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HW 06 - Plant Form and Function
University of Houston
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Category: Botany
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HW Plant Form and Function PM HW Plant Form and Function Due pm on Sunday April You will receive no credit for items you complete after the assignment is due Grading Policy Activity Plant Defenses Click here to view this animation Then answer the questions Part A Which organism does not cause disease in plants Hint Which organism has another interaction with plants ANSWER Fungus Herbivore Virus Bacteria Correct An herbivore consumes plants Part B Which structure does not protect stems and leaves from damage by herbivores Hint Which structure allows substances to enter and exit leaves ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Spines Stomata Trichomes Thorns Correct Stomata are openings that allow gases to diffuse in and out of leaves Part C True or false Plants do not produce many defenses against pathogens unless they are threatened because defensive structures and compounds require much energy and materials to produce and maintain Hint Why are induced defenses more efficient than defenses that are present all the time ANSWER True False Correct The production and maintenance of defensive structures and compounds requires more energy than a plant may have at all times Part D What is the initial localized response of a resistant plant to pathogen invasion Hint What happens to the plant cells that are invaded by a pathogen in a resistant plant ANSWER Hypersensitive response Systemin production Plant death Systemic acquired resistance Correct The hypersensitive response causes the infected plant cells to die and sends a signal to the rest of the plant to prepare its defenses Part E Which compound is not used in the localized response to pathogen invasion Hint Which compound acts as a signaling molecule in plants https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER Proteinase inhibitors Nitric oxide Phytoalexins Salicylic acid Correct Salicylic acid is a phytochemical involved in the systemic acquired resistance response in plants Part F Which of the following statements about systemic acquired resistance SAR in plants is false Hint How is SAR carried out ANSWER Salicylic acid is the only compound involved in SAR signaling Hormones produced by an attacked leaf carry a signal to the rest of the plant SAR results in the production of protective compounds distant from the site of initial infection A suite of genes called the pathogenesis-related loci is expressed in response to a signal from an attacked leaf Correct This statement is false salicylic acid is involved in the SAR response but its function is unclear and there may be other molecules involved in SAR signaling Part G How does a plant defend against herbivores Hint How do herbivores learn to avoid certain plants ANSWER Plant cells at the site of attack are killed to starve the herbivore of nutrients Plant cells produce salicylic acid to warn the rest of the plant about the attack The plant produces molecules that stimulate the herbivore's digestive enzymes The hormone systemin is produced at the site of injury and signals the plant to produce proteinase inhibitors Correct This statement is true Chapter Question Part A https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM The phase change of an apical meristem from the juvenile to the mature vegetative phase is often revealed by ANSWER a change in the morphology of the leaves produced the activation of floral meristem identity genes a change in the orientation of preprophase bands and cytoplasmic microtubules in lateral meristems the initiation of secondary growth the formation of lateral roots Correct Chapter Question Part A Which of the following would tend to increase transpiration ANSWER a thicker cuticle a rainstorm sunken stomata spiny leaves higher stomatal density Correct Chapter Question Part A Most of the growth of a plant body is the result of ANSWER morphogenesis cell elongation cell division cell differentiation reproduction Correct Chapter Question Part A How may a plant respond to severe heat stress ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM by initiating a systemic acquired resistance response by creating air tubes for ventilation by producing heat-shock proteins which may protect the plant's proteins from denaturing by reorienting leaves to increase evaporative cooling by increasing the proportion of unsaturated fatty acids in cell membranes reducing their fluidity Correct Chapter Question Part A Most of the mass of organic material of a plant comes from ANSWER water carbon dioxide atmospheric oxygen soil minerals nitrogen Correct Chapter Question Part A The hormone that helps plants respond to drought is ANSWER cytokinin ethylene abscisic acid gibberellin auxin Correct Chapter Question Part A A plant cell with a s of - MPa maintains a constant volume when bathed in a solution that has a s of - MPa and is in an open container The cell has a ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM p of MPa of MPa p of MPa of - MPa p of MPa Correct Chapter Question Part A Charles and Francis Darwin discovered that ANSWER auxin is responsible for phototropic curvature auxin can pass through agar red light is most effective in shoot phototropism light destroys auxin light is perceived by the tips of coleoptiles Correct Chapter Question Part A Some dioecious species have the XY genotype for male and XX for female After double fertilization what would be the genotypes of the embryos and endosperm nuclei ANSWER embryo X endosperm XX or embryo Y endosperm XY embryo XY endosperm XXX or embryo XX endosperm XXY embryo XX endosperm XX or embryo XY endosperm XY embryo XX endosperm XXX or embryo XY endosperm XXY embryo XX endosperm XXX or embryo XY endosperm XYY Correct Chapter Question Part A Which of the following arise directly or indirectly from meristematic activity ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM dermal tissue tubers leaves secondary xylem all of the above Correct Water Transport in Plants Transpiration BioFlix tutorial Plants lose a large amount of water from their leaves in a process called transpiration Transpiration plays a role in a number of plant processes One of the most important roles of transpiration is powering the transport of water and minerals from the roots to the leaves Transpiration depends on the specialized features of plant cells and tissues and on the macroscopic structure of leaves Before beginning this tutorial watch the Water Transport in Plants animation which focuses on the movement of water from the soil to the roots and leaves of plants and on the role that transpiration plays in this movement Part A - Key structures involved in water transport in a leaf A plant leaf is constructed from a variety of cell types with specialized structures and functions Many of the properties of leaf cells facilitate some aspect of water transport The diagram below shows a cross section through a leaf Drag the labels to the appropriate targets to match the function with the structure indicated in the diagram Labels may be used once more than once or not at all Hint The structure of leaf veins and surrounding cells The veins are the vascular bundles of the leaf They contain two types of water-conducting tissues the xylem which transports water and minerals from the roots to the leaves and the phloem which transports water and sugar from the leaves to the roots The xylem and phloem are surrounded by a single layer of cells called the bundle sheath Every cell in a leaf is connected to the bundle sheath and thus to the xylem and phloem either directly or indirectly through contact with mesophyll cells https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint How are mesophyll cells arranged inside a leaf With the exception of the cells that make up the veins most of the cells between the upper and lower epidermal layers of a leaf are mesophyll cells Which three statements below correctly describe the arrangement of mesophyll cells in a leaf ANSWER All mesophyll cells contact bundle-sheath cells Each mesophyll cell contacts the cell walls of two or more other cells Some mesophyll cells contact cells in the upper epidermis Part of the surface of each mesophyll cell is exposed to the air space inside the leaf Hint How the rate of transpiration is controlled The waxy layer on the outer surface of leaf epidermal cells has a very high resistance to water movement Stomata singular stoma are pores in the epidermis of the leaf that provide a low-resistance pathway for water to diffuse out of the leaf The size of each stoma is controlled by a pair of guard cells that surround the pore Changes in the shape of the guard cells open and close the pore thus regulating the leaf s resistance to water loss and the rate of transpiration ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The following diagram illustrates the cell types in a leaf and describes their roles in water transport Part B - The apoplastic and symplastic pathways for water transport The apoplast and symplast are two regions of the plant that serve as pathways for water and solute transport over both short and long distances These pathways are represented by the arrows in the diagram below which shows three adjacent cells in a leaf or root https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Sort each statement into the appropriate bin Hint How water crosses the plasma membrane of a plant cell The plasma membrane is the barrier that separates the inside of the cell from the outside Water molecules are small enough to move across membranes by simple diffusion through the lipid bilayer However the speed of water movement across membranes is increased by the presence of aquaporins membrane proteins that are specific for the transport of water Hint What is the role of the plasma membrane in water transport in the apoplast and the symplast The plasma membrane is a barrier that regulates the movement of most molecules and ions between the inside and outside of the cell Which two statements below correctly describe the role of the plasma membrane in water transport through the apoplast or the symplast ANSWER The plasma membrane makes water transport slower through the symplastic pathway than through the apoplastic pathway To move between the apoplast and the symplast water must cross a plasma membrane The plasma membrane prevents water from leaking out of the symplast The plasma membrane separates the apoplast from the symplast Hint What role do plasmodesmata play in water transport Plasmodesmata are unique to plant cells and are particularly important in the transport of water and small solutes Which statement correctly describes the role of plasmodesmata in water transport ANSWER Water that passes from one cell to another through a plasmodesma must cross a plasma membrane Water that passes from one cell to another through a plasmodesma must cross a cell wall Water that moves through a plasmodesma is flowing in the symplastic pathway Plasmodesmata provide the connection between the apoplastic and symplastic pathways ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The apoplastic pathway is a continuous route formed by cell walls extracellular spaces and the interior of dead xylem cells The symplastic pathway is made up of the cytoplasm of cells It is also continuous because plasmodesmata connect the cytoplasm of adjacent cells These two pathways are separated by plasma membranes Each pathway can transport water and solutes over both short and long distances Part C - The path of water movement in leaves Water follows a specific path as it moves from the xylem in the vein of a leaf to the air outside the leaf Drag the labels into the flowchart to show the sequence of events after water enters a leaf in the xylem Not all labels will be used Hint Function of xylem cells Mature xylem cells those that function in water conduction in vascular tissues of plants are dead They have lost their plasma membrane and all internal structures All that remains is the cell wall Therefore water transport in the xylem is in the apoplast In the leaves water moves freely from the xylem to the apoplast of surrounding bundle-sheath and mesophyll cells which are alive Hint Where does water evaporate in or on a leaf The movement of water from the roots to the leaves in the xylem is driven almost entirely by the evaporative loss of water from the leaves a process called transpiration Where in or on a leaf does most of the water evaporate ANSWER from the apoplast of the mesophyll cells from the external surfaces of the epidermal cells from the xylem from the stomata from the symplast of the mesophyll cells Hint What roles do the air spaces in a leaf play in water transport https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Every cell inside a leaf except those that are inside the veins has some part of its surface exposed to a large continuous air space inside the leaf What role s does this large air space play in water transport in leaves Select all that apply ANSWER It provides a large surface area over which water can evaporate inside the leaf It serves as a pathway for water vapor to diffuse from the mesophyll cells to the stomata It serves as a pathway for liquid water to move from the veins to the mesophyll cells Hint Connections between cells in the leaf Although the inside of a leaf contains a large air space the cells in the leaf are not isolated from one another by air The wall of every cell contacts the wall of at least one neighboring cell as shown in the drawing below Therefore every cell in a leaf is connected to other cells and to the xylem via the apoplast ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Because xylem cells lack cytoplasm the xylem is part of the apoplast Water moves via the apoplastic pathway from the xylem through the bundle sheath to all of the mesophyll cells of the leaf From the mesophyll cell walls water evaporates into the interior air spaces of the leaf Finally it exits the leaf as water vapor through the stomata Part D - The relationship between transpiration and other processes in plants Transpiration provides the driving force for the movement of water from the soil to the highest