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more exchange and transport systems B Flashcards

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1
Q

what is digestion

A

hydrolysis of large insoluble molecules to smaller soluble molecules (often polymers to monomers)

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2
Q

what are the substrates and products of carbohydrate digestive enzymes

A

-amylase -> starch into smaller polysaccharides
-maltase -> maltose into 2x glucose
-sucrase-> sucrose into glucose and fructose
-lactase-> lactose into glucose and galactose

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3
Q

which enzymes are involved in carbohydrate digestion and where are they found

A

-amylase in mouth
-maltase, sucrase, lactase in membrane of small intestine

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4
Q

state the digestion of starch process

A

-amylase hydrolyses starch to maltose
-amylase produced by salivary glands,released into mouth
-amylase produced by pancreas, released into small intestine
-membrane bound maltase-> hydrolyse maltose to glucose
-hydrolysis of glycosidic bond

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5
Q

state the digestion of lipid process

A
  • Bile salts produced by the liver
  • Bile salts emulsify lipid to smaller lipid droplets
  • Increasing surface area of lipids speeds up action of lipases
  • Lipase made in the pancreas, released to small intestine
  • Lipase hydrolyses lipids → monoglycerides + fatty acids
  • Breaking ester bond
  • Monoglycerides, fatty acids and bile salts stick together to form micelles
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6
Q

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels

A
  1. Micelles contain bile salts and fatty acids/monoglycerides
  2. Make fatty acids/monoglycerides more soluble in water
  3. Fatty acids/monoglycerides absorbed by diffusion
  4. Triglycerides are formed in cells
  5. Vesicles move to cell membrane
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7
Q

Explain the advantages of lipid droplet and micelle formation

A
  1. Droplets increase surface areas for lipase / enzyme action
  2. So faster hydrolysis / digestion of lipids
  3. Micelles carry fatty acids and glycerol to cell
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8
Q

which enzymes are involved in protein digestion and what is their role

A

-endopeptidase=Hydrolyse peptide bonds between amino acids in the middle of the polypeptide
-exopeptidase=Hydrolyse peptide bonds at the ends of protein molecules
-dipeptidase= Hydrolyse peptide bond between a dipeptide and produces single amino acids

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9
Q

explain co transport of glucose and sodium ions

A
  1. Na+ actively transported out of epithelial cells by Na+/K+ pump into blood
  2. Establishes concentration gradient, as there is a higher conc of Na+ ions in the lumen of the intestine than inside the epithelial cells
  3. Na+ and glucose move by facilitated diffusion down conc gradient via co-transporter proteins into epithelial cell
  4. Glucose diffuses out of the cell into the blood plasma by facilitated diffusion using another type of carrier protein
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10
Q

why do fatty acids and monoglycerides not require co transport

A

molecules are non polar, meaning they can diffuse easily across the membrane of epithelial cells

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11
Q

what is the role of haemoglobin

A

to carry oxygen around the body

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12
Q

where is haemoglobin found in humans

A

red blood cells

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13
Q

why are red blood cells good for haemoglobin storage

A
  • No nucleus – contain more haemoglobin
  • Biconcave shape – increase surface area for rapid diffusion/absorption of oxygen
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14
Q

what is the structure of haemoglobin

A
  • Quaternary structured protein – made of 4 polypeptide chains
  • Each polypeptide chain contains a Haem group containing an iron ion (Fe2+) which combines with oxygen
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15
Q

what is meant by affinity for oxygen

A

ability of Hb to bind and release oxygen

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16
Q

describe the unloading of oxygen in regions with low pO2- respiring tissues

A
  • Hb has a low affinity for O2
  • So O2 readily unloads / dissociates with Hb
  • So % saturation is low
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17
Q

describe the loading pf oxygen with high pO2- gas exchange surfaces

A
  • Hb has a high affinity for O2
  • So O2 readily loads / associates with Hb
  • So % saturation is high
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18
Q

Describe how haemoglobin is involved in absorbing oxygen in the lungs and transporting it to respiring tissues

