Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

KSB > extreme biology > Flashcards

extreme biology Flashcards

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what do plants rely on light for

A

photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how does leaf size adapt to get more light

A

make the leaf bigger to get more sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how does leaf size adapt to evade high temperature damage

A

make the leaf smaller to increase heat loss by radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

in what conditions are small leaves favourable

A

extremes of dryness, heat, draught and cold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what kind of plants do we get in hot treeless deserts

A

ephemerals, adaptors, resistors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the 4 main steps of ephemeral life cycle

A

growth
flowering
seed setting
death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

are ephemerals draught resistant

A

not particularly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is cryptobiosis

A

a metabolic state entered by organisms in response to adverse environmental conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are poikilohydric plants and give an examples

A

they are resurrection plants craterostigma plantagineum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how do poikilohydric (resurrection) plant and ephemerals differ

A

ephemerals die and leave their seeds

resurrection plants don’t die

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are phreatophytes

A

deep rooted large perennial plants that obtain a significant portion of water from the phreatic zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the phreatic zone

A

the zone of saturation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what are the 2 roost formed by the phreatophytes

A

deep tier roots that get water from the deep water table

shallow tier roots that capture rainfall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

describe the leaves of phreatophytes

A

they are tiny in order to reduce water loss and aid radiative heat loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

are stomata open or closed during the day in phreatophytes

A

they are closed to prevent water loss s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

give a example of a phreatophyte

A

creosote bush

mesquite plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the oldest plant

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are xerophytes

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is an arid climate

A

climate with low water availability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

describe the succulents of xerophytes

A

succulents contain storage of water in very sugary cores and they are found in leaves and stems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

give examples of xerophytes and note the type of succulent they have

A

aloe vera and crassula - leaf succulents

cactus - stem succulents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

describe cacti in terms of their leaves and stems

A
  • cactus spines are their leaves but they are not for photosynthesis, instead they are for protection
  • the entire stem of the cactus is photosynthetic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what are cacti areola

A

an area on the plant where a tuft of white hairs come out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

give reasons why cacti are very good at retaining water

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what conditions are high altitude cacti adapted to

A

dry, cold air and intense light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what does it mean that high altitude cacti are very pubescent and how is this of benefit

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

high altitude cacti are long/short lived and slow/fast growing

A

long

slow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what kind of conditions are euphorbias adapted to

A

dry conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

how do euphorbias protect themselves against other animals and how are they different to cacti

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what are lithops and what is there nickname

A

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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what is a compass plant

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

are most plants C3 or C4

A

C3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what are the differences between C3 and C4 metabolism

A

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).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

what are the advantages of C4 metabolism in plants

A
  • 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.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

what are the two main type of C4 metabolism

A

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.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what are the differences between the 2 types of C4 metabolism

A

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.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what percentage of plants are C4

A

3% but 5% of biomass and 23% carbon fixation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

how much less water do C4 plants lose compared to C3

A

C4 plants lose 1/2 as much water per unit CO2 compared to C3 plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

what is the most abundant protein on the planet

A

rubisco

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what does rubisco do

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

what does spatial separation mean in C4

A

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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

what increases the internal CO2 concentration

A

CO2 pumps - so that we generate an environment high in CO2 conc in the bundle sheathes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

where is malate synthesised

A

in the mesophyll cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

hoe does malate get from the mesophyll cells to the bundle sheath cells

A

it diffuses via plasmodesmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

why can’t C3 plants grow in very hot areas

A

because with increasing temp rubisco incorporates more oxygen than CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

what is marram grass

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what is the C4 time separation reaction called

A

CAM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

what are the stomatal differences between the 2 C4 pathways

A 
spatial separation - stomata closed at night and open during the day
time separation (CAM) - stomata open at night and closed during day
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

what are the steps in CAM

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

in what type of climates can slat be problematic for plants

A

marine and brackish waters and arid land areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

give examples of halophytic plants and their specialised salt organs and adaptive metabolisms

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

not all halophytes have obvious morphological features - provide an example

A

thellungia halophylia (salt tolerant) - close relative of Arabidopsis (salt sensitive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

what is the mechanism that allows thellungia halophylia to be salt tolerant

A
  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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

what are adaptations in plants to avoid anoxia from water flooding

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

what is an angiosperm

A

a plant that has flowers and produces seeds enclosed within a carpel(usually a fruit)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

what is a gymnosperm

A

no flowers or enclosed seeds, seeds often cones e.g. conifers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

describe seagrass (zostera marina)

