Dr. Bowley - Energy Flow In Plants

Front 1

What is the equation for photosynthesis?

Back 1

6CO2 + 6H2O -> C6H12O6 + 6O2

Front 2

The shorter the wavelength, the _______ the energy.

Back 2

higher

Front 3

What type of UV radiation disappears in the atmosphere?

Back 3

UV-C

Front 4

What types of UV light do we need to protect ourselves from? (i.e. what kinds of UV light can cause mutations?)

Back 4

UV-A and UV-B

Front 5

What part of the light spectrum does photosynthesis use?

Back 5

Visible light

Front 6

What part of the plant is the major site used for photosynthesis?

Back 6

The leaves - more specifically, the chloroplast is the site of photosynthesis.

Front 7

Stomata are for gas exchange. Where are they located in the plant?

A. Lower surface (abaxial)

B. Upper surface (adaxial)

C. Mainly on lower surface

D. Mainly on upper surface

E. Species dependent

Back 7

E. Species dependent

Front 8

What are grana?

Back 8

Stacks of thylakoids

Front 9

What is the thylakoid?

Back 9

A membrane bound, interconnected compartment inside the chloroplast. They are the site of the light-dependent reactions of photosynthesis.

Front 10

What is the lumen?

Back 10

The interior of the thylakoid

Front 11

What is the stroma?

Back 11

Fluid of the chloroplast

Front 12

What distinguishes chlorophyll a and chlorophyll b from one another?

Back 12

Chlorophyll a has an ethyl group, while chlorophyll be has an alkyl group.

Front 13

What is the general structure of chlorophyll a and chlorophyll b?

Back 13

Ring structure, magnesium ion in center, and a long hydrocarbon tail (allows it to work with membrane and absorb)

Front 14

What is the purpose of the porphyrin ring in chlorophyll a and chlorophyll b?

Back 14

To absorb the photon energy

Front 15

What is the purpose of the light harvesting complex?

Back 15

To capture and relay energy to reaction centre

Front 16

What occurs in the reaction centres?

Back 16

This is where light reactions begin, and it involves a special pair of chlorophyll a molecules.

Front 17

What do the electron transfer systems do?

Back 17

Deal with the high energy electrons coming off of reaction centres?

Front 18

What is the structure of photosystem 2? Where does it happen?

Back 18

-2 reaction centres in core

-LHCIIs are trimers, contain most of chlorophyll b - each trimer is a protein molecule with many chlorophyll molecules bound to it, structure captures photons, relays energy to 2 reaction centres

-Happens within thylakoid

Front 19

What are the two proteins in the centre of photosystem 2?

Back 19

D1 and D2, twist in a heix

Front 20

When is there enough energy to break water molecules in photosystem 2?

Back 20

When the Mn centre is short 4 electrons

Front 21

What does the cytochrome b complex consist of?

Back 21

Plastoquinol, cytochrome complex (production of ATP), and plastocyanin

Front 22

What does photosystem 1 consist of?

Back 22

plastocyanin, P700, 4 electrons passed to Ferredoxin, 4Fdx- ---> 4Fdx, 2NADP+ ---> 2NADPHW

Front 23

What are the major differences between Photosystem 2 and Photosystem 1?

Back 23

-Photosystem 2 is surrounded by light harvesting complex, has trimers

-Photosystem 1 has one reaction centre, four light harvesting complexes (dimers) arranged in a half-moon shape on one side, anchored to reaction centre with Lhca1

Front 24

How many photons are needed to balance the "equation" of the light reactions - how many must go into Photosystem 2 and Photosystem 1?

Back 24

8 photons are needed for the light reactions, 4 going into Photosystem 2 and 4 going into Photosystem 1.

Front 25

How many ATP are generated in the light reactions, provided it is working efficiently?

Back 25

4 ATP

Front 26

A carotenoid is an _________ pigment.

Back 26

accessory

Front 27

Carotenoids and xanthophylls provide _______________, which dissipate energy that could damage the system.

Back 27

photoprotection

Front 28

Why are plants green?

Back 28

Plants are green because chlorophyll has a low absorption of green wavelengths, so these are reflected.

