UNIT 3: PHOTOSYNTHESIS AND THE PLANT BODY
Explain how cells are able to maintain a lack of metabolic equilibrium
the product of a reaction does not accumulate but instead becomes a reactant in the next step; finally, waste products are expelled from the cell. The overall sequence of reactions is kept going by the huge ask??
trace the flow of electrons during cyclic electron flow
*only involves in photosystem * -electrons carried from P700 to FeS and on to Fd as normal -But electrons are then passed to a mobile carrier(b6) and then over to PQ, rather then being passed to NADP+ -this means electrons are donated by P700 are recycled to fill the electron deficit in P700 (ask profosser)
How does ATP differ from ADP and AMP: -AMP?
-ADP is hydrolyzed to make AMP, one of the nucleotides of which RNA is composed
differentiate between apical -Where is each found in the plant body?
-Apical meristems, located at root and shoot tips, provide cells that enable primary growth, growth in length.
Which meristem is responsible for primary growth? Secondary growth?
-Apical meristems: Primary Growth -Lateral Meristems: Secondary Growth
Describe the resulting chemical gradient of H+ ions, indicating where the pH is higher, and where it is lower
-As H+ ions are removed from the stroma and transported into the thylakoid interior by PQ(electron carrier), the concentration of H+ ions in the stroma decreases, and the concentration of OH- ions increases. -The result is that the stroma becomes more basic, reaching a pH of about 8. -At the same time, the thylakoid interior becomes more acidic (pH 4) due to the pumping of H+ ions across the membrane by PQ and the splitting of water. -This creates the powerful electrochemical gradient across the membrane that is used to synthesize ATP.
point out the site where hydrogen ions are transported across the thylakoid membrane from the stroma to the thylakoid interior as a result of the flow of electrons through the transport chain.
-As H+ ions are removed from the stroma and transported into the thylakoid interior by PQ, the concentration of H+ ions in the stroma decreases, and more water dissociates to provide more H+ ions, and so on. -In addition, some H+ ions are returned to the stroma during the process of ATP synthesis. -It takes about 3 H+ ions flowing through ATP synthase to produce one ATP. -These H+ ions may be picked up by reduced NADP and used in the Calvin Cycle, or they may be returned to the stroma solution. -there is a constant cycling of H+ ions across the membrane and back again (ask professor)
describe events occurring during each phase of the Calvin cycle. In doing so, consider the following: • the reaction in which CO2 is added.
-Calvin cycle occurs in the stroma, using electrons from NADPH and energy from ATP. One molecule of G3P exits the cycle per three CO2 molecules fixed and is converted to glucose and other organic molecules
Explain what meristems are and differentiate between apical and lateral meristems.
-Cells in apical and lateral meristems divide frequently during the growing season, generating additional cells. -
Describe the pattern of growth that leads to the rings in cross sections of a tree.
-Growth rings vary in thickness, depending on seasonal growth. -Trees grow well in wet and warm years but may grow hardly at all in cold or dry years. -Since a thick ring indicates a warm year and a thin ring indicates a cold or dry one, scientists use ring patterns to study climate changes
be able to distinguish between taproots and fibrous roots.
-In taproot systems, the role of absorption is restricted largely to the tips of lateral roots. -The adventitious roots of monocots and their lateral roots give rise to an extensive fibrous root system, in which no one root is more prominent than the others.
In photosystem I : -how this flow of electrons provides energy for the synthesis of ATP.
-Light is absorbed and the energy is used to drive electrons from water to generate NADPH and to drive protons across a membrane. -These protons return through ATP synthase to make ATP
learn to differentiate among monocot stems, herbaceous eudicot stems and woody eudicot stems: -monocot stems?
-Monocot stems have scattered vascular bundles -most of their vascular bundles near the outside edge of the stem -In such an arrangement, ground tissue is not partitioned into pith and cortex
list the three products of linear electron flow
-NADPH -ATP -oxygen
distinguish between primary and secondary phloem?
