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biological sciences year 1 > mini modules > Flashcards

mini modules Flashcards

1
Q

What is a biome?

A

a general term embracing each region with its characteristic climate, day-length, topography, flora and fauna

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2
Q

Where does a tropic rainforest occur?

A

where there is no dry season - all months have an average precipitation of at least 60 mm

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3
Q

Where are true rainforests found?

A

between 10 degrees north and 10 degrees south of the equator

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4
Q

What is the mean monthly temperature in a tropical rainforest?

A

exceeds 18 degrees celsius

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5
Q

What does the average annual rainfall lie between in a tropic rainforest?

A

1750 - 3000 mm

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6
Q

What percent of all living plant species reside in a tropic rainforest?

A

50%

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7
Q

What is habitat fragmentation?

A

the process by which habitat loss results in a division of large, continuous habitats into a greater number of small patches of lower total area and which are isolated from each other

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8
Q

What is habitat fragmentation caused by?

A

geological processes and climate change

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9
Q

What is the worlds largest biome apart from the ocean?

A

boreal forest or taiga

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10
Q

Where is the boreal forest found?

A

throughout the high northern latitudes, between tundra and temperate forest

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11
Q

What are the winters and summers like in the boreal forest?

A

long and cold winters (5-8 months). short summers always less than 4 months

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12
Q

What are the two major types of boreal forest?

A

southern - close canopy forest, northern - lignin woodland and sparse taiga

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13
Q

What kind of places are temperate deciduous forests found?

A

in areas with warm moist summers and mild winters

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14
Q

What are the typical trees in a temperature deciduous forest?

A

oak, maple, beech and elm

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15
Q

What are the usually yearly levels of precipitation in the desert?

A

25 - 200 mm - some years none

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16
Q

What percentage of the earth’s land is arid or semi-arid?

A

33%

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17
Q

What are the three types of desert climates?

A

hot, mild, cold

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18
Q

What are anthromes?

A

globally significant ecological patterns created by sustained interactions between humans and biomes

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19
Q

What is an ecosystem?

A

whole community of living organisms in conjunction with non-living components of their environment

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20
Q

What is primary productivity?

A

rate of biomass produced per unit area by plants

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21
Q

What are the units for primary productivity?

A

Jm-2day-1, kgha-1 year-1, gCm-2 year-1

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22
Q

What is gross primary productivity (GPP)?

A

total fixation of energy by photosynthesis

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23
Q

What is autotrophic respiration (RA)?

A

proportion of energy fixed by photosynthesis lost by respiration

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24
Q

What is net primary productivity (NPP)?

A

difference between GPP and RA - represents actual rate of production of new biomass available for consumption by heterotrophic organisms

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25
Q

What is secondary productivity?

A

rate of production of biomass by heterotrophs

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26
Q

What are the latitudinal trends in productivity?

A

closer to the equator there is a higher level of productivity

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27
Q

What is the term for organic matter produced by photosynthesis within ecosystem boundaries?

A

autochthonous

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28
Q

What is the term for organic matter imported from elsewhere?

A

allochthonous

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29
Q

Why is less biomass needed for the same NPP in continental shelf compared to cropland?

A

the whole algae photosynthesises but only the leaves of a tree do

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30
Q

What is the equation for consumption efficiency?

A

energy consumed (C)/energy available (T)

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31
Q

What is the equation for assimilation efficiency?

A

energy assimilated (A)/energy consumed (C)

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32
Q

What is the equation for growth efficiency?

A

energy fixed in tissues (P)/energy assimilated (A)

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33
Q

What are assimilation efficiencies like in herbivores?

A

low - around 10%

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34
Q

What are assimilation efficiencies like in carnivores?

A

high - can go up to 90%

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35
Q

How does mutualism occur with cleaner and client fish?

A

smaller fish establish a ‘cleaning station’. larger fish come up to station for ectoparasite removal. the smaller fish picks off and eats the ectoparasites

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36
Q

How does mutualism occur with ants and fungi?

A

ants keep fungi in their nests to break down leaf materials into cellulose and lignin. they keep the fungus free from pests and moulds

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37
Q

How does mutualism work involving gut inhabitants?

A

microbial populations in the rumen of cows and sheep collaborate to break down cellulose. these microbial populations are fungi, bacteria and protozoa

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38
Q

How does interspecies competition work with paramecium?

A

All three species grew well alone, reaching stable carrying capacities in tubes of liquid medium.
P.aurelia and P.caudatum together. P.caudatum declined to the point of extinction.
P.caudatum and P.busaria together. Neither species suffered a decline to the point of extinction. Stable densities much lower than when grown alone – indicating competition

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39
Q

What is Gause’s principle?

