Human Resources Project Research Paper Example | Topics and Well Written Essays - 500 words

Human Resources Project - Research Paper Example A successful training center must have a good orientation process in order to be able to welcome the new students and integrate them into the school system. Both institutions have different methods toward orientation but the anticipated goal is the same. Miami Dade College has invested a lot into orientation with a fully functional student center and online orientation programs to ensure that new students are catered for appropriately. Broward college on the other is an institution that encourages personal contact with the staff through asking questions and attending forums to ensure transition in the college. Notably, both institutions allow the transfer of learning, the Broward college allows the students to transfer from any other colleges and join their college after producing the relevant performance documents. Unlike the Broward college, the Miami Dade college only allows students from selected colleges to join their institution. Both institution’scourses are relevant in the aspect that they provide courses that meets the country’s employment niche. The Broward college goes an extra mile to propose internship programs for their students, but the Miami Dale College seems to lag behind in this area. Comments from students state that Miami Dale College staff lacks the appropriate decorum to address student issues unlike the Broward college where there are good reviews on the service provision. Miami Dale college (2013) states that employee relations ensure that the rights of the employees are protected and also that the rules are followed in the latter. Both institutions uphold high employee relations. This trivially is the key towards better organizational performance and service delivery. Both

Drivers of Risk in Healthcare

Drivers of Risk in Healthcare CHERRY AMOR B. DAWAL These summary may pertains to the sum of all informations regarding the drivers risk on the following strategic risk, financial risk, operational risk, health and safety risk, hazard risk and information risk. Strategic Risk Drivers- it is a mean of having loss that might arise from the pursuit of not successful business plan.The organization always takes struggle well with strategic risk.In conversation of the strategic risk organizational development should always be consider in the discussion. This in connection to success that it can only be driven to capability and secondly capability development work. The risk is being assessed in purpose otherwise that the objectives,use of the risk maps is more important rather than using the risk register so it may allow level of interaction and challenge. First to do is a systematic risk analysis it may start with the data presented within the organization, which may help in the more sequential pattern in identifying and prioritizing risk. In health care organization driver risk under strategic risk may then identify on the system of planning to resolve the risk. If the plan is not so well presented there could be problem on the system wherein the solving of the identified risk lies on to have a more powerful organizational development work. When health care organizationn mada poor business decisions,from the executed decision,from inadequate resource allocation and failure to respond well to improvement in the business ambiance. Financial Risk Drivers- it is the ability that the shareholders will loose money in an investment in an organization with debt. Cash flow is inadequate to support for the financial obligations.Financial obligations in health care setting takes accountability on finances when there is high portion of debt which indicates a risky investment.It is also about the expenditure to check whether the money of the company have left to keep the business operation running. One example for the healthcare setting the number of staff is just numerous that there will be problem on the cashflow for the salary and the allowances of the employee. Therefore there will befalling to repay salary and wages in timely manner ,therefore task performance will have in effect on the health setting organization. Operational Risk- Drivers-By definition it is a risk associated with the companies business operation. It does involve different kinds of risks includes fraud which is a dishonet methods to take something valuable from another person it is a deceit or trickery. Legal, and environmental issues on the operation is also included. Hospital set-up fraud is being practice by manipulating personnel inside the organization to practice mis management on finances,and operations. It is the managers who decides to make standard operating procedures or internal controls on employees to follow to work in the business. Health and safety Risk Drivers-goals for workplace in health and safety is to reduce danger and increase task implementation on health individual in safe and productive workplace. In every country and organization the aim is to reduce work toll by focusing area where the most harm occur. Occupational health plan formation will help to solve the occupational health problems.Combination of skills, knowledge and leadership with action is the first priority.Effective imposition of health and safety in workplace makes the employee happy and productive and also regulate human and business cost -injuries. Any work related injuries or disease can bring unexpected cost and even loss of valued staff member. It plays impact on body,mind, finances and interrelationship of workers in turn and the health of their families. The group of people where in fact health of workers may also be affected. By work