A

it is an angiosperm with submerged male and female parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

what has seagrass lost genes for

A

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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

what has seagrass gained genes for

A

encoding cell wall components for osmotic control to prevent saltwater driving water out of the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

how can nitrogen poverty be evaded by carnivory

A

when plants eat insects it provides them with a nitrogen source -this is useful if the soil is nutrient poor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

give examples of carnivorous plants and their mechanisms

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

give an example of how parenthood can help with nitrogen poverty

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

what doe monodominant mean

A

when more than 60% of the tree canopy is comprised by a species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

how are coco de mer and coconuts different

A

the seeds of coco de mer are not salt tolerant so they die if they fall in the sea unlike coconuts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

describe the arctic tundra environment

A

cold deserts, biodiversity is very low
little rainfall
high densities of the same species
7 months of snow cover in winter - limited light capture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

what kind of plants do we find in the arctic tundra

A

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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

some plants are able to grow in rocks, give an example

A

lichens and mosses - able to tease nutrients out of the rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

describe the Antarctica plants

A

must grow quickly and in extremely cold conditions
metabolic activity is maximised at low temperatures
there are only 2 native vascular plant species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

what are the 2 native vascular plant species of the Antarctica

A

hairgrass
pearlwort
both of these grow in small clumps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

how do lichens grow in the antarctica

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

how do mosses grow in Antarctica

A

they form colonies that collect and retain water
their photosynthetic enzymes have maximal activity at 5C
photosynthesis quickly activates after frost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

describe the plant growth in taiga

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

what is taiga

A

huge bands of forest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

what is earth’s largest terrestrial biome

A

taiga

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

what are the dangers of cold to plants

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

what do plants induce to protect themselves from the cold

A

cold tolerant mechanisms and components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

describe the preparation of taiga conifer trees for winter

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

how do membranes change in response to cold

A

unsaturation, increased phosphatidylethanolamine and decreased phosphatidylcholine, increased phospholipids, reduced galactolipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

which proteins are upregulated in response to cold

A

dehydrins - prevent membrane-membrane interactions
antioxidant systems - protection against oxygen damage
heat shock proteins
pathogenesis related proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

describe the leaves of deciduous trees

A

they generally have large light gathering leaves which are shed in winter to prevent the tree from being blown over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

what is an abscission layer

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

when does the abscission layer form

A

in spring with new leaf growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

why are new buds sticky

A

because they coat themselves in sugar as a cryoprotective mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

what are response of leaves in winter that aren’t shed

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

give an example of a plant that drops and curls its leaves

A

rhododendron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

describe the origin of conifers

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

give an example of a large conifer that was thought to feed sauropods

A

monkey puzzle tree

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

what is meant by conifers being evergreen

A

they are spring ready - have green leaves throughout the year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

what conditions are conifers best adapted to

A

dry, cold and high altitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

how are conifers designed for snow

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

what can happen to photosynthesis in conifers in winter

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

the oldest bristlecone pine was accidently burnt describe the plants soil and root system

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

crown drag is greatest in trees with narrow/broad leaves and the advantage is to be deciduous/coniferous

A

broad

deciduous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

describe an oak tree (angiosperm) (deciduous)

A

dense heavy trunk
limited sway
broad root base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

describe and pine tree (conifer) (gymnosperm)

A

lighter trunk
more sway
deep tap root

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

what is a buttress root

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

how do trees/leaves reduce crown drag

A
  • leaves twist, curl or fold to resist wind so they aren’t ripped off the tree or cause the tree to fall over
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

what can plant loneliness be caused by

A

distant colonisation
devastated land
widespread separation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

give an example of a plant that grows on devastated land

A

rosebay willowherb - grows in ash - doesn’t require soil fungi - they have feathery seeds so that they can colonise land rapidly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

give examples of plant loneliness - how do cacti combat loneliness

A

cacti are often spread out so need to try hard to find a pollinator
they often have improved advertising to attract pollinators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

give an example of loneliness in a tropical forest

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

why can’t temperate tropical rainforest plants or polar plants rely on temperature or daylight