leaves of plants Transpiration is also linked to other processes in plants including photosynthesis and the transport of mineral nutrients Which of the following statements correctly describe s a relationship between transpiration and other processes in plants Select all that apply Hint Evaporative cooling As a substance changes state from liquid to gas the temperature of the remaining liquid decreases This phenomenon called evaporative cooling occurs because the molecules that are the most likely to escape as a gas from the surface of the liquid are those with the greatest kinetic energy Their escape lowers the average kinetic energy of the molecules remaining in the liquid thereby lowering the temperature of the liquid Hint How do water and mineral nutrients move from roots to leaves Most of the water and mineral nutrients that enter a plant s roots are transported directly to the leaves Which of the following statements correctly describes the mechanisms by which water and mineral nutrients move from the roots to the leaves ANSWER Water is pulled through the xylem by transpiration in the leaves whereas mineral nutrients diffuse through the xylem from higher concentration in the roots to lower concentration in the leaves Water and mineral nutrients move together through the xylem driven by transpiration in the leaves Water and mineral nutrients diffuse from the roots to the leaves through the xylem Mineral nutrients are actively transported through the symplast of living cells in the stem whereas water is pulled through the apoplast of dead xylem cells Hint How is the diffusion of water out of leaves related to the diffusion of CO into leaves The movement of CO into the leaf which supports photosynthesis and the loss of water from the leaf in transpiration both involve the diffusion of gaseous https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM molecules Which two statements correctly describe the diffusion of water and CO and their relationship to photosynthesis and transpiration ANSWER As the number of mesophyll cells inside a leaf increases the leaf will be able to carry out more photosynthesis and will lose less water Water and CO follow different paths between the air outside the leaf and the surface of the mesophyll cells inside the leaf The rates at which CO enters the leaf and water exits the leaf are both controlled by the opening and closing of stomata Assuming that light intensity remains constant if the rate of transpiration decreases the rate of photosynthesis will usually decrease ANSWER Open stomata provide a low-resistance pathway for CO to enter and for water to exit the leaf Water is pulled from the roots to the leaves by transpiration whereas mineral nutrients diffuse from the roots to the leaves To minimize water loss during dry conditions most plants must also restrict their ability to carry out photosynthesis In most plants the highest rate of transpiration occurs when the rate of photosynthesis is also highest Transpiration is important in cooling leaves on warm sunny days The large surface area exposed to air inside the leaf maximizes the plant s ability to absorb CO while minimizing water loss through transpiration Correct Both water and CO diffuse as gases through stomata Therefore the opening of stomata to permit CO to rapidly enter the leaf also promotes water loss through transpiration Conversely when the stomata close to limit water loss under dry conditions the entry of CO into the leaf is restricted and photosynthesis slows Transpiration pulls both water and mineral nutrients from the roots to the leaves It also cools the leaves as water evaporates from cell surfaces inside the leaves GraphIt Global Soil Degradation Click here to complete the graphing activity Then answer the questions Part A - Question How big is the range of soil degradation observed between continents Hint A range indicates the difference between the largest and smallest value in a data set ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM about about about about Correct Part B - Question Which continent likely represents the largest absolute land area experiencing degradation ANSWER Europe North America Asia South America Africa Correct Part C - Question For which continents is land degradation having the least impact on global grain production ANSWER Africa and South America Africa and Asia Asia and Europe Europe and North America North and South America Correct Part D - Question Suppose you are advising the UN on global soil conservation projects Limited resources force you to focus all your efforts on only one continent Based on the information in the graph which continent would you focus on so as to have the greatest impact on global grain production Hint Where would increased soil degradation have the greatest impact on world grain production ANSWER Asia Europe Africa North America South America https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Part E - Question Which continent has the largest proportion of land with more than moderate degradation ANSWER South America North America Asia Europe Africa Correct Part F - Question Assume that these categories represent a progression of degradation through time In other words if left unchecked lightly degraded soil progresses into moderately degraded soil and so forth Which continent poses the greatest concern for future loss of agricultural productivity ANSWER Asia Europe North America South America Africa Correct Make Connections Ascent of Xylem Sap and Hydrogen Bonding Plants transport water and minerals against gravity from their roots to their shoots In order to accomplish this plants rely on long chains of hydrogen-bonded water molecules that extend all the way from the tips of their leaves to the soil The figure below on the left shows how hydrogen bonds bind a water molecule to other water molecules The figure below on the right shows how transpiration the loss of water from the stomata of leaves creates a tension that pulls water up the xylem a process that relies on the hydrogen bonding of water molecules https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Part A - Reviewing hydrogen bonding Chemical bonds hold together the atoms that make up a molecule Molecules may also be attached to one another by chemical bonds The figure shows how hydrogen bonds attach water molecules to other water molecules Drag the terms on the left to the appropriate blanks on the right to complete the sentences ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The chemical bonds between the oxygen and hydrogen atoms in a water molecule are polar covalent bonds Because of their polar covalent bonds each of the three atoms in a water molecule has a partial charge The oxygen has a partial negative charge and each hydrogen has a partial positive charge These partial charges make water a polar molecule A hydrogen bond binds the slightly positive hydrogen of one water molecule to the slightly negative oxygen of a nearby water molecule Hydrogen bonds are weak only about as strong as a covalent bond so they form break and re-form with great frequency However at any instant a substantial percentage of all water molecules are hydrogen-bonded to their neighbors Part B - Ascent of xylem sap The process that plants use to transport water and minerals from their roots to their shoots -- known as the transpiration-cohesion-tension mechanism -- relies at many points on the hydrogen bonds formed by water molecules Before looking more carefully at the role of hydrogen bonding in the ascent of xylem sap let s review the transpiration-cohesion-tension mechanism as shown in the figure https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Drag the labels to their appropriate locations on the flowchart to show the sequence of events that pulls xylem sap from the roots to the shoots of a plant Note that the steps in the flowchart correspond to the numbered locations in the image above ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct In the transpiration-cohesion-tension mechanism Transpiration describes the loss of water from the stomata of leaves As water vapor is lost through transpiration more water evaporates from the cell walls of leaf mesophyll cells The evaporation of water from leaf mesophyll cells creates a surface tension that pulls water up the xylem Water molecules pull on adjacent water molecules all the way down the xylem Water molecules also adhere to the walls of xylem cells which helps to counteract the force of gravity Water enters the xylem after it is absorbed by a plant s roots Part C - What is the role of hydrogen bonding in the ascent of xylem sap Hydrogen bonding is crucial to the transpiration-cohesion-tension mechanism Drag the labels to their appropriate locations in the table to show how hydrogen bonding is involved at different points in the ascent of xylem sap ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The transpiration-cohesion-tension mechanism relies on hydrogen bonding at multiple steps Hydrogen bonds are broken when water molecules evaporate inside leaves Surface tension helps pull water up the xylem Surface tension is the result of hydrogen bonds between water molecules at the surface of a layer of water Water molecules pull on adjacent water molecules all the way down the xylem This is possible because of the cohesion of water which is the result of hydrogen bonds between water molecules Adhesion along with cohesion helps to counteract the downward force of gravity The adhesion of water to the walls of the xylem results from hydrogen bonds between water molecules and the cell walls of xylem cells The ABC Model of Flowering As an Arabidopsis flower develops the floral meristem produces four floral structures in concentric circles or whorls In this activity you will explore how homeotic genes control the development of the flower structures Part A - ABC genes and the development of floral structures This diagram shows how gene activity in wild-type flowers affects the development of floral structures in the whorls of the floral meristem https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Use the diagram to determine what flower structures develop under the conditions described below Drag the terms on the left to the appropriate blanks on the right to complete the sentences Hint Floral meristems and the ABC model of flowering Floral meristems are modified shoot apical meristems When viewed from above floral meristem can be divided into four concentric circles or whorls Organ identity genes regulate the development of structures in each whorl either sepals petals stamens or carpels The ABC model of flowering proposes that there are three classes of organ identity genes A genes B genes and C genes that determine whether each whorl develops into a sepal petal stamen or carpel ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct This diagram shows how gene activity affects the development of floral structures in wild-type flowers Part B - The effect of mutations on flower development Scientists have studied mutant plants that lack A B or C gene activity to understand the role that these three genes play in flower development They discovered that the activity of the three genes influence each other in the following ways Where gene A is active it inhibits gene C and vice versa If either A or C gene activity is missing the other takes its place Gene B does not inhibit the activity of genes A or C Also gene B activity is not inhibited by either A or C genes In the chart below identify the structures that will develop in each whorl in the mutant flowers The structures in wild-type flowers and one mutant have already been filled in for you Drag the labels to their appropriate locations in the chart Labels can be used once more than once or not at all Hint Flower development in wild-type flowers and mutants lacking gene A The diagram below left shows how gene activity affects the development of floral structures in wild-type flowers The diagram below right shows how gene activity affects the development of floral structures in a mutant flower that lacks gene A Recall that when gene A activity is missing gene C takes its place As a result different flower structures develop https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint How is flower development affected in mutants lacking gene B Recall that gene B does not inhibit the activity of either gene A or gene C When gene B activity is missing no other gene takes its place Use this knowledge and the diagram of gene activity in wild-type flowers with A B and C genes intact to predict which whorls would be affected by the lack of gene B Select all that apply ANSWER whorl whorl whorl whorl Hint How is flower development affected in mutants lacking gene C Recall that where gene C is active it inhibits gene A If gene C activity is missing gene A takes its place Use this knowledge and the diagram of gene activity in wild-type flowers with A B and C genes intact to predict which whorls would be affected by the https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM lack of gene C Select all that apply ANSWER whorl whorl whorl whorl ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct This diagram shows the floral meristem whorls and the corresponding structures produced in wild-type flowers and in the flowers of the three types of mutants Developmental Biology of Plants Although each cell in a plant contains the same set of genes different patterns of gene expression cause cells to differentiate and develop into many different cell types within a single plant Cellular differentiation depends to a large extent on positional information and is affected by homeotic genes Part A - Pattern formation in plants The development of specific plant structures in particular locations is called pattern formation Events in a plant s early development play an important role in establishing the plant s form Complete the flowchart about pattern formation in plants beginning with the normal division of a plant zygote fertilized egg Drag the labels to their appropriate locations on the flowchart Not all labels will be used Hint Symmetry and cell division In symmetrical cell division the cytoplasm of the parent cell is distributed equally between the two daughter cells resulting in daughter cells of equal size In asymmetrical