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Sem 1: Plant Biology > Week 3 > Flashcards

Week 3 Flashcards

(129 cards)

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1
Q

What are the 6 macronutrients?

A

Nitrogen
Phosphorus
Potassium
Sulphur
Magnesium
Calcium

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2
Q

What are John Woodward’s conclusions?

A

Woodward concluded that mineral matter nourishes plants.

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3
Q

What were the impact of John Woodward conclusions?

A

These conclusions layed the foundation for the study of plant mineral nutition

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4
Q

What experiement did John Woodward do?

A

He compared plant growth in water different amounts of ‘mineral matter’ to test the assumption that water is a plant’s sole requirement.

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5
Q

What were the results of John Woodward’s experiments?

A

Spring water - plant weight increased by 55%
Rain water - plant weight increased by 62%
Thames River Water - plant weight increased by 93%

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6
Q

What is the “law of minimum”?

A

Growth of the plant will always be determined by the limited nutrient

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7
Q

When did Lawes and Gilbery start investigating plant nutrition?

A

They started in 1843 at Rothamsted, which is still researching today

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8
Q

Where does nutrient assimilation take place?

A

They take place across the surface of the plant or through the root system of vascular plants

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9
Q

What are the 8 micronutrients?

A

Iron
Nickel
Manganese
Copper
Molybdenum
Boron
Chlorine
Zinc

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10
Q

Which ions of nitrogen, phosphorus, sulphur, molybdenum and boron aren’t assimilated as compounds?

A

Nitrogen - NO3 -, NH4 +
Phosphorus - HPO4 2- , H2PO4
Sulfur - SO4 2-
Molybdenum - MoO4 2+
Boron - H3BO3

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11
Q

What is requred for the transportation of charged ion?

A

They require proteins to cross membranes

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12
Q

How do roots increase effciency?

A

They increase the surface area for absorption

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13
Q

What are the similarities between microvilli and roots?

A

They are structurally similar but inverse as they need to absorb nutrients in rather than absorb nutrients out into the blood

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14
Q

What are the adaptations to enhance nutrient capture?

A

Biochemical response - root exudates
Fungal symbiotic partners - mycorrhizae
Developmental responses - cluster roots
Prokaryotic symbiotic partners - Biological nitrogen fixation

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15
Q

How does soil pH change around the world?

A

Deserts and other dry areas are mildly alkaline comapred to forests which are strongly acidic

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16
Q

How does soil pH impact nutirents?

A

Different pHs impact the percentage of uptake of soil nutirents with each nutirent having a more optimum pH

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17
Q

What things affect soil fertility?

A

Erosion, rainfall patterns, cultural practices, soil biodiversity, soil pH and atmospheric gases

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18
Q

What are the main 3 elements in fertilizers?

A

Nitrogen
Phosphorus
Potassium

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19
Q

What are the two types of fertilizers?

A

Natural - waste products
Artifical - refinded blends of nutirent salts

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20
Q

Are resources constant around the planet?

A

No, different regions have different amounts of resources. So areas like USA have greater supply of K2O than demand but has lower N than demand compared to Russia/Eastern Europe which has greater supply of both K20 and N than demand

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21
Q

How much is the fertilizer trade worth?

A

$231 billion dollars in 2021

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22
Q

What factors impact the amount of fertilizer used?

A

Species of plant
Soil characteristics
Cultivation practices
Abiotic and biotic factors
Financial considerations
Interactions between nutrients

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23
Q

What are the problems of fertilizers?

A

Nitrogen fixation is energy demanding
Phosphate and potash mining is destructive
Huamn and animal waste can spread disease
Transport requires energy
Nutrient runoff pollutes waterways and can lead to eutrophication
Nitrous oxide derived from fertilizer is a major greenhouse gas

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24
Q

Where are minerals naturally come from?

