MCDB 1B M1

When analyzing how C3, C4, and CAM plants strategies for carbon capture and fixation A. C4 plants capture CO2 by converting PEP (phosphoenol pyruvate - 3 Carbon compound) to Oxaloacetate (4 Carbon compound). B. CAM plants utilize spatial separation of the cells, by producing mesophyll cells and bundle sheath cells that are responsible for Carbon Fixation and sugar production, respectively. C. C3 plants have RuBisCo that is highly specific to CO2 and therefore does not require isolation from O2 generated by water splitting and/or closing of the leaf stomata. D. Only C4 plants utilize PEP (phosphoenol pyruvate) as the initial 3 carbon compound that enables CO2 capture E. None of the above are true.

A. C4 plants capture CO2 by converting PEP (phosphoenol pyruvate - 3 Carbon compound) to Oxaloacetate (4 Carbon compound).

A long day plant normally flowers if day length is over 12 hours. If this plant were growing in a cycle of 13 hours light 11 hours dark and you pulsed red light in the middle of its dark period, what would you expect to happen? A. The plant will no longer flower. B. The plant will still flower. C. More information is required to answer this question.

B. The plant will still flower.

Auxin transport: A. is polar along the main axis of the plant: from shoot tips toward root tips B. requires metabolic energy in the form of establishing a proton gradient across the plant plasma membrane C. polarity is conferred by asymmetrically localized efflux carriers called PINs on individual cells D. is constantly shifting in the shoot apical meristem to initiate new organs E. all of the above

E. all of the above

Water will move from the root hairs through the cortex to the xylem if the water potentials are (in MPa) A. root hairs = 0, cortex = 0, xylem = 0. B. root hairs = -1, cortex = -1, xylem = -1. C. root hairs = -2, cortex = -1, xylem = 0. D. root hairs = 0, cortex = +1, xylem = +2. E. root hairs = 0, cortex = -1, xylem = -2.

E. root hairs = 0, cortex = -1, xylem = -2.

The photosystems allow plant chloroplasts to harvest light energy. When thinking about the two photosystems that comprise typical 'green' plants. Select one: a. Photosystem II splits water within the thylakoid lumen, increasing the H+ gradient in this membrane enclosed structure b. Photosystem I is located 'upstream' to photosystem II, in that I will donate electrons to photosystem II. c. Photosystem I is responsible for cyclic photophosphorylation to generate ample NADPH for the Calvin Benson cycle d. ATP and NADPH production occurs in the lumen of the thylakoid e. Photosystem I, II and the electron transport chain are all responsible for building the H+ gradient within the thylakoid lumen.

a. Photosystem II splits water within the thylakoid lumen, increasing the H+ gradient in this membrane enclosed structure

Phytochromes: A. Are a type of light-sensing protein. B. Change conformation under the absorption of green light. C. Have a chloroplast localization sequences as part of their primary structure. D. Are localized to the endoplasmic reticulum membrane. E. Have hydrolytic protease activity.

a. are a type of light-sensing protein

Which plant wants a higher amount of Pfr to flower? a. long day plants b. short day plants

a. long day plants Uses Pfr to drive flowering gene expression

Sucrose loading = more negative solute potential in the phloem. This results in greater negative phloem water potential compared to xylem water potential. This leads water to osmotically move to the phloem from xylem a. true b. false

a. true

The "triple response" of a seedlings: a. usually occurs underground in nature b. is mediated by pressure-induced synthesis of auxin c. includes radial swelling of stems due to the horizontal deposition of cellulose d. A and C e. A, B, and C

a. usually occurs underground in nature

Considering apical and/or lateral meristems, what is TRUE? A. Primary plant growth is a result of the lateral meristems, while secondary growth is largely a result of apical meristems. B. Lateral meristems can give rise to a diversity of the three main types of plant tissues while apical meristems give rise to the xylem and phloem. C. The vascular cambium is a lateral meristem that gives rise to xylem while the cork cambium is a lateral meristem that gives rise to phloem. D. Apical meristems are located at the root tips and the buds of the growing plant. E. These are plants cells that are not totipotent.

