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Biology Revision Year 1 > Chapter 7 - Mass Flow > Flashcards

Chapter 7 - Mass Flow Flashcards

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1
Q

What organelle do companion cells have more of?

A

Mitochondria

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2
Q

What is the role of companion cells?

A

Support sieve tube cells

Provide ATP

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3
Q

How can we use radioactive labels as evidence for mass flow?

A

Grow plant in normal atmosphere
Introduce artificial atmosphere with C14
Measure presence of C14 as it moves down stem

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4
Q

How can we use ringing as evidence for mass flow in the phloem?

A

Remove the bark (contains the phloem)
Solutes cannot move up/ down
Bulge forms
Fluid above ring has more solute than fluid below it

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5
Q

Are the cells in the phloem living or dead?

A

Living

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6
Q

What is transported in the phloem?

A

Assimilates

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7
Q

What direction do assimilates move in the phloem?

A

Up and down

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8
Q

Describe the sieve tube cells

A

Living, little cytoplasm, few organelles

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9
Q

Describe sieve plates

A

Thin pores between sieve tube cells

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10
Q

Describe the serial dilution method (briefly)

A
  • cylinders of plant tissue, slice up
  • weigh mass at start
  • submerge in solute for 1 hour
  • weigh again
  • calculate percentage difference
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11
Q

How do you calculate the percentage difference

A

Percentage difference = (difference (g) / start mass (g)) x 100

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12
Q

Make 30cm^3 of 0.75 mol dm-3 of a stock solution of 1.8 moles dm3

A

(30/ 1.8) x 0.75 = 12.5

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13
Q

What happens at the source?

A

1 - AT pumps sucrose into STE from low to high conc
2- lowering the water potential
3- water moves in by osmosis from CC
4 - creating high hydrostatic pressure

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14
Q

What happens at the sink?

A

1- uses assimilates creating low conc (eg - sucrose to starch in potatoes)
2- increases WP so water moves out by osmosis
3 - decreasing pressure in the phloem

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15
Q

What is diffusion?

A

The net movement of molecules from a high to low concentration

Passive (no ATP)

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16
Q

How does concentration affect diffusion

Example

A

The steeper the conc grad the faster the rate of diffusion

Ventilation/ circulation in lungs and counter current in fish maintain con grad

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17
Q

How does diffusion distance affect the rate of diffusion?

Example?

A

The shorter the diffusion distance the faster the rate of diffusion

Eg) thin epithelium in capillaries

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18
Q

How does surface area affect the rate of diffusion?

Example?

A

The larger the surface area the faster the rate of diffusion

Eg) folded membrane of alveoli in lungs

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19
Q

What is facilitated diffusion?

A

The passive movement of molecules across the membrane from an area of high conc to low conc via a specific transmembrane protein

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20
Q

What do protein channels transport?

A

Small polar molecules

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21
Q

What do carrier proteins transport?

A

Large molecules eg) glucose

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22
Q

describe the observation made when ringing a plant (removing the outer layer)

A

because the phloem vessels are located on the outside, swelling would occur due to accumulation of sugar, the tissue below this would die

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23
Q

what affect would high wind speed have on water uptake?

A

increase uptake

cohesion tension would pull up more as it is lost to the surroundings

24
Q

describe the differences between arteries and veins

A

ARTERIES - thick muscle, thick elastic, thick wall, no valves

VEINS - thin muscle, thin elastic, thin walls, valves present

25
Q

why are veins and arteries different?

A

because arteries need higher blood pressure, higher pressure prevents backflow. veins have lower pressure so less risk of bursting, valves in place to prevent backflow

26
Q

what is cardiac output?

A

volume of blood from one ventricle per min (dm^3min-1)

27
Q

how do you calculate cardiac output?

A

CO = HR x SV

28
Q

what affect does CO2 have on O2 affinity in haemoglobin?

A

decreases affinity

so O2 is easily unloaded

29
Q

what is the affinity for O2 in the lungs?

A

high

the O2 easily loads but cannot easily unload

30
Q

What is the role of an endopeptidase?

A

hydrolyse bonds within polypeptide chains

31
Q

What is the role of an exopeptidase?

A

hydrolyse bonds at the end of polypeptide chains

32
Q

What is the role of a membrane bound dipeptidase?

A

breaks down dipeptidases into amino acids

33
Q

How are amino acids absorbed?

A

co transport with sodium
Na+ pumped out
Na+ diffuses in via carrier protein down conc grad, aa piggybacks in against conc grad

34
Q

What are the benefits of having a low affinity for O2 in high O2 environments?

A

release more O2 at cells as Haemoglobin has a lower affinity for O2
good for small mammals who have a high rate of respiration

35
Q

What are the benefits of having high affinity for O2 in an environment where there is low O2 pp?

A

O2 loads more easily onto the Haemoglobin at the lungs

36
Q

Describe arteries

A

thick muscle
narrower lumen than veins
elastic
Arteries Away from heart

37
Q

Describe Veins

A 
thin muscle 
smooth endothelium 
larger lumen 
valves to prevent backflow 
VeIN to heart
38
Q

Describe Capillaries

A

surround all cells for exchange
endothelium is one cell thick
high surface area/rate of diffusion

39
Q

Pulmonary Artery

A

Deoxygenated blood away from heart to lungs

40
Q

Aorta

A

oxygenated blood to body

41
Q

Pulmonary Vein

A

oxygenated blood to the heart

42
Q

Vena Cava

A

deoxygenated blood from body

43
Q

What are the roles of the valves in the heart

A

ensure blood is unidirectional

44
Q

When do AV valves open?

A

when the pressure is higher in the atria than the ventricle

45
Q

When do semi lunar valves open?

A

SL valves open when the pressure is higher in v than the blood vessels

46
Q

Describe one cardiac cycle

A

Atria contract and ventricles fill with blood (AV open SL closed)
ventricles contract AV closed SL open, blood flows through the blood vessels
Blood flows into the left atrium, AV valves open, atria contract, ventricle fills, ventricle contracts forcing blood out via the aorta.

47
Q

What artery flows to the Kidneys

A

renal artery

48
Q

what is atheroma?

A

build up of fatty plaque in the arteries

49
Q

thrombosis

A

blood clot in arteries

50
Q

aneurysm

A

stretchy endothelium balloons out through muscle of an artery

51
Q

Describe how tissue fluid is formed

A

high hydrostatic pressure in blood
forces out water and small molecules
large molecules eg) proteins remain inside the capillary

52
Q

Describe how tissue fluid is returned

A

water potential in blood capillary is lower than tissue fluid bc the proteins have not moved out
water moves in by osmosis
and down the pressure gradient
excess tissue fluid drains into the lymph

53
Q

Describe the xylem

A

transports water
dead cells
unidirectional upward

54
Q

describe cohesion tension

A

transpiration out of stomata creates low pressure at top of xylem
water is pulled up creating tension

55
Q

4 factors affecting rate of transpiration

A

temperature, light (stomata only open whilst photosynthesising), Humidity + wind both affect vapour gradient

56
Q

Describe the Bohr effect

A

curve shifts to the right
Haemoglobin unloads more readily at respiring tissues
CO2 formed from respiration, altering the tertiary structure of the Haemoglobin so that it unloads more easily at respiring tissues

Biology Revision Year 1 (13 decks)

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