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Exchange Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How do microorganisms obtain nutrients and remove waste

A
  • nutrients (glucose,oxygen) move in by diffusion via their surface
  • waste (CO2) moves out by diffusion via their surface
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2
Q

Why are microorganisms able to perform exchange via their surface

A
  • have a large SA to volume ratio
  • short diffusion distance
  • have low demand
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3
Q

Why can’t plants/animals perform exchange via their surface

A
  • have a small SA to volume ratio
  • large diffusion distance
  • require specialised systems
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4
Q

Why do fish have specialised gas exchange systems

A
  • they have a small SA to volume ratio
  • large diffusion distance
  • so can’t perform gas exchange via their surface, require specialised system called gills
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5
Q

What is gas exchange

A

oxygen in, carbon dioxide out

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6
Q

Structure of gills in fish

A
  • many gill filaments and lamellae; increase surface area
  • lamellae have thin walls so have a short diffusion distance
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7
Q

What does ventilation do in fish

A

brings in pure water, high oxygen low carbon dioxide

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8
Q

What does circulation do in fish

A

brings in deoxygenated blood, low oxygen high carbon dioxide

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9
Q

What is the counter-current flow

A

water and blood pass over in opposite directions, maintaining the concentration gradient along the lamellae

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10
Q

Why do insects have specialised gas exchange systems

A
  • small SA to volume ratio
  • large diffusion distance
  • so can’t perform gas exchange via their surface, require specialised system called tracheal system
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11
Q

Structure of tracheal system in insects

A
  • starts with openings on body surface called spiracles; spiracles contain valves, if open, gas exchange, if closed, preventing water loss
  • spiracles connect to trachea
  • trachea connect to tracheoles
  • tracheoles connect directly to respiring cells
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12
Q

How does gas exchange occur in tracheal system of insects

A
  • at rest, down a concentration gradient, oxygen moves in, co2 moves out via simple diffusion
  • when active, by ventilation, air inhaled for mass flow of oxygen, air exhaled for mass flow of co2
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13
Q

Function of the lungs

A

site of gas exchange in mammals

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14
Q

Components of the lungs

A
  • trachea
  • bronchi
  • bronchioles
  • alveoli
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15
Q

Function of trachea, bronchi and bronchioles

A

transport of air and filter (bronchioles also control how much air reaches alveoli)

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16
Q

Adaptation of alveoli

A
  • million of folded microvilli (large surface area)
  • one cell thick (short diffusion distance)
  • ventilation maintains concentration gradient
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17
Q

Adaptation of capillaries

A
  • one cell thick (short diffusion distance)
  • narrow lumen (increases diffusion time, decreases diffusion distance)
  • cirvulation maintains concentration gradient
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18
Q

How does oxygen move from alveoli to capillaries

A

by simple diffusion passing through alveolar epithelium and capillary epithelium

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19
Q

How does CO2 move from capillaries to alveoli

A

by simple diffusion passing through capillary epithelium and alveolar epithelium

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20
Q

Describe the process of breathing in/inhalation

A
  • external intercostal muscles contract, rib cage moves up and out
  • diaphragm contracts (flattens)
  • increase in volume, decrease in pressure
  • air moves in
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21
Q

Describe the process of breathing out/exhalation

A
  • external intercostal muscles relax, rib cage moves down and in
  • diaphragm relaxes
  • decrease in volume, increase in pressure
  • air moves out
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22
Q

What is pulmonary ventilation

A

volume of air breathed in/out per minute

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23
Q

Formula for pulmonary ventilation

A

PV = tidal volume (volume of air breathed in/out in one breath) x ventilation rate (number of breaths per minute)

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24
Q

Function of intestines

A

site of exchange of digested nutrients in mammals

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25
Q

What is digestion

A

breakdown of large insoluble molecules into small soluble molecules (so they can move into the blood then into body cells)

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26
Q

How are lipids broken down

A

by lipase into monoglycerides and 2 fatty acids (small intestine)

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27
Q

How are proteins broken down

A

by endopeptidase/exopeptidase/dipeptidase into amino acids

endo= in stomach
exo= in small intestine
di= on lining of SI

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28
Q

How is starch/glycogen broken down

A

by amylase into glucose; if on lining of small intestine, maltase/lactase/sucrase are used

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29
Q

Where can amylase be found

A
  • salivary glands
  • pancreas
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30
Q

Where can maltase/lactase/sucrase be found

A

lining of small intestine

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31
Q

What does the small intestine absorb

A

small soluble nutrients (glucose, amino acids, monoglyceride and fatty acids, vitamins and minerals)

