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biology > organisms exchange substances with their environment > Flashcards

organisms exchange substances with their environment Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

surface area to volume ratio

A

small organisms have a very large surface area in comparison to their volume (divide volume by surface area) whilst large organisms have a small surface area to volume ratio

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2
Q

gas exchange across single-celled organisms

A

diffuse directly into or out of the cell across the cell surface membrane

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3
Q

structure of fish gills

A
  • four layers of gills on each side of head, supported by arches
  • gills are made of stacks of gill filaments
  • lamellae at right angles to gill filaments
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4
Q

process of gas exchange in fish

A
  • fish open mouth to enable water to flow over it then close
  • increases pressure
  • water passes over lamellae and oxygen diffuses into blood
  • CO2 diffuses out and into water and flows back out of gills
  • through counter-current mechanism
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5
Q

counter-current exchange principle

A
  • maintains a steep concentration gradient across entire length of lamellae
  • water and blood flow in opposite direction
  • water always has more O2 than blood
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6
Q

why can’t fish use their bodies for gas exchange?

A

waterproof, impermeable membrane with a small surface area

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7
Q

structures of dicotyledonous plants

A

stomata, spongy mesophyll and pallisade layer

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8
Q

stomata

A
  • site of gas exchange
  • pores formed by two guard cells
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9
Q

reduction of water loss in plants

A

stomata close at night when photosynthesis would not be occuring

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10
Q

spongy mesophyll

A
  • irregularly shaped cells
  • air spaces to allow diffusion between stomata and photosynthesisng cells
  • help maintain concentration gradient
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11
Q

pallisade layer

A
  • pallisade cells which contain chloroplasts
  • site of photosynthesis
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12
Q

adaptations of leaf for gas exchange

A
  • thin and flat for short diffusion path and large SA:V
  • stomata under leaf
  • air spaces in mesophyll allow gases to move around leaf for photosynthesis
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13
Q

why can’t insects use their bodies for gas exchange?

A

they have a waterproof chitin exoskeleton and a small SA:V to conserve water

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14
Q

structures and function of insect gas exchange

A

spiracles- holes on body’s surface that can open and close with use of valves
tracheae- large tubes extending through all body tissues
tracheoles- smaller branches dividing of tracheae

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15
Q

process of gas exchange in insects

A
  • gases move in and out of tracheae through spiracles
  • maintains a concentration gradient
  • contraction of muscles in tracheae allows mass movement of air in and out
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16
Q

adaptations of insects for gas exchange

A
  • tracheoles have thin walls so short diffusion distance
  • highly branched for large surface area
  • tracheae provide tube full of air so fast diffusion into tissues
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17
Q

xerophytic plants

A

plants that are adapted to survive in environments with limited water

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18
Q

adaptations of xerophytic plants

A
  • curled leaves to trap moisture to increase local humidity and therefore reduce WP gradient
  • hairs to trap moisture
  • sunken stomata to trap moisture
  • thicker cuticle to reduce evaporation
  • longer root network to reach more water
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19
Q

gross structure of the human gas exchange system

A

alveoli, bronchioles, bronchi, trachea and lungs

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20
Q

alveoli

A
  • large number of alveoli
  • thin walls
  • extensive capillary network
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21
Q

bronchioles

A
  • narrower than bronchi
  • muscle and elastic fibres
  • air into alveoli
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22
Q

bronchi

A
  • supported by rings of cartilage
  • ciliated epthelium
  • narrow
  • one in each lung
  • air into bronchioles
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23
Q

trachea

A
  • wide tube supported by cartilage
  • lined with ciliated epithelium cells
  • carries air to bronchi
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24
Q

lungs

A
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25
Q

respiration

A

chemical reaction to release energy in the form of ATP

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26
Q

breathing

A

movement of air into and out of the lungs (scientific word is ventilation)

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27
Q

what is gaseous exchange humans?

