extreme biology Flashcards
(377 cards)
1
Q
give some environmental factors that plants need to be able to cope with
A
drought cold heat light salinity flooding nitrogen poverty wind loneliness cold
2
Q
what do plants rely on light for
A
photosynthesis
3
Q
what are the advantages and disadvantages of having large leaves in warm climates
A
advantages
- more area for light capture and photosynthesis
disadvantages
- exposed to a lot of heat
- photosynthesis releases a lot of heat which can be damaging
4
Q
what doe ordinary sunlight at the surface of the earth contain and what is the effect of each of these
A
UV light - causes sunburn and is damaging to RNA/DNA
visible light - plants use the blue and red end of the visible light and reflect green light
infrared light - not used in biochemical pathways and is damaging in terms of heat
5
Q
which part of the leaves are most affected by heat and how can heat damage be reduced
A
leaves get hotter away from their edges. by increasing the amount of edge a leaf has, the more heat loss radiation can be carried out
6
Q
how does leaf size adapt to get more light
A
make the leaf bigger to get more sunlight
7
Q
how does leaf size adapt to evade high temperature damage
A
make the leaf smaller to increase heat loss by radiation
8
Q
how can leaf shape help to protect against over heating
A
we can change the orientation of leaves to avoid direct sunlight
so leaves also change shape i.e. curl up
9
Q
apart from radiation, what are other methods of heat loss form leaves
A
transpiration of water helps plants keep cool do that their biochemistry isn’t wounded
10
Q
in what conditions are small leaves favourable
A
extremes of dryness, heat, draught and cold
11
Q
in what conditions are large leaves favourable
A
where there is sufficient water for cooling and it is warm enough to avoid excessive radiative cooling
large leaves maximise light harvesting
12
Q
what adaptations have desert plants undergone
A
they are overexposed to heat so they have small leaves so that they can effectively radiatively cool because they don’t have access to enough water to cool by transpiration
13
Q
what kind of plants do we get in hot treeless deserts
A
ephemerals, adaptors, resistors
14
Q
describe the plant growth cycle in hot treeless deserts
A
in the dry season almost no plants grow but when it rains there is a massive bloom
15
Q
what are ephemerals
A
they are desert annuals
they have a short life time (weeks/months) but seeds are long lived
energy form photosynthesis in leaves allows them to produce flowers. insects then pollinate them
the plant dies and the seeds are left in the soil/sand and when it rains more plants grow
16
Q
what are the 4 main steps of ephemeral life cycle
A
growth
flowering
seed setting
death
17
Q
are ephemerals draught resistant
A
not particularly
18
Q
what is cryptobiosis
A
a metabolic state entered by organisms in response to adverse environmental conditions
19
Q
what are poikilohydric plants and give an examples
A
they are resurrection plants craterostigma plantagineum
20
Q
what is the response of resurrection pants in draught
A
during draught the plants dehydrate, shrivel and become photosynthetically inactive
it then regrows from dormant roots and shoots when watered
21
Q
describe a dehydration protection response of resurrection plants
A
- accumulation of sucrose and trehalose to protect membranes and proteins from denaturation
- when it is dry it allows all of the tissues to shrink nut they don’t die.
- as the water content goes down it starts to produce more sucrose which is a good cryo-preservative as the sugar acts against drying
22
Q
how do poikilohydric (resurrection) plant and ephemerals differ
A
ephemerals die and leave their seeds
resurrection plants don’t die
23
Q
what are phreatophytes
A
deep rooted large perennial plants that obtain a significant portion of water from the phreatic zone
24
Q
what is the phreatic zone
A
the zone of saturation
25
what are the 2 roost formed by the phreatophytes
deep tier roots that get water from the deep water table
| shallow tier roots that capture rainfall
26
describe the leaves of phreatophytes
they are tiny in order to reduce water loss and aid radiative heat loss
27
are stomata open or closed during the day in phreatophytes
they are closed to prevent water loss s
28
give a example of a phreatophyte
creosote bush
| mesquite plant
29
what is the oldest plant
the larrea tridentata found in the death valley is thought to be the oldest creosote bush ring estimated at 11700 y/o reaching up to 20m in diameter
it is a phreatophye
30
what are xerophytes
- plants that can survive very dry conditions for long periods of time and are found in arid climates
- they usually have small leaves or needles
- they have thickened leaves or stems for water storage and to act as a heat buffer
31
what is an arid climate
climate with low water availability
32
describe the succulents of xerophytes
succulents contain storage of water in very sugary cores and they are found in leaves and stems
33
give examples of xerophytes and note the type of succulent they have
aloe vera and crassula - leaf succulents
| cactus - stem succulents
34
describe cacti in terms of their leaves and stems
- cactus spines are their leaves but they are not for photosynthesis, instead they are for protection
- the entire stem of the cactus is photosynthetic
35
what are cacti areola
an area on the plant where a tuft of white hairs come out
36
give reasons why cacti are very good at retaining water
- because they have very waxy cuticles and water succulents
- they have reduced SA to volume ratio
- stomata are strategically concentrated inside the pleats (shaded most of the time) to reduce desiccation when they are open so that sunlight doesn't drive off too much water
- cacti apex are generally covered in hairs - the hairs protect it from light and heat damage - no photosynthesis occurs here
37
what conditions are high altitude cacti adapted to
dry, cold air and intense light
38
what does it mean that high altitude cacti are very pubescent and how is this of benefit
they are very hairy
- this results in light being scattered to prevent damage but it can still be let through for photosynthesis
- when stomata are open they lose less water du to the microenvironment created by the hair
- the hairs also prevent heat loss at night
- protection from herbivores and pathogens
39
high altitude cacti are long/short lived and slow/fast growing
long
| slow
40
what kind of conditions are euphorbias adapted to
dry conditions
41
how do euphorbias protect themselves against other animals and how are they different to cacti
they oose whit latex to protect themselves against grazing by insects and other animals but cacti can't doe this
cacti have areola but euphorbias don't
42
what are lithops and what is there nickname
they are called stone plants because they look like stones
- their outer leaves shed in the winter and are replaced by new ones (they need to get rid of old leaves because they are light damaged)
43
what is a compass plant
a plant that reduces heat and water loss native to new mexico
- it reduces the heating of planar faces
- they change leaf orientation so that they can still photosynthesise but prevent light and heat damage (this orientation increases water efficiency)
- they have large leaves which are held vertically
- new leaves grow in random orientation but within 2-3 weeks it twists on its petiole to a vertical position
44
are most plants C3 or C4
C3
45
what are the differences between C3 and C4 metabolism
C4 metabolism is a photosynthetic pathway that adapted from the C3 pathway in response to extreme heat and drought. It evolved independently in several lineages of vascular plants. The C4 pathway works most effectively in hot and dry climates with limited CO2. It is called C4 because instead of forming a 3-carbon compound (as in the C3 pathway), it makes a 4-carbon compound (malate).