-Primary phloem forms in primary growth regions at the tips of stems and roots, -secondary phloem is what arises from the vascular cambium.
distinguish between primary and secondary xylem.
-Primary xylem is the xylem formed during primary growth from the procambium of the apical meristem. -The secondary xylem is the xylem formed as a result of secondary growth from the vascular cambium of the lateral meristem. It is differentiated into two parts: Metaxylem and Protoxylem.
what is the sugar product of the Calvin cycle?
-The Calvin cycle reactions use chemical energy from NADPH and ATP that were produced in the light reactions. -The final product of the Calvin cycle is glucose.
function of cork cells
-The cork cells, cork cambium, and parenchyma cells formed from the cork cambium make up the periderm. -The cork cells are waterproofed with suberin and provide good thermal insulation, which may serve to protect tree stems from damage due to excessive heat or cold.
explain how the H+ gradient is storing energy
-The energy generated by the hydrogen ion stream allows ATP synthase to attach a third phosphate to ADP, which forms a molecule of ATP in a process called photophosphorylation. -the flow of hydrogen ions through ATP synthase is called chemiosmosis (ask professor)
Where does this energy come from to synthesize ATP from ADP and P1?
-The enzyme ATP synthase acts as a channel protein and helps the ions cross the membrane. -ATP synthase also uses their energy to add a phosphate group (Pi) to a molecule of ADP, producing a molecule of ATP. (ask professor)
identify the vascular cambium, explain how it produces secondary xylem and phloem: -indicate where each is located in a woody stem for xylem?
-These layers are called heartwood because they are closer to the center of a stem or root -newest, outer layers of secondary xylem still transport xylem sap and are therefore known as sapwood
identify the vascular cambium, explain how it produces secondary xylem and phloem,
-When a vascular cambium cell divides, sometimes one daughter cell becomes a secondary xylem cell (X) to the inside of the cambium or a secondary phloem cell (P) to the outside. -Although xylem and phloem cells are shown being added equally here, usually many more xylem cells are produced
What are the common names for the tissues produced by the two types of lateral meristems?
-Xylem is wood and Pholem is bark -Periderm is rhytidome
describe how the resulting electron deficit in photosystem II is filled.
-a photon hits photosystem II, the pigment molecules pass an excited state from pigment to pigment, eventually reaching P680. When P680 is excited, it becomes a very strong electron donor -P680 (in this excited state) donates an electron to molecule Q in the thylakoid membrane, reducing Q -Q reduces PQ. Note that PQ is both an electron and a hydrogen ion carrier. This means that when PQ picks up the two electrons it can carry it must also pick up two H+ ions.
identify the vascular cambium, explain how it produces secondary xylem and phloem: -indicate where each is located in a woody stem for pholem?
-bark includes all tissues external to the vascular cambium. -Its main components are the secondary phloem (produced by the vascular cambium) and, external to that, the most recent periderm and all the older layers of periderm
How does ATP differ from ADP and AMP: -ADP?
-cell stores energy by adding a phosphate group to ADP to make ATP -recovers some of this energy by hydrolyzed ATP into ADP and inorganic phosphate
lateral meristems: -Where is each found in the plant body?
-growth in thickness, known as secondary growth, is made possible by lateral meristems: the vascular cambium and cork cambium -These cylinders of dividing cells extend along the length of roots and stems.
State the function of the cork cambium
-produces parenchyma cells to the inside and cork cells to the outside.
list the two products of cyclic electron flow.