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32
Q

What does the large intestine absorb

A

water

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33
Q

Why do humans need a specialised transport system

A
  • multicellular organisms so have a large diffusion distance and high demand
  • need a transport system to deliver nutrients and remove waste from all cells
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34
Q

Name the human transport system

A

circulatory system

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35
Q

Components of the circulatory system + roles

A
  • heart (pumps blood)
  • blood vessels (carry blood)
  • blood (carries nutrients/waste)
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36
Q

Why it called the double circulatory system in humans

A

the heart pumps twice, transporting oxygenated and deoxygenated blood; generates enough pressure to supply all body cells

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37
Q

Why is it called a closed system in humans

A

blood is transported in blood vessels, helps to maintain pressure and redirect blood flow

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38
Q

Layout of circulatory system

A

artery, arterioles, capillaries, venules, veins

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39
Q

Role of artery/arterioles

A

carry oxygenated blood away from the heart

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40
Q

Role of capillaries

A

site of exchange

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41
Q

Role of veins/venules

A

return deoxygenated blood to the heart

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42
Q

Components of the heart

A
  • left and right atriums
  • left and right ventricles
  • atria pump blood to ventricles
  • ventricles pump blood out of the heart
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43
Q

Ventricles vs atria

A

ventricles are thicker since they have to pump blood further

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44
Q

Left vs right ventricle

A

left ventricle thicker as it pumps blood to the whole body

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45
Q

Name 4 blood vessels in the heart + roles

A
  • vena cava (supplies R atrium with deoxygenated blood from body)
  • pulmonary vein (supplies L atrium oxygenated blood from lungs)
  • pulmonary artery (supplies deoxygenated blood to lungs to become oxygenated)
  • aorta (supplies oxygenated blood to body)
46
Q

Role of valves

A

ensure one way flow of blood, prevents backflow

47
Q

Name the 2 types of valves in the heart

A
  • AV valve, between atria and ventricles
  • SL valve, between ventricles and arteries
48
Q

When are AV valves open or closed

A
  • open, pressure in atria greater than pressure in ventricles
  • closed, pressure in ventricles is greater than pressure in atria
49
Q

When are SL valves open or closed

A
  • open, pressure in ventricles greater than pressure in arteries
  • closed, pressure in arteries greater than pressure in ventricles
50
Q

Describe the cardiac cycle

A

Cardiac diastole:
- atria relaxed, ventricles relaxed
- AV valve open, SL valve closed

Atrial systole:
- atria contract whilst ventricles relax
- decreases volume inside atria which increases pressure
- increased pressure forced AV valves to open and pushes blood into the ventricles

Ventricular systole:
- ventricles contract whilst atria relax
- decreases volume inside ventricles which increases pressure
- pressure is now higher in ventricles so AV valves close and SL valve opens
- closure of AV valve is important to prevent backflow of blood into atria
- blood is forced out of ventricles into arteries

Diastole:
- atria and ventricles relaxed
- AV valve opens, SL valve closes
- filling starts again

51
Q

What causes the heart sounds

A

when the valves close, 1st is the AV valve, 2nd is the SL valve

52
Q

Formula for cardiac output

A

CO = stroke volume x heart rate

53
Q

What is stroke volume

A

volume of blood pumped out of heart in one beat

54
Q

What is heart rate

A

number of beats per minute

55
Q

What is cardiac output

A

volume of blood pumped out of the heart per minute

56
Q

Describe how CHD occurs

A
  • high blood pressure damages lining of coronary artery
  • cholesterol builds up beneath lining, in the wall
  • this causes turbulent blood flow
  • a blood clot forms
  • this blocks the coronary artery
  • so less blood flow to the heart muscle
  • so less glucose and oxygen delivered
  • the heart muscle can’t respire so it dies (myocardial infarction)
57
Q

Risk factors of CHD

A
  • obesity
  • smoking
  • lack of exercise
  • age, gender, ethnicity
  • saturated fats
58
Q

Exception for the role of an artery

A

pulmonary artery carries deoxygenated blood to lungs

59
Q

Exception for the role of a vein

A

pulmonary vein carries oxygenated blood to the heart

60
Q

Structure of artery/arterioles

A
  • narrow lumen, maintains pressure
  • thick wall, withstands high pressure
  • elastic tissue in wall, allows for expansion and contraction when necessary to withstand pressure
  • collagen in walls, prevents artery from tearing
61
Q

Structure of veins

A
  • wide lumen, ease off blood flow
  • thin wall
  • valves in lumen, prevents backflow of blood
62
Q

Structure of capillaries

A
  • one cell thick, short diffusion distance
  • pores between cells, allows fluid to move in and out
  • narrow lumen, increases diffusion time, decreases diffusion distance
  • many small capillaries, increase SA
63
Q