cell division the cytoplasm of the parent cell is distributed unequally between the two daughter cells resulting in daughter cells of different sizes Hint Can you define the terms associated with the development of plant form Drag the terms on the left to the appropriate blanks on the right to complete the sentences Not all terms will be used ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint Embryogenesis The diagram shows the embryogenesis of a plant zygote in a seed ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Pattern formation begins very early in a plant s development with the asymmetrical division of the plant zygote This asymmetrical cell division produces a small apical tip cell and a large basal bottom cell and initiates polarization of the plant body into a root end and shoot end Part B - Cellular differentiation As with all multicellular organisms homeotic genes in plants control morphogenesis how the tissues and organs of the plant are arranged In maize plants the homeotic gene KNOTTED abbreviated KN helps maintain the indeterminate state of shoot apical meristems In wild-type maize plants KN is expressed at high levels in the shoot apical meristem but is expressed at low levels in leaves In some mutant maize plants KN is expressed at high levels in leaves In those plants outgrowths or knots of adventitious shoot meristems shoot meristems that appear in abnormal locations on the leaves form Use this information to determine which of the following statements are true Select the four statements that are true Hint Genes of a plant cell A mature differentiated plant cell such as a leaf cell can be removed from a plant and placed in tissue culture In tissue culture the plant cell can dedifferentiate and eventually mature to develop into many different types of plant cells This observation confirms that plant cells contain all the genes necessary to differentiate into any type of plant cell Hint Gene expression The process of gene expression involves the transcription of DNA to RNA and the subsequent translation of RNA to a protein product Gene expression is a highly regulated process in which only particular genes of the entire genome are expressed at certain times producing particular protein products In multicellular organisms which are made up of different types of cells each cell type has a specific program of gene expression in which certain genes are expressed and others are not Hint Can you identify true statements about gene expression in a hypothetical plant Consider a hypothetical gene X that codes for a pigment that controls the color of a plant s flowers Which of these statements would not be true about gene X ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Some of the plant s cells would express Gene X more than other cells The protein that gene X codes for would only be produced when gene X is expressed The protein that gene X codes for would most likely only be found in the plant s petal cells Gene X would only be present in the plant s petal cells ANSWER In mutant maize leaves the KN gene is mostly not expressed In wild-type maize plants the KN gene is mostly expressed in shoot apical meristem cells Both the wild-type and mutant maize leaves have the same morphology In wild-type maize plants the KN gene is present in shoot apical meristem cells but not in leaf cells In wild-type maize plants the KN gene is expressed differentially in shoot apical meristem cells and leaf cells Leaves of the mutant maize plants produce more KN protein than leaves of wild-type maize plants Expression of the KN gene in shoot apical meristem cells produces a protein involved in the maintenance of shoot apical meristems Correct Plant cell differentiation is largely controlled by the regulation of gene expression within a particular cell The differential expression of genes results in the production of different protein products which determine the type of cell that develops Activity Solute Transport in Plants Click here to view this animation Then answer the questions Part A Which tissue acts as a filter on the water absorbed by root hairs Hint Review the path that water travels through the tissue layers of the root ANSWER Cortex Endodermis Epidermis Vascular tissue https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Endodermal cells filter solutes from water and allow them to pass through to the vascular tissue Part B True or false Root pressure can move water a long distance up the xylem because of the higher water potential of the xylem in comparison to the water potential in the surrounding cells Hint What conditions favor the movement of water by root pressure ANSWER True False Correct Root pressure can move water a short distance up the xylem because of the lower water potential of the xylem in comparison to the water potential in the surrounding cells Part C Which of the following statements about the distribution of sap throughout a plant is true Hint What drives the movement of sugars in a plant ANSWER The main component of phloem sap is glucose The mechanism that explains the movement of sugars throughout a plant is called the pressure-flow hypothesis The driving force for sugar movement is transpiration Companion cells form the conducting tissue for sap Correct This statement is true Part D Which term describes an area where sugars are used or stored Hint Consider the destination of sugars transported in the phloem ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Source Sink Stomata Leaves Correct A sink is an area where sugars are used or stored typically these are the roots and fruits of a plant Part E Which of the following statements about xylem transport is true Hint Think about which materials are transported through the xylem ANSWER Water and minerals enter the xylem by diffusion Water and minerals move through the root cortex into the xylem and upward through the stem and into leaves The xylem cells that conduct water and minerals are alive All water transported by the xylem is used for photosynthesis in the leaves Correct Water and minerals that are taken up in the soil are transported from roots to leaves by the xylem Part F What characterizes the rates of photosynthesis and transport in a plant on a dry cloudy day Hint Transport in a plant is affected by the amount of sunlight ANSWER The photosynthesis rate is low and stomata are open Both the photosynthesis and transpiration rates are high The photosynthesis rate is high and phloem transport rates are low Both the photosynthesis and transpiration rates are low Correct On a cloudy day with low soil moisture the photosynthesis rate is low and stomata are closed so the transpiration rate is low Part G True or false The rate of sugar transport in a plant depends on the rate of photosynthesis the rate of transpiration and the difference in turgor pressure between the source and the sink Hint https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Sugar transport in a plant occurs in the phloem ANSWER True False Correct While the rate of photosynthesis and the difference in turgor pressure between the source and the sink do influence the rate of sugar transport in the phloem the rate of transpiration does not transpiration mainly influences the rate of water transport through the xylem Chapter Question Part A A plant mutant that shows normal gravitropic bending but does not store starch in its plastids would require a reevaluation of the role of in gravitropism ANSWER differential growth light auxin calcium statoliths Correct Chapter Question Part A Epiphytes are ANSWER nonphotosynthetic parasitic plants plants that capture insects plants that grow on other plants fungi that form mutualistic associations with roots fungi that attack plants Correct Chapter Question Part A Auxin enhances cell elongation in all of these ways except ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM increased activity of plasma membrane proton pumps gene activation increased uptake of solutes cell wall loosening acid-induced denaturation of cell wall proteins Correct Chapter Question Part A Mycorrhizae enhance plant nutrition mainly by ANSWER providing sugar to root cells which have no chloroplasts converting atmospheric nitrogen to ammonia absorbing water and minerals through the fungal hyphae enabling the roots to parasitize neighboring plants stimulating the development of root hairs Correct Plant Responses to Light Plants are capable of detecting and responding to external signals in their environment including light Light is one factor that controls important plant functions such as seed germination and flowering Part A - Blue-light photoreceptors and phototropism Complete the flowchart to identify the process by which blue-light photoreceptors and auxin control phototropism in plants Drag the labels to their appropriate locations on the flowchart Hint Can you define the terms associated with blue-light photoreceptors Drag the terms on the left to the appropriate blanks on the right to complete the sentences Not all terms will be used ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint The acid growth hypothesis The acid growth hypothesis explains how auxin causes cells to elongate This diagram shows the process proposed by the acid growth hypothesis ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Plants bend toward light due to the lateral redistribution of auxin When a plant is exposed to light on one side the auxin that is released moves from the sunny side of the shoot tip to the shady side Auxin triggers cell elongation on that side of the plant by activating expansins which loosen connections between cellulose microfibrils in the cell wall Water can then enter the cells by osmosis increasing turgor and expanding the cells Because the auxin concentration is higher on the shaded side cells on that side elongate more than cells on the sunny side The unequal cell growth causes the plant to bend toward the light Part B - Phytochromes and seed germination Consider a plant that grows best in bright sunlight in which seed germination is controlled by phytochromes Which of the following statements describe s the structure and function of phytochromes in this plant Select all that apply Hint Structure of a phytochrome A phytochrome is composed of two identical subunits Each subunit consists of a polypeptide unit that is covalently bonded to a nonpolypeptide unit called a chromophore The chromophore is the light-absorbing portion of the phytochrome The chromophore is photoreversible and can revert between two isomeric forms depending on the color of light provided https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint Can you describe the switching mechanism of a phytochrome A phytochrome may be found in one of two isomeric forms Pr or Pfr Which statement correctly describes the switching mechanism of a phytochrome ANSWER When the phytochrome is in the Pr form it absorbs far-red light maximally and converts to the Pfr form Conversely when the phytochrome is in the Pfr form it absorbs red light maximally and converts to the Pr form When the phytochrome is in the Pr form it absorbs red light and far-red light equally and converts to the Pfr form Conversely when the phytochrome is in the Pfr form it does not absorb red light or far-red light and does not convert to the Pr form When the phytochrome is in the Pr form it absorbs red light maximally and converts to the Pfr form Conversely when the phytochrome is in the Pfr form it absorbs far-red light maximally and converts to the Pr form Hint How do phytochromes control seed germination The interconversion of Pr and Pfr forms of phytochrome controls a number of light-induced events in plants including seed germination In nature seeds germinate when they are exposed to adequate sunlight Which statement describes what happens when seeds are exposed to adequate sunlight ANSWER The ratio of Pfr to Pr increases which triggers germination The ratio of Pfr to Pr does not change which triggers germination The ratio of Pfr to Pr decreases which triggers germination ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Far-red light stimulates the plant seeds to germinate when the phytochrome is in the Pfr configuration The effects of red and far-red light on phytochromes are irreversible When a phytochrome in the Pfr configuration absorbs far-red light the phytochrome reverts to the Pr configuration Phytochromes contain photoreceptors The plant seeds are more likely to germinate after exposure to red light than after exposure to far-red light Phytochromes absorb red light maximally when the phytochrome is in the Pr configuration Phytochromes absorb red light and far-red light equally when the phytochrome is in the Pfr configuration Correct Phytochromes may exist in one of two isomeric forms Pr or Pfr Phytochromes in the Pr form absorb red light maximally When phytochromes in the Pr form absorb red light they convert to the Pfr form Phytochromes in the Pfr form absorb far-red light maximally When phytochromes in the Pfr form absorb far-red light they convert to the Pr form When seeds are exposed to adequate sunlight which contains both red and far-red light the conversion to Pfr is faster than the conversion to Pr The accumulation of Pfr triggers seed germination Part C - Photoperiodism and flowering Use the data in the table below to determine whether each plant is a short-day plant a long-day plant a day-neutral plant or a plant that cannot be classified based on the data Description Plant A Plant B Plant C Plant D Plant E Plant F flowers after a short night of uninterrupted darkness flowers after a long night of uninterrupted darkness flowers after a long night interrupted by a flash of light flowers after a long night interrupted by a flash of red light followed by a flash of far- red light flowers in spring flowers in summer flowers in fall flowers in winter https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Drag each plant to the appropriate bin Hint How to approach the problem Before you begin to analyze the data in the table list out the conditions under which long-day plants and short-day plants flower To create the two lists ask yourself these questions Which plants flower after a short period of darkness Which flower after a long period of darkness Which plants would flower if a long period of darkness was interrupted