Global Change: Plants, People and the Biosphere Flashcards
1
Q
How much has atmospheric CO2 increased since the industrial revolution?
A
It has increased by 50%.
2
Q
How much have global temperatures increased by since the industrial revolution?
A
They have increased by nearly 1.5 degrees Celsius.
3
Q
What has happened to surface air temperature in 2024?
A
The number of anomalies increased.
4
Q
What is an important driver of species distribution?
A
Climate is an important driver.
5
Q
What is an important determinant of crop productivity?
A
Climate is an important determinant.
6
Q
How much CO2 is removed per year from photosynthesis?
A
123 Gt.
7
Q
What plays a critical role in the global carbon cycle?
A
Plants play a critical role.
8
Q
How much CO2 is put into the atmosphere through respiration per year?
A
- autotrophic respiration, 60Gt
- heterotrophic respiration, 60Gt.
9
Q
What gas exchange is required for photosynthesis to occur?
A
CO2 must diffuse from the atmosphere into the leaf through stomatal pores. O2 and H2O exits the plant through the same stomatal openings.
10
Q
What reactions do photosynthesis involve and how are they linked?
A
It involves the light-dependent and light-independent reactions, which are linked via pools of ATP and NADPH.
11
Q
What reactions occur in the thylakoids and the stroma?
A
- Thylakoid, light-dependent reaction
- Stroma, light-independent reaction.
12
Q
What are the first 2 protein complexes that are involved in the light-dependent reaction and how are they linked?
A
Photosystems 1 and 2, which harvest light. The light harvesting activates linear electron transport and NADPH production is linked to PS1.
13
Q
What are the third and fourth protein complexes involved in the light-dependent reaction?
A
- Cytochrome b6f, which builds the proton gradient
- ATP synthase, which uses this proton gradient to make ATP.
14
Q
What doesn’t RuBisCO discriminate well between?
A
O2 and CO2.
15
Q
What are the three phases in the Calvin-Benson-Bassham cycle?
A
- Carbon fixation
- Reduction
- Regeneration.
16
Q
What does Rubisco do?
A
- can combine CO2 with a 5-carbon compound to create 2 3-carbon compounds.
- it can react RuBP with O2, which results in photorespiration where the recycling of the waste products results in the release of CO2.
17
Q
What does photorespiration do and what does it require?
A
It recovers carbon from 2PG through a multi-organellar process and the process requires energy (ATP) and redox power (NADH and NADPH).
18
Q
What does 2-Phosphoglycolate do?
A
It inhibits specific Calvin-Benson-Bassham cycle enzyme, and so it must be removed and converted into molecules compatible with plant metabolism.
19
Q
How can you measure photosynthesis?
A
You can measure it with a portable infrared gas analyser system.
20
Q
What is Blackman’s limiting factor analysis used to do?
A
It is used to assess the sensitivity and operating efficiency of RuBisCO.
21
Q
What does the physiological manipulation of the CO2 supply demonstrate?
A
It demonstrates photosynthetic operating efficency.
22
Q
What is a CO2 response curve?
A
It plots carbon assimilation rates as a function of CO2 concentration, and it serves as a classic example of a limiting factor plot.
23
Q
Where do many algae concentrate their CO2?
A
In pyrenoids within their chloroplasts.
24
Q
Where do cyanobacteria concentrate their CO2?
A
In protein structures called carboxysomes.
25
What happens to photosynthetic efficiency in low oxygen conditions?
The reduction in oxygenase activity and photorespiration significantly impacts carboxylation efficiency and the carbon dioxide compensation point.
26
What do C4 and CAM plants use for the primary carboxylation reaction?
The use phosphoenolpyruvate carboxylase for the primary carboxylation reaction.
27
What are some economically important crops that conduct C4 photosynthesis?
- Corn
- Sugar cane
- Sorghum
- Pearl millet
- Foxtail millet
- Tef.
28
How common is it for plants to use the C3 pathway?
The productivity of many staple diets worldwide and all major temperature and tropical forest biomes use the C3 pathway.
29
What is photosynthesis in C4 plants partitioned between?
Mesophyll cells and bundle sheath cells.
30
Where is RuBisCO restricted to in C4 plants?
It is restricted to the chloroplast of bundle sheath cells.
31
Which plants have a higher vein density?
C4 plants have a higher density than C3 plants.
32
What are mesophyll and bundle sheath cells connected by in C4 plants?
They are connected by numerous plasmodesmata.
33
What are bundle sheath cells surrounded by in some C4 plants?
Some plants have the cells surrounded by a waxy suberin layer.
34
What is seen in plants with Kranz anatomy?
Bundle sheath cells form a ring around the vascular tissue, and mesophyll cells form a ring around them.
35
What plants have a higher compensation point?
C3 plants do, and it increases with temperature.
36
What plants have a higher quantum yield?
C4 plants do, meaning that they fix more CO2 per photon absorbed.
37
What does PEPC do in C4 plants?