related factors. It is an act widely accepted that the ideal workplace is an important area for health campaign, what more accepted is the concept of the health promoting workplace . As well as the family recognize it. The ablity and the connection of a safe workplace may be interconnected through application of health and safety practices the organization may start to think safe. In HCO the following should be considered information is collected about the problem of the organization, the near misses and errors is being encourage to be reported, response is needed in the reported information, the organization should make changes in response to reporting and last is the organization should be flexible in response to safety situations.Determine whetherthe existing precaution are adequate or whether should be done.Information drive should be provided to the staff . Blood borne virus is one that is usually considered as a hazard to health workers as well as prickly needles instances. This is could be very serious problem. Substances may cause hazard in the workplace and may take in any kind such as liquids, solids,gases,mist and fumes.It may affect different areas of the body. They are classified as toxic substances. Healthcare staff are at risk and employer must take the following precaution. Creation of control of substance hazardous to health regulation that may prevent the process and activation of the harm as well as the reduction of the release of the substances to public and staff, take account relevant to the exposure,control exposure and measure appropriate to health risk,adequate control of exposure,check and review regularly elements being used,ensure the ceation and prevention will decrease the overall risk to health and safety. Hazard Risk Drivers- it could be biological, chemical,mechanical, environmental or physical agent that may in any way will cause harm. These types of hazards could also experience in HCO. Biological hazard came from organism that is foreign,chemical with virtue of its intrinsic property can cause the hazard,mechanical may involve mechanical processes,like motoe vehicles ,and others. Physical hazard is all about naturally occurring processes that has the capacity to create loss or damage. On the other hand hazard and risk oftenly used interchangeably. In relation to the statement stated above risk is the probabiltiy that the exposure to hazard may lead to negative consequence.Risk=Hazard x Dose(Exposure). Therefore a hazard will definitely will have no risk if there is no exposure to the hazard. For environmental hazard it could be both natural and man made hazard or disaster. On a day to day basis, extreme of natural phenomena have threatened humans,such as floods,volcanoes, and tsun ami.Man made could be such as threats of terrorism and failures of technology.Mitigation or reduction may include construction of prone facilities away from areas with high risk,redundancy,an emergency reserve fund,to purchase an insurance and the development and creation of operational recovery plans. In HCO set-up these particular hazard is expected and anticipated just before of the creation of the ceratin organization for such that early planning may entail protection for the site,staff,amd most importantly the HCO clients which are the patients and protection of the business as well. Information risk Drivers-every business now adays relies on information technology, the following would be the IT threats hardware and software failure,malware,viruses, spam, scams and phishing and human error. Criminal IT threats hackers,fraud,passwords theft,denialof service, security breaches and staff dishonesty. Information technology risk involve not just the negative impact of operation and service delivery which may affect the value of the organization through destruction and reduction of the worth of the organization. That is why the IT risk management is considered as a component of a wider ERM. The organization should use a systematic approach to handle the said problem for identification,assessment and management of information technology risk . If there is risk identified high probability for enabling risk associated to missing opprtunities,may happen. II. Healthcare Business Areas which are high risk company is the primary concern which account 2 based setting. A high risk industry and risk of financial drop exists. First concentrate on safety and health concern next is for companies viability and profitability. Both may affect companies status in financing,insurance and merchants accounts.The risk should be address immediately and properly so the situation will not escalate. Procedure to undergo for evaluation for inspection and auditing. For staffing shortage, staff with difficult working condition with low wages, so much workload such as overloaded number of patients, numbers of paperworks for documentation and charting of reports and billing purposes Staffing shortage may result to the overall wellness process might be hindered or prolonged,which may lead to dissatisfaction to clients and patients. Next is overcrowding ,too much number of patients in the hospital who needs immediate care, but unable to give proper patient care . Problem in bed spaces, overcrowded area and unsanitation may give more hazard and risk to patients welfare and safety. III. Potential Impact of different types of risk on the healthcare business organizations objectives. Financial objectives economic loss will occur if it will not properly handled and presented and understared. Medical objectives it is about the patients safety,quality of care and to provide patients satisfaction they do fall under the category. It emphasized on improving coordination,services, upgrading