by one flash of light Which would flower if the interruption was a flash of red light followed by a flash of far-red light Which plants typically flower from late spring to summer when nights are short Which flower from fall to early spring when nights are long Next compare the data for plants A-F to your lists to identify which plants are long-day plants short-day plants or neither For those plants that match neither list do they flower regardless of the light conditions If so consider whether those plants could be day-neutral plants Hint Can you define the terms associated with photoperiodism and flowering Drag the terms on the left to the appropriate blanks on the right to complete the sentences Not all terms will be used ANSWER Hint Can you identify what type of plant blooms under certain conditions Consider a plant that responds in the following ways under different conditions The plant flowers when nights are at least hours long The plant flowers when days are shorter than hours During a dark period of at least hours the plant will not flower if the darkness is interrupted by a flash of red light During a dark period of at least hours the plant will flower if the darkness is interrupted by a flash of red light followed by a flash of far-red light Is this plant a short-day plant a long-day plant or a day-neutral plant ANSWER short-day plant day-neutral plant long-day plant https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER Correct The diagram illustrates how various conditions affect flowering in plants Long-day short-night plants bloom when the dark period is shorter than a certain number of hours Short-day long-night plants bloom when the dark period is longer than a certain number of hours Day-neutral night-neutral plants are not affected by the relative length of night and day A flash of light is capable of interrupting the dark period of a photoperiod However a flash of far-red light can reverse the effect of a flash of red light Chapter Question Part A https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM We would expect the greatest difference in plant health between two groups of plants of the same species one group with mycorrhizae and one group without mycorrhizae in an environment ANSWER where nitrogen-fixing bacteria are abundant that has hot summers and cold winters in which the soil is relatively deficient in mineral nutrients that is near a body of water such as a pond or river that has soil with poor drainage Correct Activity Reproduction in Flowering Plants Click here to view this animation Then answer the questions Part A Which part of a plant attracts pollinators Hint Which part of a plant is often brightly colored and scented ANSWER Stamen Sepal Petals Carpel Correct The petals of a plant serve to attract pollinators Part B Which process involves the transfer of pollen grains from an anther to a stigma Hint https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Which process involves pollen ANSWER Pollination Gametogenesis Germination Fertilization Correct Pollination is the transfer of pollen grains from an anther to a stigma Part C True or false The endosperm in a seed develops into the embryo Hint What are the main parts of a mature seed ANSWER True False Correct The endosperm in a seed is not the embryo but the food supply for the embryo Part D Which term describes the male gametophytes of flowering plants Hint These cells develop into sperm ANSWER Pollen grains Micropyle Microsporocytes Megaspores Correct Pollen grains are the male gametophytes of flowering plants they contain a generative cell that develops into sperm Part E Which structure formed by the male gametophyte allows sperm to reach the ovary of a flowering plant https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint This structure forms after pollination has occurred ANSWER Stigma Anther Micropyle Pollen tube Correct The pollen tube is formed after a pollen grain is transferred to a receptive stigma and germinates forming a tube that grows down through the style to the ovary of a flowering plant Part F How is fertilization in flowering plants different from fertilization in other plant groups Hint Remember that the generative cell of the pollen grain forms two sperm nuclei ANSWER Two sperm nuclei fuse with a polar nucleus to form a diploid zygote One sperm nucleus fuses with the egg to form a diploid zygote whereas the other sperm nucleus fuses with two polar nuclei to form a cell that develops into endosperm One sperm nucleus fuses with the egg to form a diploid zygote One sperm nucleus fuses with the egg to form a diploid zygote whereas the other sperm nucleus fuses with a polar nucleus to form a diploid cell that forms a nutrient-rich tissue Correct Angiosperms are unusual in that one sperm nucleus fuses with the egg and one sperm nucleus fuses with two polar nuclei to form a triploid cell that develops into a nutrient-rich tissue that nourishes the growing embryo Part G Which of the following statements about seed formation in a flowering plant is true Hint Think about the structures in a mature seed and their functions ANSWER The terminal cell formed from mitosis of the zygote divides to form a row of single cells that eventually forms the embryo Hypocotyls are the seed leaves of the embryonic plant The swellings that develop into cotyledons are located at the end of the embryo on top of the row of single cells The basal cell formed from mitosis of the zygote divides to form a globular mass that is the route for nutrient transfer to the developing embryo https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The swellings that develop into cotyledons do indeed grow on top of the row of single cells produced by the basal cell Interpreting Data Effects of Auxin on Cell Elongation Use the graph to answer the questions Part A What does the x-axis of this graph represent ANSWER the extent that elongation is promoted or inhibited the concentration of auxin in grams per liter the concentration of auxin in the roots the concentration of auxin in liters per gram Correct Part B What does the distance between two white vertical lines on this graph represent ANSWER a -fold change in auxin concentration a doubling of auxin concentration a change in auxin concentration of g L an increase in elongation Correct https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Part C What does the point on the far right end of the blue line indicate ANSWER A very high concentration of auxin greatly promotes elongation of the roots A very high concentration of auxin greatly inhibits elongation of the roots A very high concentration of auxin greatly promotes elongation of the stems A very high concentration of auxin greatly inhibits elongation of the stems Correct Part D As labeled on the graph the blue line crosses the dashed zero line at an auxin concentration of g L What does this indicate ANSWER At this point on the graph the auxin concentration is g L At this auxin concentration elongation of stems is neither promoted nor inhibited At this auxin concentration elongation of roots is neither promoted nor inhibited At this auxin concentration elongation of stems is promoted but elongation of roots is inhibited Correct Part E Is this statement supported or not supported by the graph Very low concentrations of auxin promote elongation of the roots ANSWER supported not supported cannot be determined from the graph Correct Part F Is this statement supported or not supported by the graph Auxin concentrations below g L always promote elongation ANSWER supported not supported cannot be determined from the graph Correct https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Part G Is this statement supported or not supported by the graph Any given concentration of auxin either promotes stem elongation or promotes root elongation but never both ANSWER supported not supported cannot be determined from the graph Correct Part H Is this statement supported or not supported by the graph There are concentrations of auxin that promote stem elongation while simultaneously inhibiting root elongation ANSWER supported not supported cannot be determined from the graph Correct Activity Plant Hormones Click here to view this animation Then answer the questions Part A What is the physical basis of the phototropic response Hint What effect does auxin have on plant shoots ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Photosynthesis Cell transport Cell shortening Cell elongation Correct The phototropic response is based on cell elongation Part B True or false Auxin is asymmetrically distributed in shoots because the auxin on the side of the plant facing the source of light is destroyed Hint Review the Cholodny-Went hypothesis ANSWER True False Correct Auxin is asymmetrically distributed in shoots because the auxin on the side of the plant facing the source of light moves to the side of the plant away from the light Part C Where does the majority of stem growth in a plant occur Hint What is apical dominance ANSWER Apical meristem Lateral branches Both the apical meristem and lateral branches Axillary buds Correct The majority of stem growth in a plant occurs at the apical meristem Part D Which of the following statements about hormones is true Hint How do hormones exert their influence in organisms https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER Hormones can function at very low concentrations Hormones are produced at the sites where they are needed Hormones are small inorganic molecules Hormones are produced only in plants Correct Hormones can indeed function at very low concentrations Part E Which term describes the direction of auxin transport in a plant Hint Can auxin travel in more than one direction ANSWER Polar Circular Multidirectional Bidirectional Correct Auxin transport is polar it always travels downward Part F How does auxin produce gravitropism in a plant that is placed on its side Hint Which part of the plant exhibits gravitropism ANSWER Auxin accumulates on the side of the leaf opposite the sunlight and inhibits elongation of cells in that region Auxin accumulates on the lower surface of the root and inhibits elongation of cells in that region Auxin accumulates on the lower surface of the root and stimulates elongation of cells in that region Auxin accumulates on the side of the leaf opposite the sunlight and stimulates elongation of cells in that region Correct Auxin inhibits elongation in the region of the root where it accumulates Part G How does auxin produce phototropism https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint How does auxin cause plants to bend toward light ANSWER Auxin accumulates in cells on the side of the plant opposite the source of light and stimulates their elongation Auxin accumulates in cells on the side of the plant facing the source of light and causes them to shorten Auxin accumulates in cells on the side of the plant facing the source of light and stimulates their elongation Auxin accumulates in cells on the side of the plant opposite the source of light and causes them to shorten Correct Auxin is redistributed to cells on the side of the plant opposite the source of light and stimulates their elongation Chapter Question Part A The innermost layer of the root cortex is the ANSWER pith pericycle core endodermis vascular cambium Correct Activity How Plants Obtain Minerals from Soil Click here to complete this activity Then answer the questions Part A What name is given to the process seen in this animation To view the animation click here Then click Start on the image to start the animation https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER root hair exchange carbonation anion exchange cation exchange ion pumping Correct Cations positively charged ions in the soil solution are displacing cations on soil particles Part B The release of CO into the soil results in the formation of ANSWER carbonate ions and oxygen ions hydrogen ions and carbonate ions sodium ions and chloride ions potassium ions and calcium ions hydrogen ions and oxygen ions Correct When carbon dioxide combines with water hydrogen in the soil cations and carbonate anions are released Part C What process is the source of the CO that root hairs release into the soil ANSWER respiration and photolysis respiration photolysis photosynthesis and respiration photosynthesis Correct CO is a by-product of respiration Part D The binding of H ions to soil particles ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM displaces mineral anions is counteracted by acid precipitation promotes the clumping of soil particles displaces nitrates from soil particles displaces mineral cations Correct Positively charged hydrogen ions displace positively charged mineral ions on soil particles Part E Which of these ions is most likely to be leached from the soil ANSWER potassium ions iron ions calcium ions magnesium ions chlorine ions Correct Chlorine ions are negatively charged and are therefore not likely to be bound to negatively charged soil particles Part F Acid precipitation ANSWER increases soil fertility promotes the attachment of anions to soil particles has no effect on soil fertility decreases soil fertility enhances the diffusion of cations into root hairs Correct Acid precipitation promotes cation exchange However the precipitation then washes the ions away before they can diffuse into root hairs Part G How do cations enter root hairs ANSWER diffusion phagocytosis active transport osmosis endocytosis https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Cations diffuse into root hairs Chapter Question Part A Golden Rice ANSWER produces larger golden grains that increase crop yields contains daffodil genes that increase vitamin A content includes bacterial genes that produce a toxin that reduces damage from insect pests is resistant to various herbicides making it practical to weed rice fields with those herbicides is resistant to a virus that commonly attacks rice fields Correct Chapter Question Part A What would enhance water uptake by a plant cell ANSWER increasing the pressure exerted by the cell wall the loss of solutes from the cell decreasing the of the surrounding solution positive pressure on the surrounding solution increasing the of the cytoplasm Correct Chapter Question Part A Which of the following would not be seen in a cross-section