7 mass transport

Question 1

describe the structure of haemoglobin

Answer 1

quaternary structure
4 sub units containing a haem group

Question 2

what can each haem group do on a haemoglobin molecule?

Answer 2

combine with one molecule of oxygen

Question 3

what is oxyhaemoglobin?

Answer 3

haemoglobin that is associated with oxygen

Question 4

what is deoxyhaemaglobin?

Answer 4

haemoglobin that is dissociated with oxygen

Question 5

how do you calculate percentage saturation of haemoglobin with oxygen?

Answer 5

oxygenated haemoglobin / maximum saturation x100

Question 6

define partial pressure of oxygen

Answer 6

the amount of oxygen in a mixture of gases

Question 7

what does affinity mean?

Answer 7

a natural attraction

Question 8

why does a high ppCO2 cause a lower affinity to O2?

Answer 8

CO2 makes blood acidic which lowers the pH and changes Hb tertiary structure

Question 9

what is the role of Hb?

Answer 9

to transport oxygen

Question 10

what are the 4 chambers of the heart called?

Answer 10

right atrium
right ventricle
left atrium
left ventricle

Question 11

what are the 4 main vessels called in the heart?

Answer 11

vena cava
pulmonary artery
pulmonary vein
aorta

Question 12

do veins carry blood in or out of the heart?

Answer 12

in

Question 13

what are the 2 valves called?

Answer 13

semi lunar
atrio ventricular

Question 14

when do semi lunar valves open?

Answer 14

when there is a greater pressure in the ventricle

Question 15

when do valves open?

Answer 15

when pressure is higher behind valve

Question 16

why do valves open and close?

Answer 16

to prevent back flow of blood

Question 17

what does the septum do in the heart?

Answer 17

separate deoxygenated and oxygenated blood

Question 18

what are the three stages of the cardiac cycle?

Answer 18

atrial systole
ventricular systole
diastole

Question 19

what do systole and diastole mean?

Answer 19

systole- contraction of heart muscle
diastole- relaxed heart muscle

Question 20

what is the activity of the heart measured as?

Answer 20

cardiac output

Question 21

define cardiac output

Answer 21

volume of blood pumped out of left ventricle per minute

Question 22

what are four risk factors of coronary heart disease?

Answer 22

high cholesterol
high lipid diet
lack of exercise
smoking

Question 23

what is the structure of an artery?

Answer 23

endothelial layer: thin to reduce friction
elastic layer: thick
outer layer: made of fibrous proteins for strength

Question 24

what is the structure of a capillary?

Answer 24

only has single endothelial layer

Question 25

what is the structure of veins?

Answer 25

muscle layer thinner than artery elastic layer thin

Question 26

how is tissue fluid formed?

Answer 26

1. high hydrostatic pressure 2. forces fluid out 3. large proteins remain in capillary

Question 27

how is tissue fluid returned to the circulatory system?

Answer 27

1. lowers water potential in blood 2. due to proteins 3. water enters blood by osmosis

Question 28

where does the rest of the tissue fluid go when it doesn’t reabsorb by osmosis?

Answer 28

lymph nodes

Question 29

what factors affect transpiration?

Answer 29

light temp humidity air movement

Question 30

how does light affect transpiration?

Answer 30

stomata open in light close in dark

Question 31

how does temperature affect transpiration?

Answer 31

hotter- more kinetic energy and H2O evaporates faster

Question 32

how does humidity affect transpiration?

Answer 32

more water vapour in air = water potential more positive reduces water potential gradient

Question 33

how does air movement affect transpiration?

Answer 33

more windy = moves water vapour away from stomata pores

Question 34

what does the xylem transport?

Answer 34

water

Question 35

what does the phloem transport?

Answer 35

sugars and organic substances

Question 36

here does the xylem transport water to and from?

Answer 36

roots to leaves

Question 37

where does the phloem transport sugars to and from?

Answer 37

leaves to roots/flowers/shoots

Question 38

give 3 adaptations of the xylem

Answer 38

1. dead hollow tubes- allowed easier water flow 2. contain lignin- allow the xylem to be rigid and withstand tension 3. xylem pits- enable water to move between xylem vessels

Question 39

explain transpiration

Answer 39

stomata open water diffuses from air spaces to outside the leaf loss of water from leaf = transpiration

Question 40

explain how water enters the xylem from the endodermis

Answer 40

1. active transport of ions into xylem 2. lowers water potential in xylem 3. so water can enter by osmosis

Question 41

explain how water is transported to the leaves through the xylem

Answer 41

1. evaporation from leaves 2. creates tension (pulling force) due to negative pressure 3. H bonds form between H2O molecules (tension) 4. water molecules bind to xylem (adhesion) 5. creates a continuous column of water 6. transpiration stream

Question 42

what are solutes?

Answer 42

dissolved substances

Question 43

does the xylem require ATP to transport water?

Answer 43

no

Question 44

what is beside every sieve tube element in a phloem?

Answer 44

companion cell

Question 45

why is there a companion cell next to every sieve tube element?

Answer 45

contain many mitochondria to synthesise ATP through aerobic respiration for active transport of solutes

Question 46

describe the mass flow hypothesis for translocation in plants

Answer 46

1. in leaf, sugars actively transported into phloem by companion cells 2. lowers water potential of sieve tube so water enter via osmosis 3. increased pressure causes mass movement towards root 4. sugars stored in root for respiration