A

because the environment is very stable

they use the solar analemma instead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

what is the solar analemma

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

give some examples of common classes of extremophiles

A 
acidophile 
alkaliphile 
halophile 
hyperthermophile 
oligotroph
osmophile 
piezophile 
psychrophile 
thermophile
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

what is deinococcus radiodurans

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

how does DR repair DNA

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

what are the basic requirements for early life

A

carbon and nitrogen - they generate energy through cycles like the calvin cycle, krebs cycles and nitrogen cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

what are the 3 domains of life

A

bacteria, archaea, eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

what are the different atmosphere states in its evolution

A

anaerobic, single cells
anaerobic, photosynthesis, single cells
aerobic, eukaryotes
multicellular life, Cambrian explosion, stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
122
Q

what are the effects of oxygenation of the atmosphere

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
123
Q

what are the origins of extremophile prokaryotes

A

archaea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
124
Q

what are the 2 main biochemical cycles of life

A

calvin cycle and the krebs cycle - both use carbon for energy storage and transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
125
Q

evolution of what process lead to the great oxygenation event

A

photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
126
Q

what does photosynthesis require

A

a means by which photons are captured and their energy directed to the reaction centre where CO2 is fixed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
127
Q

what is the light harvesting complex

A

it sits embedded in a membrane and consists of proteins and pigments surrounding a reaction centre
(various pigment molecules bound to proteins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
128
Q

where is the light harvesting complex of green plants found

A

the thylakoid membranes of chloroplasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
129
Q

what are antenna pigments

A

chlorophyll b, xanthophylls, carotenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
130
Q

why is it good that absorption spectra are not overlapping

A

because when you have more than one pigment you broaden the absorption range for photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
131
Q

what is the other role of carotenoids

A

they act as an antioxidant to prevent photo-oxidative damage of chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
132
Q

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

A

reaction centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
133
Q

how is energy shuttled in photosynthesis

A

by resonance energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
134
Q

what is a photosystem

A

composed of a reaction centre surrounded by several light harvesting complexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
135
Q

what is a reaction centre

A

association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
136
Q

nitrogen fixation by pants requires …………

A

microbes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
137
Q

what fixes atmospheric nitrogen into a more suable form such as ammonia

A

diazotrophsare bacteria and archae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
138
Q

what are the steps in the nitrogen cycle

A
  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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
139
Q

as far as we know all living systems derive(d) their energy from

A

electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
140
Q

electrons are used in chemiosmosis what is this

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
141
Q

give an example of another redox reaction which creates energy other than photosynthesis

A

NO2 reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
142
Q

archaea are more closely related to …….. than bacteria and where does this evidence come from

A

eukaryotes

evidence from genes sequencing - particularly rRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
143
Q

what are the different energy sources of archaea

A

organic resources
phototrophic
carbon dioxide fixation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
144
Q

archaea membranes are comprised of …… lipids not ……. lipids

A

ether not ester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
145
Q

how do archaea reproduce

A

asexually

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
146
Q

have any pathogenic archaea been found

A

no - only mutualistic and commensals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
147
Q

what about archaea membranes stabilises them at high temperatures

A

their highly branched structure - they contain branched isoprene chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
148
Q

what can isoprene chains of archaea membranes do

A

they can be joined together between phospholipids

they can form carbon rings which increase stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
149
Q

what do methanogenic archaea do

A

they breakdown lignocellulose into simple sugars and methane (the by-product) - methanogens are key organisms in decomposition and they are obligate anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
150
Q

what are thermoacidophiles

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
151
Q

what debate about archaea is ongoing

A

whether eukaryotes are derived from them

152
Q

where are microbes that use sulphur oxidation for energy generation found e.g. paracoccus dentrificans bacterium

A

hot sulphurous springs

153
Q

what is halotolerance

A

tolerance to high slat conc

154
Q

what are halobacteria

A

photoautotrophs

155
Q

what are lipids made from

A

glycerides: glycerol + FA

156
Q

what is phosphatidycholine

A

a diglyceride which is a major phospholipid of membranes

157
Q

the degree of ………. affect van der waal forces which can change lipid properties

A

saturation

158
Q

weak attractive forces between FA chains are countered by ……..…. ……… …………

A

random thermal motion - bond rotation, stretching etc

159
Q

what is the structure of membrane glycerides

A

they have a glycerol core with usually 2 of 3 of the OH groups linked to FA by ester linkages

160
Q

the .…….. and degree of ……….. of FA determines the physical properties of the lipids

A

length

saturation

161
Q

describe saturated fat and FA

A

the molecules of saturated fat are packed closely together forming a solid - e.g. butter

162
Q

describe unsaturated fat and FA

A

the molecules of fat cannot pack closely together because they have kinks in their FA chains forming a liquid - e.g. olive oil