A

if two competing species coexist in a stable environment, then they do so as a result of niche differentiation

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40
Q

What is a population?

A

a group of organisms of one species that is usually separated in some degree from other groups of the same species by geographical or by some boundary

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41
Q

What is random spatial distribution?

A

variance is equal to the mean

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42
Q

What is contagious spatial distribution?

A

variance is greater than the mean

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43
Q

What is regular spatial distribution?

A

variance is less than the mean

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44
Q

What is the equation for rate of change of population over time?

A

intrinsic rate of increase x population

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45
Q

What occurs at carrying capacity (K)?

A

birth rate = death rate

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46
Q

What is the density dependent effect?

A

there is an inverse relationship between population density and rate of increase of a population

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47
Q

What is density independence?

A

percentage mortality stays the same with population increae

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48
Q

What is direct density dependence?

A

percentage mortality increases with population increase

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49
Q

What is inverse density dependence?

A

percentage mortality decreases with population increase

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50
Q

What is scramble competition?

A

resource is shared amongst all of the competing animals and shared would b equal and the mortality would raise immediately from 0 -100% when resource per capita becomes insufficient for survival

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51
Q

What is contest competition?

A

each successful animal gets what it requires. mortality increases with density

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52
Q

What are r-selected species?

A

potential to multiply rapidly - producing large numbers of progeny early in the life cycle

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53
Q

What are K-selected species?

A

organisms with different life histories survive where there is intense competition for limited resources

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54
Q

What is homeostasis?

A

maintenance of a relatively stable internal environment

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55
Q

What are features of the endocrine system?

A

wireless system, has specific target cell binding, hormones carried long distance in the blood, involuntary

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56
Q

What are features of the nervous system?

A

wired system, anatomical connection with target cells, neurotransmitters diffuse through short distances, voluntary/involuntary

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57
Q

What does the central nervous system divide into?

A

brain, brainstem and spinal cord

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58
Q

What is gyrification of the human cortex?

A

folding of the cortex

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59
Q

What are the two divisions of neural tissue in the CNS?

A

gray matter and white matter

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60
Q

What is gray matter?

A

primarily neuronal cell bodies

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61
Q

What is white matter?

A

myelinated neurites projecting from neurones

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62
Q

What happens in the somatic nervous system?

A

voluntary control, motor neurons to skeletal muscle

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63
Q

What happens in the autonomic nervous system?

A

no voluntary control, neurons to visceral organs

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64
Q

What is a neurite?

A

long, filamentous extensions responsible for propagating action potentials

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65
Q

What is an astrocyte?

A

a ‘star-shaped’ glial cell which supports neurone function and delivery fo molecules to/from the vasculature

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66
Q

When are astrocytes activated?

A

in response to injury, neuroinflammation or degeneration of the brain

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67
Q

What are microglia?

A

resident immune cells of the brain, surveying for pathogens and damaged material

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68
Q

What are myelinating glia?

A

they myelinate neurones by insulating them in multiple layers of sphingolipids

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69
Q

What are oligodendrocytes?

A

they myelinate multiple axons

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70
Q

What are Schwann cells?

A

they myelinate single axons

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71
Q

What are common model organisms in neuroscience?

A

rodents, zebrafish, zebra finch, fruit fly, nematode worms

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72
Q

How can intracellular recording be done?

A

intracellular electrode: measures internal voltage. extracellular electrode: measures extracellular voltage

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73
Q

What does the sodium-potassium pump exchange?

A

3 intracellular sodium ions for 2 extracellular potassium ions

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74
Q

What are the concentrations of ions in the extracellular fluid in mmol-1?

A

K+ = 2.5, Na+ = 145, Cl- = 90

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75
Q

What s the threshold stimuli?

A

-15 mV below resting potential

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76
Q

What is the absolute refractory period?

A

during the spike, a neurone cannot be stimulated

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77
Q

What is the relative refractory period?

A

during hyperpolarisation and afterpolarisation, a suprathreshold stimulus is required to trigger an action potential

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78
Q

What are the two key properties of voltage dependent ion channels?

A

ion specific and voltage sensitive

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79
Q

What region of the axon are action potentials triggered from?

A

the axon hillock

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80
Q

What is the threshold of the axon hillock?

A

the lowest across the cell

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81
Q

What are the two forms of synapses?

A

electrical and chemical

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82
Q

What are features of electrical transmission?

A

instantaneous, bidirectional

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83
Q

When do gap junctions close?

A

in response to elevated Ca2+

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84
Q

What are features of chemical transmission?

A

signal transduction is not facilitated through direct cell to cell contact, slower than electrical.