the value of patient care,and boosting the medical outcome. Management should take place,consideration of potential threat to the organization prepare to the business.Continuity plan to address threats identified,share and ensure employees the expectation in unusual functioning. Plan organization with information and procedures toprotect employee indisaster event. Information drive on emergency procedure. The employees must take all practice step to ensure the safety, both action,or inaction at work may cause harm to other. INDIVIDUAL SUMMARY PART B Risk Management on the following areas Employment practice risk management has a veri important effect on employment practices.Best risk management is the proper keeping of the personal records which may give documentation which is important in defending employment claims and have right to review of their own personal file. It is important to maintain performance records for its importance in ability to get lawsuit dismissed or win at trial.Information must be watch out to identify emplyees protection. Documentation must be ensure that it complies with the said requirement.To keep records on separate file for investigation records. Employers must have commitment to risk management ,which may utilize best employment practice,and to reduce wasteful and unnecessary employment litigation and keep premiun on lowest level. Fraud prevention measures is progressed subtantialy over the past years. The market increase in fraud risk assessment activity.Program focused on refining fraud identification and treatment, continue operation in relation to organized fraud, technical and resource capability ust be develop, work in collaboration with other agency to combat fraud and centralise the fraud analysis capability.Capacity to provide predictive warning of impending threats, includes development of appropriate risk mitigation strategies with key internal and external stakeholders. Health and Safety policy is a written policy statement which usually comprises of three elements, a statement section, which peratins about how safety should be manage ad the demonstration of organizations committment to health and safety,organization section where responsibilities are given and fit employees to overall safety management. Arrangement section contains details of specific activities and functions that has to be manage. The policy should cover all aspects the organization and must be relevant to employees. Decision has to made how to set up a policy, in small organization simple statement is more suitable for big organization lengthy policy is needed. The aim of the policy must be related to the level of risk,using the risk assessment it will help determine the explicity that is needed in the arrangement section. Reach of the policy is often the case if there is an overarching or corporate policy that may entail general issues. By informing the policy iit may depend on how big the organization is, if it is small each employee should be given a copy of the policy,if it is big notice board is necessary. What important is that the said policy is being brought to the attention of the employees. Monitoring and review is necessary and must be effective and vital, carrying out of checklist and safety inspectionshould be done so the policy must be effective enough, and also it can be achieve through audits and proper review for management reports and accident investigation. Protection of Physical assests in any business organization there is need for a balance for physical security and do business effectively at the same time. Since all organization faces risk at all times to determine how much is the risk is very important to help determine the apppropriate balance for the competing demands. Is t is necessary to provide a comprehensive approach to identify,apply, and manage physical security measures to safeguard the asset of the organization. Organization is in command to establish, implement, operate,monitor,review, maintain, and improve physical protection system.A policy which covers for commitment and willingness to lead,develop a physical assets protection policy.to establish a complete program that identify,analyze,and evaluate risk to tangible and intangeble assets.People, procedures,technologies and equiptment must be integrted to meet objective of the system, which must be constantly monitor,measure and review. Disaster management by definition it is the effective organization,which directs and utilize the present counter disaster resources which involves activities such as prevention,preparedness, recovery,mitigation and risk reduction and rehabilitation. To take preventive measures is very important to stop a hazard that it may not cause effect to the organization.Preparedness is also taken to anticipate and ensure proper actuons after the occurrence of the said event. Response is the action taken after tha said event. Recovery is the process whish is taken by the affected area, for restoration , Mitigation and risk reduction are measures which is being taken after the aftermath of the eventtaken prior to disaster impact, and lastly is rehabilitation is actions taken in after event to repair their dwellings,re -establishment of essential services and revive economic ans social activities. INDIVIDUAL SUMMARY PART C Vulnerability factors,and impacts program approaches to crisis management and healthcare business continuity planninng for the organization on the following Business Continuity Planning is also called as the business continuity and resiliency planning it may identify exposure of threats with hard and soft assets to give effective prevention and recovery,while still maintains the integrity and value of the