A

diffusion of oxygen from air in the alveoli into the blood and of carbon dioxide from the blood into the air in the alveoli

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28
Q

inhalation (inspiration)

A
  • the external intercostal muscles contract whereas the internal muscles relax, as a result this causes the ribs to raise upwards
  • the diaphragm contracts and flattens
  • the intercostal muscles and diaphragm cause the volume inside the thorax to increase, thus lowering the pressure
  • the difference between the pressure inside the lungs and atmospheric pressure creates a gradient, thus causing the air to be forced into the lungs
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29
Q

exhalation (expiration)

A
  • the internal intercostal muscles contract whereas the external muscles relax therefore lowering the rib cage
  • the diaphragm relaxes and raises upwards
  • this action in combination decreases the volume inside the thorax, therefore increasing the pressure
  • forces the air out of the lungs
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30
Q

alveolar epithelium and capillary diffusion

A
  • the exchange of oxygen and carbon dioxide occurs between the alveoli and the capillaries in the lungs
  • oxygen and carbon dioxide are exchanged in a process of simple diffusion
  • the air in the alveoli contains a high concentration of oxygen
  • the oxygen diffuses from the alveoli and into the blood capillaries, before being carried away to the rest of the body for aerobic respiration
  • the blood in the capillaries has a relatively low concentration of oxygen and a high concentration of carbon dioxide
  • the carbon dioxide diffuses from the blood and into the alveoli and is then exhaled.
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31
Q

spirometry

A

measures air volumes- spirometry measures the volume of air that is exchanged between the lungs and the atmosphere

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32
Q

digestion

A

large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes

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33
Q

pulmonary ventilation rate

A

tidal volume x breathing rate

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34
Q

tidal volume

A

the normal volume of air in each breath (norm=0.5dm3)

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35
Q

breathing rate

A

number of breathes per minute

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36
Q

digestion of carbohydrates location

A

mouth and small intestine

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37
Q

what hydrolyse carbohydrates?

A

amylases and membrane-bound disaccharides

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38
Q

role of amylase

A

hydrolyses polysaccharides into disaccharides by hydrolysing glycosidic bonds

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39
Q

role of membrane-bound disaccharides

A

sucrase, maltase and lactase hydrolyse disaccharides (e.g sucrose, maltose and lactose) into monosaccharides

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40
Q

digestion of lipids location

A

small intestine

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41
Q

what hydrolyse lipids?

A

lipase and bile salts (emulsification)

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42
Q

role of bile salts

A

emulsify lipids, forming micelles, to provide a larger surface area for lipase action

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43
Q

role of lipase

A

hydrolyses ester bonds between monoglycerides and fatty acids

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44
Q

what are micelles?

A

micelles are water soluble vesicles that contain bile salts and fatty acids/monoglycerides

45
Q

digestion of proteins location

A

stomach and small intestine

46
Q

what hydrolyse proteins?

A

membrane-bound dipeptidases, endopeptidases and exopeptidases

47
Q

role of endopeptidases

A

hydrolyse peptide bonds between amino acids in the middle of a polymer chain

48
Q

exopeptidases

A

hydrolyse peptide bonds between amino aicds at the end of a polymer chain

49
Q

membrane-bound dipeptidases

A

hydrolyse peptide bonds in a dipeptide into two amino acids

50
Q

wall of ileum structure

A
  • covered in villi
  • thin walls surrounded by capillary network
  • epthilial cells have microvilli
51
Q

absorption of monosaccharides and amino acids

A
  • sodium ions actively transported out of the epithelial cell into blood
    -reduces sodium ion concentration in epithelial
  • sodium ions can the diffuse from lumen down their concentration gradient into epithelial cell
  • does this through a co-transporter protein
  • glucose or amino acids are actively transported
  • glucose moves by facilitated diffusion from the epithelial cell to the blood
52
Q

why do fatty acids and monoglycerides not require co-transport?