A
  1. diffusion of oxygen into red blood cells
  2. in lungs high pO2 so hb has high affinity for O2 so O2 binds readily to haem group forming oxyhaemoglobin -fully saturated
  3. in tissues low pO2 and hb has low affinity for O2 so unloads readily from haem group - low saturation
  4. in respiring tissues there’s a increase in pCO2 so dissociation curve shifts to right ( bohr effect) so affinity for O2 is even lower
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19
Q

The blood leaving a muscle has a lower pH than the blood entering it. During vigorous exercise, the fall in pH is even greater. Explain what causes this greater fall in pH

A
  1. in exercise there is a faster respiration rate
  2. more CO2 produced
  3. CO2 is acidic/ forms carbonic acid
  4. lactic acid production
  5. release of H+ ions = fall in pH (becomes more acidic)
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20
Q

How does the cooperative nature of oxygen binding result in an S-shaped (sigmoid) oxyhaemoglobin dissociation curve

A
  1. Binding of first oxygen causes Hb to change shape / tertiary / quaternary structure
  2. Which uncovers Haem group binding sites
  3. Making further binding of oxygens easier
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21
Q

what are the effects of CO2 conc on dissociation of oxyhaemoglobin : Bohr effect

A
  1. Increasing blood CO2 eg. due to increased rate of respiration
  2. Lowers blood pH (more acidic)
  3. Reducing Hb’s affinity for oxygen as shape / tertiary / quaternary structure changes slightly
  4. So more / faster unloading of oxygen to respiring cells at a given pO
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22
Q

what is the advantage of oxygen dissociation curve for oxyhaemoglobin shifting to the right

A

more oxygen for muscles/tissues for aerobic respiration → produce more ATP eg. for muscle contraction

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23
Q

Explain why the gradient of the oxygen dissociation curve is shallow initially

A

shape of haemoglobin makes it difficult for first oxygen to bind so at low oxygen partial pressures little oxygen binds

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24
Q

Explain why the gradient of the oxygen dissociation curve steepens after the first molecule of oxygen has bound

A

binding of the first oxygen changes the tertiary structure of haemoglobin making it easier for subsequent oxygen molecules to bind.

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25
Q

Explain why the gradient of the oxygen dissociation curve flattens off after the third oxygen has bound.

A

with the majority of binding sites occupied it is less likely that a single oxygen molecule will find an empty site to bind to

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26
Q

explain the adaptations of haemoglobin in organisms in low O2 environments

A
  • Curve shifted left → haemoglobin has a higher affinity for oxygen
  • More oxygen associates with haemoglobin more readily (in the lungs) at the lower pO2 BUT dissociates less readily
  • Advantageous to organisms such as those living in high altitudes, underground, or foetuses
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27
Q

explain the adaptations of Haemoglobin in organisms in high O2 environments

A
  • Curve shifted right → haemoglobin has a lower affinity for oxygen
  • Oxygen dissociates from haemoglobin more readily to respiring cells at a higher pO2 BUT associates less readily
  • Advantageous to organisms such as those with a high rate of respiration (metabolic rate) e.g. small / active organisms
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28
Q

Explain why large animals have a transport system

A

-Large animals have a small SA:volume and therefore have specialised exchange surfaces.
-Transport system is required to take substances from the exchange surfaces to all of the cells in the body

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29
Q

Describe the features of a transport system in large organisms

A

-A medium to carry materials (eg blood).
-A form of mass transport to move the medium in bulk.
-A closed system of vessels to transport the medium to all areas of the body.
-A mechanism to move the medium in vessels”

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30
Q

what is pulmonary circulation

A

Deoxygenated blood in right side of heart pumped to lungs → oxygenated blood returns to left side of hear

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31
Q

what is systemic circulation

A

Oxygenated blood in left side of heart pumped to tissues / organs of body →
deoxygenated blood returns to right side

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32
Q

what is a closed double circulatory system

A

blood enclosed in vessels and passes twice through the heart for each circuit of the body