organization. In times of adverse physical condition through BCP there is a continuation of the organizations operation. It follows cycle for maintenance, analysis,solution design,implementation and testing and acceptance.It is included in the plan the event that could give negative impact on the organization. If the place is affecte the BCP would be to move to another area which is more safer for the business operation. The impact and crisis scenario would be its basis from the business recovery plan,to plan for most wide-impact is more preferable. Building loss is best example for impact scenario which encompasses most critical business functions. Localized impact scenario would be like loss of a specific floor of the building which need to be documented. Threat assessment scenario is defined as each potential threat that may require unique recovery, such as epidemic,earthquake,fire,flood,cyber attack,sabotage,hurricane, utility outage,terrorismand piracy,war,theft,and random failure of mission critical system. Recovery solution design these may occur after the analysis phase where the technical recovery will follow for the solution phase. Business environments,such as production,distribution and warehouse are the commonly affected.Solution design the most cost effective disaster recovery that qualify on the impact analysis stage.It is a minimum requirement for data. It may determine the solution phase,secondary work areas, telecommunication,data methodology,and physical data requirement.For testing it is a work procedure where the recovery process not usable already,all must be to test as are all work processess for critical functions documented? Is it changed happened on the system for critical functions?is it the documented checklist is accurate and valuable?and last are the documented work process recovered task and may defend the disaster recovery plan pertaining to staff and recovery time objective. Maintenance and update there are three periodic activities for exercising the BCP cycle maintenance manual. Confirmation of the information must be done,roll out the staff for give them awareness for the specific training for individuals, testing and verify solutions which are technical that is needed for recovery operations,testing and verify the organizations recovery procedures. REFERENCES: Manex Strategic Risk management. Retrieved from http://www.manex.au/strategic risk-management. Investopedia-Finanacial Risk.retrieved from: http://www.investopedia/financial risk.aspx When Business Strike. The business case for disruption risk management. (2007) Risk Mitigation 2012.Risk Mitigation retrieved from: http://www.ready.govt. ACC health and safety in workplace.Prevention of injuries.http://www.ac.nz. Ministry of business innovation and employment. Work for health and safety strategy  Retrived from http://www.ministry of health. Specialty insurance blog.(2009) employment practice and risk management retrieved from: http://www specialty insurance-risk-management.html Australian Government.Department of Immigration and Citizenship.Annual report 2009 Risk management and control measures. ANSI approves physical assets protection.2013.http://www.global-asset-protection-standard. Disaster Risk Management.http://www.disaster-management

Who can be integrated into the literary canon of American Literature?

This is a good question; Due to what American Literature stands for, who can be part of the literary canon? I think literature (American or otherwise) serves as a means by which one can examine a society's values, ideas, hopes, fears, and dreams through fiction or oral literature. Those who have had an impact on their society create something that many people will read of or look upon in different ethnicities, ages, social class, etc; However, does It always have to be an author or an writing documentation to exactly fit in the category of American Literature?; My opinion I would have to say no American Literature should be a Varity of people who made a difference in American not just by written literature but also by oral literature. Furthermore, Anne Hutchinson’s, known not as an author but an importance in our history (American history) should be included in our textbook and should be integrated into the literary canon for American Literature. For one she is known to be a political figure for not just women rights, but also religious rights for everyone. Secondly, she not just known for her beliefs but she is also proof of how religious and political leaders were towards women in her time period, and last but not least she is proven to be a women of multiply accomplishments in her life that actually helped society come to understanding later on. In her time Period women didn’t have rights as a religious dissenter or any type of political stand point. . She was clearly a great leader in the cause of religious toleration in America and the advancement of women in society. She basically challenged men and their authority, which was a struggle and hassle to overcome without being killed, but she did. By conducting informal... ...ican Literature book. Work Cited "Anne Hutchinson: Facts, Discussion Forum, and Encyclopedia Article." AbsoluteAstronomy.com. Encycloedia. Web. 17 Oct. 2010. . Hall, Timothy D. "Amazon.com: Anne Hutchinson: Puritan Prophet (Library of American Biography) (9780321476210): Timothy D. Hall: Books." Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & More. Web. 17 Oct. 2010. . Paine, Lisa L. "Midwifery, Childbirth, Politics, and Religion: Lessons from the Case of Anne Hutchinson, Colonial Midwife." Midwifery, Childbirth, Politics, and Religion: Lessons from the Case of Anne Hutchinson, Colonial Midwife. 13 Nov. 2000. Web. 17 Oct. 2010. .