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85
Q

What defines a neurotransmitter?

A

synthesised in pre-synaptic neurone, can be released into the cleft and elicit a response

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86
Q

What synapses are most common in the brain?

A

axodendritic

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87
Q

What does axosomatic mean?

A

synapsing at the cell body

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88
Q

What does axoaxonic mean?

A

synapsing at the axon

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89
Q

What processes are found at the synaptic junction?

A

glial, especially astrocytes

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90
Q

What is the reserve pool of neurotransmitter vesicles?

A

synaptic vesicles that are loaded with neurotransmitter are initially tethered to the acton cytoskeleton by synapsin 1. reserve pool vesicles can be released from cytoskeleton by Ca2+ dependent phosphorylation of synapsin 1

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91
Q

What kinase phosphorylates synapsin 1?

A

protein kinase C and others

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92
Q

What is priming?

A

ATP dependent process which partially fuses the synaptic vesicles with the pre-synaptic membrane

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93
Q

What proteins facilitate priming?

A

SNARE proteins

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94
Q

Where is v-SNARE?

A

synaptic vesicle

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95
Q

Where is t-SNARE?

A

presynaptic terminal

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96
Q

What blocks fusion if Ca2+ is not bound?

A

synaptotagmin

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97
Q

What allows SNARE facilitated membrane fusion to occur?

A

calcium binding to synaptotagmin causes a conformational change

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98
Q

What endocytic protein coats synaptic vesicles?

A

clathrin

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99
Q

What facilitates scission of vesicles from membrane?

A

dynamin

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100
Q

What activates dynamin?

A

GTP -> GDP + Pi

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101
Q

What do botulinum neurotoxins do?

A

bind and cleave the c-terminal of t-SNARE SNAP25 by metalloprotease activity which results in failure of neurotransmitter fusion

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102
Q

What does the tetanus toxin do?

A

enter pre-synaptic membrane and bind and cleave synaptobrevins VAMP1/2 and can result in a loss of GABA release so there is overactivity of motor neurons

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103
Q

What is VGLUT?

A

vesicular glutamate transporter

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104
Q

What is VMAT?

A

vesicular monoamine transporter (serotonin, dopamine, adrenaline)

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105
Q

What is VachT?

A

vesicular acetylcholine transporter

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106
Q

What is VGAT?

A

vesicular GABA transporter

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107
Q

What is the most common excitatory neurotransmitter in the mammalian CNS?

A

glutamate

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108
Q

What transporter loads glutamate into synaptic vesicles?

A

VGLUT

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109
Q

What do astrocytes do to glutamate?

A

convert it to glutamine by glutamine synthetase which is secreted from astrocytes

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110
Q

How is GABA synthesised?

A

synthesised from glutamate by glutamic acid decarboxylase (GAD)

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111
Q

How is GABA and glutamate produced?

A

from alpha-ketoglutarate in the Krebs cycle

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112
Q

Can a single EPSP stimulate an action potential?

A

no, one is not enough to reach threshold. many are required to overcome threshold

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113
Q

What are the cys-loop receptors for?

A

acetylcholine, GABA, glycine and serotonin

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114
Q

What are glutamate receptors for?

A

glutamate, non-selective cations

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115
Q

What are the three categories of glutamate receptors?

A

AMPA, Kainate, NMDA

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116
Q

What ion blocks NMDA receptor channels at resting potential?

A

Mg2+

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117
Q

What are are NMDA receptors blocked and antagonised by?

A

blocked = Zn2+, antagonised = Pb2+

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118
Q

What is habituation?

A

learning to ignore harmful stimulus

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119
Q

What is sensitisation?

A

learning to avoid noxious stimulus

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120
Q

How do plants decide when to flower?

A

signalling from the leaves to the growing point - the shoot apical meristem

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121
Q

What is the signal to make the plant flower?

A

from many plants - day length - photoperiod

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122
Q

What is the signal to make the plant flower?

A

from many plants - day length - photoperiod

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123
Q

What do short day plants need?

A

long nights to flower

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124
Q

What’s part of a basic flower structure?

A

sepal, petal, stamen, carpel

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125
Q

What’s part of a basic flower structure?

A

sepal, petal, stamen, carpel

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126
Q

What is self-fertilisation?

A

pollination within the same flower

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127
Q

What does pollination between different flowers promote?

A

diversity

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128
Q

What is abiotic pollination done by?

A

wind and water

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129
Q

What is biotic pollination done by?

A

insects, birds, mammals

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130
Q

What visual markings do bees see?

A

blue or yellow but not red

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131
Q

What is the preference of pollinators for smell?

A

bees, butterflies and moths = sweet smells. beetles = yeasty, spicy, fruity smells

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132
Q

What is the reward of animal assisted pollination?