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33
Q

describe the general pattern of blood circulation in a mammal

A
  1. Deoxygenated blood in right side of heart pumped to lungs; oxygenated returns to left side
  2. Oxygenated blood in left side of heart pumped to rest of body; deoxygenated returns to right
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34
Q

suggest the importance of a double circulatory system

A

-Prevents mixing of oxygenated / deoxygenated blood
=So blood pumped to body is fully saturated with oxygen for aerobic respiration
- Blood can be pumped to body at a higher pressure (after being lower from lungs)
=Substances taken to / removed from body cells quicker / more efficiently

35
Q

what is the overall function of arteries

A

carry blood away from heart at high pressure

36
Q

Explain how the structure of arteries relates to their function

A

● Thick smooth muscle tissue → can contract and control / maintain blood flow / pressure
● Thick elastic tissue → can stretch as ventricles contract and recoil as ventricles relax, to
reduce pressure surges / even out blood pressure / maintain high pressure
● Thick wall → withstand high pressure / stop bursting
● Smooth / folded endothelium → reduces friction / can stretch
● Narrow lumen → increases / maintains high pressure

37
Q

what is the overall function of arterioles

A

(division of arteries to smaller vessels which can) direct blood to different capillaries / tissues

38
Q

Explain how the structure of arterioles relates to their function

A

● Thicker smooth muscle layer than arteries
=Contracts → narrows lumen (vasoconstriction) → reduces blood flow to capillaries
=Relaxes → widens lumen (vasodilation) → increases blood flow to capillaries
● Thinner elastic layer → pressure surges are lower (as further from heart / ventricles)

39
Q

what is the overall function of veins

A

carry blood back to heart at lower pressure

40
Q

Explain how the structure of veins relates to their function

A

● Wider lumen than arteries → less resistance to blood flow
● Very little elastic and muscle tissue → blood pressure lower
● Valves → prevent backflow of blood

41
Q

what is the overall function of capillaries

A

allow efficient exchange of substances between blood and tissue fluid (exchange surface)

42
Q

Explain how the structure of capillaries relates to their function

A

● Wall is a thin (one cell) layer of endothelial cells → reduces diffusion distance
● Capillary bed is a large network of branched capillaries → increases surface area for diffusion
● Small diameter / narrow lumen → reduces blood flow rate so more time for diffusion
● Pores in walls between cells → allow larger substances through

43
Q

explain the formation of tissue fluid (at the arteriole end of capillaries)

A

● Wall is a thin (one cell) layer of endothelial cells → reduces diffusion distance
● Capillary bed is a large network of branched capillaries → increases surface area for diffusion
● Small diameter / narrow lumen → reduces blood flow rate so more time for diffusion
● Pores in walls between cells → allow larger substances through

44
Q

explain the return of tissue fluid to the circulatory system (at the venule end of capillaries )

A
  1. Hydrostatic pressure reduces as fluid leaves capillary (also due to friction)
  2. (Due to water loss) an increasing concentration of plasma proteins lowers water potential in capillary below that of tissue fluid
  3. Water enters capillaries from tissue fluid by osmosis down a water potential gradient
  4. Excess water taken up by lymph capillaries and returned to circulatory system through veins
45
Q

Suggest and explain causes of excess tissue fluid accumulation

A

● Low concentration of protein in blood plasma OR high salt concentration
=Water potential in capillary not as low → water potential gradient is reduced
=So more tissue fluid formed at arteriole end / less water absorbed at venule end by osmosis
● High blood pressure → high hydrostatic pressure
=Increases outward pressure from arterial end AND reduces inward pressure at venule end
= So more tissue fluid formed at arteriole end / less water absorbed at venule end by osmosis
=Lymph system may not be able to drain excess fast enough