Mina Loy’s poem “Lunar Baedeker” Essay

When read top to bottom, Mina Loy’s poem â€Å"Lunar Baedeker† may sound like a story of drugs, sex, and desperation. In reality, it is an encrypted biography of part of Loy’s life, as well as symbolic of the cycles of life. Let’s start with the title, shall we? â€Å"Lunar Baedeker,† the word ‘lunar’ means moon. It can also mean relating to the moon, but more importantly it can mean measured by the moon’s cycles. What in the world is a â€Å"Baedeker† though? Baedeker is actually one Karl Baedeker, a German who, in 1859, published a series of guidebooks. Mina Loy’s title, therefore, translates to either â€Å"a guide to the moon† or a † a guide to the moon’s cycle or cycles.† The first stanza is very autobiographical; it refers to Loy’s falling in love with her second husband, Fabien Avernarius Lloyd, also known as Arthur Cravan. â€Å"A silver Lucifer/ serves/ cocaine in cornucopia† Silver here can be read as a shiny, white color, or highly persuasive, or a metal that has the highest thermal and electrical conductivity. Lucifer can mean a fallen rebel or a fallen star. If you read ‘Lucifer’ as ‘star’ it fits in well with Loy’s celestial theme, but it is better construed as a fallen rebel, because Loy’s second husband, Cravan, was constantly on the run for being a draft dodger. The fact that he was silver describes him as beautiful, pure, and persuasive. The fact that silver has the highest thermal and electrical conductivity says that he had a lot of sex appeal and â€Å"sparks flew† between him and the poet. Cocaine is a highly addictive substance that causes euphoric effect. The fact that it is â€Å"served . . . in cornucopia† makes Loy sound very much like a young girl who is giddy with love and cannot get enough of her beau. A rendition of the couple’s bedroom life is in the next stanza: â€Å"To some somnambulists/ of adolescent thighs/ draped/ in satirical draperies† Though Loy has two children from a previous marriage, these lines make Loy sound like a virgin in her husband’s bed. The term ‘somnambulists’ means sleepwalkers, which keys you into this pertaining to night activities. Thighs are a common representation of sexuality, as they are so close to the sex organs anyway, and by describing what I assume are Loy’s own thighs as  Ã¢â‚¬Å"adolescent† she represents her own sexuality as immature, underdeveloped, vulnerable and unused. By being â€Å"draped/ in satirical draperies† Loy says that her immaturity is hidden, but only by clothing or cloth that intentionally exposes and criticizes her puerility. Loy’s third child, Fabienne, is referred to in the third stanza. â€Å"Peris in livery/ prepare/ Lethe/ for posthumous parvenus† Peris, which is not ‘Paris’ misspelled, is actually the plural form of the noun Peri. A Peri is a woman or girl who is descended from fallen angels and is excluded from Paradise. The term can also be used to describe a beautiful girl. Livery is servants’ clothing, implying that this ‘Peri’ is not from a wealthy family. Lethe is the river in Hades that would erase one’s memories if she were to drink from it. The ‘posthumous parvenues,’ however, is what ties this whole stanza into Fabienne. Loy’s husband, Cravan, married his wife in Mexico where he was dodging the draft. They separated and were supposed to meet up just before they returned to the United States, but Cravan never showed, nor was he ever seen again. Loy searched for him, and later he was assumed dead. Loy was already pregnant with Fabienne, and posthumous can mean ‘born after the death of the father.’ Better yet, a parvenu is one who is unaccustomed to wealth or power, but has recently gained a position of such but hasn’t gained the prestige that comes with the station. Fabienne, as a newborn, is completely unaware of the fact that she has just joined the human race. The fourth stanza of Loy’s poem, â€Å"Delirious Avenues/ lit/ with the chandelier souls/ of infusoria/ from Pharaoh’s tombstones† is a description of Loy’s search for her missing husband. The chandelier reference is also key because shortly after â€Å"Lunar Baedeker† is published, Loy opens a lamp shop and designs the lamps and fixtures herself. At the time that the poem was