-result of the cyclic path is that an H+ gradient is maintained , allowing for some ATP production but NADPH is produced (ask professor)
explain what is meant by a primary electron acceptor
-which is a molecule capable of accepting electrons and becoming reduced -primary electron acceptor is the first step of the light reactions. -As soon as the chlorophyll electron is excited to a higher energy level, the primary electron acceptor captures it; this is a redox reaction
Contrast the anatomy of Zea with the Ligustrum leaf, and give a difference between them. -Ligustrum leaf structure
-which lacks bundle sheath extensions. -Ligustrum leaf is sectioned parallel to the leaf surface through the spongy mesophyll. (ask professor)
identify lenticels
-which there is more space between cork cell -Dotting the periderm are small, raised areas -appear as horizontal slits
briefly explain the C4 process
1. In mesophyll cells, the enzyme PEP carboxylase adds CO2 to PEP, forming a four-carbon compound. 2.The four-carbon compound (such as malate) moves into a bundle-sheath cell via plasmodesmata. 3. In bundle-sheath cells, CO2 is released and enters the Calvin cycle.
Differentiate between C3 and C4 plants: -C3 plants?
>C3 plants are the first organic product of carbon fixation is a three-carbon compound, 3-phosphoglycerate -When their stomata partially close on hot, dry days, C 3 plants produce less sugar because the declining level of CO 2 in the leaf starves the Calvin cycle
Differentiate between C3 and C4 plants: -C4 plants
>C4 Plants preface the Calvin cycle with an alternate mode of carbon fixation that forms a four-carbon compound as its first product.
As the H+ ions are moved into the thylakoid lumen, a proton motive force is created: Which side of the thylakoid membrane (the thylakoid space or the stroma) will become positively charged and which negatively charged?
As a result of the H+ ions released during water-splitting and electron transport, the inside of the thylakoid membrane becomes positively charged and the outside becomes negatively charged.
describe the unusual leaf anatomy seen in C4 plants (referred to as "Kranz anatomy")
C4 leaf are usually arranged in a ring around the bundle sheath
Carbon Cycle: 1. step
Carbon fixation: -CO 2 molecule, attached to a five carbon sugar named ribulose bisphosphate (abbreviated RuBP). -The enzyme that catalyzes this first step is RuBP carboxylase-oxygenase, or rubisco . -The product of the reaction is a six-carbon intermediate that is short-lived because it is so energetically unstable that it immediately splits in half, forming two molecules of 3-phosphoglycerate (for each CO 2 fixed).
Using a corn plant in the demo as an example of a grass (Family Poaceae), point out the stem, a leaf, and a node. On the leaf, identify the blade, the parallel venation, and the sheath. -How would the arrangement of veins differ in a eudicot?
Eudicots generally have a branched network of veins arising from a major vein (the midrib) that runs down the center of the blade. (ask professor)
Is the hydrolysis of ATP to ADP and (P) an exergonic (energy-releasing) or endergonic (energy-requiring) reaction?
Exergonic Reaction: -Next, ATP is hydrolyzed, releasing ADP and (P) . Another ATP molecule can then bind.
Are roots commonly used as food more likely to be fibrous or taproots? Why?
Fibrous roots, with their thickly branching system and more numerous roots, have more surface area and more root hairs than taproot systems do to take in food and water. (ask professor)
Describe what is happening in Fig. 3.22a
How photosystem harvests light: -When a photon strikes a pigment molecule in a light-harvesting complex, the energy is passed from molecule to molecule until it reaches the reaction-center complex. -Here, an excited electron from the special pair of chlorophyll a molecules is transferred to the primary electron acceptor
Differentiate between autotrophs and heterotrophs and give examples of organisms using each nutritional mode: -heterotrophs example
Heterotrophs are the biosphere's consumers . The most obvious "other-feeding" occurs when an animal eats plants or other organisms. But heterotrophic nutrition may be more subtle.
how to determine whether a reaction is exergonic or endergonic.
If a chemical process is exergonic (downhill), releasing energy in one direction, then the reverse process must be endergonic (uphill), using energy.
Using the notes at the end of this unit, examine the microscopic slide (labeled Ligustrum leaf) containing a cross section of a privet leaf (a C3 plant) in the demo. -Describe how leaves are adapted for carrying out photosynthesis.