163
Q

phospholipids have ……….. heads and …………….. tails

A

hydrophilic head

hydrophobic tails

164
Q

different lipid classes confer different ……….. to membranes

A

shapes

165
Q

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

A

water
size, charge and shape
saturation

166
Q

other lipids such as …………. and its derivatives can be embedded in the membrane further affecting the curvature and biophysical properties of the membrane

A

cholesterol - stiffens the membrane

167
Q

when exposed to stress the heterogenous mixtures (……..) of different lipids can phase separate to form what and what is the effect of this

A

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
Q

what is an inverted micelle

A

polar head groups face inwards and non-polar tails face outwards

169
Q

what are the effects of membrane lipids becoming more unsaturated

A
  • 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
Q

increasing sterol content of membranes increases fluidity/rigidity

A

fluidity

171
Q

melting point of FA decreases/increases as the proportion of unsaturated bonds increases

A

decreases

172
Q

give 3 examples of saturated FA

A

steric, palmitic, lauric

173
Q

give 3 examples of unsaturated FA

A

oleic, linoleic and linolenic

174
Q

what is the structure of cholesterol

A

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
Q

how does cholesterol affect membrane fluidity

A

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
Q

what is cholesterol on skin transformed to in sunlight

A

vitamin D

177
Q

at low temp we increase/decrease the number of cis double bonds in FA

A

increase

178
Q

at high temp we increase/decrease the number of cis double bonds in FA

A

decrease

179
Q

freeze fracture electron microscopy of membranes can reveal ……………

A

Hex II structures and internal structure of membrane bilayers

180
Q

what is freeze fracture electron microscopy

A
  • specimen frozen
  • frozen sample is fractured
  • new exposed faces are coated in gold
  • viewed under a scanning electron micrograph
181
Q

what are the 2 appearances of Hex II structures

A

granular or tubular

182
Q

………….. shocked proteins may also form Hex II structures

A

temperature

183
Q

what are differences in osmotic water loss during freezing of cold acclimated and non-cold acclimated cells

A

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
Q

what organisms are particularly exposed to seasonal temperature changes

A

land plants

185
Q

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

A

body surfaces
extremities
they make their membranes more polyunsaturated at exposed sites

186
Q

describe archaea membranes

A
  • 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
Q

what are the different levels of protein structure

A
  • 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
Q

what kind of organisms produce heat shock proteins

A

prokaryotes and eukaryotes

189
Q

are heat shock proteins only produced in response to heat

A

no they are produced in response to other stresses too

190
Q

what are the 2 roles of heat shock proteins

A

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
Q

smaller HSPs are ………….. ………..and larger ones are involved in …………. ……………….. ………. …… ………

A

molecular chaperones

refolding and degradation of proteins

192
Q

what is a proteasome

A

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
Q

how are proteins tagged for degradation by the proteasome and what is the effect of this tagging

A
  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
Q

ER and Golgi play a key role in protein ………… and …………..

A

assembly and trafficking

195
Q

denatured proteins are stick and aggregate in the …… what process has evolved to recover this situation

A

ER

UPR - unfolded protein response - eukaryotes only

196
Q

what are the 3 key UPR pathways and what are they all regulated by

A

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
Q

what diseases are caused by upregulation of UPR

A

huntington’s, alzhiemers, Parkinson’s, mad cow

198
Q

name 2 thermostable enzymes

A

Taq DNA pol

Vent pol

199
Q

describe vent pol

A
  • 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
Q

describe Taq pol

A
  • 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
Q

describe the cell structure and memb surface of an archaea

A
  • 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
Q

what is a hexagonal phase

A

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
Q

what does H I mean

A

polar outside

204
Q

what does H II mean

A

polar inside

205
Q

animals need to shelter from the cold in subnivean habitats - what is a subnivean habitat

A

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
Q

which type of ecosystems change very little throughout the year

A

tropical rainforests near the equator

207
Q

which ecosystems change dramatically throughout the year

A

polar regions - they change dramatically with seasons which the organisms must adapt to

208
Q

why does earth have seasons

A

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
Q

what are some reasons that organism migrate

A

to avoid conditions that would make them physiologically unable to survive or that would eliminate their food supply until spring

210
Q

what are the greatest migrators in terms of distance

A

birds and cetaceans

211
Q

what are some reasons why animals don’t migrate

A

the distance is too great
there are physical barriers
they have found ways to continue feeding and coping in their present environment