Front 29

What accounts for the different shades of green seen in trees?

Back 29

Different levels of chlorophyll, carotenoids, xanthophyll and other pigments which affect the ratio of wavelengths reflected.

Front 30

What colour are foods with a high amount of anthocyanins?

Back 30

black

Front 31

What accounts for the fall colours seen in the leaves of trees?

Back 31

Loss of chlorophyll, with carotenoids and anthocyanins still present

Front 32

Cyclic electron flow consists of...

Back 32

Only Photosystem 1 and the cytochrome complex

Front 33

What is produced from cyclic electron flow?

Back 33

ATP, no NADPH or O2

Front 34

If there are photons coming into a chlorophyll molecule in the 420-460 nm range (short wavelength), these photons become excited electrons and result in a _________ ________ from both S2 (higher excited state) and S1 (lowest excited state).

Back 34

resonance transfer

Front 35

What happens if energy can not be transferred (too much energy and reaction centre can't keep up)?

Back 35

Fluorescence as well as heat will come off

Front 36

Photosystem 2 is operating normally if there is a ___ level of fluorescence.

Back 36

low

Front 37

Photosystem 2 has low activity or may have been damaged if there is a ____ level of fluorescence.

Back 37

high

Front 38

If there are photons coming into a chlorophyll molecule in the 650-750 nm range (long wavelength), these photons become excited electrons and result in either _________ ________ from S1 (lowest excited state), or will come off as ____ and ____________.

Back 38

resonance transfer, heat, fluorescence (fluorescence as a longer wavelength can't be recaptured and used)

Front 39

Photosynthesis creates and uses ___ and _____, and the byproduct is __.

Back 39

ATP, NADPH, O2

Front 40

Respiration produces ___ and ____, and the byproduct is ___.

Back 40

ATP, NADH, CO2

Front 41

What are the differences between NAD and NADP?

Back 41

-NADP has a phosphate group at the 2' C on the 5-carbon sugar.

-NAD is used in catabolic reactions (breaking down molecules to release energy)

-ADP is used in anabolic reactions (building larger molecules)

Front 42

Why are the photosystems physically separated?

Back 42

The photosystems are physically separated because if they were adjacent, Photosystem 1 would drain energy from Photosystem 2

Front 43

Where is Photosystem 1 and ATPase?

Back 43

The non-stacked regions of the thylakoid

Front 44

Where is active Photosystem 2?

Back 44

The stacked regions of the thylakoid.

Front 45

Since when photosystem 2 is active in the stacked regions of the thylakoid, protein __ is in a bad spot and it does not _______ long (half life is about _ hours).

Back 45

D1, survive, 2

Front 46

How is the D1 protein replaced?

Back 46

-Chloroplast moves inner part of the reaction centre to the non stacked area of the thylakoid

-Enzymes degrade protein

-New D1 protein synthesizes, placed back in reaction centre

-This is why part of Photosystem 2 is in the unstacked area and part is in the stacked area

Front 47

What with plants do if there are excess photons coming in?

Back 47

-Chloroplasts align along cell walls to reduce light interception - decreases light absorption by about 15%

-Carotenoids and xanthophylls release excess as heat and fluorescence

Front 48

What does the Calvin cycle use?

Back 48

ATP and NADPH

Front 49

What are the three phases of the Calvin cycle?

Back 49

1. Fixation of CO2 (catalyzed by Rubisco)

2. Reduction

3. Regeneration of the CO2 acceptor - Ribulose-1,5-Biphosphate (RuBP)

Front 50

Plants store fructose as ________ and glucose as ______.

Back 50

Fructans, starch

Front 51

Why is Rubisco the most abundant leaf protein (50% of leaf protein)?

Back 51

-Slow catalytic rate (3-10 CO2 molecules per second)

Front 52

What is the structure of Rubisco?

Back 52

-Cube shape

-8 large subunits, coded by chloroplast genome, each subunit has reaction site)

-8 small subunits, coded by nuclear genome, regulatory function

Front 53

What is the downside to Rubisco?