through the woody part of a root ANSWER sieve-tube elements root hairs parenchyma cells vessel elements sclerenchyma cells https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Activity Transport of Xylem Sap Click here to complete this activity Then answer the questions Part A The channels indicated by the pointer are ANSWER desmosomes plasmodesmata tight junctions mycorrhizae gap junctions Correct Water and ions can pass from cell to cell via these channels Also recall that plasmodesmata are a type of cell junction Part B Which of these are symbiotic associations ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM root hairs Casparian strips mycorrhizae symplast apoplasts Correct Mycorrhizae are mutualistic associations of roots and fungi Part C To view the animation click here Then click on the image to start the animation This is an animation of the movement of water and ions through the root ANSWER via a combination of the movement through plasmodesmata and across cell membranes via the apoplastic route from cell to cell across cell membranes and cell walls via the symplastic route via the mycorrhizal route Correct The animation illustrates water and ions moving along a cell wall continuum Part D In roots the forces water and solutes to pass through the plasma membranes of cells before entering the ANSWER Casparian strip endodermis phloem xylem endodermis Casparian strip Casparian strip ectoderm xylem Casparian strip endodermis xylem transpiration endodermis xylem Correct The Casparian strip is a waterproof barrier that forces water and solutes to pass through the plasma membranes of endodermis cells Part E provide s the major force for the movement of water and solutes from roots to leaves ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Bulk flow Transpiration Translocation Transfer cells Root pressure Correct Transpiration the evaporation of water from leaves exerts a pull that bears the primary responsibility for the movement of water and solutes from roots to leaves Part F bonds are responsible for the cohesion of water molecules ANSWER Ionic Polar covalent Peptide Nonpolar covalent Hydrogen Correct Hydrogen bonds among water molecules are responsible for the tendency of those molecules to stick together Part G cells are the cells that regulate the opening and closing of stomata thus playing a role in regulating transpiration ANSWER Tracheid Sieve-tube member Companion Casparian strip Guard Correct Guard cells regulate the opening and closing of stomata Experimental Inquiry What Effect Does Auxin Have on Coleoptile Growth Phototropism is the directional response of an organism to light Charles Darwin and his son Francis were among the first scientists to study phototropisms in plants The focus of their studies was dark-grown coleoptiles of canary grass and oat The coleoptile is a hollow cylindrical sheath that surrounds and protects the first leaves of a grass seedling as they emerge from the seed and grow upward through the soil https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM The Darwins noted that if dark-grown coleoptiles those that are kept in the dark so that they grow above the soil were exposed to directional light they would bend toward the light They deduced from a number of experiments that the direction of the light was sensed by the tip of the coleoptile but that the growth response water uptake and cell elongation occurred in a region well below the tip They hypothesized that a mobile chemical signal carried information from the tip of the coleoptile to the responding region In the responding region the cells on the shaded side elongate more than the cells on the illuminated side causing the coleoptile to bend toward the light Part A - Experimental technique Manipulating movement of compounds from the coleoptile tip The hypothesis that a mobile compound produced in the coleoptile tip controlled its bending toward directional light was tested by P Boysen-Jensen in His experimental setup is represented below Both dark and light treatment groups had intact coleoptiles as controls The experimental groups included coleoptiles in which the tips were removed coleoptiles that were cut with the tips separated by mica coleoptiles that were cut with the tips separated by agar Boysen-Jensen left one set of coleoptiles in darkness for hours and one set in directional light for hours and observed whether they elongated and or bended toward the light Predict how the coleoptile will grow or not grow under each treatment by dragging the labels onto the table Labels may be used once more than https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM once or not at all Hint The coleoptile tip and growth in the dark and in the light In the dark coleoptiles continue to elongate upward This growth is dependent on the presence of the coleoptile tip Chemical signals that are produced in the tip must diffuse to the region of growth below the tip for the coleoptile to elongate Removal of the tip causes elongation of the coleoptile to cease In the light just as in the dark the tip is necessary for coleoptile elongation In addition the chemical signals produced in the tip are required for bending of the coleoptile in response to directional light Hint What are the properties of the mica sheet and the agar block that are important in this experiment Insertion of either mica or agar between the tip and the rest of the coleoptile is the key treatment in this experiment Which of the following statements correctly describes the properties of the mica and the agar in this experiment ANSWER Neither the mica nor the agar is permeable to chemical compounds produced in the coleoptile tip The mica is permeable to chemical compounds produced in the coleoptile tip but the agar is not The agar is permeable to chemical compounds produced in the coleoptile tip but the mica is not Both the mica and the agar are permeable to chemical compounds produced in the coleoptile tip Hint The function of coleoptiles in seedling growth The coleoptile is a hollow cylindrical sheath that surrounds and protects the first leaves of a grass seedling as they emerge from the seed and grow upward through the soil The upward growth of coleoptiles from buried seeds is intended to rapidly deliver the young leaves to the surface of the soil where they can begin to perform photosynthesis Normally growth of the coleoptile ceases when the tip emerges from the soil allowing the young leaves to continue to grow into the light However if the seedling is grown in the dark the coleoptile continues to elongate and the first leaves remain wrapped within its sheath When a dark-grown coleoptile that has already emerged from the soil is exposed to light the coleoptile eventually stops elongating The young leaves emerge but not until after the bending response has occurred ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The Boysen-Jensen experiment demonstrated that a mobile compound produced in the coleoptile tip is required for vertical elongation of the coleoptile in the dark and for bending of the coleoptile in response to directional light The discovery that this mobile compound could pass through an agar block and still permit elongation in the dark or bending in the light was a key observation that eventually led to the identification of auxin by Frits Went Part B - Experimental results The experiments of Frits Went Following up on the work of Boysen-Jensen Frits Went placed the decapitated tips of dark-grown oat coleoptiles on tiny agar blocks permitting the chemical signal that controlled elongation in the dark and bending in the light to diffuse into the agar He then placed these agar blocks on top of decapitated dark-grown coleoptiles Agar blocks that had been exposed to a coleoptile tip pink caused the coleoptile to elongate Control blocks that had not been exposed to a coleoptile tip white did not cause the coleoptile to elongate https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM As shown in the labels below Went extended his experiments by placing the control white and treated pink agar blocks off-center on top of decapitated coleoptiles Some he left in the dark indicated by the gray background and some he exposed to directional light indicated by the yellow arrows Sort the following coleoptiles into the appropriate bins depending on if they will bend to the left bend to the right or not bend at all Hint What is the effect of directional light in this experiment Suppose the tip of a coleoptile were replaced by a treated agar block as shown in the image below How would this coleoptile respond to directional light Or would it ANSWER The coleoptile would elongate and bend toward the directional light The coleoptile would neither elongate nor bend The coleoptile would elongate vertically but not bend The coleoptile would elongate and bend away from the directional light Hint How placement of the agar block affects movement of compounds in the coleoptile Went found that the chemical signal could diffuse from the agar block into a decapitated coleoptile If centered on the decapitated coleoptile the treated agar block caused the coleoptile to elongate vertically If the agar block was placed off-center the compound entered the coleoptile only on the side exposed to the block causing a higher concentration of the compound on that side of the coleoptile This uneven distribution of the chemical caused elongation on only one side resulting in bending Hint Reviewing Went s findings about agar blocks and elongation of coleoptiles in the dark Based on his original experiments Went concluded that the chemical signal produced by the coleoptile tip could diffuse into the agar block Furthermore when the agar block was placed on top of a decapitated dark-grown coleoptile the chemical diffused from the agar into the coleoptile And the agar block https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM alone could cause the coleoptile to elongate In other words the treated agar block replaced the function of the tip in elongation of coleoptiles in the dark ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct From the bending of the coleoptiles in response to the off-center agar blocks Went concluded that it is an uneven distribution of the mobile chemical signal that causes bending He named this chemical signal auxin The results of this experiment also indicate that coleoptiles cannot respond to directional light without their tips For the decapitated coleoptiles neither the presence nor the direction of the light mattered only the placement of the agar blocks determined bending Went hypothesized that for intact coleoptiles in the dark auxin from the tip moves evenly down the coleoptile resulting in uniform vertical growth When the coleoptile tip is exposed to directional light he hypothesized that auxin accumulates in the shaded side of the tip causing more auxin to move down the shaded side of the coleoptile As a result cells on the shaded side elongate more than cells on the lighted side causing the coleoptile to bend toward the light Part C - Experimental prediction The effect of light on the amount and distribution of auxin in the coleoptile tip Based on the observations of Went and others you hypothesize that light does not affect the amount of auxin produced in the coleoptile tip You further hypothesize that light causes auxin to move from the illuminated side to the shaded side of the tip To test your hypothesis you set up the following experiment In tips A and B the tip and the agar beneath it are both divided by a piece of plastic that permits light to pass through but is impermeable to water- soluble compounds such as auxin The plastic was inserted into the tips and agar in the dark In tip C the plastic completely divides the agar but only partially divides the coleoptile tip Again the plastic was inserted in the dark Tip A is kept in the dark while tips B and C are illuminated with directional light as shown Based on Went s experiments agar blocks and should contain the same amount of auxin Assuming that your hypothesis is supported sort the remaining agar blocks according to whether you would expect them to have less auxin the same amount of auxin or more auxin than blocks and Hint In tips A and B how does light affect the amount of auxin You already know that in tip A the amount of auxin on each side of the plastic divider is the same Recall that your hypothesis states that light does not affect the amount of auxin produced in the coleoptile tip only the distribution of the auxin between the illuminated and shaded sides of the tip If your hypothesis is supported how should the auxin in the agar beneath tips A and B compare Remember that the plastic sheet is inserted before tip B is illuminated ANSWER The total amount of auxin in blocks and should be the same as the total amount of auxin in blocks and There should be more auxin in block than in either block or There should be more auxin in block than in either block or Hint In tips B and C how does partially dividing the tip affect the amount of auxin https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Tips B and C differ in that tip B is completely divided by the plastic sheet whereas tip C is only partially divided by the plastic sheet Both tips are illuminated Recall that your hypothesis states that light does not affect the amount of auxin produced in the coleoptile tip only the distribution of the auxin between the illuminated and shaded sides of the tip If your hypothesis is supported how should the auxin in the agar beneath tips B and C compare ANSWER The total amount of auxin in blocks and should be greater than the total amount of auxin in blocks and There should be more auxin in block than in either block or There should be more auxin in block than in either block or ANSWER Correct You hypothesized that light does not affect the amount of auxin produced in the coleoptile tip only the distribution of the auxin Therefore you would expect the total amount of auxin in the agar blocks beneath each tip to be the same In tip B the plastic sheet completely divides the tip which prevents any redistribution of auxin in response to directional light Therefore you would expect the amount of auxin in blocks and to be equal to each other and the same as in blocks and In tip C the plastic sheet only partially divides