A

nectar, pollen, shelter, food and shelter for young

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133
Q

What are adaptations of pollen?

A

shape, stickiness and pollinia

134
Q

What is pollinia?

A

a coherent mass of pollen grains that is the product of each anther lobe of some flowers

135
Q

What are some adaptations of floral shape?

A

mimicry, long floral tube, specialised mechanisms

136
Q

What are the specialised mechanisms of floral shape?

A

triggers, traps and narcotics

137
Q

What is the shape of wind pollinated flowers?

A

feathery stigma, no petals or sepals, hanging anthers

138
Q

What is epihydrophily?

A

when pollination happens at the surface of the water

139
Q

What is hydrohydophily?

A

when pollination happens below the surface of the water

140
Q

How do plants prevent self-pollination?

A

separation of sexes: structural, temporal, biochemical

141
Q

What is herkogamy?

A

structural separation of the sexes within the flower

142
Q

What is monoecy?

A

structural separation of the sexes within the plant

143
Q

What is dioecy?

A

structural separation of the sexes as they are in different plants

144
Q

In dioecy what does the female flower do?

A

pistillate

145
Q

In dioecy what does the male flower do?

A

staminate

146
Q

In monoecy what does the male flower have?

A

tassels

147
Q

In monoecy what does the female flower have?

A

silks and cobs

148
Q

What is protoandry?

A

anthers mature before stigma

149
Q

What is protogyny?

A

stigma matures before anthers

150
Q

What is heteromorphic incompatibility?

A

either short style, high anthers or long style, low anthers

151
Q

What is homomorphic incompatibility?

A

self incompatibility at the S locus

152
Q

What is the difference between sporophytic and gametophytic incompatibility?

A

gametophytic self incompatibility is determined by the genotype of gametes while sporophytic self incompatibility is determined by the genotype of the plant

153
Q

When is inbreeding important?

A

shortage of pollinators, environmental uncertainty, weedy species, small colonising population

154
Q

What happens when the pollen reaches the stigma?

A

hydration and germination and pollen tube is produced

155
Q

What happens if the secretory zone is removed?

A

inhibits pollen tube growth in the transmitting tissue

156
Q

What is involved in pollen fertilisation?

A

2 sperm cells, egg cell, polar nuclei, integuments

157
Q

What happens after fertilisation?

A

embryogenesis

158
Q

What happens during embryogenesis?

A

zygote (polar) -> basal cell + apical cell -> proembryo

159
Q

What structures are in the mature embryo?

A

early cotyledons, torpedo and shoot apical meristem

160
Q

Where do meristems take cells from?

A

all three layers - epidermis, ground tissue and vascular tissue

161
Q

What are segment deletion mutants?

A

parts are missing - cotyledons and shoot meristems, hypocotyl and root

162
Q

What are radial mutants?

A

abnormal cell layers occur in the plants

163
Q

What are examples of monocotyledons?

A

cereals, grasses, lilies, palm trees

164
Q

What are examples of dicotyledons?

A

oak, beech trees, daisies, beans, roses, strawberries etc

165
Q

What does a monocot seed have?

A

endosperm

166
Q

What does a dicot seed have?

A

cotyledons

167
Q

How does fruit ripen?

A

as the seed develops - it is coordinated

168
Q

How does fruit ripen in tomatoes?

A

chlorophyll is broken down, chloroplasts become chromoplasts, carotenoids are synthesised, starch converted to sugars, pectin broken down to soften the fruit

169
Q

What is a fruit in relation to the plant system?

A

ovary

170
Q

How does mechanical seed dispersal occur?

A

in witch hazel: explosive capsules. in filaree: driven burrowing

171
Q

How do plants disperse their genes?

A

pollen dispersal (unfertilised) and seed dispersal (fertilised)

172
Q

How does seed germination occur in barley?

A

seed takes up water -> embryo produces hormone = gibberellic acid (GA) -> stimulates aleurone to produce amylase -> amylase breaks down the stored starch into sugar -> sugar is used by embryo as energy source

173
Q

What does emergence into light cause in plants?

A

opening out of cotyledons. apical meristems start making leaves

174
Q

How do leaves grow?

A

shoot apical meristem drives all above ground movement, maintains a reserve population of rapidly dividing cells, leaves develop from the sides of the meristem

175
Q

Where us the peripheral zone?

A

on the side of the meristem

176
Q

Where is the rib meristem?

A

in the middle of the meristem

177
Q

Where is the central zone?

A

between the peripheral zones

178
Q

What is an invasive species?

A

a species introduced into an area outside their native range that can cause harm in that area

179
Q

What did the plant Kudzu do?

