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Animal and Plant Biology I > Plants > Flashcards

Plants Flashcards

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1
Q

What is the problem with phytoliths?

A

The silicon makes plants less digestible and grinds down teeth

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2
Q

When are insectivorous plants found?

A

Where there is a lack of nitrogen

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3
Q

What factors determine plant distribution?

A

Water. Nutrients. Grazing. Seed spreading.

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4
Q

What is the main feature of moving from aquatic to land?

A

Coping with water loss

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5
Q

How do plants get what they need on land?

A
  • Water, limiting, soil
  • CO2, air, stomata
  • Light, high UV, leaves
  • Minerals, vary, soil
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6
Q

When did stomata and cuticles start to appear?

A

When mosses evolved

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7
Q

What are the features of the liverwort?

A
  • Primitive, undifferentiated leaves
  • Pores
  • Thick, waxy cuticles
  • No roots has rhizoids
  • Lives in damp gloomy conditions
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8
Q

What are the features of Oleander?

A
  • Thick cuticle
  • Multi layer epidermis
  • Gas exchange happens at the bottom
  • Stomatal pits on the underside
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9
Q

What do we see in higher plants?

A

Leaf layer specialization. Upper surface, = light harvesting impermeable to water. Lower surface = gas exchange.

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10
Q

What are guard cells?

A
  • Pair guards stomata
  • Symplastically isolated
  • Have chloroplasts
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11
Q

What are the stages of stomata opening?

A
  • Response to light
  • H+ ions out, K+ ions out
  • Starch is metabolized
  • Results in a fall of water potential
  • Water moves in
  • Guard cells swell and stomata open
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12
Q

What is Phytohormone and what does it do?

A
  • It’s an Abscisic Acid
  • Plant signalling molecule
  • Control of guard cell turgor by light can be overridden when water is scarce
  • ABA binds to receptor on plasma membrane
  • Triggers signalling cascade
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13
Q

What do stomata have to balance?

A

Rate of CO2 entering and water vapor exiting

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14
Q

What is water potential?

A

Measure of pressure - water declines = more negative

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15
Q

What happens when roots wilt?

A

ABA is triggered.

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16
Q

What does stomatal density depend on?

A

Concentration of CO2 eg low CO2 = more stomata

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17
Q

How can plants survive with less water?

A
  • Deep roots
  • Store water eg succulents
  • Lose less water eg spikes
  • Cope with very little amounts of water
  • Have dormant seeds
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18
Q

What do cells in the epidermis do?

A

Have no photosynthetic capacity - help refract light into the cells which do

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19
Q

What is meant by autotroph?

A

Synthesis everything they need

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20
Q

Where does the Calvin Cycle occur?

A

Chloroplast

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21
Q

What is RuBisCO?

A

Enzyme for carbohydrate synthesis

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22
Q

What happens when light hits PSII?

A
  • Energy from photons excite electrons
  • Move along the photosystem
  • Electrons are replaced by splitting water
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23
Q

How is ATP generated?

A

Protons released by splitting water accumulate in the lumen. Protons are moved through ATP synthase to make ATP.

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24
Q

How is NADPH produced?

A

Through the PSI complex

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25
Q

What is the role of the Calvin Cycle?

A

To recycle compounds and use the energy to make compounds

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26
Q

What are the stages of the Calvin Cycle?

A
  1. Carboxylation - addition of CO2 to RuBP
  2. Reduction - NADPH transfers 2 electron and 1 proton, phosphate is release
  3. Regeneration - multi-step, 3 carbon compounds are reorganized and combined to produce RuBP, takes 3 turns to regenerate
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27
Q

What does RuBisCO catalyse?

A

The oxygenation of RuBP

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28
Q

Describe the problem of photorespiration.

A

Oxygenation and carboxylation of RuBP are both catalysed by RuBisCO. Meaning plants can lose 50% of fixed carbon. CO2 levels must be high to maintain carboxylation rates over oxygenation.

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29
Q

What is C3 photosynthesis?

A

Where plants only use the Calvin Cycle to fix carbon from the air

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30
Q

What is C4 photosynthesis?