the tip which allows for redistribution of auxin in response to directional light Therefore you would expect there to be less auxin in block and more auxin in block Remember that auxin accumulates on the shaded side of the coleoptile Actual experiments subsequent to Went s work provided further support for this hypothesis with regard to coleoptile tips in many grasses Chapter Question Part A https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM A fruit is ANSWER a fused carpel a mature ovule a seed plus its integuments an enlarged embryo sac a mature ovary Correct Chapter Question Part A The specific relationship between a legume and its mutualistic Rhizobium strain probably depends on ANSWER specific recognition between the chemical signals and signal receptors of the Rhizobium strain and legume species each legume being found where the soil has only the Rhizobium specific to that legume each Rhizobium strain having a form of nitrogenase that works only in the appropriate legume host destruction of all incompatible Rhizobium strains by enzymes secreted from the legume's roots each legume having a chemical dialogue with a fungus Correct Chapter Question Part A Which type of mutant would be most likely to produce a bushier phenotype ANSWER strigolactone underproducer cytokinin underproducer auxin overproducer strigolactone overproducer gibberellin overproducer Correct Chapter Question Part A Movement of phloem sap from a source to a sink ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM results mainly from diffusion depends on pumping water into sieve tubes at the source occurs through the apoplast of sieve-tube elements depends ultimately on the activity of proton pumps depends on tension or negative pressure potential Correct Primary and Secondary Growth in Plants Growth occurs throughout a plant's life because of perpetually embryonic tissues called meristems Meristems contain undifferentiated cells that divide and differentiate enabling plants to grow in length and girth Part A - Differentiating between primary growth and secondary growth Sort the terms and phrases as to whether they function in or describe primary growth or secondary growth Drag each term or phrase to the appropriate bin If the term or phrase describes both primary and secondary growth drag it to the both bin If the term or phrase describes neither primary nor secondary growth drag it to the neither bin Hint Herbaceous and woody plants Herbaceous nonwoody plants experience only primary growth They have a primary plant body that consists of tissues produced by the apical meristems Woody plants generally undergo extensive primary growth and therefore require more structural support which is provided by secondary growth The secondary plant body consists of tissues produced by two types of lateral meristem the vascular cambium and the cork cambium Hint What is primary growth Which statement s describe s primary growth Select all that apply ANSWER the only type of growth that occurs in herbaceous plants growth in length the growth in girth that occurs in stems and roots Hint What is secondary growth Which statement s describe s secondary growth Select all that apply ANSWER growth in length the growth in girth that occurs in stems and roots the only type of growth that occurs in woody plants Hint Can you match terms related to primary and secondary growth to their descriptions Drag the terms on the left to the appropriate blanks on the right to complete the sentences ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Primary growth which occurs at apical meristems results in the elongation of roots and shoots In roots primary growth increases water and nutrient absorption by increasing the root surface area exposed to the soil In shoots primary growth adds height and leaves which increase the plant's exposure to and absorption of light Secondary growth occurs at two types of lateral meristem vascular cambium and cork cambium Vascular cambium adds thickness to a woody plant by adding secondary xylem wood and secondary phloem This increases vascular flow and provides additional support Cork cambium produces the external covering of woody plants Woody plants which can live for many years experience both primary and secondary growth Herbaceous nonwoody plants on the other hand generally live only one year and experience only primary growth Recent research indicates that some herbaceous plants undergo a small amount of secondary growth in the late growing season but generally speaking herbaceous plants are composed of a primary plant body only Part B - Labeling primary growth structures Primary growth is growth in length that occurs at the tips of roots and shoots and in the axillary buds of shoots Label the following diagram of a plant the cross section of its stem and the longitudinal section of its root Note that the term zone of maturation is equivalent to the term zone of differentiation Drag the labels to their appropriate locations on the diagram of the plant below Labels can be used once more than once or not at all Hint Apical meristems and lateral meristems Meristems are areas of embryonic or undifferentiated cells that enable growth in plants There are two main types of meristems Apical meristems add cells to the tips of roots and shoots and in the axillary buds of shoots leading to elongation primary growth in these parts Primary growth produces the primary plant body which includes the dermal ground and vascular tissue systems Lateral meristems add thickness secondary growth to a plant The vascular cambium adds secondary xylem and secondary phloem The cork cambium adds a protective outer layer to the woody stem Hint Where does primary growth occur Where in a plant does primary growth occur Select all that apply ANSWER zone of cell division lateral meristems zone of elongation apical meristems cork cambium tips of roots and shoots Hint Can you match primary growth structures to their descriptions Drag the terms on the left to the appropriate blanks on the right to complete the sentences ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Primary growth occurs at apical meristems in the tips of roots and shoots and in the axillary buds of shoots Primary growth generates the primary plant body which consists of dermal ground and vascular tissues Leaves for example are composed of all three types of tissue Note that primary xylem and primary phloem are produced by apical meristems The primary growth in a root occurs behind the protective root cap in three different zones the zone of cell division which contains the apical meristem and adds new cells the zone of elongation where cells elongate and push the root tip farther into the soil the zone of differentiation or zone of maturation where cells differentiate into distinct cell types becoming vascular dermal or ground tissue Part C - Analyzing tree growth rings As you have already learned the lateral meristems are responsible for secondary growth in woody plants One type of lateral meristem the vascular cambium adds girth to woody plants by adding secondary vascular tissues The secondary xylem commonly called wood accumulates as the plant grows Predict what the cross section of a four-year-old tree trunk would look like if there were drought conditions for the first two years of the tree's life and wet conditions for the most recent two years A B C D Hint Definition of growth ring Each year a layer of wood secondary xylem is added to a woody plant such as a tree Where growth is seasonal one year's growth appears as one ring in a cross section of a tree In spring the secondary xylem cells are large with thin cell walls In the late summer and fall the cells are small with thick cell walls These differences in the secondary xylem cells result in the appearance of a light band and a dark band within a single growth ring Hint How weather affects growth rings Because trees grow well in warm wet years the growth rings for such years are thicker than the rings added in cool dry years Hint Can you identify structures involved in secondary growth The diagram below represents a two-year-old stem on a woody plant Drag the labels to their appropriate locations on the diagram ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER A B C D Correct Where growth is seasonal the yearly growth patterns of woody plants give the appearance of rings in the wood In spring secondary xylem cells are large with thin cell walls and appear as wide light bands In the late summer and fall the cells are small with thick cell walls and appear as narrow dark bands A light band and a dark band together constitute one growth ring and represent one year's growth Annual rings vary in thickness depending on weather conditions Because trees grow well in warm wet years the growth rings for such years are thick The growth rings added in cool or dry years are smaller because those conditions are not ideal for growth Scientists use tree ring patterns to analyze climate patterns and events such as fire disease and insect infestations Chapter Question Part A A mineral deficiency is likely to affect older leaves more than younger leaves if ANSWER the mineral is a macronutrient the mineral is required for chlorophyll synthesis the mineral is very mobile within the plant the older leaves are in direct sunlight the mineral is a micronutrient https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Chapter Question Part A A seed develops from ANSWER an embryo an ovum an ovule a pollen grain an ovary Correct Activity Flowering Lab Click here to complete this activity Then answer the questions Part A For a short-day plant the is critical in determining if flowering will occur ANSWER maximum number of hours of light maximum number of hours of darkness minimum number of hour of light None of these is correct since short-day plants are also known as day-neutral plants minimum number of hours of darkness Correct Short-day plants are actually long-night plants Part B For a long-day plant the is critical in determining if flowering will occur https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER minimum number of hours of light maximum number of hours of darkness maximum number of hours of light minimum number of hours of darkness None of these is correct since short-day plants are also known as day-neutral plants Correct Long-day plants are short-night plants Part C Day-neutral plants flower regardless of ANSWER night length photoperiod day length or night length day length night length or photoperiod day length Correct Photoperiod refers to seasonal changes in the relative lengths of day and night Part D Which of these would inhibit flowering in a short-day plant with a critical night length of hours ANSWER hours of light hours of dark a flash of red light a flash of far-red light a flash of red light a flash of far-red light hours of dark hours of light hours of dark a flash of red light hours of dark All of these regimens would inhibit flowering in a short-day plant with a critical night length of hours hours of light hours of dark a flash of red light a flash of far-red light hours of dark hours of light followed by hours of dark Correct The flash of red light shortens the length of the dark period so flowering would not occur Part E Which of these would stimulate flowering in a long-day plant with a critical night length of hours ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM hours of light followed by hours of dark hours of light hours of dark a flash of red light a flash of far-red light a flash of red light a flash of far-red light hours of dark hours of light hours of dark a flash of red light a flash of far-red light hours of dark hours of light and hours of dark hours of light hours of dark a flash of red light hours of dark Correct The flash of red light shortens the length of the dark period and thus flowering would occur Angiosperm Life Cycle Angiosperms or flowering plants have a life cycle characterized by an alternation of generations meaning that there are two different multicellular forms one haploid form and one diploid form In addition to the alternation of generations other aspects of the angiosperm life cycle including pollination fertilization and seed development have enabled flowering plants to populate and thrive in a variety of environments Part A - Alternation of generations in angiosperms The diagram below illustrates the alternation of generations that is characteristic of the angiosperm life cycle Label structures and processes using white labels indicate whether different structures are haploid or diploid using pink labels and indicate the types of cell division that occur at different points in the life cycle using blue labels Drag the labels to their appropriate locations on the diagram of the angiosperm life cycle Labels can be used once or more than once Use only white labels for white targets pink labels for pink targets and blue labels for blue targets Hint Definitions of haploid and diploid The term haploid means that a cell has one set of chromosomes n The term diploid means that a cell has two sets of chromosomes n Hint Distinguishing between sporophyte and gametophyte Angiosperms have two distinct forms the haploid gametophyte and the diploid sporophyte The gametophyte is highly reduced consisting of only a few cells The sporophyte tends to be the larger and more obvious form Some of the cells in a sporophyte undergo meiosis producing spores that ultimately develop into haploid gametophytes Male and female gametophytes produce the sperm and egg that fuse forming a diploid zygote This diploid zygote ultimately develops into the mature sporophyte and the cycle repeats Hint Can you match life cycle terms with their descriptions Drag the terms on the left to the appropriate blanks on the right to complete the sentences ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint Can you identify diploid structures Which of the following structures are diploid in the angiosperm life cycle Select the two that apply ANSWER embryo male gametophyte zygote female gametophyte ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The alternation of generations refers to the alternation between the diploid sporophyte and the haploid gametophytes in plants In angiosperms meiosis occurs in floral structures of the larger diploid sporophyte producing