D. Apical meristems are located at the root tips and the buds of the growing plant.

In terms of the plant cell wall, what below is FALSE? A. The primary cell wall is older and located outside of the plant secondary wall of woody plants B. The cell wall is a major compartment of the plant body, termed the apoplast C. The primary cell wall largely consists of a meshwork of hydrophilic cellulose, hemicellulose and pectin in a hydrated environment D. Have a higher pH than the cytoplasm E. Cellulose microfibrils shift in orientation as the cell expands, and more cell wall is synthesized.

D. Have a higher pH than the cytoplasm

Considering carbon dioxide and photosynthetic plant cells... A. In the presence of O2, RuBisCo can oxygenate ribulose bisphosphate, producing a 3 carbon 3PG and a 2 carbon phosphoglycolate. B. PEP carboxylase differs from RuBisCo in that it does not have oxygenase activity, improving the plant cell's capacity to capture the carbon. C. C4 and CAM plants both utilize PEP carboxylase. D. The photorespiratory cycle requires energy in the form of ATP and NADH to convert photorespiratory waste products back into 3PG. E. All of the answers are true.

E. All of the answers are true.

Auxin

promotes: -- vascular differential -- cell elongation -- cell wall loosening -- apical dominance (maintains upward growth) Polar transport aka moves downward due to the basally localized efflux carries

Under what conditions does the stomata close?

- water stress - high light - high CO2

Cytokinins

-- cell proliferation -- promote germination -- high cytokinins promotes shoots -- delays senescence Two component pathway with a receptor and an effector

Ethylne

--triple response -- stem growth -- fruit ripening two component system: - ethylene bunds to receptor in the ER which blocks repressor [CTR I] and promotes ethylene responses by EIN2 and EIN3

ABA

-- closes stomata under water stress -- major hormone implicated in stress tolerance and limiting growth transport of ABA via shoot transpiration stream to target guard cells ions go out, water follows, stomata becomes less turgid and guard cells close

Gibberellic Acid (GA)

-Induces synthesis of amylase and other hydrolases in embryoless half-seeds in isolated aleurone - perceived at the cell surface and in the nucleus ( involves G-protein & Ca2+ and cGMP as secondary messengers) - antagonistic by ABA

Movement of ions, like K+ or Cl-, from the soil into the vascular tissues of the plant: A. Requires channel or symport proteins to bypass the plant plasma membrane and gain entry into the symplastic space. B. Utilizes a chemiosmotic H+ gradient, where the plant cell wall maintains a higher, more basic pH than the cytosol. C. Requires passing through the Casparian Strip via the apoplastic pathway. D. Can occur by passive diffusion through the plasma membrane. E. A and B

A. Requires channel or symport proteins to bypass the plant plasma membrane and gain entry into the symplastic space.

If a plant cell is placed in distilled water (with no solutes)... A. The cell will have a negative water potential relative to the distilled water surrounding it. B. The water will osmotically move into the cell, decreasing the plant cell's pressure potential. C. The cell will lose turgor. D. The solute potential will become more negative as water osmotically moves into the cell. E. The pressure potential within the cell will decrease until it is equivalent to the cell solute potential.

A. The cell will have a negative water potential relative to the distilled water surrounding it.

During a drought, when plants have limited water access to water: A. The hormone ABA will be produced. B. Higher levels of K+ ions will be present in the xylem, decreasing the rate of fluid movement. C. Guard cells will increase their uptake of K+ and Cl-, lose turgor pressure, and close the stomata of the leaves. D. Plant cells comprising the plant body will gain turgor pressure. E. The plant transpiration rate out of the leaves will increase.