A

Prevents photorespiration by providing RuBisCO with saturating levels of CO2

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31
Q

Describe the process of C4 photosynthesis

A
  • Separates the CO2 uptake and the Calvin Cycle by space
  • Enzyme PEP carboxylase catalyses the addition of CO2 to a 3C compound to produce a 4C compound
  • Oxaloacetate is converted to a 4C compounds and shuttled into bundle sheath cells
  • Malate converted to a 3C pyruvate and Co2 in the bundle cells
  • 3C pyruvate diffuses back into mesophyll cells and is converted in POP
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32
Q

What do C4 plants use as their primary CO2 fixing enzyme?

A

PEPC

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33
Q

Why did C4 plants evolve from C3?

A

C3 plants were around when the concentration of CO2 was very high. C3 plants have been adversely impacted by lower CO2 concentration

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34
Q

Where is C4 photosynthesis found?

A

Hot, tropical and arid regions. Only 5% of plants are C4. Includes maise, sugarcane and tropical weeds. Used to drought.

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35
Q

Describe CAM photosynthesis?

A
  • Separated by time rather than space
  • Use PEP
  • Stomata open to take up CO2 at night
  • Carbon is fixed and stored in the vacuole
  • During the day stomata shut to conserve water
  • Material retrieved and transferred to chloroplasts
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36
Q

What are macronutrients?

A

Bulk. Need large quantities. Essentials.

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37
Q

What are some examples of macronutrients?

A

N (proteins, nucleic acids), K (osmoregulation), P (nucleic acids, ATP), Ca (membrane integrity), Mg (chlorophull, cofactor), S (amino acids)

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38
Q

What are micronutrients?

A

Small quantites

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39
Q

What are some examples of micronutrients?

A

Fe (redox systems), Mn (PSII), Zn (cofactor), B (cell walls)

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40
Q

How do the concentration gradients across the plasma membrane work?

A
  • pH and electrochemical gradient
  • Generated by proton-pumping ATPase
  • Can also create gradients by suffling things out the cytoplasm into the vacuole
  • Can’t rely on diffusion
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41
Q

What is the Symport Channel?

A

Mostly anions, high affinity for K+ because ion moves with H+

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42
Q

What is the Uniport Channel?

A

Cations like phosphate. Takes energy to make but they don’t need energy to move as its a membrane pore.

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43
Q

What is the Antiport Channel?

A

Secretes cations

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44
Q

What is the Apoplast pathway?

A

Between cells. Gradient drive. Cannot extend beyond Casparian strip

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45
Q

What is the Symplast pathway?

A

Within cells, controlled by transporters, controls entry to vascular tissues.

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46
Q

What are the main nutrients?

A

Phosphate and Nitrogen

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47
Q

What is the problem with getting phosphate?

A
  • Not very soluble in soil
  • Immobile
  • Low bio-availability
  • Forms complexes with cations in soil
  • Rock phosphate = finite source
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48
Q

Describe Liverwort getting phosphate?

A
  • Not true roots, rhizoids are mainly for anchorage
  • Very low surface area for P absorption
  • Zone of depletion quickly develops
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49
Q

How does Fungi-root symbioses work?

A
  • Mycorrhizas
  • Mutalistic symbiosis
  • Fungus penetrates the cell wall but not the cytoplasm
  • Fungi are obligate biotrophs
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50
Q

What is Arbuscular mycorrhizas structure?

A

Highly branched, maximizes SA for exchange of materials

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51
Q

Why is the relationship between fungi and mycorrhiza beneficial?

A
  • Fungus provides increased phosphorus uptake for the plant as well as other nutrients
  • Plants provide the fungus with a carbon source
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52
Q

What is the Hyphal network?

A
  • Fungus soil interface
  • External mycelium in soil
  • Massively extends roots system
  • Hyphae are fine
  • Connects plants trhough a common mycelial network
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53
Q

What do Myc factors do?

A
  • Trigger host responses via Ca2+ signalling

- Change in cytoplasmic CA concentration initiates cell processes

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54
Q

What is root hair development dependent on?

