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BIOL 266 - PLANT PHYSIOLOGY > Final > Flashcards

Final Flashcards

1
Q

What produces Gibberellins

A

all plants; most fungi do not

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2
Q

Majority of Gibberellic acids are either:

A

intermediated in the biosynthetic pathway

breakdown/inactivation products

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3
Q

Which four GAs are considered physiologically active?

A

GA1, GA3, GA4, and GA7

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4
Q

Where is GA produced?

A

produced in younger tissues and exported via phloem

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5
Q

Gibberellins are well-known for …

A

promoting plant stem elongation

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6
Q

How do GAs function?

A

By regulating gene transcription

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7
Q

What is the role of DELLA in reference to GAs?

A

DELLA proteins act as growth repressors by inhibiting GA signaling in response to developmental and environmental cues.

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8
Q

GID1 is what

A

Gibberellin receptor; found in the nucleus and cytosol

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9
Q

Why was the semi-dwarf trait less susceptible to lodging?

A

The stems were shorter and stronger

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10
Q

In wheat and maize, the semi-dwarf trait was due to …

A

a mutation in DELLA

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11
Q

True or False: GAs are involved in flowering

A

True

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12
Q

the starch in endosperm is broken down by

A

Amylases (hydrolytic enzymes)

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13
Q

The two main methods for plant tissue culture is:

A

callus culture = small chunks of non-differentiated plant tissue on agar

suspension culture = smaller chucks in a liquid medium

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14
Q

True or false: a good source of cytokinins was coconut milk

A

true

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15
Q

Kinetin is a plant hormone; true or false

A

false; Kinetin is a plant growth regulator

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16
Q

Kinetin is a product of

A

oxidative damage of adenine

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17
Q

Cytokinins is synthesized where?

A

The roots and sites of cell division (eg. the vascular cambium)

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18
Q

Cytokinins have a role in … (2)

A

regulating cell division, and regulating apical dominance

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19
Q

Plant Gall disease is due to…

A

due to bacterial production of cytokinins and auxins

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20
Q

3 steps of genetic modification/transformation using the Ti plasmid

A
  1. Insertion of gene into plasmid using restriction enzyme and DNA ligase
  2. Introduction into plant cells in culture
  3. Regeneration of plant
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21
Q

Cytokinins affect senescence how?

A

It delays it, senescence is the aging process

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22
Q

The CK receptor is found where?

A

In the ER (endoplasmic reticulum)

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23
Q

The CK receptor does what?

A

Signals transduction pathway

Regulation of transcription

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24
Q

Ethylene is primarly associated with:

A

stress responses
senescence
fruit ripening

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25
Q

True or false: Senescence and ripening have nothing in common

A

false

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26
Q

The ethylene-induced “triple response” in plant seedlings is:

A

1) decrease stem elongation
2) increased stem radial growth
3) prevention of opening of the “hook” at the top of the seedling

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27
Q

What is the best-known ethylene effect

A

stimulation of ripening in climacteric fruits (i.e apples, bananas, avocados, tomatoes)

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28
Q

Stages of fruit development

A

Cell division, cell expansion, maturation, ripening, senescence

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29
Q

Non-climacteric fruits require ethylene to ripen. True or false?

A

False

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30
Q

Sequence of events in climacteric fruits

A
  1. ethylene production
  2. an increase in respiration rate
  3. increased ACC synthase activity
  4. increased ethylene production and synthesis of degrative enzymes
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31
Q

The softening of the cell wall in fruit ripening is due to:

A

an increased activity of several enzymes; like pectinase

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32
Q

Soil with air spaces are better than water-saturated soil. True or false

A

True.

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33
Q

The results of increased radial growth due to ethylene is:

A

stem thickening

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34
Q

The hook of a stem acts as

A

protection for the apex of the shoot

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35
Q

In most plants ethylene inhibits flowering. True or false

A

true

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36
Q

Pollination increases ACC synthesis; what is the affect of this

A

Leads to earlier senescence

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37
Q

Flavr Savr tomato used what gene is used to keep it firmer longer

A

Antisense polygalacturonase gene

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38
Q

Why do Tomatoes on the vine last longer than ones off the vine?

A

it reduces ethylene leakage

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39
Q

Abscisic Acid is known as the…

A

stress hormone

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40
Q

Abscission is …

A

the shedding of plant parts after formation of an abscission zone

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41
Q

What are the roles of abscisic acid?

A

Stomatal closure

Hardening

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42
Q

All photosynthetic eukaryotic organisms use which type of photosynthesis

A

light-dependent oxygenic CO2 fixation

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43
Q

Light-dependent means…

A

light is required for this part of the process

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44
Q

Oxygenic means …

A

that O2 is produced

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45
Q

CO2 fixation means …

A

that CO2 (inorganic C) is converted to organic C

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46
Q

What is the source of electrons for photosynthesis?

A

Water

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47
Q

O2 plays an important role in photosynthesis; true or false

A

false, it is simply a biproduct of the reaction.

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48
Q

What are the end-products of photosynthesis?

A

Starch and sucrose

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49
Q

How many electrons are needed in order to reduce one inorganic carbon to an organic carbon

A

4 electrons or 2 water molecules

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50
Q

The light reactions of photosynthesis are _____ - insensitive

A

relatively temperature

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51
Q

The enzymatic reactions of photosynthesis are temperature _______

A

sensitive

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52
Q

Photosynthesis is divided into two reactions known as:

A

The light reactions and the enzymatic reactions

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53
Q

The light reactions occur where?

A

Chloroplast, and thylakoid membranes

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54
Q

The enzymatic reactions occur where?

A

Chloroplast and stroma

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55
Q

Stacks of thylakoids are called …

A

grana (granum)

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56
Q

All of the pigments are in the chloroplast, True or false

A

false, they are locating in the thylakoids

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57
Q

The energy source for photosynthesis is …

A

light

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58
Q

The two major types of pigments are:

A

Chlorophylls (which are green)

Carotenoids (which are red-orange-yellow)

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59
Q

_____ have no OH groups

A

Carotenes

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60
Q

________ have OH groups

A

xanthophylls

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61
Q

The most important function of carotenoids is …

A

photoprotection (they detoxify toxic molecules)

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62
Q

Particles of light are measured in

A

photons or quanta

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63
Q

Most common definition of Photosynthetically Active Radiation (PAR)

A

400nm to 700nm

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64
Q

Units for PAR

A

umol quanta m^-2 s^-1

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65
Q

Photosynthetic pigments have characteristic absorbance spectra, which means?