A. The hormone ABA will be produced.

Considering a tall tree that is moving water from the roots to leaves... A. The leaves, through the process of transpiration, lose water surrounding each cell in the cell wall creating tension in the water column. B. The positive pressure potential of the leaves is greater than that of the xylem. C. The water potential in the soil is more negative than in the nearby roots. D. The roots utilize positive pressure to drive water up xylem to the leaves. E. All answers are true.

A. The leaves, through the process of transpiration, lose water surrounding each cell in the cell wall creating tension in the water column.

When C3 plants are supplied with 14CO2: A. radioactivity appears first in the 3 carbon compound 3PG (phosphoglycerate) following carboxylation of RuBP (ribulose bisphosphate) B. radioactivity appears first in the 3 carbon compound G3P (glyceraldehyde-3-phosphate) following carboxylation of RuBP (ribulose bisphosphate) C. radioactivity appears first in the 3 carbon compound 3PG (phosphoglycerate) following carboxylation of 2 phospho-glycolate, the first step of Rubisco-catalyzed carbon fixation D. radioactive sugars are moved toward the young leaves at the apex via the transpiration stream in the xylem E. B and D

A. radioactivity appears first in the 3 carbon compound 3PG (phosphoglycerate) following carboxylation of RuBP (ribulose bisphosphate)

What below is FALSE regarding the light independent reactions/Calvin Cycle? A. Carboxylation (aka carbon fixation) is enzyme-catalyzed by RuBisCo, enabling CO2 to be captured and attached to the 5 carbon ribulose bisphosphate (RuBP). B. 3PG is a 3 carbon molecule, while G3P is a 4 carbon molecule. C. ATP is required to regenerate RuBP by 'sugar shuffling' the remaining G3P, enabling the cycle to restart with CO2 fixation. D. In the absence of light, the Calvin Cycle will continue to reduce 3PG to G3P until the supply of ATP and NADPH in the chloroplast is exhausted. E. Products of the Calvin Cycle are not only used to produce sugars, but also other molecules, including amino acids.

B. 3PG is a 3 carbon molecule, while G3P is a 4 carbon molecule.

Vanadate is a proton pump/ATPase inhibitor. What plant processes would you expect to inhibited or altered by this drug? A. Symplastic loading of photosynthates in the phloem. B. Opening and closing of the guard cells comprising stomata. C. Movement of water through the xylem. D. ABA-elicited loosening of the microfibrils in the plant cell wall by expansin protein activity. E. Active transport of ethylene into the plant cell.

B. Opening and closing of the guard cells comprising stomata.

When considering the movement of sap in the phloem or xylem what below is FALSE? A. Certain plant hormones can move throughout the plant body via the xylem or phloem. B. Sap movement in the xylem and phloem are both examples of symplastic movement. C. Phloem transport of sugars works on the principle of increased Psi P (pressure potential) in the areas of loading and decreased Psi P in the areas of unloading. This allows for translocation of the phloem sap. D. Sap in the phloem can undergo bidirectional movement while sap movement in the xylem is unidirectional. E. Increased solute concentration in the loading regions of phloem reduces the overall water potential in the phloem relative to the xylem. This promotes the osmotic movement of water from the xylem into the phloem.

B. Sap movement in the xylem and phloem are both examples of symplastic movement.

Gibberellins (GA): A. Are hormones that are produced by the aleurone layer of cells and perceived by the plant embryo to initiate germination. B. Research suggests that GA perception occurs at the cell membrane indicating that GA is a peptide hormone. C. Activation of the GA response pathway requires secondary messengers, including Ca2+ and cGMP. D. The GA response does not rely on transcriptional changes, but solely exocytosis of vesicles filled with alpha-amylase E. A and C

C. Activation of the GA response pathway requires secondary messengers, including Ca2+ and cGMP.

Most plant cells: A. Differentiate into dermal, vascular, or floral tissue types. B. Contain only chloroplasts, but not mitochondria. C. Are totipotent, and are capable of dedifferentiation and subsequent differentiation into different plant tissue types. D. Divide via cytokinesis using actin and myosin. E. Multiple of the above are true.