Contents of blood

A
  • plasma; carries cells and solutes
  • cells; red and white blood cells, platelets
  • solutes; nutrients, waste, protein
64
Q

How does exchange occur between capillaries and all cells

A
  • by mass flow
  • fluid moves out of blood in the capillaries carrying nutrients
  • fluid moves back into blood in the capillaries carrying waste
65
Q

What is the fluid surrounding our cells called

A

tissue fluid

66
Q

How is tissue fluid formed and returned to the circulatory system

A
  • at the start of the capillary (arterial end) , build up of hydrostatic pressure
  • this pushes fluid out of the capillary via the pores
  • the fluid carries nutrients with it
  • the fluid surrounds the cells (tissue fluid)
  • at the end of the capillary (venous end), fluid moves back in by osmosis
  • capillary has low water potential due to presence of proteins
  • any excess tissue fluid is picked up by the lymph system and deposited in the vena cava
67
Q

Why does high blood pressure cause accumulation of tissue fluid

A

increases hydrostatic pressure, so more tissue fluid is formed

68
Q

Why does diet low in protein cause accumulation of tissue fluid

A

water potential in the capillary isn’t as low as normal, so not as much fluid can move back into capillary by osmosis

69
Q

Role of red blood cells

A

carries haemoglobin, haemoglobin carries oxygen to cells

70
Q

Structure of haemoglobin

A
  • globular protein (soluble and specific 3D shape)
  • quaternary structure made of 4 polypeptide chains
  • each chain carries haem group
  • each haem group carries Fe2+
  • each Fe2+ carries an O2
  • so each haemoglobin carries 4 lots of O2
71
Q

Role of haemoglobin

A

load oxygen into lungs and deliver to respiring tissues

72
Q

What is affinity

A

the level of attraction haemoglobin has to oxygen

high affinity = strong attraction
low affinity = weak attraction

73
Q

Role of haemoglobin in oxygen transport

A
  • haemoglobin has high affinity in the lungs due to high partial pressure of oxygen and low partial pressure of carbon dioxide
  • so haemoglobin loads oxygen in the lungs and becomes saturated
  • haemoglobin is transported in blood in red blood cell
  • at respiring tissues, haemoglobin has low affinity due to low partial pressure of oxygen and high partial pressure of carbon dioxide
  • so oxygen is unloaded and haemoglobin is therefore unsaturated
74
Q

Relationship between oxygen partial pressure and affinity of haemoglobin

A
  • positive correlation, as oxygen partial pressure increases, affinity of haemoglobin increases
  • correlation is curved not linear
75
Q

Relationship between carbon dioxide partial pressure and haemoglobin affinity

A
  • negative correlation, as carbon dioxide partial pressure increases, affinity of haemoglobin decreases
  • CO2 lowers pH of blood, causes haemoglobin to change shape, lowering its affinity
76
Q

How does a fetus receive oxygen

A
  • from mother’s blood, oxygen dissociates from mother’s haemoglobin and associates with fetal haemoglobin in placenta
  • fetal haemoglobin has higher affinity than mother’s haemoglobin
77
Q

Benefit of fetal haemoglobin having high affinity

A

fetal haemoglobin’s ODC will be to the left, high affinity

78
Q

Why do adults not keep with fetal haemoglobin

A

the high affinity will mean less oxygen will be unloaded at respiring tissues

79
Q

Affinity of organisms in a low oxygen environment

A
  • high affinity, curve to the left
  • so can readily associate at low oxygen partial pressures
80
Q

Affinity of active organisms

A
  • low affinity, curve to the right
  • so more oxygen can be unloaded to meet cell’s demand for more respiration
81
Q

Affinity of small organisms

A
  • large SA to volume ratio, lose alot of heat, needs to respire to generate heat
  • low affinity, curve to the right, so unloads enough oxygen for cells which demand more oxygen
82
Q

Name the exchange systems in plants

A
  • leaf, to absorb light and CO2 for photosynthesis
  • roots, to absorb water and minerals
83
Q

Name the transport systems in plants

A
  • xylem, transports water and minerals in one direction from roots to leaves
  • phloem, transports glucose/sugars in both directions
84
Q

Role of the roots

A
  • absorb water and minerals
  • absorb water by osmosis
  • absorb minerals by active transport
85
Q

What do plants need

A
  • water, for photosynthesis, cytoplasm hydration, turgidity of cells
  • magnesium, nitrate and phosphate, mg to make chlorophyll, nitrate to make amino acids, phosphate to make ATP
86
Q

