mass transport

Question 1

why is the dissociation curve Sigmoidal s shaped?

Answer 1

co-operative binding=
-low partial pressures of O2 haemoglobin has low affinity for O2, doesnt load as readily
-as O2 partial pressures increase affinity of haemoglobin increases. when first O2 molecule loads, changes shape of haemoglobin moleucle =easier
-difficult to become 100% saturated - hard to diffuse and associate into 4th

Question 2

describe haemoglobin in low oxygen environments

Answer 2

-Hb has higher affinity for O2
-Hb loads more readily at low pO2
-curve shifts to left

Question 3

describe haemoglobin with high activity levels

Answer 3

-very active
-aerobically respire faster
-need more O2 per unit mass of tissue
-Hb has lower affinity for O2
-Hb unloads more readily at any given pO2
-curve shifted to the right

Question 4

describe haemoglobin in smaller organisms

Answer 4

-higher SA:V
-transfer heat energy to environment faster
-aerobically respre faster/high metabollic rate
-need more O2 per unit mass of tissue
-Hb loads more readily at any given pO2
-curve shifts to the right

Question 5

where does the renal artery carry blood from and to?

Answer 5

aorta to kidney

Question 6

why is the left venticle much thicker?

Answer 6

need to contract more powerfully to pump oxygenated blood around the body

Question 7

whats the importance of the septum?

Answer 7

separates sides so oxygenated and deoxygenated blood dont mix
also enables different pressures

Question 8

whats the hearts own blood supply?

Answer 8

coronary arteries

Question 9

in blood vessels how can blood flow be controlled?

Answer 9

in arterioles
-when muscle relaxes
arterioles dilate
-lumen become wider
-blood flow increases

-when muscle contracts
arterioles constrict
-lumen narrows
-blood flow decreases

Question 10

what are the 3 stages of the cardiac cycle?

Answer 10

1. ventricles relax, atria contract
2. ventricles contract,atria relaxes
   3.ventricles relax, atria relax

Question 11

when do atrioventricular valves open?

Answer 11

when pressure in the atria is greater than the ventricles

Question 12

when do semilunar valves open?

Answer 12

when pressure is higher in the arteries than in the aorta/pulmonary artery

Question 13

whats the formula for cardiac cycle?

Answer 13

stroke volume x heart rate

Question 14

define stroke volume

Answer 14

vol of blood pumped during each heart beat in cm3

Question 15

give 3 examples of contents of plasma

Answer 15

hormones
fatty acids
amino acids

Question 16

whats the role of tissue fluid?

Answer 16

transport oxygen and nutrients from blood to cells and CO2 and other waste products from cells back to blood

Question 17

where does formation of tissue fluid occur?

Answer 17

at a capillary network which surrounds cells

Question 18

how is tissue fluid formed?

Answer 18

at arteriole end:
-blood has higher hydrostatic pressure (due to left ventricle) lower osmotic pressure
-water is forced out of fenestrations
-along with dissolved substances like oxygen and glucose

Question 19

what is ultrafiltration?

Answer 19

filtration under pressure

Question 20

how is fluid returned to the capillary?

Answer 20

at venous end:
-blood has lower hydrostatic pressure
-plasma protiens lower water potential
in blood
-higher hydrostatic pressure
-water moves back in by osmosis
other waste by diffusion
-excess tissue fluid moves into lymphatic capillaries where it drains back into circulatory system via subclavian vein

Question 21

importance of the lymphatic system

Answer 21

-draining excess tissue fluid and returning to blood
-for immune system = lymph nodes produce lymphocytes
-absorp lipids from digestive system into lacteal

Question 21

describe how not excersizing increases risk of cardiovascular disease

Answer 21

high blood pressure
atheroma formation
blood clots
heart attak

Question 21

describe how a diet high in saturated fats may increase risk of cardiovascular disease

Answer 21

high blood cholesterol
atheroma formation
blood clots
heart attack

Question 21

stroke symptoms

Answer 21

think FAST
Face=distorts one side
Arms=weak limbs on one side
Speech=difficulty speaking,slurring

Question 21

describe 2 ways smoking increases risk of cardiovascular disease

Answer 21

1.carbon monoxide less oxygen in blood less oxygen to tissues heat attack 2.fewer antioxidents damage to coronary artery walls atheroma formation heart attack

Question 22

posh word for heart attack?

Answer 22

myocardial infarction

Question 23

how to make a study more representative?