written, she was probably already dabbling in the art. The â€Å"Delirious Avenues† is a reference to her constantly searching blindly, with no clues, in every place or pathway her husband could be. The people who are a part of Cravan, Fabienne and Mina herself brighten the avenues; they are the â€Å"chandelier souls,† branches, pieces of Cravan. The â€Å"Pharaoh’s tombstone† indicates that Loy finally coming to terms with the fact that her husband is most likely dead. The acceptance of the loss of Cravan comes in the next stanza: â€Å"lead/ to mercurial doomsdays/ Odious oasis/ in furrowed phosphorous† â€Å"Lead† can be interpreted in more than one-way. It can indicate that Loy was brought to a conclusion by the previous stanza, but it can also be defined as the first punch in a boxing match. This is important because Cravan was known as the â€Å"boxer poet† because he was really only a second rate poet and used prize fighting to supplement his income. â€Å"Mercurial† is a reference to Mercury, who is the Greek god of travel, cunning, and theft, and is also associated with swiftness. Mercury is also the second reference in the poem to a shiny, silver colored element; in this case it is a poisonous element. In keeping with Loy’s celestial theme, Mercury is also the closest planet to the sun. Therefore, this doomsday, the loss of her husband, came swiftly, is like poison to her heart, and the heat of the planet Mercury can be paralleled to the fire of Hell. The term â€Å"Odious oasis† is an oxymoron. Loy’s only relief in submitting to the fact that her husband would never return to her was that she could give up searching for him. Her oasis is â€Å"in furrowed phosphorous† because she feels the loneliest at night, the term phosphorous, meaning something that glows or shines, is referring to the stars in the sky. The next stanza is somewhat cryptic, though the many references to white and light and the moon, â€Å"the eye-white sky-light/ white light district,† made me think of virginity and purity. The final line, â€Å"of lunar lusts,† indicates the sexual needs or desires of one who is chaste, another oxymoron. It is most likely Loy voicing her loneliness. At this point in the poem, Loy’s blending of words happens more and more. The first line is â€Å"—Stellectric signs,† —Stellectric being the combination of constellation and electric, meaning that Loy is taking meaning from the constellations in the night sky. The first sign she sees is â€Å"‘wing shows on Starway'† If looked at from a point of view where this is an actual show, as in a theatrical presentation, a wing can be defined as a dance step, and the Starway can be the stage, something similar to Broadway. Loy’s next sign is the â€Å"‘Zodiac carrousel'† which is the cycle of astrological signs that are represented by the constellations in the night sky. A carrousel is a  children’s amusement ride where one would sit on an animal-shape, which would tie in to the zodiac. A carrousel can also mean a cycle of activity that is complex and fast-paced and difficult to break free from. This shows that Loy was in a cycle that she may have been unhappy with. Both the zodiac and the carrousel are the first two of many references to things that are cyclical, or go in circles, or are round even. The next two references to cyclical occurrences are in the next stanza. â€Å"Cyclones† are high-powered storms with low pressure at the center, 99% of which in the northern hemisphere spin in a counterclockwise motion. The fact that they run counterclockwise could be Loy’s rebellion against the cycles she is trapped in, or her feeling that she is stuck in a backward cycle, or a backward life. These cyclones consist â€Å"of ecstatic dust/ and ash† means that Loy’s grief for the loss of her husband is beyond her reason and self-control. The dust represents what something disintegrates into when it is reduced to its lowest form, and can also mean a state of humiliation. The ash, which is the carbon left after something is burned completely, is symbolic of Loy’s grief, repentance and humility. An ash is also a type of tree that has a tough, elastic wood, which represents Loy’s strength and malleability, indicating that she will heal from