46
what are the advantages of C4 metabolism in plants
* In hot, dry environments C4 metabolism is more efficient than C3 because it minimizes photorespiration, a counterproductive pathway to photosynthesis where rubisco incorporates oxygen instead of carbon dioxide. C4 plants minimize photorespiration by separating carbon fixation and the calvin cycle in space or in time. In both pathways, carbon dioxide is initially incorporated into the plant by an enzyme called PEP carboxylase which has no affinity for oxygen (avoiding photorespiration). The benefits of reduced photorespiration exceed the energy cost of C4 pathways
* C4 plants also reduce water loss by transpiration because they can keep their stomata closed more than C3 plants. The plants need to open their stomata in order to take in carbon dioxide and release oxygen into the atmosphere. During this time, water is lost by transpiration which is enhanced in hot and dry climates. The C4 pathway is more efficient at incorporating carbon dioxide compared to the C3 pathway so the stomata can be kept closed more, thus avoiding water loss.
47
what are the two main type of C4 metabolism
There are two main types of C4 metabolism – one that separates carbon dioxide fixation and the calvin cycle with space (C4 pathway) and one that separates them with time (CAM). In the C4 pathway, plants open their stomata during the day and carbon fixation occurs in the mesophyll cells where carbon dioxide is incorporated by PEP carboxylase forming malate. Malate is then transported to the bundle sheath cells via plasmodesmata and the carbon dioxide is released and incorporated into the calvin cycle by rubisco. In CAM plants, stomata are opened at night. Carbon dioxide is fixed to oxaloacetate by PEP carboxylase (the same as in the C4 pathway), then converted to malate or another type of organic acid which is stored inside vacuoles until the next day. In daylight, the CAM plants do not open their stomata, but still photosynthesize because the organic acids are transported out of the vacuole and broken down to release carbon dioxide which enters the Calvin cycle.
48
what are the differences between the 2 types of C4 metabolism
In the C4 pathway, plants open their stomata during the day and carbon fixation occurs in the mesophyll cells where carbon dioxide is incorporated by PEP carboxylase forming malate. Malate is then transported to the bundle sheath cells via plasmodesmata and the carbon dioxide is released and incorporated into the calvin cycle by rubisco. In CAM plants, stomata are opened at night. Carbon dioxide is fixed to oxaloacetate by PEP carboxylase (the same as in the C4 pathway), then converted to malate or another type of organic acid which is stored inside vacuoles until the next day. In daylight, the CAM plants do not open their stomata, but still photosynthesize because the organic acids are transported out of the vacuole and broken down to release carbon dioxide which enters the Calvin cycle.
49
what percentage of plants are C4
3% but 5% of biomass and 23% carbon fixation
50
how much less water do C4 plants lose compared to C3
C4 plants lose 1/2 as much water per unit CO2 compared to C3 plants
51
what is the most abundant protein on the planet
rubisco
52
what does rubisco do
it fixes CO2 into sugars in plants nut it is very sensitive to oxidation by pure oxygen and it evolved when oxygen levels in the atmosphere were much lower so there was less selection pressure at the time to discriminate
the fact that rubisco can't easily discriminate between oxygen and carbon dioxide lead to photorespiration
53
what does spatial separation mean in C4
physical separation of where CO2 is brought into the plant and where rubisco is active
CO2 brought into the mesophyll
rubisco active in bundle sheaths (active everywhere in C3 plants)
54
what increases the internal CO2 concentration
CO2 pumps - so that we generate an environment high in CO2 conc in the bundle sheathes
55
where is malate synthesised
in the mesophyll cells
56
hoe does malate get from the mesophyll cells to the bundle sheath cells
it diffuses via plasmodesmata
57
why can't C3 plants grow in very hot areas
because with increasing temp rubisco incorporates more oxygen than CO2
58
what is marram grass
it is found on sand dunes and curls when dry and opens when wet = opening controlled by hinge cells
stomata are in the grooves to reduce water loss
59
what is the C4 time separation reaction called
CAM
60
what are the stomatal differences between the 2 C4 pathways
```
spatial separation - stomata closed at night and open during the day
time separation (CAM) - stomata open at night and closed during day
```
61
what are the steps in CAM
CO2 is incorporated by PEP carboxylase and converted to oxaloacetate which is converted to malate which is converted to malic acid which is stored in the vacuoles during the day
during the day malic acid is moved to the cytoplasm and converted back to malate which is then pumped into the chloroplasts
CO2 is released and reacts with rubisco in the calvin cycle and pyruvate is released which goes back to the mesophyll cells
62
in what type of climates can slat be problematic for plants
marine and brackish waters and arid land areas
63
give examples of halophytic plants and their specialised salt organs and adaptive metabolisms
mangroves - slat glands - salt is secreted from glands
atriplex - slat bladders - produce gritty silver layer when excreting salt
mesembryanthemum crystallinum - ice plant - facultative CAM - shifts to CAM metabolism in dry or saline conditions
64
not all halophytes have obvious morphological features - provide an example
thellungia halophylia (salt tolerant) - close relative of Arabidopsis (salt sensitive)
65
what is the mechanism that allows thellungia halophylia to be salt tolerant
1. ion channels in thellungia roots are less permeable for Na than in Arabidopsis
2. limitation of Na uptake is the main strategy for avoiding sodium toxicity in thellungia
3. thellungi host a potential set of genes that could be used to make our crop plants more salt tolerant
66
what are adaptations in plants to avoid anoxia from water flooding
pneumatophores - specialised aerial roots that enable access to O2 in water logged habitats
hypoxic roots - if roots are often flooded e.g. lotus, they produce aerenchyma tissue in their roots. cells within the roots die to produce channels through which air can diffuse allowing the system to respire even when flooded
67
what is an angiosperm
a plant that has flowers and produces seeds enclosed within a carpel(usually a fruit)
68
what is a gymnosperm
no flowers or enclosed seeds, seeds often cones e.g. conifers
69
describe seagrass (zostera marina)
it is an angiosperm with submerged male and female parts
70
what has seagrass lost genes for
it has lost all genes for stomata, UV protection (UV light only penetrates mm), IR light (cooled by water instead) and volatile terpenes (defence mechanism against predators)
71
what has seagrass gained genes for
encoding cell wall components for osmotic control to prevent saltwater driving water out of the plant
72
how can nitrogen poverty be evaded by carnivory
when plants eat insects it provides them with a nitrogen source -this is useful if the soil is nutrient poor
73
give examples of carnivorous plants and their mechanisms
venus fly trap - reversibly depolarises cells to open and close. its hairs need to be triggered twice before it will close
bladderwart - if bladders are triggered by touch they spring opne then suck in the insect and close a digest it
pitcher plants - produce vessels, sometimes with a lid to prevent fluid dilution. the vessel fluid digests insects that land in it
74
give an example of how parenthood can help with nitrogen poverty
coco de mer
lodoicea maldavica is a monodominant palm producing the largest seeds.