A

The ability to absorb various wavelengths of light

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66
Q

Action Spectra is

A

the wavelength that can be used for a particular process

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67
Q

Absorption of a photon leads to the movement of an electron to higher energy orbital. True or false

A

true

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68
Q

What are the two photons that result in the lowest excited states?

A

red and blue

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69
Q

Antenna complexes are

A

groups of pigments that are associated with a reaction centre Chl

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70
Q

Antenna complexes funnel ____/____/____ towards the reaction centre

A

energy; excitation; exciton

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71
Q

the light reactions are the parts of photosynthesis that are directly light-dependent. These include:

A
  1. Absorption of photons by photosynthetic pigments
  2. transfer of energy of the photons to the reaction centre chlorophylls
  3. photosynthetic electron transport chain (which creates a delta [H+] across the thylakoid and also produces NADPH)
  4. utilization of the delta [H+] by ATP synthase to regenerate ATP
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72
Q

The process of light reaction photosynthesis is happening where?

A

in the thylakoids and across the thylakoids

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73
Q

The products of the light reactions are

A

NADPH and ATP

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74
Q

The enzymatic reactions include these cycles:

A

Calvin cycle (in the stroma), Starch synthesis (stroma) and sucrose synthesis (cytosol)

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75
Q

Which part of photosynthesis is not located in the chloroplast?

A

Sucrose synthesis

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76
Q

the products of the enzymatic reactions include:

A

starch and sucrose

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77
Q

In the light reactions, the pigment trap light energy. This trapped energy is used for two purposes:

A
  1. generate a [H+] gradient across the thylakoid membrane
  2. regenerate NADPH for use in the enzymatic reactions
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78
Q

A photosystem consists of …

A

a reaction centre complex and light-harvesting complexes

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79
Q

The light-harvesting complexes have no electron carriers in it. true or false

A

true

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80
Q

reaction centre chlorophylls have three possible states, and cycle through them; these states are …

A

ground state ; excited state ; oxidized state (= loss of an e-)

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81
Q

OEC means

A

oxygen-evolving complex

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82
Q

The OEC catalyzes the _________-________ ______

A

water-splitting reaction

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83
Q

In PSII, how many photons are needed to produce one oxygen

A

4

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84
Q

There are two sources of PQH2 in the photosynthetic electron transport chain. These come from?

A

PSII
Cytochrome complex

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85
Q

For every PQH2 that leaves the PSII, how many and what is moved from the stroma to the lumen

A

4 H+

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86
Q

There is a plastocyanin (PC) pool in the lumen. True or false

A

true

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87
Q

8 photons, (4 in PSII and 4 in PSI) are sufficient to meet which requirements?

a) ATP
b) NADPH
c) FNR
d) H+

A

b) NADPH

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88
Q

Delta [H+] has two sources in photosynthesis, these come from where?

A

OEC
Cyt complex/Q cycle

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89
Q

How many ATPs are required to fix each CO2 in photosynthesis?

A

3 ATP

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90
Q

8 Photons is sufficient enough to meet the requirements of both NADPH and ATP for fixing 1 CO2 molecule. True or False

A

False, 8 photons is enough for NADPH to fix 1 CO2 molecule, but does not meet the requirements for ATP

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91
Q

LEF

A

Linear electron flow

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92
Q

The LEF is …

A

Water -> PSII -> PSI -> NADPH

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93
Q

CEF

A

Cyclic electron flow

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94
Q

The CEF is …

A

PSI -> PQ pool -> cyt complex -> PC -> PSI

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95
Q

What is the best solution to creating more ATP without creating NADPH?

a) LEF
b) PQ
c) CEF
d) Cyt complex

A

c) CEF

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96
Q

Why is C3 photosynthesis called C3?

A

Because the first stable products of photosynthesis are 3 C molecules

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97
Q

C3 species represent what percentage of terrestrial plant species?

A

85-90%

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98
Q

The phosphate translocator is also known as …

A

the triose phosphate translocator (TPT)

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99
Q

Plant priorities for the Calvin cycle are (3 steps)

A
  1. build up the levels of the calvin cycle intermediated especially RuBP
  2. Start drawing off TP from the calvin cycle, for sucrose synthesis and export
  3. Starch synthesis - lowest priority, starch is temporary energy
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100
Q

The Calvin cycle uses the products of which reaction to assimilate inorganic C into organic C?

A

Light reactions

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101
Q

The phosphate translocator links _____ _______ ______ with ____ ______ _________

A

Stromal photosynthetic metabolism ; cytosolic sucrose synthesis

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102
Q

At what time of day is the chloroplast starch broken down and converted into sucrose?

A

At night

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103
Q

What is the Warburg Effect?

A

the O2 inhibition of photosynthesis; the higher the [O2], the lower the rate of net photosynthesis

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104
Q

The gross photosynthetic rate is …

A

the rate of O2 production by the OEC or the rate of CO2 uptake/fixation by Rubisco

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105
Q

Net O2 evolution is

A

gross O2 evolution (from OEC) minus processes that consume O2

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106
Q

Net CO2 fixation is

A

gross CO2 uptake (rubisco) minus processes that release CO2

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107
Q

CO2 and O2 compete for the active site on ____?

a) PSI
b) Calvin Cycle
c) CEF
d) Rubisco

A

d) rubisco

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108
Q

When rubisco and O2 bind, what type of reaction occurs?

A

Oxygenase

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109
Q

When Rubisco and CO2 bind, what type of reaction occurs?

A

Carboxylase

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110
Q

Aerobic cellular respiration consumes O2 via which chain?

A

respiratory electron transport chain

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111
Q

IRGA

A

Infra-red gas analyzers

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112
Q

What are IRGAs able to do?

A

Quantify [CO2] in air

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113
Q

CO2 can absorb certain IR wavelengths. True or False

A

True

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114
Q

Net Photosynthesis is how much C a plant gains in photosynthesis. What is the equation associated with this?

