organisms exchange substances Flashcards
(93 cards)
1
Q
when surface area increases what happens
A
sa:vol ratio decreases
2
Q
where does gas exchange occur for single celled organisms
A
through the membrane
3
Q
what are adaptations for diffusion
A
steep concentration difference
good blood supply
large surface area (alveoli)
thin membrane (short diffusion distance)
4
Q
what is flick’s law of diffusion
A
rate of diffusion = sa x concentration difference/diffusion distance
5
Q
what sa:vol ratio do fishes
A
small
6
Q
what type of membrane do fishes have
A
impermeable membrane (gases can’t diffuse through membrane)
7
Q
what is the lamella in fish
A
main site of gas exchange
8
Q
what are adaptations for fish
A
counter current flow (opposite of parallel flow) of water & blood maintains steep concentration gradient along whole length of gill
large number of gills, filaments, lamellae and capillaries which increases sa
9
Q
what are the steps for fish gas exchange
A
fish opens mouth so water can flow in, then closes it to increase pressure
water passes through lamella, oxygen diffuses into bloodstream (capillaries)
waste co2 diffuses into the water & flows back out of the gills
10
Q
what are the features in insects for gas exchange
A
spiracle
trachea
tracheoles
11
Q
insects: what is the spiracle
A
pore
controls water loss
12
Q
insects: what is the trachea
A
large tube kept open by rings of chitin
prevents collapse
13
Q
insects: what is the tracheoles
A
smaller tubes
gas exchange occurs here
14
Q
insects: what is an air sac
A
stores some air so they can respire quicker when required
15
Q
insects: how are spiracles opened and closed
A
by a valve
to control gas exchange and water loss
16
Q
at rest what do insects have in their tracheoles
A
liquid
17
Q
plants: what do air spaces create
A
high sa : vol ratio
18
Q
plants: what does the stomata do
A
controls water loss and gases entering and leaving
19
Q
how does the stomata work
A
guard cells close stomata when there’s a low water potential
this causes water to diffuse in, making it turgid and opening
20
Q
how do plants control water loss
A
thick waxy cuticle
decreased sa:vol ratio
leaf rolling
hairy leaves
sunken stomata
stomata can open and close
21
Q
what is the equation for respiration
A
glucose + oxygen -> carbon dioxide + water
22
Q
why are lungs internal
A
it has a high sa so there would be lots of water loss if it was external
23
Q
humans: what is the trachea
A
muscular airway strengthened w/ cartilage
lined w/ ciliated epithelial cells
24
Q
what are bronchioles
A
highly branched
muscle contracts and relaxes to regulate airflow into the alveloi
25
where does gas exchange take place for mammals
epithelial of alveoli
26
why is diffusion rapid in humans
red blood cells slowed, more time for diffusion
thin membrane
cells are flattened -> decreases distance
large sa
breathing ventilates lungs & heart (gradient)
27
what are the blood vessels on the right side of the heart and where do they go to
pulmonary artery to the lungs
vena cava from the body
28
what are the blood vessels on the left side of the heart and where do they go to
aorta to the body
pulmonary vein from the lungs
29
what blood is in the right and left side of the heart
right - deoxygenated
left - oxygenated
30
what valve is between the atria and ventricles
atrioventricular valves
31
what valve is between the ventricles and arteries
semi lunar valves
32
what wall is inbetween the 2 sides of the heart and what does it do
septum
separates deoxygenated and oxygenated blood
33
what are the strings of tissue attached to atrioventricular valves and what do they do
cordae tendinae
supports the valve, prevents backflow
34
what is systole
period of ventricular contraction
35
what is diastole
period of ventricular relaxation
36
what are the three stages of the cardiac cycle
diastole (all chambers relaxed)
atrial systole (atria contract)
ventricular systole (ventricles contract)
37
what happens in diastole
ventricles and atria relax
blood enters atria
elastic recoil of atrial walls generate low pressure
initially atrioventricular valves are closed
as ventricles relax, blood falls back from the aorta & pulmonary artery causing semi lunar valves to close
38
what happens in atrial systole
ventricles relax, atria contract
as blood enters atria, pressure increases in atria
atrioventricular valves pushed open
blood flows into ventricles
atria contract simultaneously forcing remaining blood into ventricles
39
what happens in ventricular systole
ventricles contract, atria relax
after slight delay ventricles contract
this increases pressure in ventricles causing atrioventricular valves to close
blood is forced into aorta & pulmonary artery, semi lunar valves open
40
what is the diaphragm
muscle separating the thorax and abdomen
41
what is the internal intercostal muscles
in between ribs, leads to expiration
42
what is the external intercostal muscles
in between ribs, leads to inspiration
43
describe inspiration
external intercostal muscles contract
ribs pulled up and out, increases volume of thorax
diaphragm contracts & flattens
increased thorax volume reduces air pressure within lungs
atmospheric pressure is greater than lung and pulmonary pressure
44
describe exhalation
internal intercostal muscles contract, external relax
ribs move down & in,
decreasing volume of the thorax
diaphragm relaxes and pushed up by abdomen, volume of thorax decreased
decreased thorax volume increases air
pressure within lungs
pulmonary pressure is greater than
lungs and atmosphere
45
how do you pulmonary ventilation rate
tidal volume x breathing rate
46
what is tidal wave
volume of air in each breath at rest
47
structure of ileum
walls folded & have microvilli
thin walls
have blood vessels
48
explain physical lipid digestion
lipids coated in bile salts in duodenum creating emulsion & micelles
49
explain chemical lipid digestion
lipase hydrolyses lipids into glycerol and fatty acids
50
what do micelles do
increase surface area for lipase to act on
51
what type of transport does glucose & galactose need to be absorbed in digestion
active transport w/ sodium ion by co transporter protein