the plant invest heavily in reproduction
coco de mer has large leaves that gather up bird droppings, petioles etc from other plants and their own pollen
the rain washes it all down tubes that feed to the ground producing a nutrient rich environment for their offspring
this mechanism improves phosphorus and nitrogen supplies which are needed to sustain costly reproctive functions
75
what doe monodominant mean
when more than 60% of the tree canopy is comprised by a species
76
how are coco de mer and coconuts different
the seeds of coco de mer are not salt tolerant so they die if they fall in the sea unlike coconuts
77
describe the arctic tundra environment
cold deserts, biodiversity is very low
little rainfall
high densities of the same species
7 months of snow cover in winter - limited light capture
78
what kind of plants do we find in the arctic tundra
plants that have short growing seasons and life cycles in summer then go into senescence in winter
plants have high nutrient efficiency and live in the shallow soil above the permafrost (frozen rock/soil)
79
some plants are able to grow in rocks, give an example
lichens and mosses - able to tease nutrients out of the rocks
80
describe the Antarctica plants
must grow quickly and in extremely cold conditions
metabolic activity is maximised at low temperatures
there are only 2 native vascular plant species
81
what are the 2 native vascular plant species of the Antarctica
hairgrass
pearlwort
both of these grow in small clumps
82
how do lichens grow in the antarctica
they find spaces where the sun melts the snow
growth season is less than 120 days per year
growth rate is 0.01-1mm per year
long life
83
how do mosses grow in Antarctica
they form colonies that collect and retain water
their photosynthetic enzymes have maximal activity at 5C
photosynthesis quickly activates after frost
84
describe the plant growth in taiga
mainly coniferous but some angiosperms
plants can deal with cold and warm temperatures due ti the continental climate
there is low species diversity but large bands of single species
85
what is taiga
huge bands of forest
86
what is earth's largest terrestrial biome
taiga
87
what are the dangers of cold to plants
- biological thermodynamic processes come to a halt
- changes in biomolecule conformation, stability and function
- perturbation of normal cellular processes
- reduced fluidity of membranes
- perturbation in the balance between production and neutralisation of ROS
- extracellular ice crystal formation depletes water in and around cells and crystals can puncture cell wall/memb and may rupture the inside of the plant
88
what do plants induce to protect themselves from the cold
cold tolerant mechanisms and components
89
describe the preparation of taiga conifer trees for winter
- they sense changes in day length/temperature which causes cold tolerant mechanisms to be triggered
- large central vacuole is replaced by lots of small vesicles to limit ice crystal formation
- starch granules disappear and other sugars accumulate
- thylakoid membranes separate and become disorganised
- changes in membrane lipid composition
- high concentrations of oligosaccharides to promote high viscosity of the cytoplasm of freeze dehydrated cells
- changes in proteins expressed
90
how do membranes change in response to cold
unsaturation, increased phosphatidylethanolamine and decreased phosphatidylcholine, increased phospholipids, reduced galactolipids
91
which proteins are upregulated in response to cold
dehydrins - prevent membrane-membrane interactions
antioxidant systems - protection against oxygen damage
heat shock proteins
pathogenesis related proteins
92
describe the leaves of deciduous trees
they generally have large light gathering leaves which are shed in winter to prevent the tree from being blown over
93
what is an abscission layer
it is a barrier across the petiole
it forms between the leaf petiole and the stem
- the leaf remains attached by the abscission layer as long as auxin is being produced i.e. the plant is growing
- when the plant prepares for winter auxin stops being produced
- the cells in the abscission layer start to separate and form a protective barrier to pathogens for when the leaf falls and prevent sap loss
94
when does the abscission layer form
in spring with new leaf growth
95
why are new buds sticky
because they coat themselves in sugar as a cryoprotective mechanism
96
what are response of leaves in winter that aren't shed
- flat surfaces radiate away heat but don't absorb much so they supercool
- to get around this, plants curl and drop their leaves in response to cold as this changes the airflow
- they also often have dense hair under the leaves which protect the stomata
97
give an example of a plant that drops and curls its leaves
rhododendron
98
describe the origin of conifers
- large continental mass called the Pangea formed which had a very dry centre because it was far from the sea
- this lead to the extinction of giant tree ferns
- conifers evolved and began colonising the continent changing its habitat
- conifers were likely the major food source of adult sauropods
99
give an example of a large conifer that was thought to feed sauropods
monkey puzzle tree
100
what is meant by conifers being evergreen
they are spring ready - have green leaves throughout the year
101
what conditions are conifers best adapted to
dry, cold and high altitude
102
how are conifers designed for snow
snow can land on them and their branches will bend and shed the snow if they get too loaded
angiosperms would probably break under the weight of snow
103
what can happen to photosynthesis in conifers in winter
some shut down photosynthesis and increase the conc of carotenoid pigments to protect against light damage
photosynthesis resumes after winter dormancy in response to daylight
104
the oldest bristlecone pine was accidently burnt describe the plants soil and root system
- they grow slowly in dolomite soils and the root system is composed of highly branched shallow roots while a few large branching roots provide support
- they are extremely draught tolerant with waxy needles, thick needle cuticles to aid water retention
- wood is very dense evading invasion by predators
105
crown drag is greatest in trees with narrow/broad leaves and the advantage is to be deciduous/coniferous
broad
| deciduous
106
describe an oak tree (angiosperm) (deciduous)
dense heavy trunk
limited sway
broad root base
107
describe and pine tree (conifer) (gymnosperm)
lighter trunk
more sway
deep tap root
108
what is a buttress root
- most rainforest soil is nutrient poor and nutrients are available largely at the soil surface
- rainforest trees tend to have very shallow roots which can often be seen above the soil
109
how do trees/leaves reduce crown drag
- leaves twist, curl or fold to resist wind so they aren't ripped off the tree or cause the tree to fall over
110
what can plant loneliness be caused by
distant colonisation
devastated land
widespread separation
111
give an example of a plant that grows on devastated land
rosebay willowherb - grows in ash - doesn't require soil fungi - they have feathery seeds so that they can colonise land rapidly
112
give examples of plant loneliness - how do cacti combat loneliness
cacti are often spread out so need to try hard to find a pollinator
they often have improved advertising to attract pollinators
113
give an example of loneliness in a tropical forest
some species are not hermaphrodites and have male and female parts on different plants so have to transfer pollen
plant species often use a pollinating insect instead of relying on wind
they synchronise their flowering using the solar analemma
114
why can't temperate tropical rainforest plants or polar plants rely on temperature or daylight
because the environment is very stable
| they use the solar analemma instead
115
what is the solar analemma
- a consequence of the earth's rotational axis being at an angle of 23.5 to the plane of its orbital and earth's orbital is elliptical
- plant detect tiny changes in when dawn occurs
- the analemma curve is bigger in the south because we have an elliptical orbit and we are tipped slightly towards the sun during the southern hemisphere's summer
116
give some examples of common classes of extremophiles
```
acidophile
alkaliphile
halophile
hyperthermophile
oligotroph
osmophile
piezophile
psychrophile
thermophile
```
117
what is deinococcus radiodurans
a radiation surviving bacterium
- DNA organised into tightly packed choroids
- meat treated with radiation thought to kill all live nut meat still spoiled and DR was isolated
- radio-resistance of DR was a side effect of dealing with long term desiccation
118
how does DR repair DNA
it can repair single and double stranded DNA