A

Nutrients

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55
Q

How does Rhizosphere increase phosphate capture?

A
  • Volume of soil influenced by the presence of the plant root
  • Some plants secrete organic acids inthe the rhizosphere
  • Citrate exchanged for phosphate
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56
Q

How do Cluster Roots increase phosphate capture?

A
  • Some plants produce cluster roots under low P conditions
  • Citrate released in a burst
  • Cluster roots secrete enzymes to release P from organic sources
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57
Q

How do Root Exudates increase phosphate availability?

A
  • In alkaline soils phosphate forms insoluble salts
  • Roots secrete organic acids, reduces local pH and release phosphate
  • Secrete mucilage habitat for bacteria that mineralise P
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58
Q

Why is Nitrogen sometimes hard to get?

A
  • Freely mobile but hard to get from
  • Acid bogs and sandy soils
  • There is heavy interplant competition
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59
Q

What is Ectomycorrhizal symbiosis?

A

Important in N capture, soils with complex organic N, occurs in fewer plant families (often forest trees). More recent.

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60
Q

What is nodulation?

A
  • In leguminous plants
  • Bacterial nitrogen fixation
  • Only prokaryotes carry out this reaction
  • Catalysed by nitrogenase complex
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61
Q

What is root nodule symbiosis?

A
  • Highly specialist association between rhizobia and leguminous plants
  • Rhizobia fix N2 making it available to plants
  • Plants provide rhizobia with carbon
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62
Q

What does Leghaemoglobin do?

A
  • Accumulates in the cytosol of rhibozium
  • Contains a haem group, is red
  • Regulates O2 to the bacteria
  • Too much inactives nitrogenase complex
  • Too little prevents O2 respiration
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63
Q

How is a nodule made?

A
  • Signal recognition
  • Contact with root hair leads to root hair deformation
  • Infection thread within the root hair cell develops
  • Bacteria enters
64
Q

What is insectivory?

A

Solution to low nitrogen. Evolved more than ones. Hairs and movement. Secretes digestive enzymes.

65
Q

What are some examples of plants that are insectivory?

A

Sundews. Venus fly trap. Bladderworts.

66
Q

What does plant parasitism achieve?

A

A solution to low N

67
Q

What was Darwins ‘abominable mystery’?

A
  • Angiosperms more successful than other plant groups

- Expanded dramatically in a short space of time

68
Q

What are the features of a buttercup?

A

Simple saucers. No pollinator guides for non-specialised pollinators. Many anthers, stigmas. Allow for multiple different pollination events

69
Q

What are the features of a Dandelion?

A

Unprotected pollen and plenty of nectar. Attracts lots of pollinators

70
Q

What is key to pollination?

A

Insects

71
Q

Why did insects aid flowering plant success?

A

Diversification of insects coincides with flowering plants. They coevolved? Floral designs recognisable. Problem: insects could have been increasing anyway

72
Q

Why did Angiosperm radiation lead to flowering plant success?

A

Early angiosperms limited to aquatic or very dry sites. Higher growth rates and increased nutrient supplies. Leaf litter easily decomposed. Nutrient feedback. Became dominant.

73
Q

Why did angiosperm diversification lead to flowering plant success?

A

Ancestral angiosperm was polypoid. Whole genome duplication predated angiosperm diversification. Provided a large number of genes.

74
Q

What are the floral colours on plants?

A

Combinations of pigment

75
Q

How many phenolic rings are there?

A

3

76
Q

What is the major class of flavonoids?

A

Anthocyanins

77
Q

What happens if you increase the number of hydroxyl groups?

A

Absorption to a longer wavelength

78
Q

What happens if you increase the number of methoxyl groups?

A

Absorption to a shorter wavelength

79
Q

What does the colour depend on?

A

Chemical sub groups attached to the B ring

80
Q

What can the petal shape determine?

A

The intensity of petal colour

81
Q

Explain the colour in a petal.