Back 53

It is bifunctional - it can carboxylate (good) and oxygenate (bad) RuBP

-3-P-Glycerate can be used in Calvin cycle

-2-P-Glycolate can not be used in Calvin cycle

Front 54

What 3 organelles does the photorespiration pathway involve?

Back 54

Chloroplast, peroxisome, mitochondria

Front 55

___ is consumed and ___ and ___ are generated in the photorespiration pathway.

Back 55

ATP, CO2, NH3

Front 56

What temperature conditions is photorespiration more likely to occur under?

Back 56

Hot, dry conditions

-As temperature increases, Rubisco's affinity for CO2 decreases and the solubility of CO2 vs. O2 decreases

Front 57

What is the difference between C3 and C4 plants?

Back 57

-C3 plants compartmentalize Rubisco in all cells of the leaf - cannot perform photosynthesis when stomata are closed

-C4 plants compartmentalize Rubisco in the bundle sheath cells (CO2 fixation & Calvin cycle in separate cells) - can perform photosynthesis when stomata are closed

Front 58

How do C4 plants perform photosynthesis?

Back 58

-Mesophyll cells fix CO2 as a 4-carbon acid (PEP carboxylase)

-4-carbon acid transported to cells surrounding leaf veins

-Bundle sheath cells convert 4-carbon acid to 3-carbon acid, CO2 released, 3-carbon acid returned to mesophyll, CO2 enters Calvin cycle

-High concentration of CO2 in bundle sheath cells essentially eliminates photorespiration (requires additional ATP)

Front 59

What are the three main variants of C4 plants?

Back 59

-Malate goes to bundle sheath, decarboxylating enzyme in bundle sheath is NADP-malic enzyme (chloroplast), C3 acid returned to mesophyll is Pyruvate

-Aspartate goes to bundle sheath, decarboxylating enzyme in bundle sheath is NAD-malic enzyme (mitochondria), C3 acid returned to mesophyll is Alanine

-Aspartate goes to bundle sheath, decarboxylating enzyme in bundle sheath is PEPCO-carboxykinase (cytoplasm), C3 acid returned to mesophyll is Alkanine/Pyruvate

Front 60

What is a protein kinase?

Back 60

A kinase transfers a phosphate from ATP to a hydroxyl group on a protein.

Front 61

What is a protein phosphatase?

Back 61

A phosphatase removes a phosphate from a protein by hydrolysis.

Front 62

What happens if PS2 gets ahead of PS1? (Photosystem energy balancing - light harvesting complex is moved)

Back 62

If PS2 gets ahead of PS1...

-Reduced plastoquinone accumulates

-Protein kinase activated

-LHCII is phosphorylated

-LHCII dissassociates from reaction centre

-Moves to PS1 in unstacked region

-More energy delivered to PS1

-As reduced plastoquinone decreases...

-Cycle reverses

-More energy delivered to PS2

Front 63

What is one way to reduce photorespiration in C3 plants?

Back 63

Increase CO2

Front 64

When is C4 photosynthesis advantageous over C3 photosynthesis?

Back 64

-Higher temperatures

-Lower CO2

Front 65

As the CO2 in the atmosphere is increasing, __ plants will grow better.

Back 65

C3

Front 66

As the temperature globally is increasing, __ plants will grow better.

Back 66

C4

Front 67

Are C3 or C4 plants more efficient are using Nitrogen?

Back 67

-C4 plants are more efficient at using Nitrogen, as they need less Rubisco

Front 68

Do C3 or C4 plants have lower transpiration rates?

Back 68

-C4 plants, because of CO2 concentrating mechanism

Front 69

For summer precipitation, what is the trend in Ontario? (And why?

A. Drier

B. Quite variable, but slightly drier

C. No change

D. Quite variable, but slightly wetter

E. Insufficient data to determine

Back 69

D. Quite variable, but slightly wetter

-Why? This is because of our close proximity to the Great Lakes.

Front 70

What is the difference between C3 and CAM plants?

Back 70

CAM plants utilize the same cells as C3 plants, however they are separated in time

-During the night, the stomates of the CAM plants open, CO2 is fixed into malate, and it is stored in vacuoles

-During the day, the stomates of the CAM plants close, malate is brought to the chloroplasts, pyruvate and CO2 are used for the Calvin cycle

Front 71

CAM plants are adapted to ____ conditions.