212
Q

why is climate change causing an issue for animals that rely on subnivean habitats

A

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
Q

give 2 examples of polar animals that are being affected by climate change

A

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
Q

describe the success of Scottish voles in using subnivean habitats in winter

A

the snow provides thermal insulation maintaining a temperature of 2-3 C under the pack - the subnivean habitat also provides protection from predators

215
Q

what caused the large increase in voles in 2011

A

prolonged snow cover

voles increased in number rapidly because they are protected from environmental conditions and predators

216
Q

how do large mammals that cannot shelter cope with the cold

A

they rely heavily on insulation to reduce heat loss - this could be fur or adipose tissue (blubber)

217
Q

why do fur and feathers reduce heat loss

A

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
Q

describe the structure of blubber

A

it has outer and inner layers

  • outer layers have a high proportion of monounsaturated FA
  • inner layers are enriched with saturated FA
219
Q

what is the double benefit of blubber

A

food store and streamlining

220
Q

what 3 ways can heat be lost from an animal surface

A

evaporation, conduction and radiation

221
Q

reducing/increasing the SA:volume reduces heat loss

A

reducing

222
Q

how do animals reduce heat loss from extremities

A

they may reduce the temperature of these structures while maintaining a high core body temperature

223
Q

what is regional heterothermy

A

reduction in the temperature of peripheral structures whilst retaining temperature in cores and other structures that will fail at low temperatures

224
Q

what problem can be presented with good insulation

A

overheating when the external temperature changes or when heat is produced during exercise

225
Q

how can insulation layers be tuned

A

by reducing or increasing the depth of fur or feathers using erector muscles in the skin

226
Q

give two ways that peripheral blood flow can be altered in response to external temperature

A

vasoconstriction - when cold - constrict vessels –> prevents heat loss
vasodilation - when hot - dilate vessels –> heat loss

227
Q

what are counter current heat exchangers

A

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
Q

surfaces that are routinely cold have high levels of ……… in their membrane lipids to keep the membrane fluid enough to function correctly

A

PUFAs - polyunsaturated fatty acids

229
Q

why are counter current heat exchangers useful in birds legs

A

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
Q

describe the counter current exchangers of marine animals

A

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
Q

are counter current exchangers used in poikilothermic (cold blooded) animals

A

yes they are used to retain heat by muscles

232
Q

describe the composition of tuna muscles

A

they have high levels of myoglobin

233
Q

what is myoglobin

A

it is similar to haemoglobin but is highly enriched in highly active muscles

234
Q

what is the rete mirabilia

A

complex interweaving of arteries and veins

235
Q

how does counter current exchange allow ectotherms to effectively act as endotherms

A

the counter current exchange systems allow them to behave like endotherms by reducing the loss of heat that they generate metabolically

236
Q

why are counter current exchangers special in leatherback turtles

A

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
Q

what is the largest species of marine turtle

A

leatherback turtle

238
Q

why are leatherback turtles referred to as gigantothermic

A

because they are very large which reduces their SA:volume reducing heat loss

239
Q

what do bumblebees use counter current exchangers for

A

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
Q

how can ice affect plants and animals

A

ice crystals are sharp and can puncture cell membranes and damage tissues and dehydrate cells

241
Q

how do animals and plants reduce their freezing point

A

they either produce certain sugars or anti freeze proteins

242
Q

give 2 examples of lowering freezing point

A
  • arctic beetle produces high levels of glycerol and sorbitol that are cryoprotective
  • glucose is a cryoprotective for freezing and storing sperm
243
Q

insects need to produce cryoprotectants in …….. of their need

A

advance

244
Q

what do antifreeze proteins prevent

A

formation of sharp ended water crystals

245
Q

how do teleost fish cope with living in waters cooler than their blood freezing temperature

A

they produce antifreeze proteins which inhibit growth of ice crystals and also accumulate to prevent growth of sharp pointed crystals

246
Q

describe the general structure of antifreeze proteins

A

they tend to have faces enriched in serine and threonine amino acids, the hydroxyls of which interact directly with ice

247
Q

what is hibernation

A

prolonged period of reduction in body temperature and metabolism

248
Q

give 3 examples of hibernating animals

A

squirrels, bats and hedgehogs

249
Q

what is torpor

A

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
Q

what is aestivation

A

period of torpor to avoid heat and draught

251
Q

give an example of an animal that undergoes torpor

A

lemurs

252
Q

what are some adaptations of squirrels for winter

A
  • 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
Q

how do animals arouse from hibernation

A

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
Q

large animals have less/more energy requirement per unit mass so less/more expenditure of body mass is required to maintain body temperature