Large surface area - To absorb light. Thin - Short distance for diffusion of CO2. Chlorophyll - Absorbs sunlight. Veins - Support and transport of water and carbohydrates. Stomata - Allow CO2 to diffuse into leaf. (ask professor)
Which tissue produces cells that result in a growth in girth?
Lateral meristems
Which tissue produces cells that result in elongation of the plant body?
Meristem: This tissue enables the monocot leaf blade to increase in length from the leaf base
Would green light be effective in supporting photosynthesis? Why or why not?
No, because The spectrum of chlorophyll a at violet-blue and red light work best for photosynthesis, since they are absorbed, while green is the least effective color.
Do C4 plants have a problem fixing CO2? Why or why not?
PEP carboxylase can fix carbon efficiently: In effect, the carbon dioxide fixed by the C4 pathway is "pumped" from the mesophyll cells into the bundle sheath cells where the Calvin cycle takes place.
Carbon Cycle: -phase 2
Reduction: -Each molecule of 3-phosphoglycerate receives an additional phosphate group from ATP, becoming 1,3-bisphosphoglycerate. -Next, a pair of electrons donated from NADPH reduces 1,3-bisphosphoglycerate, which also loses a phosphate group in the process, becoming glyceraldehyde 3-phosphate (G3P). -Specifically, the electrons from NADPH reduce a carboyxl group on 1,3-bisphosphoglycerate to the aldehyde group of G3P, which stores more potential energy. G3P is a sugar—the same three-carbon sugar formed in glycolysis by the splitting of glucose -every three molecules of CO 2 that enter the cycle, there are six molecules of G3P formed. But only one molecule of this three-carbon sugar can be counted as a net gain of carbohydrate because the rest are required to complete the cycle. -The cycle began with 15 carbons' worth of carbohydrate in the form of three molecules of the five-carbon sugar RuBP. -Now there are 18 carbons' worth of carbohydrate in the form of six molecules of G3P. -One molecule exits the cycle to be used by the plant cell, but the other five molecules must be recycled to regenerate the three molecules of RuBP.
Carbon cycle: -phase 3
Regeneration -CO 2 acceptor (RuBP). In a complex series of reactions, the carbon skeletons of five molecules of G3P are rearranged by the last steps of the Calvin cycle into three molecules of RuBP. -To accomplish this, the cycle spends three more molecules of ATP. The RuBP is now prepared to receive CO 2 again, and the cycle continues.
Is this bond between the terminal phosphate and the rest of the ATP molecule a strong or weak bond?
The reason the reaction is exergonic is that this covalent bond is unusually weak (in part because of the electrostatic repulsion of the negatively charged phosphate groups) and therefore requires only a small investment of energy to break.
define the wavelengths of light absorbed by chlorophyll a
The spectrum of chlorophyll a suggests that violet-blue and red light work best for photosynthesis, since they are absorbed, while green is the least effective color.
Is it moving the H+ ions with or against their concentration gradient?
Their energy is used to pump H+ ions from outside to inside the thylakoid against a concentration gradient. The H+ ions build up inside the thylakoid (ask professor)
What happens when a cell reaches metabolic equilibrium?
a cell that has reached metabolic equilibrium is dead!
What is the function of chlorophyll b?
ability to absorb higher frequency blue light for use in photosynthesis.
give three functions of root systems
absorption of water and dissolved minerals and conduction of these to the stem, and storage of reserve foods. (ask professor)
What molecule is transporting the protons and electrons?
chlorophyll molecule
What happens to the Calvin cycle in the dark? Hint: Where does the NADP+ and ADP required for chemiosmosis (Fig. 3.26, p. 176) come from?
does not actually occur in the dark or during nighttime. This is because the process requires reduced NADP which is short-lived and comes from the light-dependent reactions.
state their function for lenticels
enabling living cells within a woody stem or root to exchange gases with the outside air
What is a photosystem?
is composed of a reaction-center complex surrounded by several light-harvesting complexes
Define the term free energy
is the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.