A

Net photosynthesis = gross photosynthesis - respiration - photorespiration

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115
Q

Photorespiration is respiration :) true or false

A

FALSE

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116
Q

Photorespiration is considered to be energetically wasteful because:

A
  1. generates inorganic carbon (CO2) from organic carbon (i.e. it undoes photosynthesis)
  2. generates inorganic nitrogen (NH4+) from organic nitrogen, and the NH4+ must be re-assimilated into organic form in an energy-requiring process
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117
Q

How old is rubisco

A

about 3 billion years old

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118
Q

C4 plant species make up what percentage of terrestrial plants?

A

3-5%

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119
Q

CAM

A

Crassulacean Acid Metabolism

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120
Q

CAM take up what percentage of terrestrial species

A

5-10%

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121
Q

Both C4 and CAM posses the Calvin Cycle. True or false

A

true

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122
Q

Kranz means

A

wreath

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123
Q

Which type of species uses Kranz anatomy

A

C4

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124
Q

Describe Kranz anatomy

A

A vascular bundle (xylem and phloem) center, surrounded by bundle sheath cells (rubisco) which is subsequentially surrounded by mesophyll cells (PEPcase)

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125
Q

The calvin cycle only occurs in which cells of C4 plants

a) Mesophyll cells
b) Bundle sheath cells
c) Temporal cells
d) Malate cells

A

b) bundle sheath cells

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126
Q

In C4 photosynthesis, the reaction catalyzed by pyruvate, phosphate dikinase (PPDK) consumes the equivalent of how many ATP molecules?

A

two

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127
Q

Mesophyll cells utilize the Calvin Cycle, True or False

A

false, but they do use other components of photosynthesis

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128
Q

Water Use Efficiency has what equation

A

WUE = (carbon gained in photosynthesis) / (water lost in transpiration)

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129
Q

WUE is also known as the “photosynthesis-transpiration compromise”; what are the two ways to look at this?

A
  1. For a given net photosynthesis rate, C4 species have a lower g(s)
  2. For a given g(s), C4 species have a higher net photosynthesis rate
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130
Q

C4 species tend to be found mostly where?

A

warm semi-arid regions

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131
Q

C4 have a higher WUE than C3 species. True or False

A

True

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132
Q

What type of leaves/stems do most CAM species have?

A

Succulent

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133
Q

What happens to stomates in CAM species?

A

The are open at night and closed during the day

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134
Q

Stage 1 of CAM photosynthesis includes:

A

malate accumulates in the vacuole at night
stomates are open at night
CO2 diffuses into the mesophyll cells of the leaves
PEP is produced from starch breakdown and glycolysis

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135
Q

Stage 2 of CAM photosynthesis includes:

A

during the day time; malate levels decline
stomates are closed to save water
Malic enzyme decarboxylates malate to produce CO2

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136
Q

CAM is considered to be the most expensive mode of terrestrial photosynthesis; why (3)?

A
  1. costs of regenerating PEP from pyruvate (PPDK)
  2. starch re-synthesis costs from PEP (PEP ->->-> starch)
  3. ATP costs associated with malate transport across the tonoplast
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137
Q

Nitrogen is the second most important nutrient for plant growth. True or false

A

False, it the the most important

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138
Q

The two best known and most studied forms of N taken up by plant roots from the soil solution are:

A

NO3- (nitrate) and NH4+ (ammonium)

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139
Q

Urea is a form of organic N; where does urea come from?

A

Urine

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140
Q

What is the #1 form of inorganic N in aerobic soils?

A

NO3-

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141
Q

Denitrification is

A

Microbial reduction of NO3- to various gaseous N forms;

done by various anaerobic bacteria;

use NO3- as a final electron acceptor for respiration

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142
Q

Characteristics of NH4+

A

a cation; part of the cation exchange capacity of the soil; tends to be retained in the soil

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143
Q

Characteristics of NO3-

A

found mostly in the soil solution; more easily leached from soil

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144
Q

The natural input of N to a system is via the …

A

biological N2 fixation

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145
Q

Biological N2 fixation represents an ____ (input or output) of N to a system

A

input

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146
Q

The enzyme nitrogenase is exclusively a _______ enzyme

a) eukaryotic
b) prokaryotic
c) nitrogenase
d) ammonia

A

b) prokaryotic

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147
Q

Nitrogenase is a very O2-labile enzyme, thus it requires a _________________ environment in order to function

A

Anaerobic or microaerobic

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148
Q

The symbiotic bacteria in legumes is known as

A

rhizobia

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149
Q

The symbiosis occurs in vesicles in “infected” cells are known as

A

symbiosomes

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150
Q

The membrane of the symbiosome is sometimes called the …

A

peribacteroid membrane

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151
Q

Biological Nitrogen Fixation in Legume Nodules can be summarized as …

A

sucrose in, amino acids out

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152
Q

Leghemoglobin is

A

a pink-coloured O2-binding molecule found in the central portion of legume nodules

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153
Q

What is the function of leghemoglobin?

A

to regulate [O2] in the central portion of the nodule (where the bacteroids are located)

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154
Q

Leghemoglobin maintains in what type of environment?

A

Microaerobic

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155
Q

The outer layer of the leghemoglobin functions as

A

an O2 diffusion barrier

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156
Q

N sufficiency leads to

A

decreased nitrogenase activity

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157
Q

N2 fixation is response to N deficiency. True or false

A

True

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158
Q

Cyanobacteria

A

blue-green algae

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159
Q

Nitrogen in plant cells are located in:

A

proteins/amino acids
RNA
DNA
chlorophyll
ATP
etc

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160
Q

Both nitrate and ammonium transport systems exhibit

A

substrate-induction

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161
Q

Nitrate is _____ charged and must cross the plasma membrane to the ______ -charged area

A

negatively x2

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162
Q

Most ammonium transporters are…

A

uniports

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163
Q

Ammonium is directly assimilated into…

A

amino acids

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164
Q

Nitrate is not toxic at high concentrations; therefore plant cells may contain …

A

high levels of nitrate (typically stored in vacuoles)

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165
Q

The enzymes for nitrate reduction to ammonium are found in …

A

both roots and shoots

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166
Q

Different species do most of their nitrate ______ in either roots or shoots

A

assimilation

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167
Q

Nitrate that is taken up by roots may be: (3)

A
  1. assimilated into organic nitrogen in the root, which is then redistributed via phloem
  2. stored in root vacuoles
  3. sent to the shoot via xylem after which it may be stored in leaf vacuoles or assimilated into organic nitrogen via NH4+
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168
Q

Nitrate must be reduced into ____ in order for subsequent assimilation into ____

A

NH4+ ; organic N

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169
Q

Simple version of Nitrate reductase

A

(NO3-) + (2e-) -> (NO2-)

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170
Q

What energy does the GS-GOGAT Pathway require?