Back 71

arid

Front 72

Some plants can switch between C3 and CAM depending on...

Back 72

-Level of stress

-Stage of development

Front 73

How many species are C3 plants?

Back 73

Around 90%

Front 74

How many species are C4 plants?

Back 74

Less than 1%

Front 75

How many species are CAM plants?

Back 75

7-8%

Front 76

What enzyme is used to fix CO2 in C3 plants?

Back 76

Rubisco

Front 77

What enzymes are used to fix CO2 in C4 plants?

Back 77

PEP Carboxylase then Rubisco (separate cells)

Front 78

What enzymes are used to fix CO2 in CAM plants?

Back 78

PEP Carboxylase then Rubisco (same cell, different time)

Front 79

What are structural defenses?

Back 79

-Physical attributes of the plant that ward of predators (herbivores)

-E.g. raspberries have thorns, fescue has silica barbs along the leaf blade

Front 80

What are secondary metabolites?

Back 80

-Organic compounds not directly involved in the normal growth, development, or reproduction of a plant

-Can be used to ward off predators (herbivores)

-E.g. peppers have capsaicin, which causes a burning sensation in the mouth

-Beneficial examples include salicylic acid in the bark of the willow tree, which is a signalling molecule for pathogen defense, acetylsalicylic acid is ASA/aspirin

Front 81

What does alsike clover cause in horses?

Back 81

Liver damage

-Toxin unknown, likely from fungal infection of the plant

Front 82

What is usually removed during digestion in animals from chlorophyll? What is left?

Back 82

-The side chain and Mg are removed

-Phytoporphrin is left

-Most stays in gut and is secreted

-Dark green: Fresh pasture

-Brown olive: Dry hay rations

-Yellow olive: TMR with grain + forage

Front 83

If phytoporphrin is absorbed and enters the blood stream, how does the animal's body respond?

Back 83

-Normally metabolized by liver

-If liver is impaired, accumulates in blood

Front 84

What happens if phytoporphin accumulates in the blood?

Back 84

-No breakdown

-Molecules still capable of absorbing photons

-Animals do not have photosystems like plants

-Free radical are generated, causing tissue damage (photosensitization)

Front 85

What are free radicals? How are they formed?

Back 85

-Atoms or groups of atoms with an odd number of electrons

-Can be formed when oxygen interacts with certain molecules

-Highly reactive

-In animals, free radicals are generated in body parts where photons can be absorbed (photosensitization)

Front 86

What part of the light spectrum is absorbed best in a canopy? Second best? Third best? Fourth?

Back 86

-Blue (84%)

-Red (82%)

-Green (80%)

-Near Infrared (15%)

Front 87

What is the light compensation point?

Back 87

Where CO2 uptake = CO2 evolution, and O2 uptake = O2 evolution

Front 88

What is the name given to plants that have a low light compensation point and are unable to adapt to high light?

Back 88

-Obligate shade plants

-E.g. ginseng

Front 89

What is the name given to plants that have a high light compensation point and are unable to adapt to low light?

Back 89

-Obligate sun plants

-E.g. most crop species

Front 90

Which paint will have the least effect on the growth of turfgrass? Why?

A. White

B. Yellow

C. Red

D. Blue

E. Black

Back 90

A. White

-This is because white reflects more, the light transmission is the same, there is less absorption, and more photosynthesis

White < Yellow < Red < Blue < Black (least harmful to most harmful)

Front 91

Plants perceive signals. What is the order of how the plant's sensory system responds to signals?

Back 91

1. Receptor cell receives external signal

2. Receptor protein changes shape and/or is phosphorylated/dephosphorylated

3. Internal signal amplified and relayed to other cells (signal transduction)

4. Responder cells receive internal signal and change their activity

Front 92

What are the phytochromes in monocots (red light)?

Back 92

PHYA, PHYB, PHYC

Front 93

What are the phytochromes in dicots (red light)?

Back 93

PHYA, PHYB, PHYC, PHYD, PHYE

Front 94

What are the cryptochromes in plants under blue light?