C. Are totipotent, and are capable of dedifferentiation and subsequent differentiation

In C4 plants, the function of the four-carbon compound that is synthesized by PEP carboxylase in the mesophyll cells is to: A. Reduce NADP+. B. Combine with carbon dioxide to produce glucose. C. Carry carbon dioxide to the bundle sheath cells. D. Drive the synthesis of ATP E. Close the stomata

C. Carry carbon dioxide to the bundle sheath cells.

Apoplastic loading of phloem: A. Requires plasmodesmata connecting photosynthate-producing (mesophyll) cells directly to companion cells. B. Occurs at sink tissues. C. Entails that sugar entry into the companion cell occurs by active transport. D. Is the only method by which photosynthates and hormones can enter into the phloem from source tissues. E. Ensures a positive solute potential in the companion cell compared to the xylem nearby.

C. Entails that sugar entry into the companion cell occurs by active transport.

Plant cell expansion: A. is parallel to the cellulose fibrils in the primary wall B. continues after establishment of the secondary wall C. depends on having turgor pressure > 0 and primarily increases vacuolar volume D. continues in mature xylem vessel elements, allowing them to become very long E. B and C

C. depends on having turgor pressure > 0 and primarily increases vacuolar volume

What below is not a response coordinated, in part, by ethylene? A. Radial swelling due to changes in the orientation of microfibril synthesis. B. Maintenance of the apical hook, protecting the cotyledons while under soil. C. Ripening of fruits D. Closing of the stomata E. All of the above are responses to ethylene

D. Closing of the stomata

Regarding plasmodesmata, what below is FALSE? A. Plasmodesmata link neighboring cell cytosols, creating the symplastic space B. Plasmodesmata are approximately 10-30x the size of gap junctions, enabling the transit of larger molecules between cells C. Parts of the endoplasmic reticulum, called desmotubules, can be present in plasmodesmata D. Companion cells are linked to xylem tracheid and vessel elements via plasmodesmata E. Plasmodesmata are only present in plant cells and are not found in any animal cells

D. Companion cells are linked to xylem tracheid and vessel elements via plasmodesmata

Cellulose microfibrils... A. Are cross-linked by H bonds between hemi-cellulose and cellulose. B. Are typically produced in an orientation perpendicular to plant cell expansion. C. Interactions can be loosened by expansins, proteins activated indirectly by auxins. D. Can have the orientation of their synthesis altered by ethylene perception. E. All answers are true.

E. All answers are true.

In the light reactions of photosynthesis: A. Light energy is converted to metabolic energy in the form of ATP and NADH B. Regeneration (gaining back of an electron) of the photosystem II occurs by cyclic photophosphorylation C. Isolated thylakoids should produce ATP if pre-incubated in a basic buffer, then transferred to a neutral solution containing ADP + Pi, even if maintained in total darkness D. Carbon dioxide is fixed into G3P in the thylakoid lumen E. Light energy is used to generate a H+ gradient across the thylakoid membrane that drives chemiosmotic ATP synthesis

E. Light energy is used to generate a H+ gradient across the thylakoid membrane that drives chemiosmotic ATP synthesis

What below is FALSE when considering phloem? A. Enables the translocation of phloem sap carrying photosynthates and hormones. B. Enables movement action potentials. C. Directionality can change over the life span of the plant depending on the location of sources and sink tissues. D. Are comprised of living cells each of whom are physically linked to companion cells via plasmodesmata. E. Phloem cells, called tracheids, maintain membrane-bound organelles.