A

ATP and NADPH

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171
Q

The product of the GS-GOGAT pathway is

A

the amino acid glutamate

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172
Q

Ammonium represses nitrate assimilation by repressing the …

A

transcription of nitrate reductase

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173
Q

What order (from cheapest to most expensive) are the forms of inorganic N sources? (N2, NH4+ and NO3-)

A

NH4+
NO3-
N2

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174
Q

When a plant cell is pressurized, it exhibits what

A

turgor

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175
Q

Main Components of primary plant cell wall are: (4)

A

cellulose microfibrils
hemicelluloses
pectin
a small amount of proteins

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176
Q

Cellulose chains are responsible for what

A

strength and rigidity of the cell wall

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177
Q

Cellulose microfibrils have two different orientations:

A

Criss-cross pattern and Parallel

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178
Q

Hemicelluloses function to

A

cross-link adjacent microfibrils

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179
Q

The idea of cross-linking affects what part of the cell

A

cell wall rigidity

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180
Q

Pectin acts as

A

the glue between adjacent plant cells

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181
Q

Lignin adds…

A

strength to cell walls; only found in cells with primary and secondary walls

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182
Q

True or False; Wood has a high lignin content

A

True

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183
Q

Light-dependent oxygenic CO2 was invented by (thing ; not person)

A

Cyanobacteria

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184
Q

Cyanobacteria are gram-________

A

negative

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185
Q

Name the membrane enclosed organelles

A

nucleus, chloroplasts, mitochondria, vacuoles, endoplasmic reticulum, Golgi apparatus, peroxisomes

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186
Q

Types of permeable membranes

A

Semi, selectively, and differentially

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187
Q

Phospholipid bilayers have a

A

hydrophobic core and hydrophilic surfaces

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188
Q

Carrier Proteins

A

are transport proteins with substrate-specific binding sites

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189
Q

Channel proteins

A

are transport proteins that allow specific molecules to pass

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190
Q

Aquaporins

A

are membrane-spanning proteins that act as moderately selective water channels

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191
Q

DNA of plants cells can be found where?

A

Nucleus, plastids, and mitochondria

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192
Q

Main purpose of Ribosomes

A

produce proteins (via translation)

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193
Q

Chloroplasts are the site of what

A

photosynthesis

194
Q

Chloroplasts are descended from

A

Symbiotic cyanobacteria

195
Q

Chromoplasts are descended from

A

chloroplasts

196
Q

The vacuole plays a role in what

A

water relations, as a storage area for ions, and the location of anthocyanins

197
Q

The membrane that surrounds the vacuole is called the

A

tonoplast

198
Q

The interior of the vacuole is not acidic. True or false

A

False; it is slightly acidic

199
Q

Plasmodesmata are

A

cytosolic connections to adjacent plant cells

200
Q

Diffusion of molecules through the plasmodesmata is regulated by

A

desmosomes

201
Q

Mitochondria are the site of

A

aerobic cellular respiration; which functions to regenerate ATP

202
Q

Golgi Apparatus is involved in

A

protein modification and protein sorting

203
Q

The endoplasmic reticulum is

A

a membrane network that runs through the cytosol

204
Q

Rough ER has what, and is involved in what

A

Ribosomes; and is involved in protein synthesis

205
Q

Smooth ER has roles in

A

cellular metabolism

206
Q

Peroxisomes are involved in

A

photorespiration

207
Q

Glyoxysomes are involved in

A

fat breakdown

208
Q

Protein bodies are

A

protein storage organelles

209
Q

Cytosol is

A

the water-based gel-like fluid in which the organelles are found; this is an active site of metabolism

210
Q

Cytoplasm includes

A

the cytosol and the cytosolic ribosomes and the cytoskeleton

211
Q

protoplasm is

A

everything inside the plasma membrane

212
Q

Transpiration

A

loss of water vapour from plants

213
Q

Evaporation + Transpiration =

A

Evapotranspiration

214
Q

of the water that is transpired, the bulk is via ___________ on the leaves

A

stomates

215
Q

What percentage of light energy impinged upon plants is used for photosynthesis?

A

less than 1%

216
Q

In plants, water has 3 physiological importances

A

Medium for biochemical reactions; maintenance of turgor; and temperature regulation

217
Q

Two mechanisms for the movement of water:

A

Bulk flow, and diffusion

218
Q

Bulk flow:

A

mass movement of water in response to a pressure differential (from high to low; ie down a pressure gradient)

219
Q

Water movement: Diffusion means

A

net movement due to random kinetic activities or thermal motions

220
Q

Diffusion of Solutes can occur in response to

A

gradients of solute concentraion

221
Q

Net diffusion of solutes occurs from….

A

area of higher concentration to areas of lower concentration

222
Q

The larger the concentration gradient, the greater the rate of diffusion; true or false.

A

True

223
Q

What happens at equilibrium for diffusion of solutes

A

no net movement; but still gross movement

224
Q

The higher the concentration of a substance…..