Back 94

CRY1, CRY2

Front 95

What are the phototropins in plants under blue light?

Back 95

phot1, phot2

Front 96

What is Zeaxanthin?

Back 96

-A xanthophyll

-Blue response limited by guard cells

Front 97

How is competition perceived (red light)?

Back 97

-Light quality

-Light below canopy

-Changes in frequency of each of the wavelengths

-Top of canopy more red, bottom more far red

-Bottom of canopy, smaller ratio red:far red

-Smaller ratio = more competition

Front 98

What is phytochrome?

Back 98

-Protein detecting signal - relative amount of red to far red

Front 99

What is a chromophore?

Back 99

-Element that reacts to the different light signal

Front 100

___________ is photoreversible.

Back 100

Phytochrome

-Red light - cis to trans shape change

-Far red light - trans to cis shape change

-3D change in protein

Front 101

Photo-interconversion exists in phytochrome. Red lasts for ____ or _____ in the cell and is ______. Far red is ________ and ________ quickly.

Back 101

days, weeks, stable, unstable, degrades

Front 102

At 660 nm, the ratio of far red to red is ____. At 730 nm, the ratio of far red to red is ____.

Back 102

0.80, 0.03

Front 103

When sun plants detect shade, they will elongate their _____.

Back 103

stems

Front 104

When facultative species detect shade, they will alter between __________ (wait for other plant to die and let the other plants compete)

Back 104

root:shoot

Front 105

Seed germination is inhibited by ___ ___.

Back 105

far red

Front 106

Flowering responses are affected by _________.

Back 106

daylength

Front 107

Phytochrome responses set _________ _______.

Back 107

circadian rhythms

Front 108

What are the three types of daylength responses? When do they flower / when do they participate in vegetative growth?

Back 108

1. Long day plants - need short nights, flower in mid summer, vegetative growth when days are short and flowering when days are long

2. Short day plants - need long nights, flower in spring/fall, vegetative growth when days are long and flowering when days are short

3. Day neutral plants - flowering not affected by daylength

Front 109

What is an example of a long day plant? When does flowering occur (relative to critical night)?

Back 109

Red clover

When night is longer than critical night, no flowering occurs. When night is shorter than critical night, flowering occurs.

Front 110

What are the two types of long day plants? When can they flower? What are some examples?

Back 110

1. Obligate

Cannot flower if dark period is longer than critical night length

E.g. Alfalfa, red clover, flax, oats

2. Facultative

Flower faster under long-day conditions

E.g. barley, spring wheat, snapdragon

Front 111

What is an example of a short day plant? When does flowering occur (relative to critical night)?

Back 111

Coffee

When night is longer than critical night flowering occurs. When night is shorter than critical night flowering does not occur.

Front 112

What are the two types of short day plants? When can they flower? What are some examples?

Back 112

1. Obligate

Cannot flower is dark period is shorter than the critical night length

E.g. poinsettia, field beans, coffee

2. Facultative

Flower faster under short-day conditions

E.g. morning glory, sugarcane, cotton

Front 113

What are day neutral plants? What are some examples?

Back 113

Flowering not affected by day length

E.g. sunflower, tomato, geranium

Front 114

If you produce a light flash (night break) in long day plants, what happens?

Back 114

Night now shorter than critical night, flowering occurs

Front 115

If you produce a light flash (night break) in short day plants, what happens?

Back 115

Night now shorter than critical night, flowering does not occur

Front 116

Red light triggers _____ _____, far red turns it ___.

Back 116

night break, off

Front 117

What is vernalization?

Back 117

Cold treatment, prompts flowering - ensures short day plants do not flower in the fall

Front 118

Regarding vernalization, what do obligate species require?

Back 118

Cold treatment to flower

E.g. winter wheat, sugar beet, celery, cabbage, carrots, sweet clover

Front 119

Facultative species flower ______ when subjected to vernalization.

Back 119

faster

Front 120

Regarding blue light, some plants can continuously adjust leaves to be _____________ to the sun's rays (+/- 15 degrees). This _________ photosynthesis in early and late periods of the day and reorients before dawn.