E. Phloem cells, called tracheids, maintain membrane-bound organelles.

Chloroplasts: A. Are the primary source of ATP for the plant cell. B. Comprise a single membrane that surrounds the stacks of thylakoids, called grana. C. Are the location of the Calvin Cycle reactions, which occur in the thylakoid lumen. D. Have stroma that is more acidic than the thylakoid lumen. E. Utilize an electron transport chain, like mitochondria, to establish a chemiosmotic gradient of H+.

E. Utilize an electron transport chain, like mitochondria, to establish a chemiosmotic gradient of H+.

Jagendorf experiment proved the function of thylakoids by using pH changes determine thylakoid function. Given what you know about the light reactions, what is conclusions of the experiment below. a. ATP is produced b. NADPH is produced c. NADP is produced d. glucose is produced e. more than one above

a. ATP is produced

When analyzing how C3, C4 and CAM plants differ in terms of Carbon Fixation. Select one: a. C4 plants fix CO2 by converting PEP (3 Carbon compound) to Oxaloacetate (4 Carbon compound) b. CAM plants utilize spatial separation of the cells responsible for Carbon Fixation and the cells that are responsible for sugars through the Calvin-Benson Cycle c. C3 plants have RuBisCo that is highly specific to CO2 and therefore does not require isolation from O2 generated by water splitting and/or closing of the leaf stomata d. Only C4 plants utilize PEP (phosphoenol pyruvate) as the initial 3 carbon compound that CO2 is fixed into e. None of the above are true

a. C4 plants fix CO2 by converting PEP (3 carbon compound) to Oxaloacetate (4 carbon compound)

Which of the following statements about the movement of potassium ions through open stomata is true? a. K+ enters guard cells, water follows, and the cells become turgid b. K+ leaves guard cells through plasmodesmata and they become less turgid c. K+ enters guard cells and they become less turgid d. K+ leaves guard cells and they become turgid e. K+ reaches equilibrium in guard cells and their surroundings

a. K+ enters guard cells, water follows, and the cells become turgid

The photosystems allow plant chloroplasts to harvest light energy. When thinking about the photosystems that comprise typical 'green' plants... A. Photosystem II splits water within the thylakoid lumen to produce molecular oxygen and H+. B. Photosystem I is located 'upstream' to photosystem II, in that I will donate electrons to photosystem II in the Z scheme of the light reactions. C. Photosystem II is responsible for cyclic photophosphorylation to generate ample NADPH for the Calvin Benson cycle D. ATP and NADPH production occurs in the lumen of the thylakoid E. Electrons from photosystems I and II are ultimately used to reduce oxygen to molecular water.

a. Photosystem II splits water within the thylakoid lumen to produce molecular oxygen and H+.

Movement of mineral ions in the soil into a root's vascular tissue (xylem) takes place by apoplastic transport past the Casparian strip of the endodermis a. true b. false

b. false

The NADPH generated in the thylakoid stroma is used to oxidize RuBP to 3PG a. true b. false

b. false

Plants and plant cells are unique as there are defined age gradients at each level that can be observed. In terms of the plant cell wall, which statement is false? a. the primary cell wall is older and located outside of the plant secondary wall b. the site of a major plant compartment of the plant body, the symplast c. largely consists of a meshwork of hydrophillic cellulose, hemicellulose, and pectin in a well hydrated enviorment d. have a lower pH than the cytoplasm

b. is the site of a major plant compartment of the plant body, the symplast

In the light reactions of photosynthesis. Select one: a. light energy is used to generate a H+ gradient across the outer chloroplast membrane that drives chemiosmotic ATP synthesis b. isolated thylakoids should produce ATP if pre-incubated in an acidic buffer, then transferred to a neutral solution containing ADP + Pi, even if maintained in total darkness c. an excited chlorophyll molecule in the reaction center of Photosystem I acts as an oxidizing agent of water -- but a reducing agent to the Electron Transport Chain d. regeneration of the P680 in photosystem II occurs by cyclic photophosphorylation e. light energy is converted to metabolic energy in the form of ATP and NADH

b. isolated thylakoids should produce ATP if pre-incubated in an acidic buffer, then transferred to a neutral solution containing ADP + Pi, even if maintained in total darkness