It fixes CO2 effectively even when internal CO2 concentration is low, meaning that C4 plants often have an advantage over C3 when water is limited.
38
What allows for C4 plants to have lower stomatal conductance for the same CO2 assimilation rates as C3 plants?
The greater drawdown of CO2 during carboxylation by PEPC.
39
What pathway gives plants an advantage at higher temperatures, dry climates, and under high light availability?
The C4 pathway.
40
Why does running the C4 pathway come at a higher energy cost than the C3 pathway?
Because it requires at least two more ATP molecules per CO2 fixed.
41
What increases the energy costs of the C3 pathway?
Photorespiration increases the energy cost.
42
Where has C4 photosynthesis mainly evolved and why has it been selected for?
It has mainly evolved in hot and dry regions, where it has been strongly selected for repeatedly due to it increasing biomass accumulation in warm, dry conditions.
43
What are both C4 and CAM photosynthesis based around?
They are both based around PEP carboxylase that 'pre-fixes' bicarbonate into a C4 acid.
44
How are carboxylases separated in C4 photosynthesis and CAM?
C4 = spatially separated
CAM = temporally separated.
45
What are the 3 types of plant responses to environmental changes?
- stress response
- acclimation response
- adaptation response.
46
What is the stress response?
The immediate detrimental effect of stress on an individual plant, occurring over a time scale of seconds to days.
47
What is the acclimation response?
The morphological and physiological adjustments made by individual plants to compensate for a decline in performance following exposure to stress, occurring over a time scale of days, weeks, to months.
48
What is the adaptation response?
The evolutionary response resulting from genetic changes in populations, leading to morphological adaptations that compensate for a decline in performance caused by stress, occurring over a time scale of multiple generations.
49
What is the predicted impact of high CO2 concentrations on plants?
Stomatal opening and leaf evaporation rates decrease, and it also allows for higher assimilation rates and lower photorespiration rates. With the predicted increase in CO2 uptake, there will be reduced water loss and enhanced plant growth.
50
What plants are predicted to benefit more from elevated CO2 levels?
C3 plants are expected to benefit more than C4 or CAM plants.
51
What experiments allow for the study of the effects of elevated CO2 on plants and ecosystems?
Free-air CO2 enrichment (FACE).
52
What have FACE facilities been established on?
- forest
- grassland
- desert
- agriculture lands.
53
What has been learnt from over 30 years of FACE research?
An 18% increase was seen when there was adequate water and nutrients.
54
Why do leaves require less RuBisCO at high CO2 concentrations?
Because more substrate is available.
55
What do plants grown in elevated CO2 levels show?
They showed decreased protein and nutrient content.
56
When does photosynthesis increase to a thermal optimum?
As enzyme efficiency increases, then decreases at higher temperature.
57
What do natural sources of nitrogen and phosphorous in freshwater environments include?
- leaching from soils
- leaching from plant material during decomposition
- weathering rocks
- atmospheric deposition
- biological fixation through cyanobacteria.
58
What are the different orders in the variation of nutrient sources?
1st and 2nd order - low autotrophic uptake due to shading
3rd and 4th order - N and P taken up by algae, too fast for large plants
5th and 6th order - multi-cellular plants are primary users of N and P.
59
What is ecological stochiometry?
The balance of multiple key elements in organisms.
60
Which element will consumers preferentially sequester?
The element in shortest supply relative to its demand.
61
What does stoichiometry vary with?
- taxonomic group
- environment
- season
- diet
- trophic level.
62
Why is there a general increase in P relative to C and N in vertebrates with increasing body size?
It is largely due to the high P concentration in bones.
63
What is allochthonous carbon?
Carbon coming from outside the ecosystem.
64
What is autohthonous carbon?
Carbon coming from inside the ecosystem.
65
What is an example of allochthonous subsidies?
Bears and salmon, where salmon bring the marine nutrients back to freshwater ecosystems. Trees in the area grow faster in areas with salmon carcasses.
66
What is Darwin's 'entangled bank' idea?
Where marine nutrients can be driving freshwater and terrestrial food webs.
67
What is the variation of nutrient dynamics over space and time seen through?
Varying resources along spatial gradients, temporal dynamics, and alternative stable states.
68
What are alternative stable states?
Differening arrangements of an ecosystem's characteristics.
69
What are regime shifts?
The transition from one alternative stable state to another through the passing of a threshold.
70
What is a point source?
Where there's sewage pipes, like there's one pipe where it all comes from.
71
What are diffuse sources?
Where there's a field, so leaching when it remains and there's no clear source.
72
What is eutrophication?
Organic pollution causes elevated nutrient levels which promote algal growth. As dead algae decompose, the oxygen in the water is used up. Invertebrates and fish die or leave the affected area.
73
How can you look at nutrient pollution?
One can look at the species present and look for indicator species.
74
How is the ecological status of the river determined in the UK?
A lowest common denominator rule is applied to the elements, so the lowest scoring element denotes the overall status of the water body.