A

the greater its chemical potential

225
Q

Osmosis

A

the diffusion of a solvent such as water across a semi-permeable membrane separating two solutions of different concentrations

226
Q

Water Potential (greek letter psi)

A

the chemical potential of water in a system, compared with the chemical potential of pure water at atm

227
Q

dissolving a solute in water _______ the chemical potential (Ψ) of the water

A

decreases

228
Q

What is the maximum water potential

A

0MPa

229
Q

Water with any dissolved solute will have a Ψ _ 0MPa (<, >, =)

A

<

230
Q

What happens to Ψ the greater the [solute]

A

the lower it becomes (ie more negative)

231
Q

[Solute] outside > [solute]inside

A

hypertonic solution

232
Q

[solute]outside = [solute]inside

A

isotonic solution (usual state)

233
Q

[solute]outside < [solute]inside

A

hypotonic solution

234
Q

ΨS is

A

Solute potential; the effect of solutes on water potential; always negative

235
Q

Raoult’s Law

A

the vapour pressure over perfect solutions is proportional to the mole fraction of the solvent

236
Q

ΨP

A

pressure potential; is not affected by [solute]

237
Q

In general, Ψp= AP - 0.1013MPa; true or false

A

true

238
Q

Ψ equation

A

Ψs+Ψp

239
Q

water relations of the idealized cell has (2)

A
  1. extremely rigid cell wall
  2. a PM that is perfectly selectively permeable
240
Q

water relations of a less idealized cell has (2)

A
  1. cell wall that has some extensibility
  2. a PM that is perfectly selectively permeable
241
Q

As water flows into a cell following a Ψs gradient, 3 things happen

A
  1. water movement into the cells causes an increase in CellΨp
  2. The cell wall stretches in response to the increased turgor
  3. the water dilutes the solute, increasing Ψs
242
Q

What happens if CellΨs < Ψs outside the cell?

A

Plasmolysis happens; the PM pulls away from the cell wall and the protoplasm shrinks

243
Q

How do cells take up water?

A

for net water uptake Ψroot < Ψsoil

244
Q

In order to maintain ΔΨ in the correct direction, plants can increase their internal [solute]; this process is called

A

osmotic adjustment or osmoregulation

245
Q

Compatible solutes are _______ ________ for a plant to produce

A

energetically expensive

246
Q

three hypotheses for moving water upwards

A
  1. suction
  2. root pressure
  3. Capillarity
247
Q

Current model of moving water upwards

A

Cohesion-Tension Theory; liquid water is pulled up a plant, in a continuous stream, via evaporation from cell walls within the leaf

248
Q

Three main elements of the Cohesion-Tension Theory

A
  1. ΔΨ between the soil and atm is the driving force
  2. adhesion/hydration
  3. cohesion
249
Q

Driving force for water movement through a plant?

A

SPAC soil-plant-atmosphere-continuum; water uptake and transpiration are parts of one continuous stream or process

250
Q

Vascular plants have vascular tissue; which are…

A

the xylem and the phloem

251
Q

When water and dissolved inorganic ions move, they move through what?

A

the xylem

252
Q

“Wood” of a tree or shrub is comprised of

A

xylem

253
Q

The older xylem is called

A

heartwood

254
Q

The younger xylem is called

A

sapwood

255
Q

Sapwood is responsible for

A

the bulk of water

256
Q

Xylem of woody eudicots consists of four types of cells:

A
  1. tracheids
  2. vessel elements
  3. xylem fibres
  4. radial (rays) and axial parenchyma cells
257
Q

In woody plants, new xylem is produced every year by the…

A

vascular cambium (a secondary meristem)

258
Q

the cork cambium produces…

A

the bark

259
Q

Phloem accumulates in woody plants; true or false

A

false; the xylem accumulates

260
Q

Xylem fibres play a structure role in the…

A

stem

261
Q

Tracheids are…

A

the water conducting cells

262
Q

How does water move in conifers?

A

Via the tracheids; they do not have vessel elements or xylem fibres

263
Q

At maturity, are each of the following dead or alive:
Trachieds
Vessel elements
Fibres

A

dead
dead
both

264
Q

Vessel elements have this that links adjacent vessel elements

A

perforation plates ( looks like a fork thingy)

265
Q

Living, undifferentiated cells are known as

A

parenchyma

266
Q

Rays (in water) are composed of

A

parenchyma

267
Q

Vascular rays are probably involved in what

A

the refilling of xylem elements

268
Q

The vascular bundles make up the ______ in a leaf

A

veins

269
Q

What is the primary site of water uptake?

A

Roots

270
Q

Root hairs are…

A

extensions of epidermal cells

271
Q

Fine roots have what ratio

A

high surface area : volume ratio

272
Q

Root apical meristem (RAM) is

A

a zone of cell division

273
Q

Root growth is due to:

A

cell division followed by cell elongation

274
Q

Apoplast

A

the non-living part of the root; includes air spaces, cell walls and xylem

275
Q

Symplast

A

the living part of the root; including everything inside the PM

276
Q

The Casparian strip is

A

an extracellular water barrier

277
Q

Apoplastic water movement is along

A

the hydrated cell walls

278
Q

Symplastic water movement

A

is cell-to-cell, via plasmodesmata

279
Q

All water molecules must cross a PM twice, why?

A
  1. to get into the symplast
  2. to leave the symplast at the xylem
280
Q

What is the purpose of the endodermis?

A

it is a mechanism for the plant to control water movement to the xylem

281
Q

Is the Ψs high or low in the xylem

A

very high (=not very negative)

282
Q

Why are smaller diameter vessels less prone to cavitation?

A

cavitation seems to begin at surfaces; ie smaller tubes have a better surface/volume ratio

283
Q

In water movement, why does it help if stomates are open?

A

It provides a diffusion pathway

284
Q

The xylem is a part of the apoplast, but gets its water from the symplast; true or false

A

true

285
Q

Summary of the Tension-Cohesion Model

A
  1. Water has high cohesive forces
  2. water in plants forms a continuous system through water-saturated cell walls
  3. reduction in water potential at the evaporating surfaces is transmitted to the roots, causing inflow of water from soil
286
Q

Bordered pits act as _____ _____ that prevent air bubbles from spreading

A

safety valves

287
Q

Guard cells occur in, and do what

A

pairs; and regulate the size of the stomatal pore

288
Q

Guard cells differ from standard epidermal cells: (3)

A
  1. not covered by the cuticle
  2. they have chloroplasts
  3. they lack plasmodesmata
289
Q

Stomates consist of

A

the pair of guard cells and the pore between the guard cells

290
Q

In eudicot leaves, where are the stomates located

A

on the underside of the leaf

291
Q

In monocots, where are the stomates located

A

both sides of the leaf

292
Q

Stomates mediate….