Which of the following processes contributes the most to generating the negative water potential in a leaf? a. the pressure placed on the lead by cuticle (the waxy film that protects the epidermal tissues of a leaf) b. the evaporation of water from mesophyll cells c. the movement of water into the leaf by root pressure d. the increased K+ pumped out of guard cells e. the movement of water from the veins into the leaf

b. the evaporation of water from mesophyll cells

Which of the following statements regarding ethylene in plants is FALSE? a.Ethylene promotes plant senescence b. Ethylene speeds the ripening of fruit c. Ethylene perception occurs at the plasma membrane even though ethylene can easily diffuse across this membrane d. Ethylene perception and signal transduction relies on a two-component regulatory pathway. e. Ethylene synthesis in seedling plants largely stops when the seedling emerges from the soil and is exposed to light

c. Ethylene perception occurs at the plasma membrane even though ethylene can easily diffuse across this membrane

Positive pressure (Psi P) potential within a cell is most likely to result in: a. a decrease in the diffusion of ions into that cell b. the increase in the diffusion of ions into that cell c. a decrease in the uptake of water by that cell d. an increase in the uptake of water by that cell e. an increase in the uptake of both water and ions by that cell

c. a decrease in the uptake of water by that cell

In C4 plants, the function of the four carbon compound that is synthesized in the mesophyll cells is to: a. reduce NADP+ b. combine with CO2 to produce glucose c. carry CO2 to the bundle sheath cells d. drive the synthesis of ATP e. close the stomata

c. carry CO2 to the bundle sheath cells

At a source, sucrose moves into the phloem in the apoplastic pathway by: a. tension within sieve tubes produced by sucrose unloading at sink cells b. osmosis c. secondary active transport into companion cells (using the protein gradient and symport of the sugar) d. strictly symplastic movement from the adjacent mesophyll cells e. A and D

c. secondary active transport into companion cells (using the proton gradient and symport of the sugar)

An epithelial root hair plant cell has a turgor/pressure potential of 0.5 MPa and has a solute/osmotic potential of -0.75. Therefore: a. the cell has a water potential of -1.25 MPa b. the cell has a water potential of 1.25 MPa c. the cell has a water potential of -0.25 d. will take up water from the surrounding soil if the soil potential is -1.0 MPa e. c and d

c. the cell has a water potential of -0.25

When a suspension of algae is incubated in a flask in the presence of light and CO2 and then transferred to the dark, the reduction of 3PG to G3P is blocked. This reaction stops when the algae are placed in the dark because: a. the reaction requires CO2 b. the reaction is exergonic c. the reaction requires ATP and NADP+ H+ d. the reaction requires O2 e. chlorophyll is not synthesized in the dark

c. the reaction requires ATP and NADPH+ H+

The Calvin Benson cycle use the energy trapped in ATP and NADPH generated by the light reactions to build sugars from CO2. What below is FALSE regarding this sugar-building cycle? a. Initially RuBP is carboxylated by RuBisCo where atmospheric CO2 is captured and put into the cycle. b. ATP and NADPH generated by the light reactions are used to reduce 3PG to a more energetic/reduced G3P (some of which will be diverted off to build sugar!) c. More ATP (from the light reactions) are required to regenerate the remaining G3P to RuBP for the initial CO2 fixation d. In the absence of light, the Calvin Benson cycle will continue to reduce 3PG to G3P indefinitely, but will be unable to regenerate RuBP e. Photorespiration occurs when Rubisco inadvertantly captures O2 instead of CO2. I this situation, instead of generating two molecules of 3PG, photorespiration results in 1 molecule of 3PG and 1 molecule of a 2 carbon compound called 2PG (2-phosphoglycolate)

d. In the absence of light, the Calvin Benson cycle will continue to reduce 3PG to G3P indefinitely, but will be unable to regenerate RuBP

Xylem: A. Is comprised of sieve tube elements. B. Is comprised of living cells that have removed most membrane-bound organelles. C. Are linked to one another via plasmodesmata filled with desmotubules. D. Maintains negative pressure potentials to move xylem sap using the transpiration- tension-cohesion mechanism. E. Are used to move water and carbon-containing organic nutrients from the soil to growing parts of the plant.

d. Maintains negative pressure potentials to move xylem sap using the transpiration- tension-cohesion mechanism.