Answer 23

larger sample size

Question 24

explain how the xylem is adapted to its function

Answer 24

-no end walls=continuous flow of water -no organelle=hollow=eases flow of water -walls made of lignin=strength prevents collapsing, maintains adhesion -bordered pits=lateral flow of water

Question 25

describe the cohesion-tension theory

Answer 25

1.water evaporates from leaf out of stomata by transpiration 2.lowers water potential of mesophyll cells 3.water is pulled up xylem creating tension 4.water molecules cohere by hydrogen bonds 5.forming continuous water column 6.adhesion of water molecules to walls of xylem

Question 26

define transpiration

Answer 26

evaporation of water vapour from arial parts of the plants - stomata

Question 27

importance of transpiration stream

Answer 27

as water is lost from xylem in leaves its replace from below

Question 28

why is transpiration important?

Answer 28

1.photosynthesis 2.water allows cells to grow and elongate-phototropism 3.turgidity 4.evaporation cooling effect 5.flow of water carries mineral ions up plant

Question 29

how does temperature effect transpiration?

Answer 29

increase in temp more Kinetic energy of water molecules more water vapor lost via stomata

Question 30

how does humidity affect transpiration?

Answer 30

increase decreases evaporation from leaf smaller water potential gradient

Question 31

adaptations of xerophytes

Answer 31

smaller leaves thick waxy cuticle stomata close when hot hairs stomata sunk in pits rolling leaves loss of leaves high salt concentration in cells

Question 32

how do hairs on leaf help reduce water loss?

Answer 32

traps water vapour decreases water potential gradient

Question 33

how does stomata sunk in pits help reduce water loss?

Answer 33

traps water vapour close to surface of leaf decreases water potential

Question 34

how does rolling leaves help reduce water loss?

Answer 34

traps water vapour decreases water potential gradient reduces surface area

Question 35

how does a high salt concentration in cells help reduce water loss?

Answer 35

decreases water potential gradient in cells less water lost between cells

Question 36

what are xerophytes?

Answer 36

plants that can survive in dry climates

Question 37

limitations of potometer

Answer 37

1.messures water uptake not transpiration 2.cutting plant shoot may damage the plant 3. plant has no roots so no resistance to water being pulled up

Question 38

describe translocation

Answer 38

movement of assimilates like sucrose requires ATP source to sink

Question 39

define source

Answer 39

part of the plant that releases assimilates (makes)

Question 40

define sink

Answer 40

part of the plant that receives assimilates

Question 41

structure of seive tube elements

Answer 41

-few organelles,no nucleus -sieve plates form cross walls connect elements -elements lined end to end -plasmodesmata link the cytoplasm of companion cells and sieve tube elements

Question 42

structure of companion cell and function

Answer 42

-cytoplasm -many mitochondria for ATP for active transport -large nucleus so many proteins in plasma membrane and many ribosomes

Question 43

compare structure of xylem and phloem

Answer 43

xylem: -lignin -one way flow -no end walls phloem: -thin walls -two way flow -sieve plates form cross walls

Question 44

describe the mass flow hypothesis/translocation

Answer 44

1.active transport is used by companion cells to actively load sucrose into sieve tube elements reducing water potential 2.water enters the sieve tube elements by osmosis from surrounding tissues 3.this increases hydrostatic pressure in seive tube element 4.sucrose removed from sieve tube and increases water potential 5.water moves out of sieve tube and reduces hydrostatic pressure

Question 45

4 ways of evidence for mass flow

Answer 45

1.using aphids 2.ringing a tree 3.radioactive tracers 4.metabolic inhibitors

Question 46

explain how aphids can be used for evidence of mass flow

Answer 46

can investigate pressure in phloem sap flows out quicker nearer leaves than further down stem

Question 47

explain how ringing a tree can be used for evidence for mass flow (removing a ring of bark including phloem not xylem)

Answer 47

bulge forms above ringed area as sugars cant pass decreases water potential and water moves into the cells evidence for downwards flow of sugars

Question 48

how can radioactive tracers provide evidence for mass flow?

Answer 48

tracers like radioactive carbon- (14C) can be used to track movement of organic substances in a plant

Question 49

how can metabolic inhibitors be used for evidence of mass flow?

Answer 49

translocation can be stopped by using a metabolic poison e.g. cyanide that inhibits respiration so ATP cant form evidence that active transport is used

Question 50

what is evidence against mass flow?

Answer 50

1.sugar travels to many different sinks not just the one with lowest hydrostatic pressure 2.sieve plates would create a barrier to mass flow pressure needed