Differentiate between autotrophs and heterotrophs and give examples of organisms using each nutritional mode: -heterotrophs
obtain organic material by the second major mode of nutrition. Unable to make their own food, they live on compounds produced by other organisms
carotenoid pigments?
photoprotection : These compounds absorb and dissipate excessive light energy that would otherwise damage chlorophyll or interact with oxygen, forming reactive oxidative molecules that are dangerous to the cell. -Interestingly, carotenoids similar to the photoprotective ones in chloroplasts have a photoprotective role in the human eye
What is wasted during photorespiration?
photorespiration drains away as much as 50% of the carbon fixed by the Calvin cycle.
where in the chloroplast the electron transport chain for cyclic electron flow is located?
photosystem I only promotes the translocation of protons from stroma to thylakoid lumen
Contrast the anatomy of Zea with the Ligustrum leaf, and give a difference between them. -Zea leaf?
presence of a bundle-sheath surrounding the veins in the leaf which usually contains large, conspicuous chloroplasts. Another important feature of C4 plants is the close spacing of the longitudinal vascular bundles.
Explain what is meant by the phrase "energy coupling"
the use of an exergonic process to drive an endergonic one
What are vascular rays and what function(s) do they serve?
—radial files of mostly parenchyma cells that connect the secondary xylem and phloem -Function: These cells move water and nutrients between the secondary xylem and phloem, store carbohydrates and other reserves, and aid in wound repair.
Explain what meristems are
-meristems containing cells that can divide, leading to new cells that elongate and become differentiated
give the conditions photorespiration occurs
-occurs in the light ( photo ) and consumes O 2 while producing CO 2 ( respiration ). -However, unlike normal cellular respiration, photorespiration uses ATP rather than generating it.
What is the advantage of Kranz anatomy?
-As photosynthesis takes place, CO2 will be consumed and oxygen will be generated and eventually, CO2 levels will reduce. -However, because of Kranz anatomy, the CO2 levels around RUBISCO in Bundle sheath cells will always be more and it will continue to fix carbon and not give rise to photorespiration. (ask professor)
Differentiate between autotrophs and heterotrophs and give examples of organisms using each nutritional mode: -autotrophs
-Autotrophs are they sustain themselves without eating anything derived from other living beings. -Autotrophs produce their organic molecules from CO 2 and other inorganic raw materials obtained from the environment. Almost all plants are autotrophs; the only nutrients they require are water and minerals from the soil and carbon dioxide from the air.
Briefly explain how (1) C4 and (2) CAM plants avoid photorespiration under conditions of high light intensity and high temperature. -C4 plants?
-C4 plants in hot regions with intense sunlight, where stomata partially close during the day
Briefly explain how (1) C4 and (2) CAM plants avoid photorespiration under conditions of high light intensity and high temperature: -CAM plants?
-CAM plants open their stomata during the night and close them during the day, just the reverse of how other plants behave. Closing stomata during the day helps desert plants conserve water, but it also prevents CO 2 from entering the leaves.
explain how the excited electrons are passed to photosystem I
-P700 becomes a strong electron donor and reduces FeS. -FeS passes electrons to Fd and on to FAD. FAD gives up two electrons to NADP+ in the stroma, reducing it to NADPH. (ASK PROFESSOR)
trace the overall movement of electrons from water to the reduced carrier, NADPH, during linear electron flow. We suggest that you start with a photon absorbed by photosystem II, trace the fate of electrons activated by that event
-P700 molecule it excites an electron, moving it to a higher energy level. This means that when P700 absorbs light it becomes a very strong electron donor. -P700 then donates excited electrons to FeS, reducing it. FeS passes electrons to Fd, which then passes electrons to FAD. -FAD then donates electrons to a special electron carrier molecule, NADP+ , which is free in the stroma of the chloroplast. NADP+ can accept two electrons, so it picks up two electrons from FAD, picks up a proton (H+) from the stroma, and is reduced to form NADPH. -electrons started at P700 (1), were passed along the thylakoid membrane by several electron transport molecules (2), and end up on NADPH (3). Now that P700 has given up electrons, it becomes a very strong electron acceptor
As the H+ ions are moved into the thylakoid lumen, a proton motive force is created: How does this electrical gradient influence the movement of ions like H+?