75
How many UK rivers meet "good ecological status"?
Only 14% of rivers meet the status.
76
What is the driving force of abundance and diversity shifts in plants and animals?
Nutrient pollution.
77
What are the 3 types of formation of coral reefs?
- fringe reefs
- barrier reefs
- atolls.
78
What are the two distinct bigeographic regions of coral reefs?
- the Indo-Pacific and the tropical West Atlantic.
79
What are the requirements for corals?
- between 18 and 30 degrees Celsius
- no sudden changes in salinity
- high light intensity
- low turbidity and oligotrophic waters.
80
What is the simple body plan of corals?
It is with 2 layers, the ectoderm, and the endoderm, with mesoglea sandwiched in between.
81
What group do the reef-building corals belong to?
The scleractinian corals.
82
What is a corallite?
A protective cup made of secreted calcium carbonate.
83
What are zooxanthellae?
They are dinoflagellates that are photosynthetic algae that are in the endodermal layer they can also be free-living. They are essential for coral growth.
84
What did the old coral energy budget assume?
It assumed there was no feeding observed, but this could not account for lost carbon.
85
What was the coral reef productivity paradigm in 1990?
During the day, photosynthetic activity draws down CO2; however, at night, respiration produces CO2. Photosynthesis is sufficient to meet most of the respiratory requirements. Requirements for inorganic nutrients can be met from flow of water from the surrounding ocean. Corals don't feed much and obtain all or most of their carbon from photosynthesis. They recycle C and N very tightly within their tissues and almost nothing leaks out.
86
When looking at coral energy budgets in 2015, what did it show?
That in terms of carbon, only 1 species of 5 came close to supporting itself with heterotrophy alone.
87
What was found from a lab experiment where 3 species of corals were bleached and the photosynthesis and heterotrophy were looked at?
All three species depend on their symbionts to fulfil their carbon needs. After bleaching, species which are known to be bleaching tolerant could sustain itself by feeding.
88
What are the consequences of bleaching?
It causes a loss of photosynthesis, it depletes energy reserves and reduces biomass.
89
What might be important for surviving bleaching events?
The corals being plastic and switching to heterotrophy if the symbiosis breaks down.
90
How is some excess organic carbon released from corals?
It is probably released as exudates and mucus.
91
What can corals produce?
They can produce copious mucus strands and tunics.
92
What does mucus production of coral depend on?
It depends on the time of year and other environmental conditions.
93
Why might corals produce mucus?
At low tide, they use mucus to protect themselves from intense UV exposure.
When submerged, they produce mucus in response to stress.
94
What does the corals releasing excess organic carbon do?
It fuels bacteria and supports foodwebs.
95
What is crucial for reef productivity?
Primary production by the zooxanthellae.
96
How is nitrogen taken up and fixated in corals?
Algae take up inorganic nitrogen from the water while diazotrophs that are closely associated with corals do nitrogen-fixation.
97
What can lead to catastrophic phase-shifts as macroalgae outcompete coral?
Agricultural run-off and overfishing can lead to this.
98
What can additional nitrogen do?
It can enhance symbiotic activity, but it can also lead to the breakdown of the relationship between symbiont and host.
99
What does the addition of nitrogen reduce?
It reduces calcification rates. It also enhances the density of algae and the levels of chlorophyll A that they contain.
100
What does the addition of phosphorous do?
It enhances calcification rates. It also enhances the density of algae.
101
What do fish-derived nutrients do?
They have been seen to clearly enhance coral growth rates.
102
What does the effect of seabirds have on coral bleaching?
They have been seen to have no effect on resistance to bleaching while it is debated.
103
What does Gause's competitive exclusion principle say?
It says that species can't be exactly the same and coexist.
104
What is niche separation seen in?
It is seen in MacArthur's warblers where each species feeds on different parts of the tree.
105
What is the R* theory good for understanding?
How plants compete for a single limiting resource.
106
What were Tilman's diatoms used for?
They were used to study the R* theory and get the R* value.
107
What does R* theory allow you to do?
It allows you to predict the outcome of competition.
108
What allows for more than one species of plant to coexist?
The fact that plants need a suite of essential resources that are non-substitutable.
109
What defines a zero net growth isocline (ZNGI)?
The minimum requirement of the two or more resources used.
110
What do ZNGIs denote?
The minimum concentration of the two resources that the species needs to maintain a positive population growth rate.
111
What is a consumption vector?
It described the relative requirements of species A for the two limiting resources.
112
What are outcomes for the 2-species Lotka-Volterra model?
It has many possible outcomes and an important one is that stable coexistence is possible.
113
What does the resource-ratio hypothesis explain?
It explained how two species could coexist on two essential limiting resources.
114
Can you do a plot with multiple ZNGIs?
Yes, it can show which plants will coexist and which ones will outcompete the others.
115
What is the park grass experiment?
It is the oldest ecological experiment, and it was established at Rothamstead in 1856 in one field. It looks at different treatments, like manure and fertiliser.