A

the photosynthesis-transpiration compromise

293
Q

Photosynthesis has a _____ water cost
a) slow
b) high
c) low
d) fast

A

b) high

294
Q

Boundary layer is…

A

an unstirred layer of air that is around all objects

295
Q

The boundary layer represents a

A

resistance to diffusion of gases

296
Q

Three factors that affect boundary layer conductance/resistance

A

leaf size, leaf shape, wind speed

297
Q

What are two ways to increase boundary layer depth

A

having stomates in crypts, and leaf pubescence

298
Q

Stomatal conductance (gs) is under the direct control of

A

the plant

299
Q

Changes in gs are caused by…

A

the guard cells changing shape

300
Q

Guard cells are said to integrate what

A

environmental signals

301
Q

What are 4 main signals that promote stomatal opening:

A

light (PAR)
blue light
low internal [CO2]
high external PH2O(g)

302
Q

Signals that promote stomatal closure

A
  1. darkness
  2. water stress
303
Q

Severe water stress will lead to

A

complete stomatal closure, no matter what other signals are being observed

304
Q

Water stress override is mediated by what plant hormone

A

Abscisic Acid (ABA); this hormone lets the guard cells know to close the stomate

305
Q

Two signals lead to elevated [ABA] in the guard cells:

A
  1. loss of leaf cell turgor
  2. loss of turgor in fine roots lead to the production of peptide signal
306
Q

Stomatal opening is based on

A

water relations

307
Q

As Ψp increases, the guard cells lengthen; meaning…

A

the pore opens

308
Q

Blue light is detected by

A

guard cell phototropin; this initiated a signal transduction pathway

309
Q

Activation of the H+-ATPase results in

A

hyperpolarization of the plasma membrane

310
Q

Hyperpolarization activates what type of channel

A

Voltage-gated K+ channels on the plasma membrane

311
Q

K+ is balanced by which two anions

A

Cl-, and malate 2-

312
Q

PEP comes from…

A

starch breakdown (glucose -> glycolysis)

313
Q

When stomates close, H+-ATPase activity decreases, which three solutes leave the cell

A

K+
Cl-
Malate 2-

314
Q

Girdling

A

removing a strip of bark all the way around a tree. Removes material all the way to the xylem

315
Q

Girdling leads to

A

swelling above the girdle and shrinkage below the girdle

316
Q

Is phloem alive or dead at maturity?

A

alive

317
Q

Sieve elements are the

A

major conducting cells in phloem

318
Q

Companion cells are responsible for

A

loading solute into the sieve element

319
Q

The source for photosynthate is

A

mature leaves or almost mature leaves

320
Q

Sinks for photosynthate include (3)

A

roots, developing leaves, developing fruits

321
Q

Sinks for organic N include

A

developing leaves, developing fruits, roots

322
Q

How many rounds of cell division does it take for the formation of sieve elements and companion cells

A

1

323
Q

Cell division occurs in zones called

A

meristems

324
Q

the vascular cambium is also a site of cell division; true or false

A

true

325
Q

Younger leaves and internodes will exhibit ____ ________

A

cell expansion

326
Q

The growth rate of an individual cell is controlled by what two important factors:

A

1) Wall extensibility
2) yield threshold

327
Q

Expansins are

A

small non-enzymatic proteins that break the bonds of hemicelluloses and cellulose

328
Q

Photoreceptors are

A

pigments that absorb light for the use in a physiological process

329
Q

Phytochromes are

A

a class of photoreceptor

330
Q

Phytochromes act as dimers, each dimer has

A

a chromophore (light-absorbing) attached to a protein

331
Q

Pr means

A

red light absorbing phytochrome

332
Q

Pfr means

A

far red light absorbing phytochrome

333
Q

Pfr can absorb

A

both red light and far red light

334
Q

Pfr can promote and inhibit a particular process. true or false

A

true

335
Q

Short day plants (SDPs) have

A

a maximum light period, beyond which flowering will not happen

336
Q

Long day plants (LDPs) have

A

a minimum light period, which must be exceeded for flowering

337
Q

Day Neutral plants have

A

no effect of photoperiod on flowering

338
Q

The last night break will always determine flowering; which break promotes this flowering?

A

Far red

339
Q

Which type of light promotes seed germination

A

red

340
Q

Red light and blue light do what to stem elongation

A

inhibit it

341
Q

Far red light does what to stem elongation

A

promotes

342
Q

High Pfr:Pr indicates what

A

the plant is shaded or you have neighbours, GROW BIGGER (elongate stem to avoid competition)

343
Q

Phytochrome-interacting factors (PIFs) are transcription factors that are

A

regulatory proteins that bind to promoters of genes

344
Q

Cryptochromes are

A

receptors for blue light and UV-A

345
Q

Cryptochromes are involved in (3)

A

blue-light mediated inhibition of stem elongation

blue-light mediated promotion of leaf

setting of the biological clock

346
Q

Phototropin

A

is a plant blue light and UV-A receptor

347
Q

UV_B is the trigger for what kind of production

A

anthocyanin

348
Q

two important commonalities between plants and animals in regards to hormones

A
  1. must have a receptor
  2. has a signal transduction pathways
349
Q

Plants have one specific hormone-producing organ; true or false

A

false; plant hormones are often transported but can have an effect on the organ they were produced in

350
Q

Most hormone effects are due to the interactions of 2+ different hormones; this generality is typically called

A

cross-talk

351
Q

Which type of tissue tends to produce more hormones? (Older or younger)

A

Younger

352
Q

Five well-known classes of plant hormones are

A

Auxin
Gibberellins
Cytokinins
Ethylene
Abscisic Acid

353
Q

What was the first plant hormone to be discovered?

A

Auxin

354
Q

What is a coleoptile?