Back 120

perpendicular, increases

Front 121

In plants that solar track, some have a sensor in the ________, like alfalfa, and others use the _______ parts of the ____, like sunflowers.

Back 121

pulvinus, younger, stem

Front 122

Many processes oscillate through the day. Gene expression can be either _______ patterns or _________ rhythms.

Back 122

diurnal, circadian

Front 123

Circadian rhythms are cycles about __ _____ in length, and continues if placed in constant _____ or ____.

Back 123

24 hours

Front 124

Sensitivity to red/far red is _________, and the night break response follows the same pattern.

Back 124

circadian

Front 125

Why do legumes lower their leaves at night?

Back 125

-Reduce capture of moonlight by about 80-95%

-Reduces effect moonlight might have on circadian rhythms

Front 126

What is a source? What is a sink? What parts of the plants are they?

Back 126

-Source: a plant organ that produces sugars

-Usually the leaves

-Sink: a plant organ that consumes or stores sugars

-Usually young leaves, developing seeds, new growth, nodules, roots

Front 127

Some perennial species have storage organs that can act both as sinks and sources. When are the storage organs sinks and when are they sources?

Back 127

-Sink during deposition of reserves

-Source during regrowth - mobilization of reserves

-E.g. alfalfa - crown and upper tap root

Front 128

When a leaf is transitioning from a sink to a source, what part of the leaf is first to stop importing and what part is last to transition?

Back 128

The leaf tip is the first to stop importing, and the leaf base is the last to transition.

Front 129

How do cucurbits and woody plants transport sugars?

Back 129

Primitive loading system - concentration gradient

Front 130

How do grasses and most crop species transport sugars?

Back 130

More efficient in cool temperatures and drought - ATP dependent

Front 131

What direction can xylem (stores water and water-soluble nutrients) flow?

Back 131

Root to shoot/leaf (upwards only)

Front 132

What direction can phloem (stores sugars, proteins, and other organic molecules) flow?

Back 132

Can be either direction (root to shoot/leaf or shoot/leaf to root)

Front 133

Within an individual sieve tube element directional flow can be ____________ at any given time.

Back 133

undirectional

Front 134

What are the two ways phloem can unload?

Back 134

1. Symplast unloading

-Hight to low concentration gradient

2. Apoplast unloading

-Typicaly for most sinks, energy required

Front 135

Legumes have two sources of nitrogen. What are they?

Back 135

1. Soil nitrate (NO3) or ammonium (NH4+

Front 136

How does nitrogen conversion differ in temperate species and warm season species?

Back 136

1. Temperate species

-Most nitrate assimilation in the roots

-Transport Nitrogen as glutamine/asparagine

2. Warm season species

-Many transport nitrate through the xylem

-Then assimilate it in the leaves

Front 137

Unlike animals, plants can store _______ with no detrimental effect.

Back 137

nitrate

Front 138

In corn, where is nitrate concentration the highest?

A. Ear

B. Leaf

C. Upper stalk

D. Middle stalk

E. Lower stalk

Back 138

E. Lower stalk

Front 139

Drought _____ ___ the rate of _______ to ________ conversion.

Back 139

slows down, nitrate, ammonium

Front 140

During drought, there are highest levels of nitrate in the _____ leaves and stems.

Back 140

lower

Front 141

If the plant is ______ pollinated and growth is short, levels of nitrates will be ____.

Back 141

poorly, high

Front 142

What is the cause of death in animals that have nitrate toxicity?

Back 142

Anoxia

Front 143

What are the three types of mutualistic associations? What are some examples?

Back 143

1. Resource exchange

-Legume-rhizobia - carbohydrates for fixed nitrogen

-Plant-mycorrhizal relations - carbohydrates for phosphate, water

2. Service-resource exchange

-Plant pollinator - nectar for pollen dispersal

3. Service exchange (rare)

-Acacia and ants - thorns protect ants, ants deter herbivores

Front 144

Rhizobia are free-living ________ that can induce ____ nodule formation and fix ________ in symbiosis with host legumes.

Back 144

bacteria, root, nitrogen

Front 145

What is the plant equivalent of the mammalian myoglobin?