116
What provides a relatively small number of niche axes along which species can coexist?
The plants competing for a small number of essential non-substitutable resources.
117
What is problematic with the park grass experiment?
There is no randomisation and little replication.
118
What did the park grass experiment find?
It found that as biomass increases, species richness declines linearly. As pH increases, species richness increases non-linearly.
119
What are two possible hypotheses as to why fertilisation collapses diveristy?
- the addition of huge amounts of nutrients removed nutrient limitation and collapses small-scale heterogeneity in supply rates
- the addition of nutrients shifts the system to one in which only light is limiting, as light is a directional resource and competition for light is strongly asymmetrical.
120
What was found after a factorial experiment looking at grassland communities that have been removed and put into a glasshouse?
It showed that fertilised treatments lost species, but the addition of light to the understory completely reversed this effect.
121
What is one of the most species-rich plant communities in Europe?
It is calcareous grasslands.
122
What are the major causes of loss of calcareous grasslands?
- conversion to arable and horticulture
- 'improvement' through the addition of chemical fertilisers.
123
What is an option to replace grazing in public and dog walking areas?
An option is annual cutting at the end of the summer.
124
What happens as the effect of sowing increases?
It increases as the intensity of management interventions increases.
125
What did Tilman observe?
He noticed that there was a negative correlation among species between the ability to colonise and competitive ability for the main limiting resource.
126
What does Levins basic metapopulation model show?
It describes how the fraction of sites occupied depends on the colonisation rate and mortality rate. It also shows that in theory, a single species cannot fully occupy a habitat.
127
What does the two-species metapopulation model assume?
It assumes that species 1 is the superior competitor, and species 2 is the inferior competitor and that there is competitive asymmetry. If the mortality rate of species 2 is greater than or equal to species 1, then it must have a higher colonisation rate to persist. But, stable coexistence of two species is possible.
128
What does Tilman's model predict about seed sizes?
It predicts that the large-seeded species will be able to exclude the smaller-seeded ones if their colonisation limitation is overcome. It was found that at high input rates, large-seeded species increasingly dominated.
129
What does the Janzen-Connell effect argue?
It argues that diversity could be maintained by species-specific herbivores. It suggests that predation on seeds is extremely high around the parent tree and only seeds that travel some distance from the adult survive and recruit.
130
How does the Janzen-Connell effect work?
If a species cannot recruit near to conspecifics, then this limits its population growth. As a species becomes more abundant, the probability of recruitment will fall. If each species has its own specific herbivore, then potentially this allows very large numbers of species to coexist.
131
What is the evidence for the Janzen-Connell effect?
The evidence comes from Barro Colorado Island in Panama, where wide variation among species in the effect of conspecifics on survival of seedlings, but it is generally negative. There is little variation in the effect of heterospecifics, but these are generally clustered around zero.
132
What is the definition of biodiversity from the convention on biological diversity?
The variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.
133
What terms can biodiversity be defined by?
- taxonomic diversity
- phylogenetic biodiversity
- genetic diversity
- functional diversity.
134
What are bio-geo-chemical ecosystem processes?
Flows of energy and matter within and among ecosystems.
135
What is the old paradigm?
That environmental variation drives biodiversity and ecosystem functioning.
136
What is seen with the latitudinal diversity gradient?
There is a generally positive relationship between productivity and diversity, but this is not for all groups. This is also correlation, so not necessarily causation.
137
What is the theory of niche complementarity?
It is where diverse communities of complementary species fill up more of the potential niche space, aka niche packing.
138
What is one way to test the link between productivity and diversity?
One way is to do species knockouts in a controlled environment and then look at the productivity of these environments given that some species are removed.
139
What do the controlled environment knockout species experiments show?
They show that biodiversity loss reduced productivity.
140
What is the problem with the controlled environment knockout species experiments?
One problem is that the pattern does not show the process, so is niche complementarity or is it a dominant species that has high productivity.
141
What is the solution to the problem created by species knockout experiments?
The solution is meta-analysis and creating working out how much of the pattern is due to complementarity and how much is due to a dominant species, and to compare these.
142
What was the results found from meta-anlysis?
It rejected the idea of one dominant species and reinforced the idea that the results seen were more commonly due to niche complementarity.
143
What is evidence for niche complementarity?
The positive saturation effect of biodiversity against ecosystem function.
144
What is the new paradigm?
That biodiversity and environmental variation jointly drive ecosystem functioning.
145
Why are diverse communities more productive?
Because they contain key species that have a large influence on productivity, and greater variation in functional traits among organisms that increases total resource capture and other forms of niche complementarity.
146
What can niche differentiation in mixtures lead to?
It can lead to complementarity.
147
What is modern intensive agriculture based on?
It is based on productive monocultures that rely on intensive use of inputs and resources.
148
What is one of the key ways to increase diversity in agro-cropping ecosystems?
One of the key ways is through intercropping.
149
What do managed ecosystems tend to exert control on?