A

introduced to USA and Asia in late 1800 as an ornamental plant. In 1900s was planted in USA to reduce soil erosion. Plant grew very rapidly and enshrouded the ground, shrubs, trees, houses, cars

180
Q

What did the prickly pear do?

A

imported into Australia in 19th century as a natural agriculture fence. it became a widespread invasive species and rendered 40,000 km2 of farm land unproductive

181
Q

How was the prickly pear stopped?

A

a mouth from South America whose larvae eats prickly pear was introduced in 1925 and almost wiped out population

182
Q

What are examples of habitat modification?

A

grazing, browsing and rooting introduced mammals. aquatic introduced plants overgrow and shade out native plants

183
Q

What can herbivory do?

A

often devastates native plant species, and sometimes entire communities

184
Q

What is an example of herbivory?

A

european rabbits damaging native plants of islands

185
Q

What is an example of a virus having an indirect and direct effect?

A

rabbits were grazing which encouraged wild thyme growth which the Large Blue butterfly fed on. virus was introduced and rabbit population fell to a low level. wild thyme was now not encouraged and so the Large Blue became extinct

186
Q

What are some invasive species in the UK?

A

rhododendron, mink, signal crayfish, muntjac deer, himalayan balsam, japanese knotweed

187
Q

What is one of the world’s most invasive species according to the World Conservation Union?

A

Japanese Knotweed

188
Q

How is Japanese Knotweed invasive?

A

has an invasive root system and strong growth can damage concrete foundations, buildings, flood defences and paving

189
Q

How much does it cost to remove japanese Knotwood?

A

£70 million to eradicate it from 10 acres in 2012

190
Q

What insect was released to combat Japanese Knotwood?

A

Japanese psyllid insect

191
Q

What percentage of the population was living in cities at the turn of the 20th century?

A

15%

192
Q

When do urban heat islands form?

A

when industrial and urban areas produce and retain heat

193
Q

Why are do cities usually have higher surface temperatures?

A

as there is less vegetation and exposed soil, the suns energy is absorbed by buildings and asphalt

194
Q

What can urbanisation cause environmentally?

A

highly fragmented, heterogenous and altered environments. also associated with declines in animal and plant richness, abundance and diversity

195
Q

What is ruderal vegetation?

A

empty lots, abandoned farmland, and other green space is cleared but not managed

196
Q

What are urban avoiders?

A

very sensitive to human habitat disturbances e.g. large mammals, old forest birds

197
Q

What are urban adaptors?

A

frequently found in sub-urban matrix areas

198
Q

What are urban exploiters?

A

dependent on human resources

199
Q

How to help with light pollution?

A

 Unnecessary lights extinguished or not installed
 Spectrum chosen to minimise impacts (not uv or blue)
 As bright as necessary for purpose
 Directly only where needed
 Only illuminated as long as necessary

200
Q

How to help with light pollution?

A

extinguish unnecessary lights, direct only where needed, only illuminated as long as necessary

201
Q

Are urban or rural health levels better?

A

urban

202
Q

What is tillage?

A

agriculture by preparation of soil by mechanical agitation

203
Q

What does primary tillage do?

A

loosens the soil and mixes in fertiliser and/or plant material, resulting in soil with rough texture

204
Q

What does secondary tillage do?

A

produces finer soil and sometimes shapes the rows, preparing the seed bed

205
Q

What are the positives of tillage?

A

loosens and aerates, mixes harvest residues, mechanically destroys weeds, dries the soil before seeding

206
Q

What are the negatives of tillage?

A

soil loses nutrients and water storage ability, lessens cohesiveness of the soil inducing erosion, reduces microbes, eutrophication

207
Q

What is drainage?

A

system by which water is drained on or in soil

208
Q

What is intercropping?

A

growing two or more crops in proximity

209
Q

What is resource partitioning?

A

planting a deep-rooted crop with a shallow-rooted crop or planting a tall crop with a shorter one that requires shade

210
Q

What is temporal intercropping?

A

practice of sowing a fast-growing crop with slow-growing crop

211
Q

What is relay intercropping?

A

second crop sown during the growth, near the onset of reproductive development, of the first crop

212
Q

What is trap cropping?

A

planting crop nearby that is more attractive to pests than crop production

213
Q

What is a repellent intercrop?

A

repelling crop masking the smell of production crop?

214
Q

What is push-pull cropping?

A

mixture of trap cropping and repellent intercropping

215
Q

What is grazing?

A

method of feeding in which a herbivore feeds on plants or grasses

216
Q

What are the two types of plant defences against grazing?

A

constitutive or induced

217
Q

When are constitutive defences present?