46
Q

what do the coronary arteries do

A

Deliver oxygenated blood to cardiac muscle

47
Q

what does the aorta do

A

takes oxygenated blood from heart → respiring tissues

48
Q

what does the vena cava do

A

takes deoxygenated blood from respiring tissues → heart

49
Q

what does the pulmonary artery do

A

takes deoxygenated blood from the heart → lungs

50
Q

what does the pulmonary vein do

A

takes oxygenated blood from the lungs →heart

51
Q

what do the renal arteries do

A

take deoxygenated blood → kidneys

52
Q

what do the renal veins do

A

take deoxygenated blood to the vena cava from the kidneys

53
Q

How the structure of the heart relates to its function

A
  • Atrioventricular valves= Prevent backflow of blood from ventricles to atria
  • Semi lunar valves= Prevent backflow of blood from arteries to ventricles
  • Left has a thicker muscular wall= Generates higher blood pressure, For oxygenated blood has to travel greater distance around the body
  • Right has thinner muscular wall = Generates lower blood pressure, For deoxygenated blood to travel a small distance to the lungs where high
    pressure would damage alveoli
54
Q

what are the three stages of the cardiac cycle

A

-atrial systole
-ventricular systole
-diastole

55
Q

what happens within the atrial systole stage of the cardiac cycle

A

● Atria contract → volume decreases, pressure increases
●ventricles relax
● Atrioventricular valves open when pressure in atria exceeds pressure in ventricles
● Semilunar valves remain shut as pressure in arteries exceeds pressure in ventricles
● So blood pushed into ventricles

56
Q

what happens within the ventricular systole stage of the cardiac cycle

A

● Ventricles contract → volume decreases, pressure increases
●atria relax
● Atrioventricular valves shut when pressure in ventricles exceeds pressure in atria
● Semilunar valves open when pressure in ventricles exceeds pressure in arteries
● So blood pushed out of heart through arteries

57
Q

what happens within the diastole stage of the cardiac cycle

A

● Atria & ventricles relax → volume increases, pressure decreases
● Semilunar valves shut when pressure in arteries exceeds pressure in ventricles
● Atrioventricular valves open when pressure in atria exceeds pressure in ventricles
● So blood fills atria via veins & flows passively to ventricles

58
Q

describe the equation for cardiac output

A

Cardiac output (volume of blood pumped out of heart per min) = stroke volume (volume of blood pumped in each heart beat) x heart rate (number of beats per min)

59
Q

How can heart rate be calculated from cardiac cycle data?

A

Heart rate (beats per minute) = 60 (seconds) / length of one cardiac cycle (seconds)

60
Q

what is an atheroma?

A

-a fibrous plaque formed from the build up and hardening of white blood cells, lipids and connective tissue

61
Q

give two effects an atheroma has on the artery its in

A

-blocks the lumen of an artery
-restricts blood flow

62
Q

what are the risk factors for cardiovascular disease

A

-poor diet-> e,g, high salt diet increases the risk of high blood pressure
-high blood pressure-> increase risk of blood clotting
-age-> risk increases with age
-sex-> men have an increased risk
-smoking->e.g. nicotine increases risk of high blood pressure
-genetics-> some people have alleles which increase risk

63
Q

describe the function of xylem tissue

A

Transports water (and mineral ions) through the stem, up the plant to leaves of plants

64
Q

Suggest how xylem tissue is adapted for its function

A

● Cells joined with no end walls forming a long continuous tube → water flows as a continuous column
● Cells contain no cytoplasm / nucleus → easier water flow / no obstructions
● Thick cell walls with lignin → provides support / withstand tension / prevents water loss
● Pits in side walls → allow lateral water movements

65
Q

Explain the cohesion-tension theory of water transport in the xylem

A
  1. Water lost from leaf by transpiration through stomata
  2. Reducing water potential of mesophyll cells
  3. So water drawn out of xylem down a water potential gradient
  4. Creating tension in xylem
  5. Hydrogen bonds result in cohesion between water molecules (stick together) so water is pulled up as a continuous column
  6. Water also adheres (sticks to) to walls of xylem
  7. Water enters roots via osmosis
66
Q

what is used to estimate rate of transpiration

A

potometer

67
Q

describe how to set up a potometer

A
  1. Cut a shoot underwater at a slant → prevent air entering xylem
  2. Assemble potometer with capillary tube end submerged in a beaker of water
  3. Insert shoot underwater
  4. Ensure apparatus is watertight / airtight
  5. Dry leaves and allow time for shoot to acclimatise
  6. Shut tap to reservoir
  7. Form an air bubble - quickly remove end of capillary tube from wate
68
Q