A
  • Cells in a petal contain the same amount of pigment
  • Darker patches = different shaped epidermal
  • Can be conical or have a mutation that results in flattened cells
82
Q

What do flower petals have to attract bees?

A

Blue halos

83
Q

What are blue halos on petals?

A

Repeated arrays of nanostructures. Scatters blue lights

84
Q

What are floral electric fields?

A

A charge that attracts bees

85
Q

Describe bee orchids.

A
  • Sexual attraction of bees to orchids
  • Co-evolution of bee and orchid chemistry
  • Have the right pheromones (14/15 of the sexual attractants)
86
Q

Why are seeds important?

A
  • Storable food supply
  • Can cause famines
  • Allow plants to survive mass extinction events
  • Plants can germinate more quickly
  • Seed vaults
87
Q

What is an examples of a Seed vault?

A

The Arctic ‘Doomsday Vault’ - has been to supply seeds to Syria. Important resource for the world

88
Q

What problem does pollination provide?

A

Conflict between certainty of fertilisation and outbreed - evolved new strategies to avoid inbreeding

89
Q

What are some examples of how plants pollinate?

A

Vector animals or wind/water

90
Q

Describe pollination strategy of exploitation of echolocation.

A
  • Cuban bat = messy eater
  • Drinks nectar from rainforest vine Marcgravia evenia and gets covered in pollen
  • Takes pollen to another plant for pollination
  • Dish shaped leaf halves foraging time for visitng bats
91
Q

Describe pollination strategy of multiple rewards?

A
  • Thermogenic flower (produces heat)
  • Attracts scarab beetles who are facultative endotherms
  • Would have to move to keep warms
  • Beetle gets heat
  • Beetle leaves to pollinate another flower and reproduce
92
Q

Describe pollination strategy of deceit by resource mimicry.

A
  • Dead horse arum volatiles are like a rotting carcass and flies respond the same way
  • Flies go in on the floor, get trapped and covered in pollen
  • They are released in the morning to pollinate another flower
93
Q

Describe pollination strategy of Wind Pollination: Trees

A
  • Flowers in catkins pollination early in year

- No attraction required

94
Q

Describe pollination strategy of Wind Pollination: Grasses

A
  • Hanging anthers

- Feathery stigmas

95
Q

Describe how plants avoid inbreeding by Dicogamy.

A
  • Anthers and stigma matures sequentially
  • Female stigma matures first (protogyny)
  • Stigmas open (cross pollination favoured)
  • First 5 anthers (cross and selfing possible)
  • Stigmas wither (next 5 anthers, mature can act as male parent to another flower)
96
Q

Describe how plants avoid inbreeding by Fail Safe Mechanisms.

A
  • Ensures pollination by selfing in protandrous flowers (male/pollen first)
  • Secondary pollen presentation: stigma lobes initially receptive to cross pollen then curl round and collect pollen
  • Male produces pollen, female ensures fertilisation
97
Q

Describe how plants avoid inbreeding by Dioecy and Monoecy.

A
  • Male and female flowers on separate male and female plants
  • In some plants dioecy is due to sex chromosomes
  • Monoecious, male and female plants on a single plant
98
Q

Describe how plants avoid inbreeding by Self Incompatibility

A
  • Inability of pollen to fertilise ovules of the same flower

- Self incompatible same SI alleles, no fertilisation

99
Q

Describe how plants avoid inbreeding by Sporophytic and Gametophytic Incompatibility

A
  • Sporophytic, SI alleles are produced by diploid sporophyte and deposited on the developing polen grains
  • Gametophytic, SI proteins produced by haploid pollen cells
100
Q

Why was the evolution of fertilisation and dispersal important?

A
  • Problems when plants moved to land
  • First evolved sperm which still used water
  • Pollen and seeds were much more effective
101
Q

What fertilisation does a Cycad use?

A

Uses sperm. They’re dioecious. Need raid to propel sperm from male cone to female cone.

102
Q

What is meant by Sporophyte?

A

Diploid state. Produces a flower

103
Q

What happens when a flowering plant goes through meiosis during reproduction?

A

Produces Megaspores and Microspores. Known as the haploid state. Gamete generation.