- upon damage it brings its DNA into a compartmental ring like structure where it s repaired
- nucleoids then fuse from the outside of the compartment with the damaged DNA
119
what are the basic requirements for early life
carbon and nitrogen - they generate energy through cycles like the calvin cycle, krebs cycles and nitrogen cycle
120
what are the 3 domains of life
bacteria, archaea, eukaryotes
121
what are the different atmosphere states in its evolution
anaerobic, single cells
anaerobic, photosynthesis, single cells
aerobic, eukaryotes
multicellular life, Cambrian explosion, stability
122
what are the effects of oxygenation of the atmosphere
- oxygenation of the atmosphere by photosynthetic pigments is thought to have caused precipitation of iron from the seas that lead to the iron rich strata now used for iron ore
- oxygenation also resulted in a radiation of greenhouse gasses such as CO2 which lead to the great cooling leading to snowball earth
123
what are the origins of extremophile prokaryotes
archaea
124
what are the 2 main biochemical cycles of life
calvin cycle and the krebs cycle - both use carbon for energy storage and transfer
125
evolution of what process lead to the great oxygenation event
photosynthesis
126
what does photosynthesis require
a means by which photons are captured and their energy directed to the reaction centre where CO2 is fixed
127
what is the light harvesting complex
it sits embedded in a membrane and consists of proteins and pigments surrounding a reaction centre
(various pigment molecules bound to proteins)
128
where is the light harvesting complex of green plants found
the thylakoid membranes of chloroplasts
129
what are antenna pigments
chlorophyll b, xanthophylls, carotenes
130
why is it good that absorption spectra are not overlapping
because when you have more than one pigment you broaden the absorption range for photosynthesis
131
what is the other role of carotenoids
they act as an antioxidant to prevent photo-oxidative damage of chlorophyll
132
each antenna complex has between 250-400 pigment molecules and the energy they absorb is shuttled to the specialized chlorophyll a proteins complex known as the .……….. …………. of the photosystem
reaction centre
133
how is energy shuttled in photosynthesis
by resonance energy transfer
134
what is a photosystem
composed of a reaction centre surrounded by several light harvesting complexes
135
what is a reaction centre
association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor
136
nitrogen fixation by pants requires ………...
microbes
137
what fixes atmospheric nitrogen into a more suable form such as ammonia
diazotrophsare bacteria and archae
138
what are the steps in the nitrogen cycle
1. atmospheric nitrogen absorbed by nitrogen fixing bacteria in plant roots or taken into the grounf by decomposers
2. nitrogen fixing soil bacteria result in ammonification giving ammonium
3. nitrifying bacteria result in nitrification producing nitrites
4. nitrates are produced form nitrites by nitrifying bacteria
5. denitrifying bacteria convert nitrates int atmospheric nitrogen or nitrate assimilation occurs into plants which are eaten by animals
139
as far as we know all living systems derive(d) their energy from
electrons
140
electrons are used in chemiosmosis what is this
where electrons flow down their conc gradient and H are pumped against their conc gradient across the membrane
when H flow back down their conc gradient they pass through ATP synthase, generating ATP
141
give an example of another redox reaction which creates energy other than photosynthesis
NO2 reduction
142
archaea are more closely related to …….. than bacteria and where does this evidence come from
eukaryotes
| evidence from genes sequencing - particularly rRNA
143
what are the different energy sources of archaea
organic resources
phototrophic
carbon dioxide fixation
144
archaea membranes are comprised of …… lipids not ……. lipids
ether not ester
145
how do archaea reproduce
asexually
146
have any pathogenic archaea been found
no - only mutualistic and commensals
147
what about archaea membranes stabilises them at high temperatures
their highly branched structure - they contain branched isoprene chains
148
what can isoprene chains of archaea membranes do
they can be joined together between phospholipids
| they can form carbon rings which increase stability
149
what do methanogenic archaea do
they breakdown lignocellulose into simple sugars and methane (the by-product) - methanogens are key organisms in decomposition and they are obligate anaerobes
150
what are thermoacidophiles
can cope with extreme temp and pH e.g. picrophilustorridus
- thick extracellular protein mucilage
- they have an S layer
- they oxidise sugars via modified glycolysis (entner dudoroft)
- 12% of genes are transporters
151
what debate about archaea is ongoing
whether eukaryotes are derived from them
152
where are microbes that use sulphur oxidation for energy generation found e.g. paracoccus dentrificans bacterium
hot sulphurous springs
153
what is halotolerance
tolerance to high slat conc
154
what are halobacteria
photoautotrophs
155
what are lipids made from
glycerides: glycerol + FA
156
what is phosphatidycholine
a diglyceride which is a major phospholipid of membranes
157
the degree of ………. affect van der waal forces which can change lipid properties
saturation
158
weak attractive forces between FA chains are countered by ……..…. ……… ………...
random thermal motion - bond rotation, stretching etc
159
what is the structure of membrane glycerides
they have a glycerol core with usually 2 of 3 of the OH groups linked to FA by ester linkages
160
the .…….. and degree of ……….. of FA determines the physical properties of the lipids
length
| saturation
161
describe saturated fat and FA
the molecules of saturated fat are packed closely together forming a solid - e.g. butter
162
describe unsaturated fat and FA
the molecules of fat cannot pack closely together because they have kinks in their FA chains forming a liquid - e.g. olive oil
163
phospholipids have ……….. heads and …………….. tails
hydrophilic head
| hydrophobic tails
164
different lipid classes confer different ……….. to membranes
shapes
165
the charged headgroups such as phosphatidylcholine are attached to the remaining OH groups of glycerol projected into the ........ phase. the ........, ............ and ....... of these groups plus the degree of ............. of FA tails controls the shape of the molecule and affects the curvature of the membrane
water
size, charge and shape
saturation
166
other lipids such as ............. and its derivatives can be embedded in the membrane further affecting the curvature and biophysical properties of the membrane
cholesterol - stiffens the membrane
167
when exposed to stress the heterogenous mixtures (........) of different lipids can phase separate to form what and what is the effect of this
rafts
pools of a single class of lipids which can lead to physical change in the bilayer structure
inverted micelles and hexagonal II can form
168
what is an inverted micelle
polar head groups face inwards and non-polar tails face outwards
169
what are the effects of membrane lipids becoming more unsaturated
- introduction of kinks in the FA chains which reduces the van der waals between chains
- reduction of the temperature of the liquid crystalline --> gel phase transition (Tm) - melting temperature - membranes stay fluid for longer when temperature decreases
- membranes in the gel phase are not fluid and are functionally altered
- L-alpha and Hex II transitions are also important
170
increasing sterol content of membranes increases fluidity/rigidity
fluidity
171
melting point of FA decreases/increases as the proportion of unsaturated bonds increases
decreases
172
give 3 examples of saturated FA
steric, palmitic, lauric
173
give 3 examples of unsaturated FA
oleic, linoleic and linolenic
174
what is the structure of cholesterol
it has a rigid ring system and a short branched hydrocarbon tail
it is largely hydrophobic but has a polar OH group making it amphipathic
175
how does cholesterol affect membrane fluidity
interaction of membranes with relatively rigid cholesterol decreases the mobility of the hydrocarbon tails of phospholipids
cholesterol interferes with close packing of FA tails
membranes with more cholesterol have fluidity intermediate between the liquid crystal and crystal states
cholesterol stiffens the membrane
176
what is cholesterol on skin transformed to in sunlight
vitamin D
177
at low temp we increase/decrease the number of cis double bonds in FA
increase
178
at high temp we increase/decrease the number of cis double bonds in FA
decrease
179
freeze fracture electron microscopy of membranes can reveal ...............
