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Plants & Microbial Sciences > Easter > Flashcards

Easter Flashcards

1
Q

What is biodiversity?

A

The different kinds of species and life found in an area

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2
Q

How do humans effect biodiversity?

A
  • 20-40% of primary productivity effects
  • Biofuels generates further stress
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3
Q

How is mapping of biodiversity achieved?

A

Species range mapping
1. Sample
2. Analyse
3. Map or model

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4
Q

Describe the degree of biodiversity around the world

A

Poles - low
Tropics - high
Mountain ranges
- High due to elevation gradient, change in environment within short distances
- Isolation of areas, leading to speciation

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5
Q

What governing body regulates and targets biodiversity and extinctions? Give examples of what they do

A

The International Union of Conservation of Nature (IUCN)
- Generate red lists to mark endangered animals

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6
Q

What does the Millennium Ecosystem Assessment show?

A
  • Mankind has increased the rate of extinctions
  • Done by mapping changes in the number of species, using fossils and models to also predict future changes
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7
Q

Why is the rate of extinction not as great as expected?

A
  1. Species- area relationship
    - Shows a slope of 0.25, suggesting that changing area occurs much faster than its effect and change in rate of extinction
  2. Extinction takes time
    - there may not be a viable population however it can take time for them to fully die out
    - 0.2 - 0.5% species per year
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8
Q

What can be done to tackle the effects of anthropogenic actions on biodiversity? (3)

A
  1. Identify areas at risk (by mapping)
  2. Inform and promote governments to act (e.g. Dasgupta review, COP panels)
  3. Develop protected networks (put into legislation)
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9
Q

How can deforestation rates be quantified?

A
  1. Satellite imaging, detecting reflectance of different surfaces
    - e.g. Landsat 1972, at 30m resolution
  2. Ground based imaging
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10
Q

What is the difference between Euchromatin and Heterochromatin?

A
  1. Structure
    - Euchromatin is less condensed, more accessible, less DNA methylation
  2. Transcriptional activity
    - Euchromatin - transcriptionally active
    - Hetero - inactive
  3. Genetic content
    - Hetero - contains lots of repetitive DNA sequences
  4. Function
    - Hetero - gene silencing, maintenance of structure
    Euchromatin- active gene expression
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11
Q

What is the Normalised Difference Vegetation Index (NDVI)?

A
  • Used to asses the density and health of vegetation
  • Can be used to monitor changes over time
  • Measures the near infrared reflectance band and red reflectance band
    NDVI = (NIR-R)/(NIR+R)
  • Used by farmers, habitat managers etc.
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12
Q

What is the value range for NDVI and what do they mean?

A

Range from -1 to 1
1 = densely vegetated and healthy
-1 = signifies no vegetation e.g. rock
0 = minimal vegetation e.g. soil or urban areas

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13
Q

What is an example of deforestation tracking?

A

Deforestation tracking in Chile
Echeverria et al., 2006
- Showed an increase in deforestation and fragmentation

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14
Q

How can fragmentation be quantified?

A

Lidar imaging using a plane
- Can be used to monito number of patches and patch size
- As well as changing size of the core area
- Can be used to produce a 3D image of the forest area

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15
Q

What are the 4 key consequences of fragmentation?

A
  1. Increased access
    - Increases deforestation
    - Illegal logging
    - Settlement formation
    - Farming/ pasture land formation
    - Overexploitation, bushmeat and orchids
  2. Increased edges
    - Increased mortality of trees
  3. Negative effect on carbon emissions
  4. Disconnection effect on habitats and ecology
    - increased extinction rates, theory of Island biogeography developed by McArthur and Wilson in 1967
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16
Q

What are some studies into the effects of fragmentation?

A

Laurence at al., 2000
- Death of large trees in the edge border between 0-300m in
- Greater percentage of death of trees with a larger radius
Putz el at., 2014
- Carbon loss due to fragmentation is equivalent to 9-24% of carbon emissions of deforestation

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17
Q

How can fragmentation be minimised or dealt with?

A
  • Produce larger fragment areas that remain as core areas
  • Ensure the fragments are still in close proximity
  • Formation of corridors to connect different fragments e.g. land buying in the USA and Mexico to avoid disjoint over state lines and border lines
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18
Q

How can different forest types be identified?

A

Hyperspectral data collection
- Use a plane and collect reflectance of a variety of different wavelengths that are reflected from different forest types

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19
Q

How can the history of vegetation be constructed?

A
  • Pollen analysis
    Shows abundance and types of plants
  • Fossils
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20
Q

How has the landscape of the UK changed since 130,000 Ya?

A

Used to be Savannah like with low density due to the presence of large animals
- After interglacial period
More grasslands and woodlands developed
- Then humans began to change the landscape ~2000
- An account was taken in the Doomsday book
- Continual decrease in biodiversity due to settlement expansion and conversion of land to arable land

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21
Q

What is arable land?