104
Q

What happens to the megaspores in flowering plant reproduction?

A

3 megaspores degenrate and one divides 3 times. Cell division.

105
Q

What is the alteration of generation?

A

Life cycle in plants that have distinct haploid and diploid stages.

106
Q

How does alteration of generation work?

A
  • Diploid goes through meiosis and grows in a hploid organism
  • Haploid produces gametes
  • Gametes fertilised
  • Grows into a diploid organism
107
Q

What is fertilisation like in ferns?

A
  • Gamete is hermaphrodite
  • More likely to generate a sporophyte
  • Cross fertilisation is not guaranteed
108
Q

What is fertilisation like in Gymnosperms?

A
  • Haploid state is suppressed and internalised
  • Heterospory, clear distinction between male and female parts
  • Megaspore is shed and is a free living sporophyte
  • Wind dispersal
  • Can avoid self fertilisation events
109
Q

Where is the Gametophyte in flowering plants?

A

Enclosed in the sporophyte

110
Q

What does the microspore produce in flowering plants?

A

Pollen grain

111
Q

What does the megaspore produce in flowering plants?

A

Embryo sac

112
Q

What does the double fertilisation in flowering plants produce?

A

Zygote. Endosperm

113
Q

Describe the gametophytic generation in flowering plants.

A
  • Male gametophyte grow through the sporophytic tissue
  • Ovule enclosed undergoes meiosis
  • Sometimes just the nucleus divides
  • Get a multicelled gametophyte
  • Polar nuclei cell that contains two haploid nuclei
  • 7 celled, 8 nucleate embryo sac
  • Female will be fertilised by the two male gametes travelling down the pollen tube
114
Q

Describe persistence as a strategy for reproduction.

A

Many plants can occupy the same habitat over time. Develop a suitable ecosystem

115
Q

Describe multiplication as a strategy for reproduction.

A

Many plants are good at increasing their number so they can conquer new territories

116
Q

Describe dispersal as a strategy for reproduction.

A

Many plants have evolved to colonise new territories by developing sophisticated dispersal mechanisms

117
Q

What are some examples of plants that use persistence?

A
  • Vegetative preoduction in grasses
  • Marram grass (sand dunes & salt marshes)
  • Trees
118
Q

What are some examples of plants that use multiplication?

A

Pando the trembling giant - single root system with genetically identical shoots or trees

119
Q

What are some examples of plants that use multiplication and dispersal?

A

Viola secual - produces a capsule that disperses seeds

120
Q

What are some examples of plants that use dispersal?

A

Mistletoes - parasatic plant - hooks into xylem and phloem. Marsupial eats the seeds and disperses them

121
Q

How many times have parasitic plants evolved?

A

12/13 times

122
Q

How does a Dodder plant use volatiles?

A

Reduced yield of crop plants and is good at selecting a host. Seeds germinate and vines find it. Detects by chemicals produce. Uses volatile cues for host location and to direct grwoth

123
Q

Describe the parasitic plant Rafflesia

A

Largest flower in the world. Lives inside the host plant and cannot see it until it flowers

124
Q

Describe the parasitic plant Mistletoe

A

Parasitism evolved 5 times and independently

125
Q

Describe the Potato Blight.

A

Causes famines. Millions died of starvation. Microorganism - oomycetes. Phytophthora infestans

126
Q

How are potatos infected from potato blight?

A

Forces stomata open. Releases chemicals which fools the plant. Provides a root to grow into the plant.

127
Q

What is innate immunity in plants?

A

The epidermis, thich walls and waxy cuticle

128
Q

How do pathogens avoid this defense system?

A

Enter through wounds. Through stomata - secrete chemicals that keep stomata open. Enzymes to soften and digest walls. Viruses (ssRNA) can move through plasmodesmata.

129
Q

What are biotrophic pathogens?

A

Obtain resources from living cells and weaken the plants

130
Q

What are necrotrophic pathogens?

A

Kills cells before colonising - kills the plant

131
Q

What does the cell wall mean when there is an infection in the plant?