Hex II structures and internal structure of membrane bilayers
180
what is freeze fracture electron microscopy
- specimen frozen
- frozen sample is fractured
- new exposed faces are coated in gold
- viewed under a scanning electron micrograph
181
what are the 2 appearances of Hex II structures
granular or tubular
182
.............. shocked proteins may also form Hex II structures
temperature
183
what are differences in osmotic water loss during freezing of cold acclimated and non-cold acclimated cells
non-acclimated - plasma memb produce intracellular vesicles when they dehydrate - material lost by endocytotic vesiculation - lysis
acclimated - plasma memb produce extracellular protrusions when they dehydrate - exocytotic extrusions and re-expansion
184
what organisms are particularly exposed to seasonal temperature changes
land plants
185
although mammals and birds can regulate their body temp they may not be able to control the temp of their ...... ......... and ......... how do they get around this
body surfaces
extremities
they make their membranes more polyunsaturated at exposed sites
186
describe archaea membranes
- they have phospholipids
- they have a different stereoisomer of glycerol
- they have ether linkages instead of ester linkages
- they have isoprene chains instead of FA
- they have branching isoprene side chains which can join together between phospholipids and they can also form carbon rings - they increase the structural stability of the membrane
187
what are the different levels of protein structure
- primary - the order of amino acids in a polypeptide chain
- secondary - formation of alpha helices and beta sheets by H bonding in the polypeptide backbone
- tertiary - interaction between R groups - disulphide bridges, ionic interactions, hydrophobic/hydrophilic interactions - development of 3D structure
- quaternary - interactions of different polypeptide chains either by non-covalent interactions (as in collagen and haemoglobin) and/or cys-cys disulphide bonds (as in antibodies)
188
what kind of organisms produce heat shock proteins
prokaryotes and eukaryotes
189
are heat shock proteins only produced in response to heat
no they are produced in response to other stresses too
190
what are the 2 roles of heat shock proteins
1 - degrading or repairing misfolded proteins arising from heat shock
2 - act as molecular chaperones that bind to enzymes and prevent thermally induced misfolding - under normal conditions these chaperones assist the folding or some proteins when they emerge from the ribosome
191
smaller HSPs are .............. ...........and larger ones are involved in ............. .................... .......... ...... .........
molecular chaperones
| refolding and degradation of proteins
192
what is a proteasome
the cells protein recycling plant
protein complexes which degrade unneeded or damaged proteins by proteolysis, a reaction that breaks peptide bonds
enzymes that help are called proteases
193
how are proteins tagged for degradation by the proteasome and what is the effect of this tagging
1. they are tagged with ubiquitin which is catalysed by ubiquitin ligases
2. once tagged, this is a signal to other ligases to attach additional ubiquitin molecules.
3. the result is a polyubiquitin chain that is bound by the proteasome allowing it to degrade the tagged protein
4. degradation yields peptides which are further broken down into amino acids and used to sequence new proteins
194
ER and Golgi play a key role in protein ............ and ..............
assembly and trafficking
195
denatured proteins are stick and aggregate in the ...... what process has evolved to recover this situation
ER
| UPR - unfolded protein response - eukaryotes only
196
what are the 3 key UPR pathways and what are they all regulated by
all regulated by binding of BiP-aHSP70
1. PERK - arrest of general translation but triggers transcription and translation of factor ATF4
2. degradation of misfolded proteins
3. active signalling pathways that lead to increased chaperones involved in protein folding
if these objectives are not achieved then the UPR triggers apoptosis
197
what diseases are caused by upregulation of UPR
huntington's, alzhiemers, Parkinson's, mad cow
198
name 2 thermostable enzymes
Taq DNA pol
| Vent pol
199
describe vent pol
- used for PCR and isolated from Thermococcus litoralis archaean
- cell wall consists of S layer that doesn't form hexagonal lattices
- found in deep hydrothermal vents, shallow submarine thermal springs or oil wells
- anaerobic organotrophhyperthermophile
- grows between 55-100 C
- non motile
- vent pol has lower error rate than Taq pol due to its proof reading abilities
200
describe Taq pol
- heat tolerant and active >75 C and can be used in PCR
| - Taq pol has more intramolecular attractions than normal DNA pol so can hold together better
201
describe the cell structure and memb surface of an archaea
- S layer composed of 2 proteins - surface covering and memb anchoring
- gram positive - contains pseudomurein layer as well as S layer
- cytoplasmic memb composed of diether lipids
202
what is a hexagonal phase
formed by some amphiphilic molecules when they are mixed with polar solvent. the amphiphilic molecule aggregate into cylindrical structures and are disposed on a hexagonal axis - micelles fused together
203
what does H I mean
polar outside
204
what does H II mean
polar inside
205
animals need to shelter from the cold in subnivean habitats - what is a subnivean habitat
the habitat under dense snow pack using its protection from wind chill and the insulation that the snow can provide through the air it holds keeping the temperature higher than outside
206
which type of ecosystems change very little throughout the year
tropical rainforests near the equator
207
which ecosystems change dramatically throughout the year
polar regions - they change dramatically with seasons which the organisms must adapt to
208
why does earth have seasons
because it is orbitally inclined - the earths orbit around the sun is elliptical such that the earth is closer to the sun in the southern hemispheres summer
209
what are some reasons that organism migrate
to avoid conditions that would make them physiologically unable to survive or that would eliminate their food supply until spring
210
what are the greatest migrators in terms of distance
birds and cetaceans
211
what are some reasons why animals don't migrate
the distance is too great
there are physical barriers
they have found ways to continue feeding and coping in their present environment
212
why is climate change causing an issue for animals that rely on subnivean habitats
climate change is causing unusual warm periods in winter which is causing the snow to be too thin, or thaw and refreeze to create an ice layer that is non-conductive to the survival of lemmings for example
213
give 2 examples of polar animals that are being affected by climate change
lemmings - subnivean habitats affected
| reindeer - rely on being able to paw through the snow to get food but the icy layer formed prevents this and they starve
214
describe the success of Scottish voles in using subnivean habitats in winter
the snow provides thermal insulation maintaining a temperature of 2-3 C under the pack - the subnivean habitat also provides protection from predators
215
what caused the large increase in voles in 2011
prolonged snow cover
| voles increased in number rapidly because they are protected from environmental conditions and predators
216
how do large mammals that cannot shelter cope with the cold
they rely heavily on insulation to reduce heat loss - this could be fur or adipose tissue (blubber)
217
why do fur and feathers reduce heat loss
they have an insulating effect because of the air they hold
| layers of fur can be adjusted seasonally to make it denser in the winter
218
describe the structure of blubber
it has outer and inner layers
- outer layers have a high proportion of monounsaturated FA
- inner layers are enriched with saturated FA
219
what is the double benefit of blubber
food store and streamlining
220
what 3 ways can heat be lost from an animal surface
evaporation, conduction and radiation
221