A

Land that can be used to grow crops

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22
Q

What is a woodland?

A

Land that contains a shrub layer and woody trees, however not as dense as a forest
- can be exploited for timber

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23
Q

What are pastures and meadows?

A

Pasture- area of land for grazing livestock
Meadows - area of land cut for hay

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24
Q

How has nature protection been established in the UK?

A

Introduction of national reserves in 1949
- 224 national nature reserves (NNRs)
- Sites of Special scientific interest (SSSI) that are protected

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25
Q

What are calcaerous grasslands? How have they changed?

A

Calcaerous grasslands are grass areas grown on calcaerous rock
- Have a high pH of around 7-8
Changes = Decrease in presence due to conversion to arable land and settlement expansion

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26
Q

Why is grazing important?

A
  • Increases biodiversity by allowing other plants to grow
  • Prevents full succession to woodlands
  • Helps plants build up resilience
  • Nutrient recycling
27
Q

What types of species are found in woodlands?

A

Spring ephemeral - bluebells and Oxlip
- bloom in early spring to avoid shading from taller trees
Trees- oak, beech and maple
Shrubs- hawthorn

28
Q

How can woodlands be managed?

A

Rewilding
- Reduce fragmentation
- re-introduce species
Management of wildlife
Selective logging

29
Q

What are linked traits and what is crossover recombination?

A

Linked traits- genes that are found on the same chromosome
Crossover recombination - Crossover of chromosomes, resulting in splitting of linked traits

30
Q

What are the characteristics of cereals that make them good crops (3)?

A
  1. High protein and starch content
  2. Storable
  3. Germinate every year
31
Q

How was the hexaploid wheat genome formed?

A
  • Hybridization of 3 diploid progenitors
  • Contributing to A, B and D genomes
32
Q

What is conscious and unconscious selection?

A

Conscious selection - targeted selection, e.g. via CRISPR e.g. Sr gene for stem rust resistance, DREB genes
Unconscious selection - selection that is not controlled e.g. natural selection e.g. Ph1, B and Q gene

33
Q

What is the role of the Ph1 gene? What are the effects of ph1 mutation?

A

Regulates homologous pairing during meiosis
- Carried out by regulating CDK which controls cell cycle progression
- Ensures that homeologues don’t pair up
MUTANT = Infertile

34
Q

What are the roles of the Br, Q and tg gene?

A

Br = brittle, mutation reduces brittleness, causing retention of grain
Q and tg = cause soft shell

35
Q

What genetic changes occurred in the green revolution and who pioneered it?

A

1960s Norman Borlaug
- Rht gene causes reduced height
- Regulates DELLA and GA signalling
DELLA = inhibits growth
GA = inhibits DELLA by ubiquitination

36
Q

Give an example of disease resistance in wheat

A

Sr gene conferring resistance against most variants of stem rust fungus
- Except Ug99

37
Q

How can genetic diversity be reintroduced to wheat?

A

Find extant progenitors that are related to Triticum
- Generate synthetic wheat
- Within the genome will be wild genes

38
Q

Compare and contrast conscious and unconscious selection in crop domestication, providing examples.

A

Time - Conscious is more rapid, Unconscious occurs over long tie and many generations
Scale - Conscious targets a specific species e.g. crop, while unconscious can target a whole ecosystem
Intent- Conscious aims to increase yield and economic value of plant, while unconscious increases survival chances e.g. shattering seeds

39
Q

Describe a gene that has been selected for crop domestication

A

Rht
- Rht represses GA, and preserves DELLA that inhibits growth
- Achieved by removing N terminus so GA + GID-1 can’t bind
- This causes reduced height
- Increases yield and reduces lodging
- Developed by Norman Borlaug, via unconscious selection
Q gene
- Alters shape and size of the flower by altering APETALA
- Leads to greater ease of threshing, decreased fragility of rachis
- Increases yield, by greater efficiency of farming and reduced lodging
- Unconscious selection

40
Q

What are the uses of hybrid vigour?

A
  • Crossing of ecotypes and different species to generate a fitter offspring
  • Can be used to introduce wild genes, increasing genetic diversity
  • This can be used to develop disease resistance
  • A form of supercrop can be formed with all the desired phenotypes
41
Q

What is genetic bottlenecking? What are the disadvantages and how can it occur?

A
  • Inbreeding/ continuous selection of plants that results in a reduction of genetic diversity
  • Can be done to acquire a desired phenotype
  • Decreased disease resistance
    OCCURRENCE
  • Isolation, fragmentation
  • Overhunting
  • Natural disasters
42
Q

What are the uses of CRISPR in the lab?