-PS I is made up of the electron carrier plastoquinone (Pq), a cytochrome complex, and a protein called plastocyanin (Pc). -Each component carries out redox reactions as electrons flow down the electron transport chain, releasing free energy that is used to pump protons (H + ) into the thylakoid space, contributing to a proton gradient across the thylakoid membrane
Using the notes at the end of this unit, examine the microscopic slide (labeled Ligustrum leaf) containing a cross section of a privet leaf (a C3 plant) in the demo. -How do leaves solve the problem of maintaining an adequate surface to volume ratio for obtaining carbon dioxide while at the same time preventing excessive water loss?
-Plants reduce water loss by closing their stomata, developing thick cuticles, or by possessing leaf hairs to increase the boundary layer. -Stomata are quick to respond to environmental cues to protect the plant from losing too much water, but still allowing in enough carbon dioxide to drive photosynthesis
What happens to the ADP, P1, and NADP+ formed during the Calvin cycle of photosynthesis?
-The ADP and NADP+ that result from the Calvin cycle shuttle back to the light reactions, which regenerate ATP and NADPH. (ask professor)
List the two basic processes in photosynthesis ?
-The light reactions in the thylakoid membranes split water, releasing O2, producing ATP, and forming NADPH. -The Calvin cycle in the stroma forms sugar from CO2, using ATP for energy and NADPH for reducing power
explain how the two processes are coupled, i.e., dependent on each other
-The light reactions use solar energy to make ATP and NADPH, which supply chemical energy and reducing power, respectively, to the Calvin cycle. The Calvin cycle incorporates CO 2 into organic molecules, which are converted to sugar -light reactions provide the NADPH and ATP that the Calvin cycle requires.
Point out the two sources of H+ ions in the interior of the thylakoid
-The oxygen atom immediately combines with an oxygen atom generated by the splitting of another water molecule, forming O 2 (ask professor)
Which one (taproot vs. fibrous root system) is typical of monocots? Eudicots?
-The root system of monocots is a fibrous system -eudicots are generally characterized by having primary roots that give rise to a taproot system
what tissues each produces for vascular cambium and cork cambium?
-Vascular cambium: produces xylem and phloem cells, -Cork cambium produces produces a secondary protective tissue, the periderm
Are the H+ ions moving by active transport, facilitated diffusion, or simple diffusion?
-active transport using photon energy occurs during photosynthesis. -During photosynthesis, proteins use the energy of photons to create a proton gradient across the chloroplast thylakoid membrane. That energy is used to pump H+ ions into the thylakoid. (ask professor)
explain what is meant by a reaction center
-are special b/c of their molecular environment— -their location and the other molecules with which they are associated—enables them to use the energy from light not only to boost one of their electrons to a higher energy level, but also to transfer it to a different molecule
give the relationship between ∆G with exergonic reaction
-chemical mixture loses free energy (G decreases), ∆G is negative for an exergonic reaction. -occur spontaneously. (Remember, the word spontaneous implies that it is energetically favorable, not that it will occur rapidly.) -The magnitude of ∆G for an exergonic reaction represents the maximum amount of work the reaction can perform. * The greater the decrease in free energy, the greater the amount of work that can be done
learn to differentiate among monocot stems, herbaceous eudicot stems and woody eudicot stems: - herbaceous eudicot stems?
-composed of an epidermis, cortex, xylem, phloem and pith. -They are also known for their vascular bundles that are isolated into a specific area of the stem. -have a pith.