reducing/increasing the SA:volume reduces heat loss
reducing
222
how do animals reduce heat loss from extremities
they may reduce the temperature of these structures while maintaining a high core body temperature
223
what is regional heterothermy
reduction in the temperature of peripheral structures whilst retaining temperature in cores and other structures that will fail at low temperatures
224
what problem can be presented with good insulation
overheating when the external temperature changes or when heat is produced during exercise
225
how can insulation layers be tuned
by reducing or increasing the depth of fur or feathers using erector muscles in the skin
226
give two ways that peripheral blood flow can be altered in response to external temperature
vasoconstriction - when cold - constrict vessels --> prevents heat loss
vasodilation - when hot - dilate vessels --> heat loss
227
what are counter current heat exchangers
the arteries leading to the peripheral structures are closely positioned with veins returning from that structure
heat is exchanged between them, warming the venous blood travelling to the heart and cooling the arterial blood going to the periphery such that heat loss is reduced
228
surfaces that are routinely cold have high levels of ……… in their membrane lipids to keep the membrane fluid enough to function correctly
PUFAs - polyunsaturated fatty acids
229
why are counter current heat exchangers useful in birds legs
birds have very thin legs which have high SA:volume ratio - they exhibit highly efficient counter current exchange systems to prevent excessive heat loss
230
describe the counter current exchangers of marine animals
marine mammals often live in waters that are cooler than their cores (they are endotherms) and have counter current heat exchangers in their limbs, flukes and dorsal fins
231
are counter current exchangers used in poikilothermic (cold blooded) animals
yes they are used to retain heat by muscles
232
describe the composition of tuna muscles
they have high levels of myoglobin
233
what is myoglobin
it is similar to haemoglobin but is highly enriched in highly active muscles
234
what is the rete mirabilia
complex interweaving of arteries and veins
235
how does counter current exchange allow ectotherms to effectively act as endotherms
the counter current exchange systems allow them to behave like endotherms by reducing the loss of heat that they generate metabolically
236
why are counter current exchangers special in leatherback turtles
they allow them to be the only reptile hunting in cold deep waters
the counter current exchange systems are at the base of their limbs and retain heat in their muscles
they also have thick layer of fat and oil insultation
237
what is the largest species of marine turtle
leatherback turtle
238
why are leatherback turtles referred to as gigantothermic
because they are very large which reduces their SA:volume reducing heat loss
239
what do bumblebees use counter current exchangers for
to retain heat in their flight muscles and not lose it via blood circulation to the abdomen
they can fly at cooler temperatures and higher altitudes as a result of this
240
how can ice affect plants and animals
ice crystals are sharp and can puncture cell membranes and damage tissues and dehydrate cells
241
how do animals and plants reduce their freezing point
they either produce certain sugars or anti freeze proteins
242
give 2 examples of lowering freezing point
- arctic beetle produces high levels of glycerol and sorbitol that are cryoprotective
- glucose is a cryoprotective for freezing and storing sperm
243
insects need to produce cryoprotectants in …….. of their need
advance
244
what do antifreeze proteins prevent
formation of sharp ended water crystals
245
how do teleost fish cope with living in waters cooler than their blood freezing temperature
they produce antifreeze proteins which inhibit growth of ice crystals and also accumulate to prevent growth of sharp pointed crystals
246
describe the general structure of antifreeze proteins
they tend to have faces enriched in serine and threonine amino acids, the hydroxyls of which interact directly with ice
247
what is hibernation
prolonged period of reduction in body temperature and metabolism
248
give 3 examples of hibernating animals
squirrels, bats and hedgehogs
249
what is torpor
period of inactivity often with reduced temperature and metabolism for a short term
it is usually overnight/diurnal and in response to temperature or food supply fluctuations
250
what is aestivation
period of torpor to avoid heat and draught
251
give an example of an animal that undergoes torpor
lemurs
252
what are some adaptations of squirrels for winter
- heartrate decreased by 90%
- cellular lipid composition altered
- extra types of lipid transporter proteins in heart muscle cells
- head and brown fat receive more blood than other organs
253
how do animals arouse from hibernation
organs in the thorax and head warm first followed by other tissues
heat is produced by two main mechanisms
1 - shivering to produce heat from muscle activity
2 - activation of brown fat which generates heat through activation of mitochondria
254
large animals have less/more energy requirement per unit mass so less/more expenditure of body mass is required to maintain body temperature
less
| less
255
large animals have small/large SA:volume so lose more/less heat so can survive on fat stores
small
| less
256
arousing energetically is too ………. for large animals
costly
257
do bear enter full hibernation and why are they considered hibernators
no their temperature isn't as low but breathing and heart rate drop significantly
bears maintain a higher temperature to keep their organs active
they are considered hibernators because metabolic activity is lowered
258
how do polar bears survive the winter
- fat storage
- black skin - UV absorbance
- compact ears and tail
- PUFAs on cold contact areas
- hollow hairs for insulation and buoyancy
259
list some facts about polar bear reproduction and adaptations
- they are polygamous and mate in spring
- fertilized ovum undergoes delayed implantation - cubs born soon after implantation
- gestation period of 8 months
- mother inhabits 2 chamber cave deep in snow
- females nurse young for 2.5 years
- sexual maturity at 3-4 years
- milk contains 33% fat
- lactating females go into dormancy during denning
260
what are the effects of climate change on polar bears
- triplets becoming rare when previously common
- % cubs reaching 12 months decreased
- fewer cubs weaned by 18 month than previously
261
what other animals other than polar bears are affected by loss of ice
walrus - cannot feed without ice and need to come up and rest to prevent excess heat loss in water
they now have to rest on land and juveniles get crushed
262
what are the 3 options to cope with heat for animals
evade - shelter
evaporate - sweat
endure
263
why do some spider role down sand dunes
to avoid contact with the hot surface
264
how do lizards minimise contact with hot surfaces
they raise their body off the ground to minimise contact and alternate the legs that they stand on
265
how do sidewinder rattle snakes avoid heat contact
they move sideways up sand slopes helping them survive in deserts - sideways movement reduces heat contact because the point of contact is smaller and alternates
266
up too what temperature can the antelope ground squirrel tolerate and above this temperature what does it do
can cope with up to 42.3 C
| they hide in burrows to evade heat above this temperature
267
how do great gerbils evade heat
they seek refuge in burrows
| patches of bare earth form above and around the burrow which reflect light keeping the burrow cool
268
what is the Bernoulli effect
burrows show this effect
| it reduces CO2 conc in the burrow and cools it
269
give 2 examples of animals which seek refuge in burrows showing the Bernoulli effect
leaf cutting ants
| praire dogs
270
the larger the body mass the more/less insulation needed
less - elephants have very thin pelts
271
what is spatially confined insulation
having thick pelts in some places and thin in others e.g. guanaco
272
large animals don't lose so much heat due to their …………...…..