haploid microspores in the anthers and haploid megaspores in the ovaries These microspores and megaspores divide by mitosis and form the haploid male and female gametophytes respectively Pollination occurs when the male gametophyte contained in a pollen grain is transferred to the stigma of a flower Sperm travels to the female gametophyte where fertilization fusion of sperm and egg forms a diploid zygote The zygote develops into an embryo and eventually an adult sporophyte The cycle repeats each time allowing for the production and development of new individuals Part B - Fertilization and seed development You have learned that the fusion of egg and sperm produces a zygote But how does the sperm reach the egg and how does the zygote develop into a seed which eventually germinates and grows into a mature sporophyte In this activity you will demonstrate your understanding of double fertilization and seed development in angiosperms Drag the statements to their appropriate locations on the flowchart of pollination fertilization and seed development Hint What are the definitions of terms relating to fertilization Drag the terms on the left to the appropriate blanks on the right to complete the sentences ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint What is double fertilization The diagram below shows the steps involved in double fertilization Drag the labels to their appropriate locations on the diagram ANSWER Hint How a zygote forms and develops In double fertilization one sperm fertilizes the egg forming a n zygote The first division of the zygote produces a basal cell which produces a suspensor that allows for nutrient flow from the parent plant to the embryo and a terminal cell which gives rise to most of the cells of the embryo The terminal cell divides and gives rise to the protoderm ground meristem and procambium which are the progenitors of the adult epidermis ground https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM tissue and vascular tissue respectively ANSWER Correct During pollination a pollen grain is transferred from an anther to a stigma Once the pollen grain lands on a suitable stigma it germinates and forms a pollen tube a structure that grows down through the style to the ovary Once in the pollen tube the generative cell from the pollen grain divides by mitosis forming two sperm The sperm travel down the pollen tube and are discharged into the female gametophyte In a process called double fertilization one sperm fertilizes the egg forming the zygote the other sperm fuses with two polar nuclei in the female gametophyte forming a triploid n nucleus The zygote develops into the plant embryo and the triploid nucleus divides and gives rise to the endosperm Double fertilization prevents the waste of the plant's resources by ensuring that the nutrient-rich endosperm only develops if the egg is fertilized After double fertilization the ovule starts to develop into a seed containing the plant embryo As the embryo develops the three tissue systems are established and the cotyledons seed leaves form The seeds of many species dry out as they mature These dry seeds lie dormant until suitable germination conditions occur Part C - Angiosperms and life on land Many aspects of the angiosperm life cycle make flowering plants particularly well-suited to life on land In fact angiosperms are the most diverse and widespread https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM of all plants Which six of the following statements reflect angiosperm adaptations to life on land Hint Reproductive challenges of life on land In seedless plants gamete transfer relies on water because the flagellated sperm must swim through a film of water to reach the egg Moisture also keeps the gametophytes of seedless plants from drying out Seed plants on the other hand have adaptations that enable sperm to reach the egg without water protect the gametophytes from drying out and from the ultraviolet radiation in sunlight Hint Advantages of reduced gametophytes Angiosperms compared to seedless plants have a reduced gametophyte stage Scientists think that reduced gametophytes may be advantageous because the delicate gametophytes can be protected for example from desiccation UV radiation or some predators in the body of the diploid sporophyte which can respond more efficiently to changing environmental conditions In addition the female gametophyte obtains nourishment from the sporophyte Hint Function of fruits in seed dispersal A fruit is derived from the ovary of a flower and encloses one or more seeds Fruits can be fleshy such as in apples or dry such as in nuts and grains Fruits protect the seeds from harsh environmental conditions and aid in seed dispersal The method of seed dispersal depends on the type of fruit surrounding the seed s With fleshy fruits such as berries animals eat the fruits and seeds They digest the fleshy tissue and pass the seeds in their feces The spiny fruits of cockleburs stick to animal hair or clothing In some cases this stickiness enables the seeds to be carried long distances Some dry fruits such as in dandelions can act as parachutes and carry the seeds on the wind The buoyant fruits of coconuts enable them to travel in the ocean Hint How do the characteristics of flowers relate to their role in pollination One function of flowers is to facilitate pollination or the transfer of pollen from the anther of one flower to the stigma of another Pollinators can be biotic living organisms such as bees or birds or abiotic wind or water Drag the terms on the left to the appropriate blanks on the right to complete the sentences ANSWER ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Seeds protect and nourish plant embryos and fruits protect the seeds Fertilization in angiosperms is dependent on the presence of water Seeds enable plant embryos to be dispersed long distances from the parent plant via wind or animals In angiosperms a gametophyte protects a dependent sporophyte from desiccation Flowers attract animal pollinators carrying pollen from other plants of the same species Floral parts of the sporophyte protect the reduced female gametophyte from drying out and from UV radiation Spores contain a supply of stored food enabling the embryo to remain dormant until conditions are suitable for germination In many angiosperms the male gametophyte contained in a pollen grain can be transported many miles away by wind or animal pollinators Fruits aid in the dispersal of seeds by wind or by animals that carry or eat the fruits Correct As plants evolved and populated terrestrial environments one challenge that had to be dealt with was the absence of water Angiosperms have met this challenge in part with adaptations that enable them to reproduce without water The following table lists some differences between nonvascular plants such as mosses and angiosperms Note how the angiosperm adaptations enable them to reproduce in dry terrestrial environments Nonvascular plants Angiosperms reduced dependent on gametophyte dominant sporophyte for nutrients and protection dependent on dominant nourishes and sporophyte gametophyte protects gametophyte from for nutrients desiccation UV radiation and predators nourish and protect plant seeds no seeds embryos with nutrient stores and tough outer coats enable pollination and flowers no flowers fertilization in the absence of water protect female gametophyte in ovary aids in protection and fruit no fruit dispersal of seeds by animals wind or water pollen grains transferred from pollination no pollen anther to stigma by animals wind or rarely water flagellated nonflagellated sperm travel fertilization sperm must through pollen tube to reach swim to egg female gametophyte water through water unnecessary Chapter Question Part A Double fertilization means that ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM one sperm is needed to fertilize the egg and a second sperm is needed to fertilize the polar nuclei the egg of the embryo sac is diploid every egg must receive two sperm to produce an embryo every sperm has two nuclei flowers must be pollinated twice to yield fruits and seeds Correct Chapter Question Part A Which of the following is an adaptation that enhances the uptake of water and minerals by roots ANSWER cavitation active uptake by vessel elements mycorrhizae pumping through plasmodesmata rhythmic contractions by cortical cells Correct Chapter Question Part A Some of the problems associated with intensive irrigation include all but ANSWER soil salinization land subsidence mineral runoff overfertilization aquifer depletion Correct Chapter Question Part A The symplast transports all of the following except ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM proteins sugars mRNA viruses DNA Correct Activity Root Stem and Leaf Sections Click here to complete this activity Then answer the questions Part A Xylem is indicated by the letter ANSWER A B D C E Correct This is xylem https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Part B The letter A indicates the ANSWER vascular cylinder epidermis cortex xylem endodermis Correct The epidermis is the outmost layer of tissue Part C The letter A indicates the ANSWER cortex pith xylem phloem vascular bundle https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The cortex is indicated by the letter A Part D Pith is indicated by the letter ANSWER C B A D E Correct This is pith Part E Ground tissue is indicated by the letter ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM D E C B A Correct This is ground tissue Part F In leaves chloroplasts are found in ANSWER phloem cuticle xylem palisade mesophyll guard cells Correct Both the palisade and spongy mesophyll contain chloroplasts Part G The region surrounded by guard cells is indicated by the letter ANSWER C E B D A Correct Guard cells regulate the opening and closing of stomata https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Water Transport in Plants The Transpiration-Cohesion-Tension Mechanism BioFlix tutorial The transport of water and mineral nutrients from the roots to the leaves in plants depends on three properties of water surface tension adhesion and cohesion Because of these properties the loss of water through transpiration in the leaves pulls water up to the leaves through the xylem Before beginning this tutorial watch the segment of the Water Transport in Plants animation that focuses on the transpiration-tension-cohesion mechanism of water transport Part A - The relationship between hydrogen bonding and surface tension adhesion and cohesion Surface tension adhesion and cohesion are properties of water that arise from the ability of water molecules to form hydrogen bonds with each other and with other polar molecules What distinguishes surface tension adhesion and cohesion from one another is where the hydrogen-bonded molecules are found The diagram below shows the air-water interface at the top of a narrow tube filled with liquid water Space-filling models of several water molecules are shown with their O atoms in red and H atoms in white Notice that each of the pink targets labeled a-g lies within a rectangle that surrounds either a pair of water molecules or a water molecule and a molecule in the wall of the tube Label each target to indicate if the interaction between the molecules inside the rectangle contributes to surface tension T adhesion A or cohesion C Note that one target should be left blank because the molecules inside that rectangle are not involved in any of these interactions Hint Hydrogen bonding Hydrogen bonding is the electrostatic attraction between polar molecules It arises from the uneven distribution of charge within the molecules In a water molecule for example the two hydrogen atoms have a partial positive charge represented by and the oxygen atom has a partial negative charge represented by These partial charges interact with partial charges of opposite sign on other polar molecules leading to the attraction that underlies surface tension adhesion and cohesion Hint What is surface tension Which two statements below about surface tension are correct ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Surface tension can be generated anywhere in a column of liquid Interactions between the liquid and gaseous phases have a major effect on surface tension If a liquid has a high surface tension then its surface is easily deformed The high surface tension of water results from hydrogen bonds between molecules at the surface of the water Surface tension tends to resist stretching of the liquid s surface Hint What distinguishes cohesion from adhesion Cohesion and adhesion are closely related properties of water and both contribute to the transport of water in the xylem Which two statements below about cohesion and adhesion are correct ANSWER Adhesion and cohesion both depend on the presence of hydrogen bonds Cohesion is the tendency of water molecules to stick to other polar molecules Adhesion is the tendency of water molecules to stick to each other Cohesion is the tendency of water molecules to resist being pulled apart ANSWER Correct Surface tension and cohesion result from hydrogen bonds between water molecules whereas adhesion results from hydrogen bonds between water and other polar molecules Surface tension most commonly occurs at air-water interfaces where it resists breakage of the surface Hydrogen bonds tend to pull water molecules at the surface together reducing the curvature of the surface Cohesion tends to keep water molecules that are away from surfaces from separating Adhesion makes water stick to hydrophilic surfaces such as cell walls Part B - Processes that affect the strength of transpirational pull Water s properties of surface tension cohesion and adhesion are central to the ability of transpiration to pull water up from the roots to the leaves through the https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM xylem Sort each statement into the appropriate bin to indicate if the change described in the statement would increase decrease or not affect the pull that transpiration generates in the xylem of a tree Hint How water loss and adhesion affect the curvature of the water surface on mesophyll cell walls This segment from the Water Transport in Plants animation begins with the cell wall completely covered with a layer of water As evaporation