A

less

less

255
Q

large animals have small/large SA:volume so lose more/less heat so can survive on fat stores

A

small

less

256
Q

arousing energetically is too ………. for large animals

A

costly

257
Q

do bear enter full hibernation and why are they considered hibernators

A

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
Q

how do polar bears survive the winter

A
  • fat storage
  • black skin - UV absorbance
  • compact ears and tail
  • PUFAs on cold contact areas
  • hollow hairs for insulation and buoyancy
259
Q

list some facts about polar bear reproduction and adaptations

A
  • 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
Q

what are the effects of climate change on polar bears

A
  • triplets becoming rare when previously common
  • % cubs reaching 12 months decreased
  • fewer cubs weaned by 18 month than previously
261
Q

what other animals other than polar bears are affected by loss of ice

A

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
Q

what are the 3 options to cope with heat for animals

A

evade - shelter
evaporate - sweat
endure

263
Q

why do some spider role down sand dunes

A

to avoid contact with the hot surface

264
Q

how do lizards minimise contact with hot surfaces

A

they raise their body off the ground to minimise contact and alternate the legs that they stand on

265
Q

how do sidewinder rattle snakes avoid heat contact

A

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
Q

up too what temperature can the antelope ground squirrel tolerate and above this temperature what does it do

A

can cope with up to 42.3 C

they hide in burrows to evade heat above this temperature

267
Q

how do great gerbils evade heat

A

they seek refuge in burrows

patches of bare earth form above and around the burrow which reflect light keeping the burrow cool

268
Q

what is the Bernoulli effect

A

burrows show this effect

it reduces CO2 conc in the burrow and cools it

269
Q

give 2 examples of animals which seek refuge in burrows showing the Bernoulli effect

A

leaf cutting ants

praire dogs

270
Q

the larger the body mass the more/less insulation needed

A

less - elephants have very thin pelts

271
Q

what is spatially confined insulation

A

having thick pelts in some places and thin in others e.g. guanaco

272
Q

large animals don’t lose so much heat due to their ………………..

A

small SA:volume

273
Q

smaller animals lose a lot of heat ………. due too high SA:volume so they need to be well insulated

A

radiatively

274
Q

why do elephants and rabbits have high SA:volume in ears

A

so that they can lose heat but radiation

275
Q

how is heat loss from ears adjustable

A

increased temp - temp ears rises because they open up blood vessels in the ears to allow for radiative cooling

276
Q

which 3 mammals sweat

A

horses, humans, patas monkeys

277
Q

how do horses dissipate heat when exercising

A
  • 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
Q

what type of protein is latherin

A

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
Q

latherin decreases/increases the surface tension of sweat, facilitating evaporative cooling at the hair tips

A

decreases

280
Q

why doe zebras have stripes

A
  • flies can’t settle easily in the stripes
  • thermoregulation
  • confuse predators
281
Q

describe the thermoregulating effect of zebra stripes

A
  • 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
Q

how do birds cool since they don’t sweat

A
  • they do gular flapping which increases airflow over the wet surfaces in order to evaporatively lose heat
283
Q

how do dogs lose heat

A

they pant and extend their tongues to increase the amount of wet surface (watery mucosal surface) exposed to the air

284
Q

what is the difference between dog and human panting

A

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
Q

why do camels have insulation in the summer and winter

A

winter - toe prevent heat loss

summer - protect against solar irradiation

286
Q

what happens if you shave a camel in summer

A

it would lose 50% more water due to having to cool more

287
Q

how do camels save on the expense of water cooling

A

they allow their temperatures to go up and their temperature becomes stable when they get water again

288
Q

can humans tolerate fluctuating body temperatures like large desert animals

A

no - our organs would be damaged with temperature fluctuation

289
Q

how is the temperature of the human brain maintained

A

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
Q

what is the brian counter current exchange system called

A

the rete mirabilia - extensive breaking up of veins and arteries to increase heat exchange

291
Q

why don’t rats or dogs need counter current exchangers

A

rats are evaders

dogs have efficient evaporative cooling

292
Q

how are the kidneys adapted in desert animals

A

kidneys are almost spherical

the loop of henle is much longer so they can withdraw much more water from their urine

293
Q

does the increase in length of the loop of henle in desert animals change the plasma conc