- composition
- density
- spatial arrangement
- phylogeny of organisms.
150
What is intercropping?
Cultivation of multiple species on the same land at the same time.
151
What is the difference between intercropping and crop rotation?
Crop rotation is different crops in different years whereas intercropping is within the same year.
152
When can monocultures produce high yields?
When environmental variability can be reduced by inputs to maximise yield of a single species.
153
When will no single species exhibit high yield under the wider range of conditions and why?
Where it is costly or impossible to use inputs, and it is due to niche differences between species.
154
What do additive designs of intercropping look at?
They look at appropriate crop combinations and studies of weed impacts, so you plant your crops at a fixed density and then add weeds in between and look at yield.
155
What do substitutive designs of intercropping look at?
They look at appropriate crop combinations, and it looks at 50/50 with the same density.
156
What can diversifying species mixtures lead to?
- complementary partitioning of resources including type, time and space
- reduced natural enemy impacts like pests and diseases
- more favourable biotic and abiotic conditions
- reduction of environmental stresses
- yield stability over time and space.
157
What are 2 good examples of intercropping?
- corn-bean-squash companion planting
- shade-grown coffee.
158
What does intercropping do to insect abundance?
It has been seen to reduce insect abundance when comparing many different study results.
159
What has intercropping been seen to suppress?
- natural enemies across a range of crop species
- weeds across a wide range of crop species from different plant families and groups.
160
What are the barriers and challenges of intercropping?
- it is traditionally harvested by hand instead of machines
- infrastructure is optimised from a standardised single crop
- markets don't work around this idea
- there are vested interests into intensive monocultures
- optimal conditions are needed to be maintained
- not the money
- need more research into complementary mixtures.
161
Where is crop cultivation evidence first seen?
In the fertile crescent.
162
What are the general features of landraces?
- are often visually distinct and identifiable
- are genetically adapted to the local environment
- often have a specific historical origin
- are often associated with a particular geographic region.
163
When did varieties start, what did they involve and what are their genetics like?
Varieties started in the early 19th century and it involved conscious human selection. They are genetically homogenous/homozygous and this has an advantage of standardisation and uniformity.
164
What did scientific breeding result in?
It resulted from the rediscovery of Mendel's law and from developing ideas of the mechanism of inheritance.
165
What is the basic aim of scientific breeding?
It is to generate and harness genetic diversity and then select plants with improved characteristics.
166
What are the basic generic steps of scientific breeding?
1. The female parent is emasculated so that it can't self pollinate, and pollen is transferred from the male parent with a paint brush to make the cross.
2. Pollinated plants are bagged to ensure that the female parent receives pollen only from the chosen male parent.
3. Seeds are collected from the pollinated plants and sown out to produce an F1 population in which all the plants are uniform.
4. See from the F1 plants is collected and sown to produce an F2 population in plants.
5. The plant breeder starts to select the plants with the best characteristics from which see will be saved for sowing the next generation.
6. The process of selection and resowing continues and moves from the glasshouse into small plots in the field.
7. At each state, the breeder is measuring yield and quality characteristics and looking for disease resistance.
8. The final stage of selection is from yield plots grown in the field at diverse locations around the country before the variety is entered into registration.
167
What does pedigree breeding involve?
It involves crossing carefully chosen parents. Seeds form the best of the F2 is grown over several generations and the best pure lines are selected for varietal trials.
168
What is exploited in hybrid breeding?
It exploits 'hybrid vigour' or 'heterosis' in the F1 generation.
169
What do parallel selection programmes in northern and southern hemispheres allow for?
They allow for two generations per year.
170
How can the pace of breeding be increased?
It can be increased using double haploids. With this, haploid plants are generated and then made diploid, meaning that doubled haploids are 100% homozygous in one generation.
171
What has molecular genetics transformed in plants?
It has transformed breeders understanding of the function of individual genes and increased the speed with which genetic variation can be analysed.
172
What does transformation allow for in plants?
It allows desired traits to be added, modified or deleted in a plant variety without reshuffling entire genomes.
173
What are the percentages of land grown with GM crops in the USA as of July 2020?
90% for maize
92% for soyabean
92% for cotton.
174
What are the advantages of working with arabidopsis?
- it has it whole genome sequenced
- mass scale plant propagation is very easy.
175
What is the gene regulatory network controlling seed dispersal?
IND is a gene that encodes for the cells that control for the opening of the pods. There is a transcription factor, FUL, which is found in the valve and represses expression of IND in the valve. IND is found in the thin layer of tissue between the valve and the replum.
176
What activated IND in seed pod shattering?
GA4 activates IND.
176
What do GA4 mutants have in arabidopsis?
They appeared to have a defect in valve margin development, so they didn't have a fully developed valve margin.
177
What technique was used to make varieties of Brassicacae with less pod shattering?
The CRISPR route was used to target GA4 genes.
178
What was targeted by CRISPR to control Brassica sulphur metabolites?
MYB28 was targeted.