A

always

218
Q

When are induced defences present?

A

produced or mobilised to the site where the plant is injured

219
Q

What are long term effects of pesticides?

A

changes to habitat and food chain

220
Q

What is one of the three major drivers of biodiversity loss?

A

fertilisers

221
Q

In 2018, what percentage of globally consumed fish came from aquaculture?

A

62.5%

222
Q

What are the main challenges faced by intensive aquaculture?

A

to reduce its ecological footprint, to reduce the risk of disease, to prevent the introduction of invasive species

223
Q

How does Diplostomum sp. infect a fish?

A

Adult parasite within intestine -> parasite eggs released in faeces, miracidium hatches and penetrates snail -> asexual reproduction within snail -> cercaria penetrates fish -> metacercaria in eye lens -> fish eaten by definitive host -> adult parasite within intestine

224
Q

What is proliferative kidney disease caused by (a seasonal salmon disease)?

A

PKX (unknown)

225
Q

Why are fish parasites so common?

A

fish are abundant and diverse and aquatic medium is ideal for continuous parasite transfer

226
Q

What is Gyrodactylus salaris?

A

small ectoparasitic worm - direct life cycle, rapid reproduction

227
Q

What did Norway do to get rid of Gyrodactylus salaris?

A

rotenone - disrupts electron transport chain

228
Q

What are methods of detecting fish parasites?

A

during food processing (candling/electromagnetic sensor), disease recognition/research (microbiology, molecular)

229
Q

How to prevent fish parasites?

A

maintain optimal environmental conditions for the host, prevent introduction of infectious organisms, ensure optimal nutrition, minimise stress

230
Q

What are some control measures for fish parasite?

A

biological - predation of intermediate hosts by other fish, cleaner fish, selective breeding. physical - increased flow rate, filtration, UV light sterilisation

231
Q

What is epidemiology the study of?

A

nature, distribution, causation, transfer, prevention, control

232
Q

What are some bacterial diseases?

A

whooping cough, meningitis, tetanus, tuberculosis, STDs

233
Q

What are two major global bacterial diseases?

A

Mycobacterium tuberculosis and Vibrio cholerae

234
Q

What is an opportunistic pathogen?

A

capable of causing damage and infection in a compromised host

235
Q

What is an obligate pathogen?

A

causes damage and infection as part of its growth and replication

236
Q

What is a facultative pathogen?

A

causes disease as one part of its life cycle or when in a different host

237
Q

What is a commensal pathogen?

A

induces either no damage or clinically inapparent damage to the host but may elicit an immune response

238
Q

What is an example of a obligate pathogen?

A

Mycobacterium tuberculosis, gram-positive, aerobe

239
Q

What is an example of a facultative pathogen?

A

Vibrio cholerae, gram-negative, anaerobe

240
Q

What is an example of an opportunistic pathogen?

A

Pseudomonas aeruginosa, gram-negative - present in people with cystic fibrosis

241
Q

What is an example of a commensal pathogen?

A

Lactobacillus acidophilus, gram-positive

242
Q

How are cystic fibrosis lung infections diagnosed?

A

sampling -> cough swab -> microbial growth -> pure culture -> pathogen identification -> antibiotic susceptibility or reference centre follow up -> treatment and management

243
Q

How do we identify a strain of bacteria?

A

ribotyping, macrorestriction, PCR-fingerprinting, DNA sequencing

244
Q

How do we identify a species of bacteria?

A

MLST - multilocus sequence typing

245
Q

How does MLST work?

A

sequence several conserved genes, get approximately 500 base pairs from a PCR fragment, define genetic linkage between strains, globally searchable strain database

246
Q

What are bacterial pathogen virulence factors?

A

aids host colonisation, allows immune evasion, host cell invasion or escape, host destruction

247
Q

What can multiple virulence plasmids encode?

A

enterotoxins, haemolysins, pilli, urease

248
Q

What is a microbiome?

A

loads of local niches interacting with each other

249
Q

What are essential roles of the human bacteriome?

A

allows us to extract energy from food, produces essential vitamins, regulates immune system, regulates glucose levels and metabolism

250
Q

Which pathogens always infect us?

A

obligate

251
Q

Which pathogens can be beneficial and do not cause infection?

A

commensal

252
Q

Which pathogens can sometimes be non-pathogenic?

A

opportunistic

253
Q

What is dysbiosis?

A

any change to the composition of resident commensal microbial communities relative to the community found in healthy individuals

254
Q

What can affect a healthy gut microbiome?

A

lifestyle, genetics, mode of birth, medical practices

255
Q

How many different species of bacteria are in the human gut?

A

> 1000

256
Q

What are culture dependent sample methods?