A

no the plasma conc stays the same

294
Q

what is the thermoregulation effect of desert snakes not hissing

A

hissing causes water loss so desert snakes use sonic rattle instead or rub their scales together

295
Q

how do beetles in the desert acquire rainfall

A

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
Q

how do sangrouse transport water to their chicks

A

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
Q

what are the 2 species of camel

A

dromedary and Bactrian

298
Q

why do camels have humps

A

for localised fat storage - it reduces the amount of insulation by compartmentalising it on their backs

299
Q

how are camels adapted in terms of their lipids and cytoskeleton

A

they have altered lipids
they have a strengthened cytoskeleton
they have a high protein to lipid ratio

300
Q

what is one of the hottest terrestrial environments on earth

A

the Saharan desert

301
Q

describe the Saharan silver ant

A

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
Q

in what 3 ways do the silver hairs of the Saharan silver ant protect against overheating

A
  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
Q

brine shrimp are found in salt lakes what are their cryoprotective adaptations

A
  • 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
Q

what is cryptobiosis

A

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
Q

give 2 examples of deep diving cetaceans

A

sperm whale

fin whale

306
Q

give 2 examples of deep diving pinnipeds

A

elephant seal

California sea lion

307
Q

give an examples of a deep diving reptile

A

leatherback turtle

308
Q

give an example of a deep diving sirenian

A

west indian manatee

309
Q

give an example of a deep diving mustelid

A

sea otter

310
Q

what is biofluorescence

A

emission of light

311
Q

what are some problems faced by deep diving mammals

A 
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
Q

for every 10m of depth in the ocean how many atmospheres do we increase by

A

1atm = 10m

313
Q

give examples of gas filled spaces which are crushed in deep diving and why this is bad

A

the trachea and lungs can be crushed which can result in tissue damage

314
Q

at high pressures why is it dangerous for gases to be absorbed by the blood

A

oxygen becomes toxic and nitrogen becomes narcotic

315
Q

why is there a high risk of embolism with deep diving

A

bubbles of gas come out when the pressure decreases going towards the surface and these gases coming out of solution can cause embolisms

316
Q

what is an embolism

A

obstruction of an artery, typically by a clot of blood or an air bubble

317
Q

why are there thermoregulation challenges with deep diving

A

it gets colder the deeper you go because there is no warm solar irradiation

318
Q

what is the diving response

A

the physiological changes during diving

319
Q

give some examples of diving responses

A 
bradycardia 
anaerobic metabolism 
vasoconstriction
changes in organ perfusion patterns 
changes in pH of blood, partial pressure and oxygen content
320
Q

what is bradycardia

A

slow heart rate

321
Q

why do animals revert to anaerobic metabolism when diving and what is the consequence of this

A

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
Q

what is vasoconstriction and why does it occur when diving

A

when the blood vessels narrow

prevents excess heat loss by reducing the blood flow to the periphery

323
Q

what is meant by changes in organ perfusion

A

changes in the amount of blood going to different organs

324
Q

what are some diving responses in humans

A 
apnoea
bradycardia 
reduced cardiac output 
reduced blood supple to extremities 
gradual increase in mean arterial blood pressure
325
Q

what is the aerobic dive limit

A

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
Q

why do weddell seals only dive for short periods for the majority of their dives

A

so they don’t reach their aerobic dive limit - during short dives they remain aerobic with little lactate accumulation

327
Q

how can ADL be calculated

A

from the size of the oxygen stores and the animals metabolic rate - this can approximately indicate the animals maximum dive duration

328
Q

longer dives need longer surface recovery time to repay ……..… …………

A

oxygen debt

329
Q

carrying oxygen in the blood while diving makes the blood more ……………… which can cause a range of vascular issues

A

viscous

330
Q

compare renewal of air in the lungs in a single breath in humans vs. manatees and cetaceans

A

manatees and cetaceans can renew 90% in one breath but humans can only renew 10%

331
Q

distribution of oxygen stores is different/the same in different species

A

different

332
Q

where are the 3 main places that oxygen is stored

A

blood, muscle and lungs

333
Q

how do the oxygen stores of humans and weddell seal differ

A

seals store more oxygen in the blood and muscle than humans

humans strore more oxygen in the lungs than seals

334
Q

why is myoglobin highly concentrated in muscle in deep divers

A

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
Q

why is it best to have little air in the lungs when deep diving

A

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
Q

which cetacean has the most rete mirabilia

A

sperm whales

337
Q

where are rete mirabilia found in cetaceans

A

inner dorsal wall of the thoracic cavity and in the periphery

338
Q

are rete mirabilia in sperm whales counter current exchange systems

A

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
Q

how are blood stores in cetaceans used in diving

A

they have stores of rbcs that are compressed when they dive and the blood cells go into the blood increasing its volume