179
What is the result of wild species genetic architecture being altered by human selection?
It results in new forms of plants altered to meet human needs.
180
When did cultivation begin replacing foraging?
3,000 to 11,000 years ago.
181
What does the understanding of grain crop domestication have?
It provides a model for understanding domestication in general.
182
How many independent regions has cultivation arisen as identified by archaeological studies?
24 regions.
183
What originated in the 'Fertile Cresent'?
Whet originated there.
184
What is the domestication syndrome?
The characteristic collection of phenotypic traits associated with the genetic change to a domesticated form of an organism from a wild progenitor form.
185
What do domesticated species often exhibit?
They often exhibit convergent phenotypic evolution.
186
What are some of the traits of the domestication syndrome?
- loss of seed dormancy
- changes in physiology
- changes in architecture
- loss of photoperiod sensitivity
- increase in seed size
- loss of shattering.
187
What has happened to grain size in domestication?
Grain size has increased in wheat, rice, maize and barley.
188
Where is deeper soil burial more common?
It is more common in soils disturbed by human tillage.
189
When do larger seeds perform better than smaller seeds?
Following deeper burial in the soil.
190
When did the loss of seed shattering evolve?
It evolved over 1,000s of years.
191
What does different crop species having similar rates of selection for loss of seed shattering suggest?
It suggests that selection pressures are similar across different taxa, places and time periods.
192
What is the 'hallmark' of domestication in grain crops?
The 'hallmark' is a loss of seed shattering.
193
What does the loss of seed shattering render crops dependent on and what is it attributed with?
Loss of seed shattering renders crop dependent upon humans for
propagation and survival and it is attributed to the use of a sickle for harvesting as this selects for plant seed retention.
194
What did naked grain in maize lead to?
It led to the crop being less labour-intensive, and it transferred from grains covered in hard podcases to easily-milled naked grains.
195
What is the stickiness of rice due to?
It is due to reduction in
amylose levels in grain starch. It results from intron 1 splice-donor mutation in the waxy gene, causing loss of starch-granule bound starch synthase.
196
What are the cultivated plants the product of?
They are the products of initial domestication and subsequent diversification.
197
What are the selective sweeps?
Reductions in nucleotide variation that have resulted from strong selective pressures on particular loci.
198
What did human selection drive?
Both the initial domestication and the subsequent diversification.
199
What are the 3 green revolutions?
- Neolithic (11,000 - 3,000 BCE)
- Semi-dwarf crops (1940s-1950s)
- Precision breeding (2015-......).
200
What's happening to the monthly average surface temperatures by year?
They are increasing.
201
What is the projection of population growth?
It is projected to be decreasing and the world population will keep growing and then plateau.
202
What is part of the problem of global warming?
The process of food production.
203
What are landraces?
They are locally adapted genotypes.
204
What have different varieties of plants do?
They have increased genetic uniformity.
205
What did Norman Borlaug get a Nobel Peace Prize for?
He created wheat varieties with educed height which led to less lodging and more energy going into the grain, leading to higher yield.
206
What is the biology that underpinned Norman Borlaug's Green Revolution?
Gibberellic acid.
207
What leads to wheat of a reduced height?
GA-resistant DELLA.
208
What does transformative technology include?
- whole genome sequencing
- gene modification
- genome editing.
209
What is an example where whole genome sequencing has been used?
An example is it being used for finding the resistance gene to stem rust.
210
What does the development of genetically modified crops depend on?
It depends on plant transformation.
211
What is the difference between GMOs and CRISPR?
GMOs have a whole gene replaced with a foreign gene, while CRISPR changes part of a gene.
212
What do 50% of the world's food calories come from?
Four crops:
- wheat
- rice
- maize
- sugar cane.
213
What is 75% of arable land i the UK taken up by?
- wheat
- barley
- oilseed rape.
214
What does self-pruning editing lead to in physalis?
It leads to compact fluorescence and improved fruit sets.
215
What are the opportunities of underutilised crops?
- Increasing plant-based protein in human diet
- Introduce crops with higher resilience towards climate change
- Better suited for certain geographical locations
- May reduce need for fertiliser/chemical input.
216
What are the challenges of underutilised crops?
- Low yield due to lack of domestication
- May contain anti-nutritional/toxic compounds
- Unpopular with farmers due to lack of suitable machinery, low yield
- Introduction to consumers/legislation.
217
What are some primary macronutrients for plants and what are they needed for?
- nitrogen, for healthy green foliage
- phosphorous, for strong roots and blooms
- potassium, for healthy plant growth.
218
What is disrupting the corresponding nutrient cycles beyond the safe level?
The global flow of phosphorous into the ocean and the industrial fixation of nitrogen.
219
Where are nitrogen-converting enzymes found?
They are often found in very diverse microorganisms and many of these enzymes have only recently been identified.
220
What do microorganisms involved in the nitrogen cycle do?
They carry enzymes that perform 14 redox reactions and the reactions involve reduction, oxidation, disproportionation and comproportionation.