Role of the xylem

A

transport water and minerals from roots, up the plant, to the leaves

87
Q

Structure of xylem

A
  • long continuous hollow tube (no resistance to water flow)
  • narrow lumen
  • wall made of lignin, lignin is strong, waterproof and adhesive
  • wall contains pores so water and minerals can leave
88
Q

How does water move up the xylem

A
  • loss of water at the leaves (transpiration)
  • water moves from the xylem to the leaf by osmosis (transpiration pull)
  • this applies tension to the column of water in the xylem
  • the column of water moves up as one as the water particles stick together; cohesion tension theory
  • it’s supported by capillary action, adhesion and root pressure
89
Q

Why does the diameter of a tree decrease during the day

A
  • more light and higher temperature
  • increases rate of transpiration
  • increases transpiration pull
  • water pulled up xylem by cohesion tension as the water particles stick to the wall of the xylem
90
Q

Structure of leaves

A
  • upper layer called upper epidermis
  • waxy cuticle on upper epidermis (barrier to reduce water loss)
  • beneath upper epidermis are palisade cells
  • palisade cells are where photosynthesis takes place
  • beneath palisade cells are spongy mesophyll cells which are loosely packed leaving air spaces to allow for gas exchange
  • lower layer called lower epidermis
91
Q

Adaptations of palisade cells for photosynthesis

A
  • located near top of leaf, closer to sunlight
  • large size, large surface area for sunlight
  • thin cell wall, short diffusion distance for CO2
  • contains many chloroplasts, site of photosynthesis
  • large vacuole, pushes chloroplast to edge of cell closer to light
92
Q

Structure of chloroplast

A
  • double membrane
  • contains thylakoids
  • thylakoids contain chlorophyll
  • stack of thylakoids called granum
  • thylakoids surrounded by fluid called stroma
93
Q

How does exchange occur in leaves

A
  • lower epidermis of plant contains guard cells
  • when turgid, guard cells form opening called stomata
  • gas exchange occurs via stomata
94
Q

What exchange occurs in leaves during the day

A
  • plant photosynthesises and respires
  • CO2 moves in for photosynthesis
  • Oxygen moves out
95
Q

What exchange occurs in leaves at night

A
  • plant only respires
  • oxygen moves in for respiration
  • CO2 moves out
96
Q

What is transpiration

A

loss of water vapour from the leaf via the stomata

97
Q

How does transpiration occur

A
  • moist lining of spongy mesophyll cells evaporate forming water vapour
  • water vapour builds up in air spaces
  • if water vapour concentration is high enough and stomata is open, water vapour diffuses out
98
Q

Factors that increase rate of transpiration

A
  • sunlight; more sunlight means more stomata open, increases SA for transpiration
  • temp; higher temp means more evaporation
  • wind; more wind maintains concentration gradient
  • humidity; less humidity means less water vapour in surrounding air, increase in water vapour
99
Q

What is a potometer

A

apparatus used to measure rate of transpiration

100
Q

How does a potometer work

A

as transpiration occurs from the leaves, plant will pull up more water from the potometer by cohesion-tension causing the bubble to move towards plant

101
Q

How to measure rate of transpiration

A

rate of transpiration = volume of transpiration/time

102
Q

How to set up a potometer

A
  • choose healthy leaf and shoot
  • cut shoot underwater and connect to potometer underwater
  • ensure potometer is air and water tight
103
Q

What does a potometer measure

A

rate of water uptake as a result of water loss from a plant

104
Q

What is a xerophyte

A

a plant adapted to reduce water loss (reduce transpiration)

105
Q

Adaptations of xerophyte

A
  • spiky leaves, reduced surface area
  • thick, waxy cuticle, waterproof, impermeable barrier
  • densely packed spongy mesophyll, less air spaces, less water vapour build up
  • hairy leaves, traps moist layer of air, reduces concentration gradient
106
Q

Function of phloem

A

transport organic materials like sugars and minerals

107
Q

Structure of phloem

A

made of 2 parts, sieve tube with companion cells alongside)

108
Q

Role of sieve tube in phloem

A

transports organic substances

109
Q

Role of companion cells in phloem

A

help with ATP production

110
Q

How does the phloem transport organic material like sucrose

A
  • by mass flow
  • sucrose loaded into phloem at source
  • H+ ions actively transported from companion cells into source
  • so H+ ions diffuse back into companion cells from source
  • they also pull in sucrose with them by co-transport
  • sucrose then diffuses into sieve tube
  • this lowers water potential of sieve tube so water follows by osmosis
  • this water will carry the sucrose by hydrostatic pressure
  • sucrose unloaded from phloem at sink
  • sucrose moves out of phloem into sink by diffusion
  • water follows by osmosis

Biology (5 decks)

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