A

they are non-polar so can diffuse across the membrane of the epithelial cells

53
Q

absorption of fatty acids and monoglycerides

A
  • micelles contain bile salts and fatty acids/monoglycerides
  • bring them to the lining of the ileum
  • fatty acids/monoglycerides are absorbed by diffusion
  • maintains a higher concentration gradient of fatty acids
  • triglcyerides are reformed in golgi
  • vesicles move to cell membrane
54
Q

haemoglobin structure

A
  • quaternary structure
  • four polypeptide chains
  • 2 alpha-globin and 2 beta-globin chains
  • each chain has a prosthetic haem group
  • haem group contains Fe2+ ion
  • subunits held together by disulphide bonds
  • hydrophobic R group face inwards and hydrophillic R groups outwards so they are water soluble
55
Q

role of haemoglobin

A

allow oxygen molecules to bind to haem groups, forming oxyhaemoglobin, where they are carried around body to respiring cells

56
Q

how many oxygen molecules can haemoglobin hold?

A

4

57
Q

affinity

A

the ability of haemoglobin to attract or bind to oxygen

58
Q

saturation of haemoglobin

A

haemoglobin is holding 4 oxygen molecules

59
Q

loading/association of haemoglobin

A

binding of oxygen to haemoglobin

60
Q

unloading/dissociation

A

oxygen unbinds from haemoglobin

61
Q

oxyhaemoglobin dissociation curve

A

oxygen is loaded in regions with a high partial pressure of oxygen (alveoli) and unloaded in regions with low partial pressures of oxygen (respiring cells). this is shown by a sigmoid curve.

62
Q

co-operative binding

A
  • hard for first molecule of O2 to bind to haemoglobin
  • when it does, this changes the shape of haemoglobin
  • this makes it easier for further oxygen molecules to bind
  • it is hard for the 4th molecule to bind because it id harder to find a binding site
63
Q

the bohr effect

A

when high carbon dioxide concentrations cause the oxyhaemoglobin curve to shift to the right because affinity decreases

64
Q

high pCO2 (respiring cells)=curve shifts to the…

A

right because affinity decreases so oxygen can be unloaded

65
Q

low pCO2 (alveoli)=curve shifts to the…

A

left because affinity increases so oxygen can be loaded

66
Q

animals with low affinity for oxygen

A

have faster metabolisms

67
Q

effects of altitude on affinity for oxygen

A

high affinity so loads more oxygen

68
Q

features of mammilian circulatory system

A

closed- blood remains within blood vessels
double- blood passes through heart twice in each circuit

69
Q

gross structure of the human heart

A

right side:
- right atrium and ventricle
- vena cava
- pulmonary artery
left side:
- left atrium and ventricle
- aorta
- pulmonary vein

70
Q

features of cardiac muscle

A

myogenic and never fatigues

71
Q

coronary arteries function

A

supply cardiac muscle with oxygenated blood

72
Q

atrioventricular valves

A

between atria and ventricles

73
Q

semilunar valves

A

between ventricles and arteries

74
Q

function of valves

A

open when pressure is higher behind valve and open when its lower on front to keep blood flowing unidirectionally to prevent blackflow

75
Q

cardiac cycle stages

A

diastole, atrial systole and ventricular systole

76
Q

what happens during atrial diastole?

A
  • atria and ventricular muscles are relaxed
  • blood enters atria
  • this increases pressure in atria
77
Q

what happens during atrial systole?

A
  • atria muscle contract
  • increase blood pressure
  • AV valves open
  • blood pumped to ventricles
  • volume decreases in atria
78
Q

what happens during ventricular systole?

A
  • ventricular muscles contract
  • increases pressure
  • AV valves close
  • SL valves open
  • blood pumped into arteries
79
Q

structure of arteries

A
  • thick muscle layer so constriction and dilation can control blood volume
  • thick elastic layer to maintain blood pressure as walls stretch and recoil
  • thick walls to prevent bursting
80
Q

structure of atreioles

A
  • thick muscler layer (thick than arteries) to help restrict blood flow into the capillaries
  • thinner elastic layer as pressure is lower
  • thinner walls as pressure is lower
81
Q

structure of veins

A
  • relatively thin muscle so can’t control blood flow
  • relatively thin elastic layer as pressure is low
  • thin walls as pressure is low and helps blood flow
  • has valves
82
Q

structure of capillary beds

A
  • no muscle or elastic layer
  • wall is one cell thick to provide short diffusion distance
83
Q

importance of capillary beds

A

capillaries form capillary beds as exchange surfaces. they have a narrow diameter to slow blood flow and red blood cells are squahsed against walls. this maximises diffusion.