52
what type of transport does fructose need to be absorbed in digestion
facilitated diffusion by transport protein
53
explain lipid absorbtion
micelles deliver fatty acids and monoglcerides to ileum epithelial cells by simple diffusion
er and golgi apparatus modify to form triglyceride (chylomicron)
chylomicron leaves cell through exocytosis (vesicle) enter lacteals
lymph in lacteal transport to capillary
54
how are proteins digested
endopeptidases - hydrolyse peptide bonds in the middle
exopeptidases - hydrolyse peptide bonds on the ends
membrane bound dipeptidases - hydrolyse bond between two amino acid
55
explain carbohydrate digestion
salivary glands contain amylase
hydrolyse starch into maltose
in the duodenum pancreatic amylase or membrane bound disaccharidases maltose becomes alpha glucose
absorbed in ileum
56
what is the structure of haemoglobin
quaternary structure
4 polypeptide chains each with an iron ion containing haem group
57
how does oxygen bind to haemoglobin
attaches to the iron ion on haem group
58
what is the process of oxygen binding to haemoglobin called
associates/ loading
59
what is unloading/ dissociation the process of
haemoglobin releasing oxygen
60
what does affinity mean
strength of attraction
ability for haemoglobin to bind to oxygen
61
where does haemoglobin's affinity tend to change
high affinity for oxygen in lungs/exchange surfaces
low affinity in muscles/ respiring cells
62
why does haemoglobin's affinity change
in high presence of CO2 haemoglobin's affinity is low, changes shape, readily dissociates w/ oxygen
63
why is it difficult for oxygen to bind to haemoglobin at low concentrations
the four polypeptides of haemoglobin are closely united
64
explain the oxygen dissociation curves
when oxygen binds to haemoglobin it changes the shapes so its easier for others to bind
increase in partial pressure causes second oxygen to bind
after the third oxygen likelihood of fourth O2 binding is lower due to limited space
65
what is positive cooperativity
a small increase in partial pressure causes second O2 to bind
66
what does it mean if the oxygen dissociation curve is towards the left
higher affinity, associates readily
low CO2
67
what does it mean if the oxygen dissociation curve is towards the right
lower affinity, dissociates readily
high CO2
68
what is the relationship between pH and CO2
and how does pH effect haemoglobin
low CO2 high pH
high CO2 low pH
high pH changes haemoglobins shape to readily associate w/ oxygen
69
what are the features of an artery
thick muscular tissue - constrict and relax, control pressure
small lumen
thick elastic - stretch & recoil, pressure
collagen wall - resist bursting under pressure
70
what are the features of a vein
thin muscle layer
large lumen
valves
71
what are the features of a capillary
thin walls - diffusion distance
highly branched
narrow, be near cells
space for wbc to deal w/ infections
72
what is tissue fluid
exchange medium formed in blood plasma
supplies glucose, O2, amino acids to tissue
removes waste products
73
explain how tissue fluid works
high hydrostatic pressure at arterial end forces fluid into tissue
lower water potential of plasma causes water to move back into capillaries
74
explain what happens at the arterial end of tissue fluid
high hydrostatic pressure, fluid forced out
plasma proteins in blood
hydrophilic so reduced water potential in blood
water moves back in blood by osmosis
hydrostatic greater than osmotic pressure
proteins too large to leave plasma
75
explain what happens at the venous end of tissue fluid
lower hydrostatic pressure
proteins still in plasma, oncotic pressure high, water potential low
water moves back in, osmosis
tissue nutrients absorbed into blood
remaining returns to lymph
76
what is hydrostatic pressure
the pressure that any fluid in a confined space exerts
77
describe a xylem vessel
hollow dead continous tubes
thick walls
cohesion tension
passive process
78
define transpiration
water absorbed through root hair cells
transported through xylem vessels
as water evaporates from stomata more is pulled through xylem
79
what are the two pathways for water in transpiration
cell wall (apoplast)
cytoplasmic (symplast)
80
what is evidence for cohesion tension theory
if xylem is damaged water doesn't leak out, air is drawn proving it's under tension
81
what factors effect transpiration
temperature
humidity
wind
light intensity
82
how does humidity effect transpiration
concentration gradient not steep so less diffusion happens
83
how does wind effect transpiration
increases rate of evaporation and steep concentration gradient maintained
84
how does bright light effect transpiration
more photosynthesis so stomata open for gas exchange so more transpiration can happen
85
how does increased temperature effect transpiration
molecules have more energy so more evaportion happens
86
what are the components of the phloem
sieve tube elements
sieve tube plate
companion cells
sink cell
source cells
87
how does sucrose enter the phloem
co transport w/ hydrogen, after hydrogen active transport into cell wall from companion cell
88
explain the mass flow hypothesis
high conc grad of sucrose in phloem t/f low water potential
water moves by osmosis (xylem), increase hydrostatic pressure
t/f pushes sucrose towards sink cell
water moves out again
sucrose used in respiration or storage
89
what experiments support mass flow theory
ringing
tracer
90
explain the ringing experiment
phloem and bark cut off mid of tree
tree swollen above rings, full of sugars
tissue below withers and dies
91
explain the tracer experiment
plant grown in isotope C14, isotope is seen in x ray blackened (sugar) and in areas containing phloem
92
name two pieces of evidence for the mass flow hypothesis
concentration of sucrose is higher in leaves (source) than in roots (sink)
companion cells have many mitochondria and readily produce ATP
93
name two pieces of evidence against mass flow hypothesis
function of sieve plates is unclear, would seem to hinder mass flow
sucrose is delivered at same rate to all regions rather than quicker to regions w/ low sucrose