A

Each plant cell is trapped so each individual cell has to fight then communicate to other cells

132
Q

What is an oomycete?

A

Causes the potato blight. Genome has been sequenced to find resistance

133
Q

What are virulent pathogens?

A

Overcome host defenses and lead to disease

134
Q

What are avirulent pathogens?

A

Damage only a small part of the plant because the host can contain the infection. More common

135
Q

What are the 2 parts of the plant immune system?

A

Basal resistance and specific resistance.

136
Q

Describe Basal Resistance

A
  • Pathogen attacks
  • Molecules produced by pathogens are recognized by the plant
  • Become ligands
  • Triggers defense response
  • Binds, conformational change
137
Q

What is Pattern Triggered Immunity?

A

Type of basal immunity. Recognition of conserved microorganism associated molecular patterns by specific transmembrane receptors. Protect host against non-specialised pathogens

138
Q

What are Microbe Associated Molecular Patterns (MAMPs)?

A

Molecule signature typical of whole classes of microbes. Recognition of microbes in innate immunity.

139
Q

What are Damage Associated Molecular Patterns (DAMPs)?

A

Recognize damaged fragments of the cell wall that are breaking off. Elicits a response

140
Q

What are Pattern Recognition Receptors (PRRs)?

A

Pathogens could cause a change in the shape of receptor which is the recognized

141
Q

What is Flg22?

A

Flagellin is a protein present in the flagella of bacteria, recognizes highly conserved molecules from a broad class of pathogens

142
Q

What is specific resistance?

A

Responds to specific pathogens

143
Q

How is specific resistance different from basal resistance?

A

Specific resistance consists of receptors located inside the cell as opposed to on the cell membrane

144
Q

What are the receptors used in specific resistance?

A

R proteins - each black a specific AVR protein

145
Q

What are the stages of specific resistance?

A
  1. Pathogens secrete AVR proteins - enter the cell
  2. R proteins recognise a specific AVR
  3. R protein will bind with an AVR protein and prevents it from blocking plants basal resistance
  4. Directly activates defensive genes
146
Q

Describe the gene-for-gene model of plant immunity.

A
  • Depends on interactions between specific plant and pathogen genes
  • Resistance varieties and sensitive varieties offlax
  • Can look at old genes, single gene is responsible
147
Q

Describe how a Pseudomonas Syringe works.

A
  • Produces AVR protein
  • Plant has evolved produces a protein which sense the interaction of the AVR
  • Gene for gene resistance
  • Triggers another defence
  • Known as the guard hypothesis, no contact between Prf and AVR, mutations have much less effect
148
Q

What are Pseudomonas?

A

Protein that raises the freezing point of water so it kills the plant as water freezes

149
Q

What do Pseudomonas produce?

A

Syringomycin - destabilises the cell membrane

150
Q

What is a hypersensitive response?

A
  • Pathogen detected
  • Sacrifices infected cells and the ones surrounding
  • Uninfected cells raplidly produce reactive oxygen species and die
  • Produces a plug to stop it spreading
  • Forms a barrier of dead tissue
151
Q

Describe the immunity experiment by Frank Ross

A

Infected a tobacco plant with tobacco mosaic virus. Infected one leaf, after 7 days infected a second leaf. Second leaf showed no signs of infection

152
Q

How many plant pathogen viruses are there?

A

450

153
Q

Describe targeted response.

A
  1. Virus infects plant cell (inject ssRNA genome)
  2. During replication dsRNA are formed
  3. Plants recognize dsRNA as foreign
  4. Enzymes cleave the dsRNA into fragments of 21 nucleotides - interfering RNA
  5. Fragments enable the plant to target and destroy ssRNA molecules
  6. Plant acquires immunity
154
Q

What are the majority of plant viruses?

A

ssRNA

155
Q

Describe Rhizobium radiobacter

A

Bacteria enters through wound. Develops tumour. Cons the plant into producing useful compounds - bacter can metabolise. Bacterial Ti plasmid inserted in the plants genome.

Animal and Plant Biology I (3 decks)

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