Describe how a potometer can be used to measure the rate of transpiration

A
  1. Record position of air bubble
  2. Record distance moved in a certain amount of time (eg. 1 minute)
  3. Calculate volume of water uptake in a given time:
  4. Calculate rate of water uptake - divide volume by time taken
69
Q

Describe how a potometer can be used to investigate the effect of a named
environmental variable on the rate of transpiration

A

● change one variable at a time (wind, humidity, light or temperature)
● Keep all other variables constant

70
Q

Suggest limitations in using a potometer to measure rate of transpiration

A

● Rate of water uptake might not be same as rate of transpiration
● Rate of movement through shoot in potometer may not be same as rate of movement through shoot of whole plant

71
Q

what are the different environmental variables affect transpiration rate

A

-light intensity
-temperature
-wind intensity
-humidity

72
Q

how does light intensity affect transpiration rate

A

(Increases rate of transpiration)
● Stomata open in light to let in CO2 for photosynthesis
● Allowing more water to evaporate faster
● Stomata close when it’s dark so there is a low transpiration rate

73
Q

how does temperature affect the transpiration rate

A

(increases rate of transpiration)
● Water molecules gain kinetic energy as temperature increases
● So water evaporates faster

74
Q

how does wind intensity affect the transpiration rate

A

(increases rate of transpiration)
● Wind blows away water molecules from around stomata
● Decreasing water potential of air around stomata
● Increasing water potential gradient so water evaporates faster

75
Q

how does humidity affect the transpiration rate

A

(decreases rate of transpiration)
● More water in air so it has a higher water potential
● Decreasing water potential gradient from leaf to air
● Water evaporates slower

76
Q

describe the function of the phloem tissue

A

Transports organic substances eg. sucrose in plants

77
Q

Suggest how phloem tissue is adapted for its function

A

● No nucleus / few organelles → maximise space for / easier flow of organic substances
● End walls between cells perforated (sieve plate)
● Many mitochondria → high rate of respiration to make ATP for active transport of solutes

78
Q

What is translocation?

A

● Movement of solutes such as sucrose
● From source cells (where made, eg. leaves) to sink cells (where used / stored, eg. roots) by mass flow

79
Q

Explain the mass flow hypothesis for translocation in plants

A
  1. At source, sucrose is actively transported into phloem sieve tubes / cells
  2. By companion cells
  3. This lowers water potential in sieve tubes so water enters (from xylem) by osmosis
  4. This increases hydrostatic pressure in sieve tubes (at source) / creates a hydrostatic pressure gradient
  5. So mass flow occurs - movement from source to sink
  6. At sink, sucrose is removed by active transport to be used by respiring cells or stored in storage organs
80
Q

Describe the use of tracer experiments to investigate transport in plants

A
  1. Leaf supplied with a radioactive tracer
  2. Radioactive carbon incorporated into organic substances during photosynthesis
  3. These move around plant by translocation
  4. Movement tracked using autoradiography
81
Q

what is the supporting evidence for mass flow

A

-metabolic inhibitors stops translocation-> ATP must be needed
-autoradiography
-heat treatment or cooling reduces translocation-> respiratory enzymes are needed

82
Q

what is the opposing evidence for mass flow

A

-not all solutes move at the same rate
-not all solutes move in opposite directions
-solutes must travel to many sinks

83
Q

Use your knowledge of gas exchange in leaves to explain why plants grown in soil with very little water grow only slowly

A
  1. Stomata close;
  2. Less carbon dioxide (uptake) for less photosynthesis/glucose
    production;

biology year 1 (10 decks)

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