84
Q

tissue fluid definition

A

fluid containing water, glucose, amino acids, fatty acids, ions and oxygen which bathes the tissues

85
Q

formation of tissue fluid

A
  • high hydrostatic pressure at arteriole end
  • pressure forces blood out of capillaries
  • only small substances escape through gaps in capillaries
86
Q

reabsorption of tissue fluid

A
  • water potential of blood is lower than water potential of tissue fluid
  • water moves by osmosis down concentration gradient back to blood at venule end when hydrostatic pressure decreases
  • rest of tissue fluid is absorbed into the lympathic system and returns to blood
87
Q

cardiac output

A

CO = stroke volume × heart rate

88
Q

xylem

A

long continuous columns that transport water that also provide structural strength to stem

89
Q

phloem

A

transport organic substances to all cells in a plant

90
Q

structure of phloem

A
  • sieve tube elements: tube to transport sucorse, have end plates for flow of solution
  • companion cells: provide ATP for AT
91
Q

cohesion-tension theory process

A
  • water is lost from leaf due to transpiration/evaporation
  • lowers water potential of leaf
  • water pulled up through xylem (creating tension)
  • water molecules cohere through hydrogen bonding
  • forming a continuous column of water
  • adhesion of water molecules to walls of xylem (capillarity)
92
Q

mass-flow hypothesis process

A

mass flow from the source to the sink
- sucrose actively transported into sieve tube elements
- lowers water potential of phloem
- water from xylem moves in via osmosis
- increase in water increases hydrostatic pressure
- sucrose solution is forced out to sink
- sucrose used in respiration or as starch

93
Q

transpiration

A

loss of water vapour from the stomata by evaporation

94
Q

factors that affect transpiration

A
  • temperature (+ve)
  • light intensity (+ve)
  • wind intensity (+ve)
  • humidity (-ve)
95
Q

translocation

A

movement of organic materials around plant

96
Q

tracers

A
  • plants grown in radioactively labelled carbon dioxide
  • this is absorbed into plant and used in photosynthesis to creature sugars
  • xray film show sections containing sugars turn black (phloem)
97
Q

ringing experiments

A
  • ring of bark and phloem are removed from a tree trunk
  • trunk swells above the removed section
  • liquid contains sugar
98
Q

muscle in atria

A

thin as they only need to pump blood to ventricles so less contraction is needed

99
Q

muscles in ventricles

A

thick as they pump blood to the lungs and the rest of the body, the keeps the blood at a higher pressure

100
Q

pressure in right ventricle

A

low as blood is only being pumped to lungs, this prevents damage to capillaries

101
Q

pressure in left ventricle

A

high as blood is being pumped to the body so there are large contractions

102
Q

vena cava

A

carries deoxygentaed blood from body into right atrium

103
Q

pulmonary vein

A

carries oxygenated blood from lungs left atrium

104
Q

pulmonary artery

A

carries deoxygenated blood from right ventricle to lungs

105
Q

aorta

A

carries oxygenated blood from left ventricle to body

106
Q

renal vein

A

carries deoxygentaed blood away from kidneys to heart

107
Q

renal artery

A

supplies kidney with oxygenated blood

108
Q

evidence for mass flow

A
  • sap is released when the stem of a plant is cut, showing there is pressure in sieve tubes
  • concentration of sucrose is higher in leaves than roots
  • increase in sucrose at leaves is followed by increase in sucrose at phloem
  • metabolic poisons/ lack of oxygen inhibit transolcation
109
Q

evidence against mass flow

A
  • structure of sieve tube elements seems to hinder mass flow
  • not all solutes move at the same time
  • sucrose is delivered at the same rate to all regions, rather than going faster to ones with low sucrose concentration

biology (21 decks)

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