continues loss of water begins to expose cellulose microfibrils in the wall Note that water tends to stick to the cellulose microfibrils a property called adhesion The water surface which was nearly flat before evaporation started is now very curved in the regions close to and between the exposed cellulose microfibrils Think about the consequences of this increased curvature in terms of surface tension and transpirational pull Hint What biological and environmental factors determine the rate of transpiration Under normal conditions water loss from a leaf is balanced by water entering the leaf from the xylem so that the water content of the leaf remains constant Many factors can alter this balance and thus affect the rate of transpiration Sort each factor into the appropriate bin depending on whether the factor is controlled by the plant is controlled by the environment or does not normally affect the rate of transpiration ANSWER Hint What is the relationship between curvature of the water surface transpirational pull and rate of transpiration The two diagrams below show the air-water interface between two cellulose microfibrils in a mesophyll cell wall Drag the blue labels to the blue targets to indicate the rate of transpiration in each condition Drag the pink labels to the pink targets to indicate the transpirational pull in each condition https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER ANSWER Correct The generation of transpirational pull in leaves depends on the interaction of water with the cellulose microfibrils in mesophyll cell walls Because the microfibrils are hydrophilic water adheres strongly to them Therefore as water evaporates from the cell walls it is lost first from the regions between the microfibrils As a result the water surface between the microfibrils becomes more curved which increases the surface tension and the transpirational pull Part C - The roles of surface tension cohesion and adhesion in water movement in the xylem https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Surface tension cohesion and adhesion play different roles in the transport of water from the roots to the leaves in the xylem One role is to generate the force that ultimately pulls the water up through the xylem Another role is to transmit that force uniformly throughout the xylem A third role is to help oppose the force of gravity which tends to pull water downward in the xylem Drag a label to each target in the table to indicate the role that surface tension adhesion and cohesion play in the transport of water in the xylem Labels may be used more than once Hint The label generates pull belongs in only one target in the table Hint Surface tension and water movement in the xylem At an air-water interface hydrogen bonds between water molecules make it difficult to break the water surface This property is called surface tension Inside a leaf water evaporates at the air-water interface between microfibrils in the mesophyll cell walls As water evaporates the air-water interface retreats farther into the cell walls increasing the curvature of the water surface This increase in curvature increases the surface tension which in turn pulls water from surrounding cells The pulling of water from surrounding cells by surface tension is the origin of the transpirational pull that draws water up through the xylem Hint How does cohesion contribute to the movement of water in the xylem Cohesion is the result of hydrogen bonding between neighboring water molecules Each water molecule can form a maximum of four hydrogen bonds oriented in different directions as shown in the figure below Thus except near surfaces where this pattern of hydrogen bonding is disrupted cohesion tends to draw water molecules together equally in all directions Imagine that the water molecule at the top of the figure is being pulled up by an unspecified force How would this pulling affect the water molecule in the middle ANSWER The molecule would be pushed to one side or the other There would be no effect The molecule would be pushed down The molecule would be pulled up Hint What counteracts the effect of gravity on water in the xylem When water flows up a stem in the xylem its movement occurs against the force of gravity However even when there is no transpirational pull for example when the stomata are closed at night the xylem remains full of water Which interaction prevents water from moving down the xylem even when transpiration is not occurring https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM ANSWER surface tension between water and air in the leaves cohesion between water molecules in the xylem adhesion of water to the cell walls of the xylem surface tension between water and cell walls of the xylem ANSWER Correct Surface tension in leaves generates the force that pulls water through the xylem Cohesion between water molecules in leaves stems and roots transmits that force Adhesion of water to plant cell walls in leaves and stems opposes the force of gravity which tends to pull water downward in the xylem Chapter Question Part A The black dots that cover strawberries are actually individual fruits The fleshy and tasty portion of a strawberry derives from the receptacle of a flower with many separate carpels Therefore a strawberry is ANSWER a simple fruit with many seeds both a simple fruit and an aggregate fruit both a multiple fruit and an aggregate fruit both an aggregrate fruit and an accessory fruit both a multiple fruit and an accessory fruit https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct Activity Leaf Abscission Click here to complete this activity Then answer the questions Part A Evergreen trees lose their leaves ANSWER every winter in the spring steadily all year every fall in the summer Correct Evergreen trees which retain most of their leaves during the winter lose leaves steadily throughout the year Part B To view the animation click here Then click on the image to start the animation The abscission layer is indicated by the letter ANSWER A C B D E Correct This is the abscission layer which forms where the petiole joins the stem Part C https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM The breakdown of chlorophyll reveals the pigments of a leaf ANSWER phycoerythrin melanin xanthophylls carotenoid anthocyanin Correct The breakdown of chlorophyll unmasks the yellow and orange carotenoid colors Part D The formation of the abscission layer cuts off transport of substances to and from the leaf As the concentration of sugar trapped within a leaf increases pigments are produced ANSWER carotenoid xanthophyll anthocyanin phycoerythrin melanin Correct Anthocyanin pigments which have a deep red coloration are produced when sugar gets trapped in leaves Part E The protective layer that forms between the abscission layer and the stem consists of ANSWER densely colored cells filled with a waxy layer irregularly shaped cells with very thick lignified secondary walls a layer of green palisade cells weak colorless thin-walled cells mycorrhizae Correct These cells form a protective seal in the place where the leaf will detach Part F After leaf abscission growth will resume from the ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM petiole axillary bud abscission layer palisade layer protective layer Correct The axillary bud is an embryonic shoot found at the angle between the stem and leaf Part G trees lose their leaves in preparation for winter ANSWER Pine Fir Conifer Spruce Deciduous Correct Deciduous trees such as maples shed their leaves in preparation for the winter Activity Seed and Fruit Development Click here to complete this activity Then answer the questions Part A What is endosperm ANSWER tissue that develops into a protective seed coat surrounding the embryo via cotyledons a source of food for the embryo the leaves that are a part of the embryo the female portion of a flowering plant the male portion of a flowering plant https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Correct The triploid endosperm is a source of nourishment for the embryo Part B The pointer is indicating a diploid cell that develops into the ANSWER endosperm embryo seed coat ovule carpel Correct This region of an ovule develops into an embryo Part C Fruits evolved primarily as structures specialized to ANSWER provide a source of food to the plant's embryo provide food for humans protect pollen protect seeds disperse seeds Correct Fruits evolved as seed-dispersing structures Chapter Question Part A https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM The pollen produced by wind-pollinated plants is often smaller than the pollen produced by animal-pollinated plants A reason for this might be that ANSWER wind-pollinated flowers don't need large pollen grains because they don't have to attract animal pollinators small pollen grains can be carried farther by the wind animal pollinators are more facile at picking up large pollen grains wind-pollinated plants in general are smaller than animal pollinated plants wind-pollinated plants release pollen in the spring before the plant has stored enough energy to make large pollen grains Correct Chapter Question Part A A small flower with green petals is most likely ANSWER moth-pollinated wind-pollinated bee-pollinated bat-pollinated bird-pollinated Correct Chapter Question Part A The signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of ANSWER red light followed by far-red light during the night far-red light during the night far-red light during the day red light during the day red light during the night Correct Activity Fruit Structure and Development https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Click here to view this animation Then answer the questions Part A Why do fleshy fruits often have seeds with very tough seed coats Hint How are fleshy fruits dispersed ANSWER So the seeds can survive the mechanical forces and conditions in an animal's gut So the seeds can adhere to passing animals So the seeds can be dispersed by propulsion So the seeds can extend the distance they travel by catching breezes Correct Animals are the most common dispersal agents for fleshy fruits and seeds must survive the passage through an animal's digestive tract Part B What characterizes the fruit of seeds that are dispersed by the wind Hint How can seeds be dispersed by the wind ANSWER They contain a large amount of sugar They are large They are very fleshy They have structures to extend the distance they travel on the wind Correct The fruits of seeds that are dispersed by the wind often have external structures that allow them to extend the distance they travel on the wind Part C True or false Fruits provide food to the developing plant https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint How do fruits contribute to the fitness of flowering plants ANSWER True False Correct Fruits protect seeds and aid in their dispersal the endosperm provides food to the developing plant Part D Which part of a flower develops into the seed Hint Remember that the seed contains the developing plant ANSWER Carpel Pericarp Ovule Endosperm cell Correct Once pollination has occurred the fertilized ovule develops into the seed Part E Which term describes the portion of a peach that can be eaten by humans Hint This structure protects seeds and aids in their dispersal ANSWER Endosperm Seed coat Pericarp Zygote Correct The edible portion of a peach is the pericarp or fruit wall which is a protective structure that encloses the seed and aids in its dispersal Part F True or false The endosperm tissue that nourishes the developing plant has the same nutritional characteristics regardless of the plant species https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM Hint Humans can consume endosperm tissue from plant species such as corn or beans ANSWER True False Correct The characteristics of the endosperm tissue vary by plant species some tissues contain large amounts of starch corn while others contain large amounts of protein beans Activity Soil Formation and Nutrient Uptake Click here to view this animation Then answer the questions Part A What are the largest particles formed from the breakdown of rock ANSWER Clay Gravel Sand Silt Correct Gravel particles are the largest particles formed from the breakdown of rock Part B Which of the following is an elemental ion Hint What is the difference between an elemental ion and a molecular ion ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM HCO K K NO Correct K is an elemental ion Part C True or false Soil texture affects the amount of water available to plants water is held best by clay and sand particles Hint Which soil particles retain the most water ANSWER True False Correct Soil texture does indeed affect the amount of water available to plants but water is held best by the smallest soil particles clay and silt Part D Which of the following steps occurs first during soil formation Hint Remember that soil formation begins with solid rock and takes many years ANSWER Organic material is added to the rock surface Weathering of solid rock occurs Mosses grow on the rock surface Lichens grow on the rock surface Correct Weathering is the process by which solid rock is broken down into smaller pieces and is the first step in soil formation Part E Why is the decomposition of dead organisms important for soil formation Hint Remember that the decomposition of dead organisms adds organic matter to the soil ANSWER https session masteringbiology com myct assignmentPrintView displayMode studentView assignmentID Page of HW Plant Form and Function PM The process produces acidic compounds that dissolve the rock surface The process makes negatively charged ions more easily absorbed by plant roots The process increases the amount of silt in the soil The process adds organic matter to the soil which is necessary to support the growth of larger plants Correct Decomposition of dead organisms adds organic matter or humus to the soil humus is necessary to support plant growth Part F Which of the following statements about nutrient uptake by plants is true Hint Think about how plants obtain vital minerals from the soil ANSWER Root hairs increase the volume of roots for more efficient absorption of water and nutrients Plants can easily absorb mineral ions
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