Back 145

Leghaemoglobin

Front 146

Temperate legumes and warm season legumes fix Nitrogen differently - what are the differences and some examples of each type of legume?

Back 146

1. Temperate legumes

-Alfalfa, clover, peas

-Fixed Nitrogen transported as Amides

2. Warm season legumes

-Soybeans, field beans

-Fixed Nitrogen transported as Ureides

Front 147

Theoretically, at its most efficient, how much ATP is required to reduce one N2?

Back 147

16

-However, efficiency varies among species

Front 148

Through the association of roots and fungi, the fungi receive ______ while the plant receives more _________ including phosphorus (which results in better root functions).

Back 148

carbon, nutrients

Front 149

What are the two types of Plant-Mycorrhizae associations? What plants do they include?

Back 149

1. Ectomycorrhizae

-On root surface and outside cell walls

-10% of plant families

-Many woody plants (conifers, oak, walnut)

2.Endomycorrhizae (Vesicular-Arbuscular)

-Hyphae grow through the cell walls

-Form arbuscules to increase surface area for nutrient exchange with cell

-80% of plant species

Front 150

Plant-Mycorrhizae associations, unlike Rhizobia, are not hot ________.

Back 150

specific

Front 151

What is the cost of Plant-Mycorrhizae association (in terms of fixed carbon)?

Back 151

7-10% of fixed carbon

Front 152

The benefit of Mycorrhizae ______ among plants.

Back 152

varies

Front 153

Is there plant to plant Carbon transfer (concerning Mycorrhizae)?

Back 153

No

Front 154

What is an endophyte?

Back 154

An endosymbiont (either bacterium or fungus)

-Most of its life cycle occurs in the plant

-Does not cause disease

-E.g. fescues and ryegrasses

-Benefits:

-Fungus: a home and nutrients

-Plant: protection from herbivores

Front 155

The endophyte that thrives on fescues and ryegrasses grows between cells of _____ ______ tissue. It is transmitted through the seed.

Back 155

above ground

Front 156

What is the plant life cycle of an endophyte found on a ryegrass or fescue? (4 steps)

Back 156

1. Endophyte is found in scutellum of infected seed

2. Endophyte grows into the emerging leaf

3. Endophyte is concentrated at base of leaves (not in the roots)

4. During flowering, endophyte grows up stem and into scutellum of developing seed.

Front 157

Endophytes provide _________, including lolines, which provide an insecticide and insect deterrent, and ergopeptines, which provide anti-insect properties and have a positive influence on growth regulators.

Back 157

alkaloids

Front 158

What is the effect of lolines on mammals?

Back 158

-Vasoconstrictive properties

-Elevated body temperature

-Gangrene - rear hooves and tail tip

Front 159

What is the effect of endophytes (on fescues and ryegrasses) on horses? On cattle? On sheep?

Back 159

Horses

-Poor reproduction

Cattle

-Reduced weight gain, greater heat stress

-Reduced milk

-Fescue foot

Sheep

-Ryegrass staggers

-Reduced weight gain

-Heat stress

Front 160

Turfgrass is likely to be enhanced with __________ because it helps it grow better and makes it more ______ _________. Forage is likely to be free of __________ because it poses dangers to herbivores.

Back 160

endophytes, insect resistant, endophytes

Front 161

Striga is a parasitic ____ that colonizes corn, millets, rice, sorghum, and sugarcane. It _______ yields.

Back 161

weed, reduces

Front 162

The African Stemborer is a moth that affects corn and sorghum, which _______ yields. Together with striga it can _______ a crop.

Back 162

reduces, wipeout

Front 163

The ____-____ method uses plants to deter pests (____), and attract natural enemies (____).

Back 163

push-pull, push, pull

Front 164

______ grass is used for push-pull control - it attracts egg laying _____ and, when larvae bore, the grass produces a gummy compound which ___________ the larvae. It is, more specifically, the pull part of the method.

Back 164

Napier, moths, immobilizes

Front 165

_________ is used to push moths away, by releasing oximene and nonatriene.

Back 165

Desmodium

Front 166

Desmodium helps in the control of ______ because its roots produce isoflavanones, which in turn stimulate ___________ of the Striga seed, inhibit attachment of the Striga roots to maize roots, and this combination reduces Striga and benefits the legume's ________ ________.

Back 166

Striga, germination, Nitrogen fixation

Front 167

How can you place Desmodium and Napier grass in a corn field to effectively utilize the push-pull method?

Back 167

-Border of 2-3 rows of Napier grass (which is also harvested as a forage crop - push)

-Alternate rows of Desmodium (pull)

Front 168

Molasses grass ______ the African sugarcane borer.

Back 168

pushes

Front 169

Soil bacterium can be used as a biological _________, which produces _______ proteins that are toxic to insect larvae.

Back 169

pesticide, crystal

Front 170

When Bt is introduced into crop plants, it lets the plant be able to _____ the insect that affects them.

Back 170

deter

Front 171

Aphids feed on phloem sap, and are vectors for _______. When aphids are attacked or disturbed, they release an ______ pheromone, and neighbouring aphids ________. The pheromone also attracts natural _______.

Back 171

viruses, alarm, disperse, enemies

Front 172

Cyanogenic compounds are an example of an antagonistic association, and are linked to a _______ unit or a pair of _______ units. When broken, cyanide compounds are ________.

Back 172

glucose, glucose, released

Front 173

Cyanogenic glycosides are stored in ________. The release enzyme is in the _______. If a cell is injured, the enzyme and substrate mix, releasing ___ (due to bruising, trampling, etc.)

Back 173

vacuoles, cytosol, HCN

Front 174

HCN ______ cytochrome c oxidase in electron transport chain. This results in ___ formation stopping, and, if in sufficient quantity, _____ follows rapidly. HCN resistant respiration exists in ______ plants, where ubiquinone is oxidized by the enzyme alternate _______, where it bypasses complexes 3 and 4 of the chain.

Back 174

blocks, ATP, death, higher, oxidase

Front 175

HCN resistant respiration has a _____ ATP yield than the full pathway.

Back 175

lower

Front 176

HCN is found in _______, which is a stable food in tropical Africa and Latin America.

Back 176

cassava

Front 177

Food preparation _______ the problem of HCN in cassava. Proper preparation involves _______ and soaking the cassava. HCN poisoning results from the crop being improperly prepared, resulting in ______ or _____.

Back 177

reduces, grating, goiter, death

Front 178

Why not remove the cyanide trait in cassava?

Back 178

-Removing the trait would result in reducing its insect and rodent resistance, as well as its storage quality

Front 179

Apricots, bitter almonds, and apple seeds all contain ___, but death is ____.

Back 179

HCN, rare

Front 180

Sweet clover has a ____ tap root, that has _______ tolerance and breaks hardpans in ____.

Back 180

deep, drought, soil

Front 181

In the 1920s, there was a new disease in cattle, whereby cattle were dying after dehorning and earnotching. What was this from?

Back 181

Mouldy sweet clover feed

Front 182

The blood of cattle will not ____ when fed mouldy sweet clover, as it contains a competitive inhibitor which impairs conversion of Vitamin _ oxide to Vitamin _.

Back 182

clot, K, K

Front 183

When subclover was introduced into sheep pastures in the early 1930s, it resulted in a quadrupling of ____________. However, by the 1940s there were widespread breeding problems - the number of lambs has __________ by 70%, there was a high incidence of ________, and virgin ewes and wethers were _________.

Back 183

productivity, decreased, abortion, lactating

Front 184

What are phytoestrogens?

Back 184

Compounds that have a similar shape to natural estrogens

Front 185

Why do plants have phytoestrogens?

Back 185

-Disease resistance as they are precursors of phytoalexins

-Isoflavones are always there (e.g. red clover, sub-clover)

-Coumestans are released in response to an injury (e.g. alfalfa, white clover)

Front 186

Red clover is fed with the leaves and stems, so commonly isoflavone (phytoestrogen) content is _______, whereas subclover is often only consumed by the leaves and contains ____ Isoflavone.

Back 186

diluted, more

Front 187

What are some ways you can limit phytoestrogen effects in sheep?

Back 187

-Limit legumes during flushing and mating

-Use low-estrogenic varieties