small SA:volume
273
smaller animals lose a lot of heat ………. due too high SA:volume so they need to be well insulated
radiatively
274
why do elephants and rabbits have high SA:volume in ears
so that they can lose heat but radiation
275
how is heat loss from ears adjustable
increased temp - temp ears rises because they open up blood vessels in the ears to allow for radiative cooling
276
which 3 mammals sweat
horses, humans, patas monkeys
277
how do horses dissipate heat when exercising
- they sweat heavily
- horse sweat is low in slat and high in protein
- latherin is a detergent like protein present in horse sweat and causes the foaming of a sweating horse
- the function of latherin is to wet the hair to facilitate translocation of sweat to the surface o the pelt from the skin to allow for evaporative cooling
- horses have a thick oily pelt and latherin opens up and exposes the hydrophobic core and binds to oily hairs
278
what type of protein is latherin
it is part of the PLUNCs protein family that are produced in various forms in the oral and upper respiratory tract of humans
in horses latherin may have originally been a salivary protein that adapted to facilitate sweating
279
latherin decreases/increases the surface tension of sweat, facilitating evaporative cooling at the hair tips
decreases
280
why doe zebras have stripes
- flies can't settle easily in the stripes
- thermoregulation
- confuse predators
281
describe the thermoregulating effect of zebra stripes
- black stripes get hotter because they absorb IR better
- the hairs on the black stripes erect more often for more efficient radiative cooling
- the black stripes also produce more latherin
282
how do birds cool since they don't sweat
- they do gular flapping which increases airflow over the wet surfaces in order to evaporatively lose heat
283
how do dogs lose heat
they pant and extend their tongues to increase the amount of wet surface (watery mucosal surface) exposed to the air
284
what is the difference between dog and human panting
humans increase frequency of breathing which is energetically costly - usually due to exhaustion
dogs increase the depth of each pant not the frequency- they do it for heat loss
285
why do camels have insulation in the summer and winter
winter - toe prevent heat loss
| summer - protect against solar irradiation
286
what happens if you shave a camel in summer
it would lose 50% more water due to having to cool more
287
how do camels save on the expense of water cooling
they allow their temperatures to go up and their temperature becomes stable when they get water again
288
can humans tolerate fluctuating body temperatures like large desert animals
no - our organs would be damaged with temperature fluctuation
289
how is the temperature of the human brain maintained
it has a counter current system that prevents heating and cooling
the veins at the nasal are very cool due to evaporation on nasal membranes when we inhale - this also humidifies air going into the lungs
veins integrate with the arteries coming for the heart which maintains the blood temperature going to the brain
290
what is the brian counter current exchange system called
the rete mirabilia - extensive breaking up of veins and arteries to increase heat exchange
291
why don't rats or dogs need counter current exchangers
rats are evaders
| dogs have efficient evaporative cooling
292
how are the kidneys adapted in desert animals
kidneys are almost spherical
| the loop of henle is much longer so they can withdraw much more water from their urine
293
does the increase in length of the loop of henle in desert animals change the plasma conc
no the plasma conc stays the same
294
what is the thermoregulation effect of desert snakes not hissing
hissing causes water loss so desert snakes use sonic rattle instead or rub their scales together
295
how do beetles in the desert acquire rainfall
they rely on mist for water
the beetles posture themselves in the direction of mist and they have an elytra surface on their back
the mist condenses on their back and they absorb it
296
how do sangrouse transport water to their chicks
they fly to a water source, soak up the water into their feathers and take it to their chicks to avoid predation and travel to watering areas
297
what are the 2 species of camel
dromedary and Bactrian
298
why do camels have humps
for localised fat storage - it reduces the amount of insulation by compartmentalising it on their backs
299
how are camels adapted in terms of their lipids and cytoskeleton
they have altered lipids
they have a strengthened cytoskeleton
they have a high protein to lipid ratio
300
what is one of the hottest terrestrial environments on earth
the Saharan desert
301
describe the Saharan silver ant
they are thermophilic scavengers meaning that they feed on animals that die from overheating
the silver effect means they can reflect IR light
they must keep their temperature below 53.6 C
they need to reduce heat absorption and dissipate excess heat to minimize the amount of time spent in refuge
302
in what 3 ways do the silver hairs of the Saharan silver ant protect against overheating
1. total internal reflection - hairs enhance reflectivity in the visible and near IR
2. where solar radiation becomes negligible, hairs act as an anti-reflection layer enhancing emissivity and increasing the ability to offload excess heat
3. the ants bare undersides reflect IR from the desert floor more efficiently than if covered by hairs
303
brine shrimp are found in salt lakes what are their cryoprotective adaptations
- they tolerate varying levels of salinity
- their eggs are metabolically inactive
- they remain in stasis for 2 years in dry oxygen free conditions
- they are cryptobiotic
- while in cryptobiosis they can survive extreme temperature
304
what is cryptobiosis
a metabolic state of life entered when adverse environmental conditions occur. metabolic activity is reduced to an undetectable level. when preferable conditions return organisms return to normal metabolic levels
305
give 2 examples of deep diving cetaceans
sperm whale
| fin whale
306
give 2 examples of deep diving pinnipeds
elephant seal
| California sea lion
307
give an examples of a deep diving reptile
leatherback turtle
308
give an example of a deep diving sirenian
west indian manatee
309
give an example of a deep diving mustelid
sea otter
310
what is biofluorescence
emission of light
311
what are some problems faced by deep diving mammals
```
increased pressure
gas filled spaces are crushed
gasses are absorbed/dissolved in the blood at high pressure
high risk of embolism
challenges with temperature regulation
need different sensory perception
need to adapt metabolism
```
312
for every 10m of depth in the ocean how many atmospheres do we increase by
1atm = 10m
313
give examples of gas filled spaces which are crushed in deep diving and why this is bad
the trachea and lungs can be crushed which can result in tissue damage
314
at high pressures why is it dangerous for gases to be absorbed by the blood
oxygen becomes toxic and nitrogen becomes narcotic
315
why is there a high risk of embolism with deep diving
bubbles of gas come out when the pressure decreases going towards the surface and these gases coming out of solution can cause embolisms
316
what is an embolism
obstruction of an artery, typically by a clot of blood or an air bubble
317
why are there thermoregulation challenges with deep diving
it gets colder the deeper you go because there is no warm solar irradiation
318
what is the diving response
the physiological changes during diving
319
give some examples of diving responses
```
bradycardia
anaerobic metabolism
vasoconstriction
changes in organ perfusion patterns
changes in pH of blood, partial pressure and oxygen content
```
320
what is bradycardia
slow heart rate
321
why do animals revert to anaerobic metabolism when diving and what is the consequence of this
they don't have sufficient oxygen
| the anaerobic metabolism results in a build up of lactate in the body due to muscles entering anaerobic metabolism
322
what is vasoconstriction and why does it occur when diving
when the blood vessels narrow
| prevents excess heat loss by reducing the blood flow to the periphery
323
what is meant by changes in organ perfusion
changes in the amount of blood going to different organs
324
what are some diving responses in humans
```
apnoea
bradycardia
reduced cardiac output
reduced blood supple to extremities
gradual increase in mean arterial blood pressure
```
325
what is the aerobic dive limit
the dive duration after which there is an increase in post-dive conc of lactate in the blood - the point where anaerobic respiration comes in
326
why do weddell seals only dive for short periods for the majority of their dives
so they don't reach their aerobic dive limit - during short dives they remain aerobic with little lactate accumulation
327
how can ADL be calculated
from the size of the oxygen stores and the animals metabolic rate - this can approximately indicate the animals maximum dive duration
328
longer dives need longer surface recovery time to repay ……..… …...…...