A
  • Generate inducible second knockouts/mutations
  • These may be lethal and so need to be induced into a plant that already contains one mutation, as growth of double mutant may not occur
43
Q

State some uses of genetic screens and mutant lines (5)

A

Discover/ Monitor
- Flower time
- Leaf development
- Hormone signalling
- Metabolism
- Circadian rhythms

44
Q

Describe EMS as a chemical mutagen

A

Causes C:G to switch to A:T
- Results in amino acid change
- Premature stop codon

45
Q

What is QTL analysis used for?

A

Analyse of quantitative traits
- Affected by multiple genes
- Often show normal distribution

46
Q

How does skewed crossover occur?

A
  • Crossing over of individuals, showing uneven spread of phenotype
  • Some degree of linkage drag
  • Some regions show low recombination (e.g. transposon and DNA methylated rich)
47
Q

Describe marker assisted selection

A
  1. Use marker such as SNP and microsatellites
  2. Markers are linked with traits
  3. Monitor presence of markers, assist for selection
    = Increases efficiency of introgression
48
Q

What is heterosis?

A

When F1 population shows better phenotypes that the parents, opposite of inbreeding depression

49
Q

What are the 3 reasons for heterosis?

A
  1. Complementation - cross inhibits deleterious gene from being expressed
  2. Overdominance - heterozygous mix is better than homozygous e.g. Single flower truss in tomatoes
  3. Epistasis - interactions between other alleles more beneficial
50
Q

How can male sterility be engineered?

A
  1. Spray with N-acetyl phosphinothricin
  2. Forms toxin that destroys tapetum
  3. Lack of tapetum prevent pollen development
51
Q

What is apomixis?

A

Asexual reproduction
- used to generate clone descendant
- Naturally carried out by blackberries and dandelions
1. Bypasses meiosis
2. Bypasses fertilisation

52
Q

What are 2 genes that generate lab induced apomixis?

A
  1. Baby boom TF
    - Stops the need for fertilisation
  2. MiMe
    - Converts meiosis to mitosis
    - Removes a round of division
    - Generates diploid daughter
53
Q

What is somaclonal variation? Provide an example

A

Phenotypes are different in clones due to epigenetics
- Lamarckian evolution suggests that the environment can alter genes
e.g. Karma transposon that is methylated, to generate a deleterious phenotype

54
Q

What are the two ways in which clones can be generated?

A
  1. Vegetative propagation
    - Stem and root cuttings planted and form new plants
  2. Cloning in the lab
    - Grow plant tissues on plates
55
Q

What are 3 ways in which nutrient uptake can be engineered to be better?

A
  1. Change in transporter expression
    - e.g. Pht5 overexpression
  2. Nodulation changes
    - generate crops that can symbiosis with rhizobia
  3. Plant artificial chromosomes
    - introduce beneficial genes
56
Q

What are transposons?

A

Mobile elements that move in the genome
- Discovered by Barbara McClintock in maize
- Heavily methylated regions
- Able to disrupt genes

57
Q

What are 3 ways in which photosynthesis efficiency can be increased?

A
  1. Engineering active site of Rubisco (affinity)
  2. C4 plants
  3. Developmental regulation
    - optimise factors by changing architecture
    - Develop tolerance to certain conditions such as sub1 (flooding)
58
Q

Describe the advantages of producing clones versus hybrids during crop breeding.

A
  1. Genetic uniformity
  2. Desirable traits are kept
  3. Rapid multiplication (via cuttings and lack of breeding required)
  4. Heterosis (hybrid vigour)
  5. Genetic diversity (for pathogen resistance)
59
Q

What is cytoplasmic male sterility (cms)? Give some examples

A

Lack of male organs due to mutations or changes to mitochondrial or chloroplast genome
- Leads to lack of ability for self fertilisation
- T-urf13 in Maize
- Boro II in rice, increase ROS so lack of pollen

60
Q

What is co-suppression?

A

Integration of transgene led to endogenous gene silencing
e.g. changes in pigmentation in Petunia

61
Q

What are TALENs?

A

Transcription Activator Like Effector Nucleases
- Repeat variable diresidues (RVD), bind specifically to DNA and regulate expression
- used to study effects of knockouts

62
Q

Give examples of conscious and unconscious selection in wheat

A

Conscious - Sr gene for stem rust resistance,
Unconscious - Br and Q gene, Ph1 (homologous not homeologous recombination)

63
Q

Give examples of post-translational modifications that occur in plants

A

NRT1.1 - phosphorylation = HA, dephosphorylation LA
TPK1: Activated by Ca2+ and 14-3-3 proteins
H+ ATPase: Pi and 14-3-3 binding

64
Q

What are the various roles of suberin?

A
  • Wound healing
  • Casparian strip formation, controlling apoplastic movement (e.g. of Fe2+)
  • Drought and salinity tolerance

Plants & Microbial Sciences (4 decks)

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