Which of the following factors has a direct impact on the orientation and expansion of planet cells? a. initial cellulose microfibril orientation b. lignin deposition c. turgor pressure d. all of the above

d. all of the above

A plant cell placed in distilled water will: a. expand until the solute potential reaches that of the distilled water b. become more turgid until the solute potential reaches that of the distilled water c. become less turgid until the solute potential reaches that of the distilled water d. becomes more turgid until the pressure potential of the cell reaches its solute potential e. becomes less turgid until the pressure potential of the cell reaches the outside water potential

d. becomes more turgid until the pressure potential of the cell reaches its solute potential

In CAM metabolism: a. fixed carbon is shuttled from mesophyll to bundle sheath cells b. the problems of photorespiration are reduced by isolating the enzyme PEP carboxylase from high levels of dissolved O2 c. carbon fixation by the Calvin cycle occurs at night to avoid photorespiration d. carbon is fixed via C4 metabolism at night and by the Calvin cycle in the day e. fixed carbon is stored in the vacuole in the form of G3P, a 4 carbon compound

d. carbon is fixed via C4 metabolism at night and by the Calvin cycle in the day

Phytochrome: a. Is a protein photoreceptor that enables plants to measure blue light quantity, quality, and duration b. Has a role in promoting germination of seeds exposed to far red light c. Is an example of a two-component regulatory system where as a receptor the protein is localized to the membrane. d. Refers to a family of proteins that have light sensitive pigment molecules called chromophores. e. have both a peroxisomal localization sequence and protease domain

d. refers to a family of proteins that have light sensitive pigment molecules called chromophores

Which statement regarding the primary cell walls of plants is false? a. they contain pectins b. they contain hemicellulose c. the primary cell walls of two adjacent cells are separated by the middle lamella d. they contain high concentrations of hydrophobic lignins

d. they contain high concentrations of hydrophobic lignins

Short-day plants: a. flower when grown in 10 hour days, regardless of the duration of the night period b. will flower if given a pulse of darkness in the middle of a long light period c. will flower if given a pulse of red light in the middle of a short dark period d. will not flower if given a pulse of red light in the middle of a long dark period e. will not flower if given a pulse of far red light in the middle of a long dark period

d. will not flower if given a pulse of red light in the middle of a long dark period

The Casparian strip: A. is a waxy layer in the walls of endodermal cells B. is the site of movement of water and minerals through the membranes of endodermal cells C. provides an opportunity for regulation of mineral uptake from the soil by the plant D. is found throughout the entire plant, including the leaves E. A and C only

e. A and C only

when sucrose is added to phloem cells at a source via the apoplastic pathway of loading: a. water follows by osmosis and hydrostatic pressure pushes sucrose toward a sink b. water follows primarily by mass/bulk flow through abundant plasmodesmatal connections to adjacent mesophyll cells c. most of the sugar is loaded directly into the sieve tub elements, bypassing the companion cells d. active transport of sucrose molecules from a leaf's apoplast to its phloem requires cotransport with protons e. A and D

e. A and D

Gibberellins (GA) stimulates the synthesis of alpha-amylase. Select one: a. In the aleurone layer of cells b. Via the promotion of transcription of the alpha amylase gene c. By the recognition of GA both intracellularly and at the cell surface d. GA responses are negatively regulated by auxin e. A, B, and C