oxygen debt
329
carrying oxygen in the blood while diving makes the blood more ……………… which can cause a range of vascular issues
viscous
330
compare renewal of air in the lungs in a single breath in humans vs. manatees and cetaceans
manatees and cetaceans can renew 90% in one breath but humans can only renew 10%
331
distribution of oxygen stores is different/the same in different species
different
332
where are the 3 main places that oxygen is stored
blood, muscle and lungs
333
how do the oxygen stores of humans and weddell seal differ
seals store more oxygen in the blood and muscle than humans
| humans strore more oxygen in the lungs than seals
334
why is myoglobin highly concentrated in muscle in deep divers
myoglobin has a higher affinity for oxygen than haemoglobin so would strip oxygen from blood
muscle is tolerant to hypoxia so we get withdrawal of oxygen from the muscle which protects other organs form damage
335
why is it best to have little air in the lungs when deep diving
they get crushed
when air in the lungs is compressed this delivers huge amounts of nitrogen to the blood which has narcotic effects
the nitrogen bubbles out and can cause the bends which increases embolism risk
336
which cetacean has the most rete mirabilia
sperm whales
337
where are rete mirabilia found in cetaceans
inner dorsal wall of the thoracic cavity and in the periphery
338
are rete mirabilia in sperm whales counter current exchange systems
no - in this case it is a blood storage system - the complex array of blood vessels allow more blood storage and so the ability to store more oxygen - the volume of blood increases but its conc doesn't - this is the same in spotted dolphins
339
how are blood stores in cetaceans used in diving
they have stores of rbcs that are compressed when they dive and the blood cells go into the blood increasing its volume
340
how is blood storage maximised in pinnipeds
the venous systems are enlarged and increased in complexity
they have a sinus (inflation of the vena cava) and blood is stored there
they also store blood in the spleen - diving capacity is correlated with spleen size - the spleen is contracted when blood is required in the circulatory system
341
what causes a stitch
contraction of the spleen to release its blood storage
342
do deep diving animals have larger lungs than land animals
no - diving lungs are generally less lobes and have increased cartilage support with very small residual volumes
343
what does the diaphragm oblique in cetaceans allow for
allows the viscera (guts) to move forward under compression
344
describe the trachea of diving animals
short with well reinforced rings
345
which whales collapses its trachea
baleen whales
346
which whales keep their trachea open
toothed whales
347
how is pressure difference decreased in the trachea
by pushing air into the trachea
348
why do cetacean ribs need to be modified
to allow their lungs to collapse - air is then expelled in to the bronchioles and the trachea
349
whales/pinnipeds dive with full lugs
| whales/pinnipeds exhale before diving
whales
| pinnipeds
350
what is the bends
gas coming out of solution on decompression
351
what can the bends cause in certain bones
dysbaric osteonecrosis
352
what is dysbaric osteonecrosis
bone death caused by nitrogen embolism (the bends) - they get cavities in their bones and spongy bones
353
what evidence indicates that leatherback turtles are deep divers
bone cavities
354
why don't leatherback turtles have scutes/scales
so their bodies are much more flexible which allows them to dive to great depths
355
why do leatherback turtles have extensive brown fat
because that's where mitochondria are concentration
356
as well as brown fat what other type of fat is concentrated in leatherback turtles
adipose tissue
357
why do leatherback turtles have counter current exchangers
to increase blood volume
358
which gene results in increased spleen size in humans
PDEIOA - provides people with larger reservoir of oxygenated blood cells
359
which genes affects the human diving reflex
BDKRB2
360
name 2 high altitude birds
bar headed goose
| rippell's griffon vulture
361
amphibians are negative/positive pressure breathers
positive
362
most non avian reptiles, birds and mammals are positive/negative pressure breathers
negative pressure breather using rib ventilation
363
mammals have elaborate alveolated lungs to increase …….... for gas exchange
SA
364
the oxygenated/deoxygenated air in humans/birds mixes
| the oxygenated/deoxygenated air in humans/birds doesn't mix
humans mix - don't evacuate all the air from the previous breath
birds no mix - air goes into sacs then moves through a one way system
365
why do birds lungs need to be more efficient than human lungs
so they can gather more oxygen for flight and high altitudes
366
what are some notable aspects of the bar headed goose
- larger wing area for weight than other geese
- breath more efficiently under low oxygen and are able to reduce heat loss
- haemoglobin has higher oxygen affinity than other geese to fuel flapping flight
- flight muscle undergoes an increase in bulk prior to migration
- they have high proportion of oxidative fibres and capillaries per muscle fibre than expected
all these differences exist without prior exercise or hypoxia exposure
367
describe the mitochondria of bar headed goose
no special features in terms of respiratory capacities, oxygen kinetics or phosphorylation efficiencies but are distributed towards the subsarcolema and adjacent to capillaries
368
what are the 3 high altitude human communities
Tibetans (60)
Andeans (60)
Ethiopians (64)
369
what are the adaptations of high altitude humans
- larger hearts and lungs
- altered cerebrovascular responses
- no change in amino acid sequence of haemoglobins or myoglobins
- higher oxygen level in placental blood
370
which high altitude human community uses erythrocytosis
Andeans
371
which high altitude human communities exhibit arterial hypoxaemia
Tibetan
| Andeans
372
what is erythrocytosis
increase in the total rbc mass secondary to a number of non-hematogenic systemic disorders in response to a known stimulus
373
what is arterial hypoxemia
low level of oxygen in the arterial blood which can cause tissue hypoxia
374
what are the differences between Tibetans and Andeans
Tibetans have different physiological traits
- decreased arterial oxygen content
- increased resting ventilation, lack of hypoxic pulmonary vasoconstriction
- lower incidence of reduced birth rate
- reduced haemoglobin concentration
375
what do lowland humans develop when they go to high altitude
they develop increased haemoglobin concentration to compensate for the hypoxic high altitude environment
376
Andeans and Tibetans can saturate there blood more easily with oxygen than ……………….
Ethiopians or sea level people
377
Andeans and Tibetans have the same problems but they solves them in different ways, explain
- Andeans have more haemoglobin than Tibetans
- Tibetans use smaller amounts of oxygen more efficiently
- they both have genes advantageous for high altitudes but Tibetans have other advantageous genes that Andeans don't
