevent back flow
36
Q

What are arteries and their properties

A
  • Transports blood away from the heart
  • Thick muscle wall; to maintain high pressure
  • Elastic fibres; to allow arteries to stretch
  • Folded endothelium; allows arteries to stretch
37
Q

What are capillaries and their properties?

A
  • A network of arterioles that surround body cells
  • Close to cells; creating a short diffusion pathway
  • Large surface area
  • 1 cell thick; short diffusion pathway for efficient exchange
38
Q

Steps of pressure filtration

A
  • High Pa at the capillary end creating a Pa gradient
  • Fluid flows down Pa gradient into surrounding space, leaving plasma protein
  • Pa inside capillaries reduces, so Pa lower at capillary bed then capillary end
  • Plasma proteins reduce the Ψ, so a Ψ gradient is established and water diffuses in via osmosis
  • Excess tissue fluid flows into lymphatic system recycling it into the bloodstream
39
Q

What is atheromas?

A
  • The deposition of materials in the walls of the arteries
40
Q

What is fibrous plaque?

A

Deposition of white blood cells and fatty materials over time which harden

41
Q

Consequences of narrower lumen of the arteries

A
  • Blood flow is restricted
  • Increased blood pressure
  • Can lead to cardiovascular disease
42
Q

What is thrombosis?

A
  • When platelets accumulate and form clots

- It can block blood flow

43
Q

What is an aneurysm

A
  • A swelling
44
Q

What causes Thrombosis?

A
  • When atheromas damage the artery wall causing it to burst open
45
Q

What causes aneursyms?

A
  • The damage caused by atheromas increases blood pressure

- This causes the elastic fibres to swell

46
Q

Risk factors that contribute to cardiovascular disease

A
  • High cholesterol diet
  • High blood pressure
  • Smoking
47
Q

How does a diet high in cholesterol cause coronary heart disease(CHD)?

A
  • Narrows the lumen
  • Restricting blood flow to cardiac muscle
  • Causing myocardial infarction (heart attack)
48
Q

What is the equation of cardiac output?

A

CO = SV x HR

49
Q

What holds the valves in place?

A
  • Cords

- Heart strings

50
Q

Name an organism with a single circulatory system?

A

Fish

51
Q

What does systole mean?

A

Contract

52
Q

What does diastole mean?

A

Relax

53
Q

What organ are hepatic arteries/veins linked to?

A

Liver

54
Q

What organ are renal arteries/veins linked to?

A

Kidneys

55
Q

What causes the AV valves to close?

A

Pressure in ventricles is higher than the pressure in the atria

56
Q

What causes the SL valves to close?

A

Pressure in the arteries is higher than the pressure in the ventricles

Biology Paper 1 (7 decks)

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