A

Rock weathering
Decaying matter
Organic matter
Inorganic matter

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25
How much does food production increase inbetween 1960 and 2000?
1.8x10^9 to 3.5x10^9
26
How much does nitrogen fertilizer use increase inbetween 1960 and 2000?
10x10^12g (10 Tg) to 88x10^12 (88 Tg)
27
How abundant is nitrogen in plants and the atmosphere?
Most abundant elements in atmosphere 4th most abundant element in a plant after C, H and O
28
Why is nitrogen is important?
In amino acids Nucleic acids Chlorophyl Other small molecules
29
What element is often the limiting nutrient for plants?
The limiting nutrient for plant growth is nitrogen
30
What is the difference between nitrous oxide and nitric oxide?
Nitrous oxide - N2O Nitric Oxide - NO
31
What is the difference between nitrous acid and nitric acid?
Nitrous acid - HNO2 Nitric acid - HNO3
32
What do nitrifying bacteria do?
Convert ammonium to Nitrogen dioxide to nitrate This releases energy
33
What do plants to produce organic nitrogen?
Using energy and the enzyme nitrate reductase NO3- to NO2- to NH4+ to R-NH3
34
Do plants prefer NH4+ vs NO3-?
Plant preferences for NH4+ vs NO3- vary by species, other metabolic processes, temperature, water, soil pH
35
What are HATS?
High affinity transporters - can transport either ammonium, nitrate, amino acids and urea depending on the transporter in high concerntrations
36
What are LATS?
Low affinity transporters - can transport either ammonium, nitrate, amino acids and urea depending on the transporter in low concerntrations
37
What happens to nitrate within the plant?
Other Channels contribute to nitrate transport within and between cells
38
Name Ammonium channels?
AMT 1.1 = HATS
39
Name nitrate uptake channel?
NAR 2.1 = HATS NRT 1.2 = LATS
40
Name an amino acid uptake channel?
AAP1
41
Name an urea uptake channel?
DUR 3 - HATS TIPS - Passive
42
What happens to uptaken NH4+?
It gets assimilated into organic compounds like glutamine
43
What happens to uptaken R-NH3?
It gets assimilated into NH4+?
44
What is glutamine used for?
It is converted into all other nitrogen containing compounds
45
What is remobilization?
Amino acid recycling and photorespiration which produces NH4+
46
What happens to recycled and uptaken NH4+?
It is converted into glutamine using glutamate by glutamine synthetase (GS)
47
What happns to the glutamine?
Some is incorporation into nitrogen-containg compounds Some of the nitrogen is split and bonds with 2-oxoglutarate to glutamate using glutarate aminotransferase (GOGAT) which then bonds wirh NH4+
48
Can nitrogen go through GS many times?
Yes, they can go through GS many times many times as amino acids are recycled during growth and senescence and relewased due to photorespiration
49
What does a plant do in response to nitrogen deficit?
Activation of some NO3- and NH4+ transporters Preferential growth of root relative to shoot
50
What are metabolic adaptations to low nitrogen?
Decreased accumulation of N-rich chlorophyll Increased accumulation N-free anthocyanins Smaller pools of N-containing compounds (amino acids) Larger pools of N-free compounds (starches, organic acids) Accelerated senescence and nitrogen remobilization
51
What happens to roots when nitrogen is abundant?
Plants allocate less biomass to their roots
52
What happens when nitrogen distrubution is patchy?
Roots distrubution proliferate in nutrient rich patches
53
In an experiment where half roots are in low NO3- conditions the other in high how did the roots grow?
They grow heavily in the nutrient rich areas but only partially in nutrient poor areas
54
What is co-cropping?
Growing crops with legumes to enrich soil N content
55
What is grop rotation?
Rotating crop in order to maximise growth rate and replace some lost minerals
56
How can you determine n content?
By determining chlorophyl content which is measured by reflected light
57
What is the transmission ratio of chlorophyll?
Ratio of 653nm to 931 nm
58
What is the Haber Bosch process?
Industrial production of ammonia
59
When was the Haber Bosch process invented?
1910
60
What are the problems of the Haber Bosch process?
Requires expensive metal catalyst High pressure and temperature
61
What is the advantage of the Haber Bosch?
The industrial production of ammonia means that large amounts of fertilizer allowing farming to meet rapid population increase
62
What is the Rhizobia that is in a symbiotic relationship with soybeans?
Bradyrhizobium japonicum
63
What is the advantage of soybean production?
5-10x more protein then dairy cattle and more than 15x than meat production They dont need to add N fertilizer
64
What happens to an uninoculated legume plant?
Whiter less developed leaves Smaller leaves
65
What are AM fungi?
Arbuscular mycorrhizal fungi
66
How many plants have a symbiotic relationship with AM fungi?
80% of land plants
67
What do AM fungi provide plants?
Increases surface area so increased absorbtion of Phosphorus, Micro-nutrients and water
68
When did AM fungi, plant symbiotic relationship evolve?
Approxiamately 400 mya, land plants evolved 450 mya
69
When did the symbiotic relationship between Rhizobia and legumes?
65 mya
70
What groups are considered legumes and have evolved a relationship with Rhizobia?
Fabales, Fagales, Cucurbitales and Rosales
71
What is special Gunnera and Nostoc?
The only intracellular symbioses
72
What is the first step in the formation of plant nodulations?
Molecular dialogue between the host plant and microbial symbionts using diffusible signals
73
What is the structure flavonoids?
Polyaromatic secondary metabolites consisting of a 15-carbon skeleton
74
How are flavonoids produced?
Phenylpropanoids pathway
75
What are examples of flavonoids?
Flavonol, flavone, flavanone and isoflavone
76
What are nodulation factories?