Photosystem I
-electrons reach another group of pigments(photosystem 1) and get energized again by light -electrons power a few more pumps-more H+ pumped into thylakoid -NADP+ pick up electrons and forms NADPH - H+ flows back out of thylakoids through ATP synthase which makes ATP(ask profesor)
What is the role of the pigment molecules in the light- harvesting complex?
-enable a photosystem to harvest light over a larger surface area and a larger portion of the spectrum than could any single pigment molecule alone. -
Differentiate between exergonic and endergonic reactions
-exergonic reaction proceeds with a net release of free energy -An endergonic reaction is one that absorbs free energy from its surroundings
point out where the H+ ions return to the stroma.
-greater concentration of hydrogen ions—and positive charge—in the thylakoid interior space. -This difference in concentration and charge creates what is called a chemiosmotic gradient. -It causes hydrogen ions to flow back across the thylakoid membrane to the stroma, where their concentration is lower. (ask professor)
indeterminate growth
-growth occurs throughout the plant's life, a process called indeterminate growth. Plants can keep growing because they have undifferentiated tissues called meristems containing cells that can divide, leading to new cells that elongate and become differentiated
learn to differentiate among monocot stems, herbaceous eudicot stems and woody eudicot stems: -woody eudicot stems?
-is composed of a cork, cork cambium, epidermis, cortex, xylem, phloem, vascular cambium, and a pith. -It is responsible for the making and separation of both xylem and phloem.
How does ATP differ from ADP and AMP: -ATP?
-is composed of an adenosine unit ( a complex of adenine and ribose sugar) and three phosphate groups arranged in sequence -and three phosphate groups arranged in sequence. The last two phosphates are attached by high-energy bonds
signifance of photorespiration
-photorespiration may provide protection against the damaging products of the light reactions, which build up when the Calvin cycle slows due to low CO -optimize the Calvin cycle—even in hot, arid climates. The two most important of these photosynthetic adaptations are C 4 photosynthesis and crassulacean acid metabolism (CAM).
Differentiate between autotrophs and heterotrophs and give examples of organisms using each nutritional mode: -examples for autotrophs
-plants are photoautotrophs, organisms that use light as a source of energy to synthesize organic substances -Photosynthesis also occurs in algae, certain unicellular eukaryotes, and some prokaryotes
give the relationship between ∆G with endergonic reaction
-reaction essentially stores free energy in molecules (G increases), ∆G is positive. -Such reactions are nonspontaneous, and the magnitude of ∆G is the quantity of energy required to drive the reaction.
Explain what is meant by photorespiration
-rubisco adds O 2 to the Calvin cycle instead of CO 2 . -The product splits, and a two-carbon compound leaves the chloroplast. Peroxisomes and mitochondria within the plant cell rearrange and split this compound, releasing CO 2
Explain the difference between determinate growth
-they stop growing after reaching a certain size
Use Fig. 3.23 (p. 173) (or the diagram accompanying the photophosphorylation slideshow on the website) to: a) indicate where in the chloroplast the electron transport chain for cyclic electron flow is located?
-thylakoid membranes of chloroplast
How are the two concepts related?
-transfer of energy to produce ATP and maintaining the energy
Name the two lateral meristems, indicate where each is found, and what tissues each produces. (Fig. 3.41, p. 193 may be helpful.)
-vascular cambium and the cork cambium -formed in stems and roots after the tissues of the primary plant body have differentiated.
Explain the role of ATP as the immediate source of energy in performing the two different kinds of cellular work diagrammed in Fig. 3.8: -Mechanical work?
ATP binds noncovalently to motor proteins and then is hydrolyzed, causing a shape change that walks the motor protein forward
Explain the role of ATP as the immediate source of energy in performing the two different kinds of cellular work diagrammed in Fig. 3.8: -Transport Work
ATP phosphorylates transport proteins, causing a shape change that allows transport of solutes.