A

selective agar used to grow certain types of microorganism

257
Q

What are culture independent methods of sampling?

A

16S RNA gene - used to measure the evolutionary distance between organisms. whole genome sequencing

258
Q

What are antimicrobials?

A

synthetics or natural compounds which exhibit selective toxicity by inhibiting microbial pathways without adversely affecting the host

259
Q

Antimicrobials are classified according to similarities in what?

A

molecular structure, mechanism of action, spectrum of antimicrobial activity

260
Q

What are antibiotics?

A

antimicrobial agents that are produced naturally by microorganisms such as certain species of bacteria and fungi

261
Q

What do bacteriostatic agents do?

A

inhibit important biological processes - they have weak target binding and if removed the cell will continue growing

262
Q

What do bactericidal agents do?

A

kill the cell - strong target binding, cell count remains constant but viable cell count decreases

263
Q

What do bacteriolytic agents do?

A

kill and lyse the cell, releasing their cytoplasmic content - rupture cytoplasmic membrane, total and viable cell counts decrease

264
Q

What antibiotics target cell walls?

A

beta-lactam antibiotics - they possess a beta-lactam ring which interferes with transpeptidation (leads to peptidoglycan synthesis)

265
Q

What are examples of beta-lactam antibiotics?

A

penicillin and cephalosporins

266
Q

What are nucleic acid synthesis inhibitors?

A

quinolones disrupt bacterial metabolism by interfering with bacterial DNA gyrase - preventing supercoiling of DNA

267
Q

What is an example of a quinolone?

A

ciprofloxacin - used to treat urinary tract infections

268
Q

What do protein synthesis inhibitors do?

A

bind with high affinity to 30S ribosomal subunit, resulting in ribosome misreading mRNA - aminoglycosides

269
Q

What do tetracyclines do?

A

bind to 50S subunit causing partial inhibition of protein synthesis and resulting in imbalance of the proteome?

270
Q

Why has Big Pharma abandoned antibiotics?

A

lack of financial incentive/profit, the last entirely new class of antibiotics was discovered in the late 1980s

271
Q

What is the cost of developing new antibiotics?

A

$1.5 million

272
Q

What has led to high level of antibiotic resistance?

A

misuse and overuse of antibiotics in medicine and agriculture, patients not taking antibiotics as described, poor infection control in hospitals

273
Q

What are antimicrobial drug resistance mechanisms?

A

modification of the drug target, enzymatic inactivation, removal of the cell through efflux pumps, metabolic bypassing, decreased uptake, lifestyle changes

274
Q

What did most bacteria resistant to penicillin contain?

A

80% contained penicillinase, a type of beta-lactamase enzyme which hydrolyses the beta-lactam in penicllin - encoded by blaZ gene

275
Q

What are the three methods of horizontal gene transfer?

A

transformation, transduction, conjugation

276
Q

How does transformation work?

A

uptake of naked DNA by bacteria

277
Q

How does transduction work?

A

bacterial DNA transfer between bacteria

278
Q

How does conjugation work?

A

direct DNA transfer between bacteria

279
Q

How to fortify the gut microbiome?

A

prebiotics, probiotics and symbiotics

280
Q

What are prebiotics?

A

a selectively fermented ingredient that results in specific changes in the composition of the gastrointestinal microbiota

281
Q

What are probiotics?

A

live microorganisms which when administered in adequate amounts confer a health benefit on the host

282
Q

What are symbiotics?

A

mixture of probiotics and prebiotics

283
Q

Why are biofilms important for infection?

A

can penetrate deep into tissue, making their removal difficult - cells shedding from biofilm can cause systemic infection - can’t be engulfed by phagocytes due to size

284
Q

Why is parasitology important?

A

parasitism is highly successful and >50% of animals are parasites

285
Q

What is a DALY?

A

disability adjusted life years

286
Q

What is parasitology?

A

study of parasites from Animal and Protista kingdoms: protozoa, parasitic worms, arthropods, chordates

287
Q

What is phoresis?

A

two symbionts travel together - no harm - no physiological or chemical independence

288
Q

What is mutualism?

A

both partners benefit- no harm - association is not obligatory

289
Q

What is commensalism?

A

usually only one partner benefits - no harm - association is not obligatory

290
Q

What is parasitism?

A

one partner lives at the metabolic expense of another - harm - obligatory independence

291
Q

What are the two types of location within a host for a parasite?

A

ectoparasite and endoparasite

292
Q

What is a definitive host?

A

parasite reaches sexual maturity

293
Q

What is an intermediate host?

A

parasite develops & often reproduces asexually

294
Q

What is a paratenic host?