221
What happens in the nitrogen cycle?
- In anoxic soil (e.g. waterlogged) denitrification can become dominant.
- N2O 300 times more potent as a greenhouse gas.
- NO reacts with atmospheric O3 (i.e. depletes) to produce HNO2.
- NO3-assimilation in plants, reduced by NADPH to NO2- in cytosol and ferredoxin reduction of NO2- to NH3 in chloroplasts.
- Dissimilatory NO3-reduction (DNRA) occurs in nutrient rich anoxic environment 8e- process.
- Ammonification carried out by many organisms (breakdown of amino acids).
- Ammonia normally as NH 4 + but some losses to atmosphere as NH3 (about 15% of N release to atmosphere) most releases at N2 or N2O.
222
Where can microbes of the nitrogen cycle be found?
They can be found in marine environments and plant/soil environments.
223
What are the 2 steps of nitrification?
- ammonia is converted into nitrite by ammonia-oxidising bacteria
- nitrite is converted into nitrate by nitrite-oxidising bacteria.
224
What allows for nitrate reduction to happen?
A variety of naturally occurring bacteria convert nitrate to nitrite to gaseous forms of nitrogen in the absence of oxygen that is released to the atmosphere.
225
What encourages denitrification to happen?
Absence or very low levels of O2 and the presence of a C source encourage the microorganisms to obtain the O2 they need by breaking down the nitrate molecule.
226
What was the world's first commercial organic fertiliser?
Guano.
227
When was guanine first obtained and what from?
It was first obtained from guano in 1844.
228
Who looked at the synthesis of chemical fertilisers?
Fritz Haber looked at artificial nitrogen fixation and then Carl Bosch scaled it up.
229
How many people does nitrogen-based mineral fertilisation sustain?
1 out of 2 people globally.
230
What is the most used macronutrient in fertiliser?
Nitrogen.
231
What is nearly two-thirds of applied nitrogen lost by?
- lost to the environment
- leaching into soil
- leaching into water, lakes, and rivers
- emitted into air.
232
What is precision farming?
It uses information from drones or satellite imagery to allow us to see exactly where fertilisers are needed the most.
233
What 4 key metrics could researchers measure using satellite imagery and geospatial datasets?
- cropland nitrogen balances
- nitrogen pollution
- yield gaps
- the natural vegetation potential.
234
What is one of the most pressing pollution issue facing humanity?
It is nitrogen pollution.
235
How are nitrogen oxide emissions impacted by the application of fertilisers?
The emissions are produced by microbes in nearly all soils and applying fertilisers makes nitrogen readily available for microbes to convert.
236
How is the World Bank's fertiliser price index changing in the future?
It is rising to more than triple of those in 2020.
237
How can legumes help with nitrogen fertilisation?
High-performing legumes can fix lots of nitrogen, which can take the place of $1 per kg in fertiliser to meet requirements.
238
What does increasing the proportion of legume crops in a rotation do?
It reduces the use of chemical fertilisers.
239
What are the constraints of endophytic nitrogen fixation in agriculture?
- there is promiscuous colonisation
- it is tightly regulated
- it can result in the release of fixed nitrogen.
240
Where does nitrogen fixation occur?
It occurs in different plant-microbe associations.
241
What is a nitroplast?
It is a nitrogen-fixing organelle that is a bacterial endosymbiont of marine algae evolved to an organelle of the unicellular algae.
242
How much of the biosphere's available nitrogen is house in the symbiotic bacteria within legume nodules?
50% of the biospheres available nitrogen.
243
Is nodule symbiosis a common trait?
No.
244
What is a key trait for a binoculant?
Effectiveness is a key trait.
245
What are the current challenges of using legumes?
- competitiveness and effectiveness traits are not always linked
- legumes can be nodulated by highly competitive but not necessarily effective rhizobia.
246
What are the challenges for engineering nitrogen fixation into cereals?
- it needs a lot of energy so must provide a carbon source for nitrogen fixers
- nitrogenase is inactivated by oxygen
- bacteria need to be induced to secrete ammonia to the plant.
247
What are the steps in engineering nitrogen fixation in cereals?
1. Expressing nitrogenase in cereal plant cells
2. Getting rhizobia to communicate with cereals and allow them to be nodulated
- Expressing nitrogenase in cereal bacterial colonisers.
248
What was the first intraspecies transfer of nitrogen fixation from and to and when was it accomplished?
It was from Klebsiella to E.coli and it was accomplished in the 1970s.
249
What are the global challenges in agriculture?
- climate change
- rising temperatures
- growing population
- forest decline
- loss of biodiversity
- fossil fuels
- eutrophication.
250
What is the longest-running scientific experiment in the world?
The Broadbank wheat experiment in Rothamstead.
251
What was found out about phosphate fertiliser at Rothamstead Estate?
- ammonium phosphates gave the greatest yields of ammonia salts.
- bones treated with sulfuric acid produce superphosphate which also increases yields.