A

a hollow sheath in the seedlings of grasses and some other monocots

355
Q

Auxin is responsible for

A

promoting elongation growth

356
Q

Auxin is synthesized in the

A

coleoptile tip

357
Q

Auxin is redistributed towards…

A

the dark side and moves down the seedling

358
Q

Indoleacetic Acid (IAA)

A

the major auxin in all plants

359
Q

Shoot-derived auxin regulates

A

secondary root production

360
Q

externally applied auxins promote

A

adventitious root formation on stems

361
Q

Apical dominance

A

suppression of axillary bud growth by apical bud/apical meristem (plants grow tall, not wide)

362
Q

What are two things that auxin stimulates

A

H+-ATPase activity; and transcription

363
Q

Which model is known for auxin transport

A

chemiosmotic-polar diffusion model

364
Q

Auxin is transported via

A

the vascular parenchyma cells

365
Q

What are some examples of amendments

A

plant ash, lime, or organic material

366
Q

amendments are known to (benefit of….)

A

increase crop yield

367
Q

Elements found in plants were often not a reflection of what was in the soil; true or false

A

false, it is a reflection of what is in the soil

368
Q

two criteria of plant mineral nutrition identification

A
  1. the species in questions must be unable to complete its life cycle in the absence of the element
  2. the function of the element cannot be replaceable by another element
369
Q

How many elements are known to be essential for plants?

A

17

370
Q

The three most common essential elements are…

A

C, H, O

371
Q

Many Halophytes grow better in the presence of high levels of

A

Na+

372
Q

Rice and Horsetails grow better in the presence of

A

Si

373
Q

Legumes indirectly benefits from the presence of

A

Co 2+

374
Q

Mineral element uptake by roots can be called

A

solution mining

375
Q

How many different nitrate transporters are there in roots of Arabidopsis

A

about 5

376
Q

Luxury consumption

A

many of the macronutrients may be taken up far in excess of what is needed for growth

377
Q

“Hidden hunger” means

A

that the plant is not displaying visual deficiency symptoms

378
Q

Excessive nutrients can cause

A

toxicity and reduced yield

379
Q

Two possible mechanism for metal toxicity

A
  1. high concentrations of metals in the soil solutions
  2. metal can hitch a ride on other transport systems
380
Q

Soil can be defined as

A

rock and organic matter on their way to the ocean

381
Q

Five compartment/fraction model includes:

A

1) non-exchangeable
2) soluble
3) exchangeable
4) plant material
5) dead organic matter

382
Q

Litter

A

minerals become available after microbial breakdown of complex organic molecules

383
Q

Humus

A

composed of humic acids; top of soil horizon - large part of the soil

384
Q

Soluble fraction

A

the mineral nutrients that are dissolved in the soil solution

385
Q

soluble fraction contains a portion of the ______ and the majority of the ______ except for phosphate

A

cations; anions

386
Q

Exchangeable fraction

A

soil has negative charges -> attracts cations
equilibrium between soluble and exchangeable minerals

387
Q

Cation exchange capacity

A

the ability of a soil to bind cations

388
Q

Loam

A

approx. equal amounts of sand, silt, and clay - or 40:40:20

389
Q

Silt

A

intermediate sized soil particles; smaller than sand, larger than clay

390
Q

Availability of cations in the soil solution depends upon the

A

strength of adsorption to the soil

391
Q

the stronger the adsorption, the less available for uptake by roots, which also means

A

more resistant to leaching

392
Q

Soil cation concentrations are said to be “buffered” meaning

A

as cations are taken from the soil solution by plant roots (or lost by leaching) can be replaced by cations from soil particles

393
Q

What are some approaches of trying to identify limiting nutrients?

A
  1. soil analysis
  2. visual diagnosis
  3. Plant analysis
  4. Experiment approach
394
Q

Chlorosis

A

yellowing of the leaves

395
Q

necrosis

A

localized death (brown areas)

396
Q

Complications of visual diagnosis of mineral nutrient deficiencies:

A
  1. species-specific differences
  2. different deficiencies can lead to similar symptoms
  3. excess nutrients can lead to toxicity symptoms
  4. chlorosis and necrosis are also associated with infection
397
Q

What will looking for evidence of re-mobilization show you? (mineral nutrient deficiency)

A

it won’t tell you what the deficiency is, but will tell you what it is not

398
Q

When determining if the element is structural or catalytic; what will it tell you about the deficiency?

A

Structural: can lead to developmental problems
Catalytic: leads to problems with the photosynthetic apparatus

399
Q

PM of root cells are full of

A

transport proteins

400
Q

What is the importance of the PM electrochemical gradient?

A

affects the costs of nutrient transport

401
Q

The electrochemical gradient is the combination of

A

the electrical gradient and the chemical (=concentration) gradient

402
Q

Three ways for mineral nutrients to come into contact with roots

A
  1. diffusion
  2. carried in bulk flow with water
  3. roots can grow towards a deposit
403
Q

Root Morphology

A

dry weight/mass allocated to roots varies between species and environmental conditions

404
Q

What is the importance of Surface Area (plant mineral nutrition)

A

absorption of mineral nutrients occurs across a membrane, the greater the membrane surface area, the greater area for absorption

405
Q

Root turnover

A

produced then die

406
Q

loss of roots is due to

A

predation by soil organisms

senescence

407
Q

Soil organic matter if from

A

leaves and roots, and microbes that decompose the plant organic matter

408
Q

Necromass

A

deadmass

409
Q

two broad categories of mycorrhizae

A

ecto (outside) and edno (inside)

410
Q

Mycorrhizae

A

fungus-roots

411
Q

Ectomycorrhizae are very common in

A

trees

412
Q

Arbuscular Mycorrhizae’s exchange site is in

A

the arbuscle located in the white roots

413
Q

Mycoheterotrophs

A

plants that are described as mycorrhizal cheaters or parasites; they tap into exisiting networks for their own gain, but make no contribution

414
Q

Holoparasites

A

have no leaves and no photosynthetic capacity; parasitic

415
Q

Hemiparasites

A

have leaves and can do photosynthesis; parasitic

416
Q

Plant movement can be divided into two broad categories:

A

nastic movements and tropisms

417
Q

Nastic movements include

A

Nyctinasty
Hydronasty
Seismonasty/ Thigmonasty

418
Q

Nyctinasty

A

leaf movement in response to day and day; controlled by both the environmental and internal biological clock

419
Q

Nastic Movements are

A

triggered by external stimulus, but the direction of the stimulus does not determine the direction of movement