A

parasite undergoes no development but remains infective to another host

295
Q

What is a reservoir host?

A

animal that harbours a parasite which can be transmitted to humans

296
Q

What are characteristics of microparasites?

A

epidemic disease, specific resistance to infection, high reproductive potential

297
Q

What are characteristics of macroparasites?

A

endemic disease, non-specific host resistance, low reproduction potential

298
Q

What are examples of microparasites?

A

prions, viruses, bacteria, protozoa

299
Q

What are examples of macroparasites?

A

flatworms (Platyhelminths), round worms (Nematoda), Arthropoda, Monogenea (direct life cycle), Digenea

300
Q

What are Monogenea?

A

mostly fish parasites - single host life cycle, direct life cycle

301
Q

What are Digenea - Schistosoma?

A

they have more than one host, infect humans, lives in veins around the colon, eggs live in faeces and get in water, intermediate host is a snail

302
Q

What is a Nematoda - Trichinella spiralis?

A

can be acquired from a zoonotic infection, lives in microvilli of the gut, changes the anatomy of host cell to make it a ‘nursery’ for juvenile worm

303
Q

What is Monogenean attachment?

A

posterior opisthaptor equipped with suckers, clamps, hooks and/or glands

304
Q

What is Digenean attachment?

A

oral and ventral suckers

305
Q

What is Cestode attachment?

A

scolex

306
Q

How do microparasites feed?

A

absorb nutrients via cell surface

307
Q

How do macroparasites feed?

A

surface browsing, blood feeding, bulk tissue feeding, nutrient uptake across the body wall

308
Q

What is the life cycle of a Polystoma (blood feeder)?

A

dimorphic life cycle (two different adult morphs)

309
Q

What are problems associated with blood feeding?

A

waste products of blood digestions (haematin etc), lack of B vitamins, clotting agents, exposure to host’s immune system

310
Q

What are morphological adaptations of parasites?

A

increased body surface, modified mouthparts

311
Q

What are physiological and behavioural adaptations?

A

symbiotic micro-organisms to counteract vitamin B deficiency, production of anticoagulants, acidification of host’s gut through secretion of H+, migration along the host’s gut

312
Q

What is premunition?

A

host recovers form disease and is resistant to reinfection but some parasites remain and reproduce at a slow rate

313
Q

What is concomitant immunity?

A

parasite elicits protection against re-infection, but parasite itself remains unaffected by immune response

314
Q

How do parasites evade the host’s immune response?

A

antigen disguise, antigen polymorphism, shedding antigens, immunomodulation of host (causing lymphocytes to produce wrong cytokines)

315
Q

What is oviparous reproduction?

A

eggs released into the environment and develop outside parent’s body

316
Q

What is ovoviviparous reproduction?

A

encapsulated embryos develop within parent’s body

317
Q

What is viviparous reproduction?

A

embryos develop within parent’s body (no egg shell)

318
Q

What are hermaphrodites?

A

occurrence of both sexes in the same individual

319
Q

What are advantages of being a hermaphrodite?

A

increases chance of finding a mate, increases egg output, potential for self-fertilisation

320
Q

What is protandry?

A

male organs develop before female

321
Q

What is protogyny?

A

female organs develop before male

322
Q

What are the types of transmission?

A

contact transfer, ingestion of intermediated or paratenic hosts, release of eggs, free living larvae

323
Q

What does Dicrocoelium dendriticum do?

A

parasite manipulates behaviour of the ant - infected ant migrate up blade of grass until they reach the top then they do a handstand and remain in that position all day to be eaten by a goat. Three hosts - goat, ant, snail

324
Q

What does taxoplasma gondii do?

A

if mice/rats are infected they lose their fear of cats- then cats get infected (only definitive host)

325
Q

What percentage of humans that have taxoplasma gondii are asymptomatic?

A

15-85%

326
Q

How can toxoplasma be transmitted?

A

faecal-oral from cat, oral-raw meat/unpasteurised milk, blood transfusions

327
Q

For parasites to adapt they have to respond to what?

A

discontinuity in space and time, host immunity, host evolution

328
Q

Why are parasite life cycles so complex?

A

greater niche space for reproduction, increase the likelihood for transmission

329
Q

What is the oldest parasite?

A

> billion years, mitochondrium - ancient bacterium transformed into mutualist

330
Q

What is the Red Queen dynamic?

A

hosts and parasite much evolve quickly to keep from falling behind and going extinct

331
Q

What are medicinal uses of parasites?

A

maggots - used to clean wounds, secrete antimicrobial. whipworms - parasite worms may prevent Crohns disease. worms vs asthma - probiotic worms

biological sciences year 1 (16 decks)

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