340
Q

how is blood storage maximised in pinnipeds

A

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
Q

what causes a stitch

A

contraction of the spleen to release its blood storage

342
Q

do deep diving animals have larger lungs than land animals

A

no - diving lungs are generally less lobes and have increased cartilage support with very small residual volumes

343
Q

what does the diaphragm oblique in cetaceans allow for

A

allows the viscera (guts) to move forward under compression

344
Q

describe the trachea of diving animals

A

short with well reinforced rings

345
Q

which whales collapses its trachea

A

baleen whales

346
Q

which whales keep their trachea open

A

toothed whales

347
Q

how is pressure difference decreased in the trachea

A

by pushing air into the trachea

348
Q

why do cetacean ribs need to be modified

A

to allow their lungs to collapse - air is then expelled in to the bronchioles and the trachea

349
Q

whales/pinnipeds dive with full lugs

whales/pinnipeds exhale before diving

A

whales

pinnipeds

350
Q

what is the bends

A

gas coming out of solution on decompression

351
Q

what can the bends cause in certain bones

A

dysbaric osteonecrosis

352
Q

what is dysbaric osteonecrosis

A

bone death caused by nitrogen embolism (the bends) - they get cavities in their bones and spongy bones

353
Q

what evidence indicates that leatherback turtles are deep divers

A

bone cavities

354
Q

why don’t leatherback turtles have scutes/scales

A

so their bodies are much more flexible which allows them to dive to great depths

355
Q

why do leatherback turtles have extensive brown fat

A

because that’s where mitochondria are concentration

356
Q

as well as brown fat what other type of fat is concentrated in leatherback turtles

A

adipose tissue

357
Q

why do leatherback turtles have counter current exchangers

A

to increase blood volume

358
Q

which gene results in increased spleen size in humans

A

PDEIOA - provides people with larger reservoir of oxygenated blood cells

359
Q

which genes affects the human diving reflex

A

BDKRB2

360
Q

name 2 high altitude birds

A

bar headed goose

rippell’s griffon vulture

361
Q

amphibians are negative/positive pressure breathers

A

positive

362
Q

most non avian reptiles, birds and mammals are positive/negative pressure breathers

A

negative pressure breather using rib ventilation

363
Q

mammals have elaborate alveolated lungs to increase ………. for gas exchange

A

SA

364
Q

the oxygenated/deoxygenated air in humans/birds mixes

the oxygenated/deoxygenated air in humans/birds doesn’t mix

A

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
Q

why do birds lungs need to be more efficient than human lungs

A

so they can gather more oxygen for flight and high altitudes

366
Q

what are some notable aspects of the bar headed goose

A
  • 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
Q

describe the mitochondria of bar headed goose

A

no special features in terms of respiratory capacities, oxygen kinetics or phosphorylation efficiencies but are distributed towards the subsarcolema and adjacent to capillaries

368
Q

what are the 3 high altitude human communities

A

Tibetans (60)
Andeans (60)
Ethiopians (64)

369
Q

what are the adaptations of high altitude humans

A
  • larger hearts and lungs
  • altered cerebrovascular responses
  • no change in amino acid sequence of haemoglobins or myoglobins
  • higher oxygen level in placental blood
370
Q

which high altitude human community uses erythrocytosis

A

Andeans

371
Q

which high altitude human communities exhibit arterial hypoxaemia

A

Tibetan

Andeans

372
Q

what is erythrocytosis

A

increase in the total rbc mass secondary to a number of non-hematogenic systemic disorders in response to a known stimulus

373
Q

what is arterial hypoxemia

A

low level of oxygen in the arterial blood which can cause tissue hypoxia

374
Q

what are the differences between Tibetans and Andeans

A

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
Q

what do lowland humans develop when they go to high altitude

A

they develop increased haemoglobin concentration to compensate for the hypoxic high altitude environment

376
Q

Andeans and Tibetans can saturate there blood more easily with oxygen than ……………….

A

Ethiopians or sea level people

377
Q

Andeans and Tibetans have the same problems but they solves them in different ways, explain

A
  • 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

KSB (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions