AGR4512 Final Exam study guide

The initial fixation of CO2 in C4 plants is by this enzyme:

PEP carboxylase (PEPCase)

The deposition of assimilate into various plant parts is referred to as:

Partitioning

These crops have a fibrous root system:

Sorghum

Plant species that flower independently of photoperiodic condition are known as

DNPs

Root hairs develop from the:

Epidermis

What affects the light absorbing properties of chlorophyll?

the number and location of single and double bonds

As leaf area index increases above about 4.0:

- None of these answers are correct

The following methods could be used to measure the water status of individual plants:

- Pressure bomb - RWC - Xylem sap flow - IRGA

k values of 0.9

- a. Are representative of sunflower or clover - b. Indicate planophile leaves

Plant growth is a function of:

- a. Genotype - d. phene performance - c. the interaction between genotype and environment - b. Environment

The boundary layer above the leaf surface:

- a. Is thicker in still air - b. Causes some resistance to both water vapor out of the leaf and carbon dioxide movement into the leaf - c. Usually contains a higher amount of water vapor than the atmosphere above it

Which of the answer(s) can maximize WUE?

- a. Photosynthesis - b. Humid environments - d. Full canopy cover

Non-destructive measures of LAI:

- a. Usually underestimate LAI - d. Can be measured with an LAI-2200

Mycorrhizae:

- b. Are fungi - e. Greatly increase the surface area of roots

Which of the following statements are true about osmotic potential?

- b. Solutes in water reduce osmotic potential - a. Is independent of the specific nature of the solute - c. Solutes reduce the free energy of water

Isotopes are _____________________________ forms of the same element that differ in their number of __________ .

- both radioactive and nonradioactive -neutrons

Dormant seeds ____________ go into Phase III, which is characterized by cell ____________ .

- do not -division

Types of HR include:

- inverse HR - lift of deep water into dry, shallow soil layers - fog uptake - desiccation due to tissue dehydration

What is/are true about Rhizobia in nitrogen fixation

- japonicum species is specific only to soybean crop - Some species are specific to inoculate only one crop - Nitrogenase is an enzyme produced by rhizobia - Some species may cross-inoculate wide range of crops

Photorespiration involves:

- the Warburg effect - the C2 oxidative pathway - the oxygenation capacity of Rubisco

PRD was first developed in_____________for the production of _____________ and utilizes root signals and their impact on ____________________.

-Australia - grapes -stomatal conductance

____________________ occurs at temperature below optimal for growth and cell membranes become destabilized via __________________ . _______________ occurs from formation of intra- and extracellular ice.

-Chilling injury -reduced membrane fluidity -Freezing injury

____________ crops are more sensitive to water deficit stress, mainly because in these crops ____________________ .

-Determinant -plasticity is lower

WUE is the ratio of _____________________ to _____________________ and it is negatively affected by ____________________.

-Dry matter or Yield -water used by crop -vapor pressure deficit

The following nutrient elements are more available in acidic soils compared to the basic soils:

-Iron -Copper -Zinc

Mobile nutrients in the plant include:

-N -P -Cl

BNF is catalyzed by _______________ enzyme. During this process ______________ reduces Fe protein and Fe protein reduces _______________ which eventually reduces N2.

-Nitrogenase -Ferredoxin -MoFe protein

Minimum fluorescence (Fo) is measured when the major electron receptors of ________ are _________

-PSII -oxidized

_____________ stress effects initiate and accelerate the disruption of cellular integrity. ___________ stress effects directly alter the physical and biochemical properties of cells.

-Secondary -Primary

Properties of the seed that interfere with imbibition are said to have _________________________ , while physiological constraints to germination are known as _______________________.

-coat-imposed dormancy -embryo dormancy

Cell walls of the ____________ may contain Casparian strip which prevents the ___________ flow of water.

-endodermis -apoplastic

Generally, transpiration ______________ with increasing VPD ______________________________________________

-increases -up to a limit when stomata begin to close.

When experiencing water deficit, a plant will most likely exhibit _______________ before ____________

-loss of turgor -cavitation

Green plants have relatively ______________reflectance and transmittance in the__________________ of the spectrum because plant (chlorophyll) absorb this portion of the spectrum for photosynthesis.

-low -visible region

Hydraulic Redistribution is the ___________ movement of water through roots from moist to dry soils and may also ___________ nutrient availability. Maximum hydraulic lift may occur during ______________ stage of crop.

-passive -increase -reproductive

WUE is defined as the ratio of _________ to _________ and is generally higher in _________ plants.

-photosynthesis -transpiration -C4

The embryo of a seed consists of three parts: 1. ___________ , or embryonic root, 2. the ____________ , which forms stem of germinating seedlings, and 3. the _____________ , which become the first true leaves of the plant.

-radicle -hypocotyl -cotyledons

The most water deficit sensitive stages of growth are stages involving _______ cell expansion and the __________ water requirements.

-rapid -maximum

When water evaporates from any part of plant, the ________________ at the evaporating surface causes movement of water from ___________ to the evaporating surfaces

-reduction in potential -xylem

Measurements of NDVI are based on the fact that healthy vegetation ______________ a large portion of near-infrared light, while unhealthy vegetation __________ more red light.

-reflects -reflects

Fv/Fm is

-reported in many studies that measure fluorescence -relatively insensitive to mild stress - relatively easily measured

Two factors that can affect nitrogen fixation in crops include _________________ and ________________ .

-soil nitrogen content -inoculant source

Two factors that can affect nitrogen fixation in crops include ______________ and ______________.

-soil nitrogen content -inoculant source .

Fv is

-the difference between Fo and Fm -occurs once a saturating pulse of light is given to a dark adapted leaf -variable fluorescence

Coping strategies plants have for mineral stress include _______________________ and ________________

-vacuolar sequestration of ions -exclusion of salt

Major driving force for water flow from soil to root xylem is ___________ and from root xylem to leaf xylem is__________________

-water potential - pressure potential only

Chlorophyll fluorescence accounts for approximately ______ percent of the total light absorbed by a leaf.

1-2 %

The sequence of events in germination is as follows: 1.____________ 2.___________ 3.___________

1. imbibition 2. water potential reaches equilibrium 3. radicle ruptures the testa

The following isotopes are in the highest percentage in our atmosphere:

12C, 14N, 16O

What is the radioactive isotope of carbon?

14C

The first product formed after fixation of CO2 in C3 plants is:

3-phosphoglycerate (PGA)

PAR encompasses the following wavelenths of light:

400-700 nm

Photosynthesis of single leaves of C3 plants saturates (reaches its maximum level) at:

50 % of full sunlight

The amount of radiation striking the earth's surface is about ______ of the radiation received at the top of the atmosphere.

65%

Stomatal closure under water deficit stress is FIRST mediated by an increase in ___________________________

ABA concentration

Photosynthesis of single leaves of C4 plants saturates (reaches its maximum level) at

Above full sunlight

Maximum light interception by a crop is first reached at:

An LAI of 3-4

Early in the vegetative stage of growth, the apical meristem of a soybean plant is located:

At the top of the shoot

Leaves begin to export more assimilate than they import when they:

Attain about 50% of full size

Rate of photosynthesis in C4 plants are higher than C3 because:

Carbon concentrating mechanism at the site of Rubisco increases efficiency of this enzyme in C4

The development of cells into specialized structures is known as:

Cell differentiation

The following crops have a determinate growth habit:

Corn and Wheat

What is the type of meristem that helps increase the diameter of stems?

Lateral

Light compensation point is the:

Light intensity at which net photosynthesis is zero

Carbon isotope ratios (13C/12C) for C3 plants are:

Lower than for C4 plants

Which of the following is the most common form of nitrogen transported in xylem:

NO3

What is the first step of nitrate assimilation in the plant?

Nitrate is reduced to nitrite in the cytosol

As leaf area index increases above about 4.0:

None of these answers are correct

The form of phytochrome that absorbes red light is:

Pr

A closed canopy soybean crop in comparison to a maize crop

Should have an LAI of approximately 4 and 100% light interception, both similar to maize

Dark reactions of photosynthesis occur in this part of the chloroplast:

Stroma

Solar Radiation travels through space in the form(s) of

Waves and particles

CER can be a negative value:

When irradiance is zero and respiration is occurring

In the summer (July), DLI is

about equal in Florida and Maine

Which statement is false about individual root hairs:

can maximally absorb nutrients and water over their entire surface area throughout their life cycle.

Tropospheric ozone is:

considered a pollutant

The following characteristics determine the amount of solar radiation received at the earth's surface:

day length, latitude, sun angle

What important characteristic is important for a root hair to escape the zone of depletion?

enhanced length

As the wavelength of light increases, its frequency and energy:

frequency decreases, energy decreases

The dark reactions or Calvin-Benson cycle of photosynthesis

has three primary steps

Which one of the processes listed below is one of the primary phases involved in root hair development?

initiation

Non-radiative dissipation is the process of the conversion of _______ to __________

light energy kinetic energy

Inside a dense corn canopy, the ratio of R/FR would be:

lower than at the top of the canopy

The first product formed after fixation of CO2 in C4 plants can be:

oxaloacetate (converted to malate)

What wavelength of the spectra has the lowest absorption level by the atmosphere?

radio

Movement in the phloem:

Is acropetal and basipetal

Carbon dioxide diffuses:

1.6 times slower than water vapor through the stomatal opening

Light reactions occur in this part of the chloroplast:

Granum

Transpiration depends on:

the difference in the water vapor concentration in the leaf and the air/(divided by)/ The sum of the stomatal and boundary layer resistances

The carboxylation step in the Calvin-Benson cycle involves:

the reaction of carbon dioxide and water to form PGA