e. A, B, and C

When considering phloem loading, unloading and transport, what below is incorrect? a. Phloem loading (of some plants) requires channel proteins to export sugars into the apoplastic space between parenchymal cells and companion cells b. Phloem loading and unloading requires a proton gradient established by an ATPase that pumps protons into the plant cell wall. (Make sure you understand how this works in loading and unloading). c. Phloem transport of sugars works on the principle of increased Psi P in the areas of loading and decreased Psi P in the areas of unloading. This allows for bulk flow of the phloem d. Like vessel elements in xylem, phloem sieve tube elements are like stacked cans that allow for the movement. However, unlike vessel elements sieve tube elements are alive and allow for bidirectional movement of the phloem. e. Increased solute concentration in the phloem reduces the overall water potential in the phloem (vs the xylem). This allows for the osmotic movement of water from the xylem into the phloem located at both the source and sink areas.

e. Increased solute concentration in the phloem reduces the overall water potential in the phloem (vs the xylem). This allows for the osmotic movement of water from the xylem into the phloem located at both the source and sink areas.

Age gradients within the plant body: A. include phloem that is oldest toward the outermost cell layers and xylem that is oldest toward the innermost cell layers of a tree trunk B. reflect plant cells' lack of mobility due to their shared walls that are glued together by the middle lamella. C. include walls that are youngest immediately adjacent to the plasma membrane and progressively older toward the middle lamella D. include an apical-basal gradient where the youngest cells are near the apices (tips) of the plant E. all of the above

e. all of the above

Auxin transport: a. is polar whereby auxin travels from shoot tips down the plant towards the roots b. produces a gradient of auxin required to establish organ formation and phototropic responses c. Auxin is at highest concentration, near its sources, like the apical meristems d. directionality of auxin movement (conferring polarity) is conferred by basally localized efflux carries called PIN proteins e. All of the above are true

e. all of the above

When you think about the two pathways by which the phloem can be loaded with sugars generated by the mesophyll cells of the leaf, what is FALSE below? a. Sugars move towards the phloem through mesophyll cells by the symplastic pathway. This is due to diffusion of the sugar down it's concentration gradient. b. Entry into the phloem (through the companion cell) can be either through a symplastic or apoplastic pathway c. In the apoplastic loading pathway, movement of sugars into the companion cells requires ATP and a H+ gradient to pull the sugar into the companion cells (against the sugar gradient) through a protein symporter d. The increased concentration of sugars at the source increases the pressure potential of the phloem, resulting in the movement of phloem sap (tree blood) to sink areas (which have less pressure). e. all of the above are true

e. all of the above are true

The transpiration tension cohesion mechanism explains how water is moved through the plant from the roots to the leaf tissue. What below is incorrect in regards to this mechanism? a. the leaves, through the process of transpiration, lose water that surrounds the mesophyll cells in the apoplastic space to outside of the leaf. This reduction of water surrounding each cell (in the cell wall) increases the negative pressure potential (Psi P) creating negative tension. b. The negative tension created by the mesophyll cells is greater than that of the xylem, the water-conducting vascular tissue. This explains how leaves stay hydrated (and replaces the water lost due to transpiration). c. The removal of water from the xylem 'veins' in turn establishes tension on the entire column of water contained in the xylem (through the veins, through the shoot, to the root). d. Due to the polar nature of water, which allows for hydrogen bonding between these molecules (resulting in cohesion), the water column is maintained (no breakage). Thus, as leaves transpire they create negative tension that draws water into them. This negative potential in turn draws water up the xylem to replace the respired water. e. all of the above are true and explain the mechanism

e. all of the above are true and explain the mechanism

The ATP needed in the Calvin cycle: a. is produced by both cyclic and noncyclic (aka the Z scheme) photophosphorylation b. is used during the "sugar shuffle" that regenerates RuBP c. is used during the carboxylation of RuBP d. all of the above e. only A and B

e. only A and B