252
What are the main types of organic phosphorous fertilisers?
- map and dap
- superphosphate
- rock phosphate
- compost
- fish meal
- bone meal.
253
What happens to roots in low-phosphate soil?
They branch more and are at a higher density due to the need to find more phosphate.
254
Why does global mismanagement of the finite phosphorous threaten food security?
as many farmers struggle to afford sufficient phosphorus fertiliser for their crops, while its overuse pump millions of tonnes of phosphorus into lakes and rivers each year, damaging biodiversity and affecting water quality.
255
Why is phosphate a finite resource?
Because it is a mined resource, and the rock is a non-substitutable, non-renewable natural resource, essential for fertilisers, animal feed, food security and industrial applications.
256
How much of the phosphorous used in agriculture is consumed by humans?
Approximately 10%.
257
What countries were responsible for 72% of the global production of phosphate rock in 2021?
- China
- Morocco
- USA
- Russia.
258
How much mined phosphorous is left?
About 100-300 years left.
259
What is the 'Helsinki Declaration' and what did it want countries to adopt?
It called for transformation across food, agriculture, waste and other sectors to deliver much-needed improvements to global phosphorus sustainability. It also called for countries to adopt a 50, 50, 50 goal.
260
What is the '50, 50, 50' goal?
A 50% reduction in global pollution of phosphorus and a 50% increase in recycling of the nutrient by the year 2050.
261
What are sustainable solutions for reducing phosphorous consumption?
- apply manure to crops
- moving towards a more sustainable diet, so reduce P needed to grow animal feed
- reducing global waste, so less need for so much food
- improve water treatment to remove phosphorous from sewage.
262
How much of the ice-free terrestrial earth surface is covered by agriculture?
35-40%.
263
How much of the planet's terrestrial net primary productivity is appropriated by humans?
30%.
264
What is agroecology?
The application of ecological understanding and principles to agriculture
OR
the study of ecological processes that operate in agricultural production systems.
265
What is agroecology synonymous with?
Sustainable, environmentally-friendly farming.
266
How has agricultural intensification moved?
It has gone from manuring and composting to natural pest control and hedgerows and has moved to inorganic fertilizers, pesticides, and fences.
267
What does fragmentation from transformation do to populations?
It moves from large populations with easy dispersal, to small, extinction-prone populations and low connectivity inhibits recolonisation and range-shifts in response to climate change.
268
How much of the global greenhouse gases are due to the food system?
It is responsible for around 24%.
269
What is the impact of agricultural diversification practises on biodiversity and ecosystem services?
They generally have a positive impact without compromising yields.
270
What are the strategies of nature-friendly farming used at Hope Farm RSPB?
- reducing hedge cutting
- providing insect-rich flower habitats and seed-rich habitats
- safe nesting spaces with lapwing and skylark plots
- using no pesticides
- reduced pesticide and inorganic fertilisers
- soils are managed to promote richer habitats for invertebrates.
271
What is the problem with environmentally-friendly farming strategies in the Global South?
Models used in high-income countries use economic benefit systems and there is limited population growth and little potential for further intensification and with the Global South, it comes at the expense of economic development until growing populations have food security.
272
What are the top 5 producing nations of palm oil?
- Indonesia
- Malaysia
- Thailand
- Nigeria
- Colombia.
273
What are the positive impacts of palm oil?
- major driver of development
- significant contributor to export earnings in SE Asia
- higher income for smallholders compared with alternatives
- 30x more employment per ha
- significant poverty reduction
- resettling families
- high employment.
274
What are the top 5 consumer nations of palm oil?
- India
- China
- Indonesia
- Malaysia
- EU.
275
What is the demand for vegetable oil projected to be in 2050?
It is projected to double by 2050.
276
What is the problem with boycotting palm oil?
It is likely to transfer the problem to other less efficient crops, which use 4x more land area.
277
Where does palm oil grow?
It grows where terrestrial biodiversity peaks.
278
How much deforestation is caused by palm oil development only?
It causes less than 0.5%.
279
What makes biodiesel fuel?
- Palm oil
- Soybean
- Rapeseed oil
- Sunflower oil.
280
What is better for climate change, biodiesel fuel or fossil fuels?
Fossil fuels.
281
What happens to biodiversity when cattle pastures are converted to oil palm in the neotropics?
Diversity increases.
282
What is land sparing?
Where some land is farmed intensively to maximise yields while other land is protected as a reserve.
283
What is land sharing?
Where all land is farmed, but using wildlife-friendly technique which may reduce yields.
284
What areas are most at risk from leakage/displacement?
- The Columbian Llanos
- Bolivian Beni Savanna
- Guinean Savanna.
285
What does the RSPO require of plantations?
They require that areas of "high conservation value" are maintained and/or enhanced in plantations.
286
How many plantations contain at least one large high conservation value area?
Almost half of all plantations.
287
What are riparian reserves?
They are strips of forests that are retained alongside rivers through plantations that are protected by law.