Are chemical signals which signal to plants to start the formation of plant root nodules
77
What is scientific name of nodulation factors?
Lipochitooligosaccharides (LCOs)
78
What is the structure of the backbone of nod factors?
A chitin (saccaharide) backbone Usually 3 to 5 Beta-1,4linked N-acetylglucosamine residues
79
Where is the acyl chain located?
On the non-reducing terminus
80
What's important about the R groups?
They are decorations which are added to the backbone which vary between Rhizobium strains and species
81
What things that can be added to the R groups of nod factors?
Acetyl, methtl, sulfate and sugar moieties
82
What produces nod factors?
Nod factors are mediated by nod genes
83
What does gene D do?
Controls expression of other nod genes
84
What happens when flavonoids are perceived?
NodD binds to nod box found in promoters of nod genes
85
What does nod A,B,C do?
Codes for the Nod-facotor backbone
86
What does nod E and F code for?
They determine which acyl chain is added to Nod Factor backbone
87
What does nod H code for?
O-sulfation of Nod factor
88
What does nod L code for?
O-acetylation of Nod factor
89
What does node I J code for?
Nod factor export (ABC transporter)
90
What is the second stage of plant nodule formation?
Host plant signalling
91
What happens when nod factors bind to plants?
This activates Ca 2+ spiking machinery
92
What happens when Ca 2+ spiking machinery activates?
Ca 2+ spike pccurs
93
Where does calcium spiking occur?
Calcium spiking occurs in the nucleus
94
What is useful for scientists about calcium spiking?
One of the earliest measureable responses to Nod factor (within minutes)
95
What decodes for the calcium?
A unique calcium and calmodulin-dependant protein kinase (CCaMK)
96
What is the 3rd stage of plant nodulation formation?
Attachment and infection
97
What does Nod factors do to root hairs?
Nod factors induce root hair deformation in legumes
98
What do the Rhizobia do in response to deformed root hairs?
Rhizobia form a biofilm and attach to root hairs
99
What happens to plant lectin in acidic and basic conditions?
Acidic - localised on root hair tips Basic - Solubilized so an alternative method of attachment is used
100
What is released by the bacteria to attach to root hair in basic conditions?
The extracellular rhizobial protein rhicadhesin which attaches to the rhizobial cell surface and the root hair in a calcium-dependant manner
101
What is the biofilm made by bacteria made from?
Cellulose
102
What happens to the Rhizobia when the root hair curls?
The rhizobia are entrapped with in the root hair curl
103
What is the name of the micro-colony entrapped with in the root hair cell?
The micro-colony within is called the shepherd's crook
104
What happens to after the bacteria are trapped by root hair cell?
Hydrolysis of the plant cell wall and invagination of the plasma membrane leads to the formation of a tubular strucutre termed the infection thread
105
What happens to the root to form the infection thread?
Extensive cytoskeletal remodelling, inclusing reorganisation of actin filaments and microtubules
106
What is the final step of plant nodulation formation?
Symbiotic organ formation
107
What keeps the bacterial infection tightly coordinated?
The organogenesis of nodules Plant hormones
108
What does Ethylene, jasmonic acid, salicylic acid and ABA do?
Negetively regulate Nod factor-induced calcium spiking, early gene expression and infection thread initiation
109
What does cytokinin, ABA and auxin do in the cortex and pericycke cells?
Cytokinin, ABA and auxin balance dictate where lateral roots or nodules will be initiated
110
What is the final function of ABA?
Coordinating the epidermal and cortical programs as it plays roles during both stages
111
What are the key features of inderminate nodules?
Elongated in shape Tip-growing meristem Initiated from inner cortical cells Found in Medicago and Pisum
112
What are key features of determinate nodules?
Round in shape transient meristem Initiated from outer cortical cells Found in Lotus and Glycine
113
What are the 4 zones of the nodules?
1 - Meristem 2 - infection 3 - Nitrogen fixation 4 - senescence
114
What establishes a symbiosis?
Symbiosis signalling
115
What are bacteroids?
Bacteria which have differentiated form of rhizobia - bacteroids 'N2 fixing form'
116
What happens to the bacteria in the nodules?
They are released from infection threads as infection droplets and are engulfed by the cytoplasmic membrane to form peribacteroid
117
What is kept low in order to start nitrogen fixation?
O2 levels are kept low by lehaemoglobin
118
What can fix nitrogen?
Nitrogen fixation is exclusively a prokaryotic property
119
What fixes nitrogen in the bacteria?
Nitrogenase - a multi protein component enzyme
120
What codes for the nitrogenase enzyme?
nif genes
121
What is the equation for nitrogen fixing?
N2 + 16 ATP + 8 H+ + 8 e- = 2NH3 + 16ADP + 16 Pi + H2
122
What is the metal component used in the fixing of nitrogen?
FeMoCo
123
What is the speed of nitrogenase?
Nitrogenase is slow 12 electron pairs per second, only 3 molecues of N2 per second
124
How demanding is nitrogenase for energy?
Nitrogenase is very energy demanding 16 ATP per N2 fixed 20 grams of glucose per gram of NH3 synthesised
125
How sensitive is nitrogenase to oxygen?
Nitrogenase is very sensitive to oxygen Iron protein has a half life of 30 seconds in air
126
What are bacteroids fed?
Carbon in the form of dicarboxylic acids (malate) and amino acids
127
What is made by the plants to help nitrogenase?
homocitrate
128
What is the function of homocitrate?
A FeMoCo cofactor
129
What happens to the NH4+ produced by the bacteria?
It is assimilated by the plant via glutamine synthetase

Sem 1: Plant Biology (10 decks)

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