420
Q

Nastic movements are driven by

A

pulvini; thickened zones of petioles that possess motor cells

421
Q

Hydronasty

A

movement in response to water stress

422
Q

Seismonasty/Thigmonasty

A

Movement due to touch or vibration

423
Q

Tropisms include

A

Thigmotropism
Phototropism
Heliotropism/Solar tracking
Skototropism

424
Q

Thigmotropism

A

directional response to touch

425
Q

Phototropisms

A

growth towards the light; this growth is irreversible

426
Q

Heliotropism/Solar tracking

A

growth towards the sun (helio) ; growth via pulvini (solar)

427
Q

Skototropism

A

Skoto means darkness; growth towards the dark

428
Q

Gravitropism

A

(=geotropism) - growth in response to gravity

429
Q

Positive gravitropism

A

growth in the same direction as the gravitational froce

430
Q

negative gravitropism

A

growth in the opposite direction to the gravitational force

431
Q

Orthogravitropism

A

vertical growth in response to gravity

432
Q

Diagravitropism

A

horizontal growth (gravity)

433
Q

Plagiogravitropism

A

growth at an angle

434
Q

Agravitropism

A

no response to gravity

435
Q

Both roots and shoots exhibit gravitropism; true or false

A

true

436
Q

If you remove the root cap, what will happen in regards to gravitropism

A

gravitropism disappears

437
Q

Statocytes are

A

the cells that contain statoliths; statocytes are the site of gravity perception

438
Q

What do the statoliths sink onto?

A

1) ER
2) Cytoskeleton
3) PM

439
Q

PIN3 and PIN7 are

A

auxin efflux transport proteins

440
Q

Stems and coleoptiles exhibit what type of gravitropism

A

negative gravitropism

441
Q

Shoots do not have statoliths; true or false

A

false, they do

442
Q

Circumnutation

A

is the rhythmical circular, bending movements of plant tips as the plants grow

443
Q

Gregarious flowering

A

mass flowering

444
Q

Circadian Rhythms

A

oscillate within a period of 24h

445
Q

In sensitive plants, continuous darkness continues the leaf to

A

open and close

446
Q

the mechanism to rest the circadian clock is thought to be

A

an environmental cue, e.g. dawn/light

447
Q

Entraining

A

refers to the fact that biorhythm exhibits the same periodicity as the environmental fluctuation or factor

448
Q

Light acts as a rest button in the leaf _____ entrainment

A

nyctinasty

449
Q

in nyctinasty clock resetting, dawn…

A

advances the clock

450
Q

in nyctinasty clock resetting, dusk…

A

delays the clock

451
Q

Photoperiodism

A

response to daylength

452
Q

Critical daylength

A

is the maximum daylength for flowering in an SDP or the minimum daylength for flowering in an LDP

453
Q

LDs promote

A

stem elongation and tillering (=formation of side shoots)

454
Q

SDs promote

A

tuber formation

455
Q

Plant cold hardiness

A

ability to withstand low temperatures

456
Q

LT means

A

lethal temperature

457
Q

Freeze-induced electrolyte leakage

A

common method used for determining the cold hardiness of plant tissues

458
Q

Tissue damage is associated with high conductivity because

A

the cells rupture and leak “electrolytes” into the water in a vial

459
Q

What are two good reasons to synchronize flowering with time of year?

A
  1. in seasonally cold climates
  2. some species are vary dependent on outcrossing
460
Q

arable land

A

suitable for plant-based agriculture

461
Q

How did global agriculture accommodate the continuous increase in population size?

A
  1. increases in land area used for agriculture
  2. improvements in crop agriculture
462
Q

Two main types of agricultural improvements

A
  1. higher yielding crop varieties
  2. high input (fertilizers and biocides) agriculture
463
Q

artificial selection

A

keep selecting/planting the largest seeds from the crop, and you are applying selection pressure for large seeds

464
Q

Green revolution

A

concerted global crop breeding program, focused on corn/maize, wheat, rice

465
Q

Liebig’s law:

A

yield is determined by a minimum or limiting factor

466
Q

Law of Decreasing Productivity

A
  1. yield depends on each growth factor
  2. the increase in yield is proportional to the different between the actual yield and the maximum yield
467
Q

Optimisation of Fertilizer Application; major reasons:

A
  1. too much or too little will negatively affect yield
  2. expensive
  3. loss to the environment
  4. environment costs of fertilizer production/extraction
468
Q

N fertilization of some sort is required for continuous reliable yields; (characteristics?)

A

must replace what is lost by harvesting
harvesting removes a lot of N in organic form
the higher the protein content, the great the N removal from the system

469
Q

Sources of Nitrogen for Agriculture

A

manure, seaweed, plant ashes, dead fish, guano, growing of legumes

470
Q

Saltpetre has three distinct uses

A
  1. component of gunpowder
  2. meat preservative
  3. agricultural fertilizer
471
Q

endophytes are

A

microbes that live within plant tissues

472
Q

GMO

A

genetically modified organisms

473
Q

Downsides to GMOs

A
  1. human health concerns
  2. Glyphosate-resistant weed (gene flow, natural solection)
474
Q

Bt-modified crops

A

Bacillus thuringiensis; produces three different groups of proteins that are insecticidal against different insect groups,

475
Q

Dead zones are due to nutrient pollution such as:

A

sewage, animal waste, fertilizer run off

476
Q

How to improve crop productivity?

A

continuation of plant breeding programs; decrease the loss of crops due to pathogens and pests

477
Q

What are two approaches for developing salt-tolerant crops

A
  1. look for wild relatives that have greater salt tolerance to crops
  2. genetically modify exisitng crops
478
Q

Suggested benefits of organic farming:

A
  1. less use of fertilizers
  2. fewer off-target effects of biocides
  3. fewer environmental problems from spills/disposal of biocides
  4. lower biocide residues on food
479
Q

How productive is organic farming?

A

general consensus is that organic methods provide lower yield than conventional high input methods

480
Q

How productive is organic farming?

A

general consensus is that organic methods provide lower yield than conventional high input methods

481
Q

Advantages of GM crops

A
  1. may have lower cost of production
  2. lower biocide use
  3. lower losses to pests
  4. perhaps better nutritional quality

BIOL 266 - PLANT PHYSIOLOGY (2 decks)

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