this l oss. The dust and ashes â€Å"whirl† in this cyclone, another indicator of a circular, cyclical pattern. The next part of the stanza refers to â€Å"crusaders/ from the hallucinatory citadels/ of shattered glass/ into evacuate craters† The hallucinatory citadels is the safety and security Loy thought she had with Cravan. The shattered glass represents Loy’s broken dreams about her ruined marriage and the evacuate craters, which are probably on the moon, are the emptiness into which her broken dreams are siphoned. Crater is another important hint to Loy’s personal life also. Loy was a painter and an artist and a crater can also be a dimple in a painted surface, meaning that there were visible flaws in Loy’s life. Though Loy’s dreams concerning Cravan are broken and gone, she still had goals and aspirations, in fact, she has â€Å"A flock of dreams† still. Those dreams do sometimes â€Å"browse on Necropolis† which means she often thinks of and dreams about her lost husband, Necropolis being the city of the dead. The next stanza is a return to Loy’s lunar theme, and also a reference to a used and tarnished womanhood. â€Å"From the shores/ of oval oceans† The word oval means elliptical and egg shaped, which the orbits of the planets and moons are, but also it is derived from the Latin word ovum, which our word for the female sex cell. The â€Å"oxidized Orient† is the phrase that truly represents a tarnished womanhood. Oxidation is when something has been exposed to oxygen, which has cause a corrosion that is often black, brown or green. Orient is another reference to the moon, which in turn represents chastity. Orient can mean the East, where the sun and moon rise from, or rising in the sky, and also the luster of a pearl. The next image that Loy presents us with is the loss of her thirst for life. In â€Å"Onyx-eyed Odalisques/ and ornithologists/ observe the flight/ of Eros obsolete† dark eyed concubines and studiers of birds watch, inspect, and celebrate as Loy’s no longer useful lust, as Eros is the Greek god of erotic love, and her life-preserving instinct, which is also represented in Eros, leave her. The next stanza where Loy refers to her â€Å"‘Immortality'† as it â€Å"mildews/ in the museums of the moon† Immortality could refer not only to her unending love for Cravan, but also the possibility of her being famous for her writing or her art. The fact that it can mildew means that there truly is no such thing as immortality, but if there was, it would be in a place where it would be looked at and not used: a museum. This museum would be in the moon because the moon represents an unreachable place or goal. The next two lines are direct references to the moon. The â€Å"‘Nocturnal cyclops'† would be the one-eyed being that is active only at night. With the â€Å"‘Crystal concubine'† crystal represents something transparent and pretty, while concubine represents an unmarried woman who lives with a man, which is symbolic of the moon’s relationship with the sun. The very last stanza of â€Å"Lunar Baedeker† is full of meaning. It refers to the moon as â€Å"Pocked with personification† One general thinks that pocked means  to have craters or indents, when in reality it means to have pustules that are filled with infection. By being â€Å"Pocked with personification† the moon is infected with human attributes. The moon is also considered â€Å"the fossil virgin of the skies† Fossil here refers to the fact that the moons representation of purity and chastity are outdated and a remnant of the past. This is also another allusion to astrology in that the virgin, or Virgo, is a sign of the Zodiac. The final three words of this poem are very powerful. When thoroughly considered they represent an inner struggle and inner turmoil. To wax is to increase, grow or intensify, but it can also mean rage. Wane, on the other hand, means to decrease in size and diminish, but it can also be used to describe a loss of power or a fall from power. â€Å"waxes and wanes—-† This is symbolic of Loy’s struggle with her anger and pain after the loss of her husband, and in waning, she relents to her feelings.

Ap Bio Chapter 35 Notes

Chapter 35 Plant Structure, Growth, and Development Lecture Outline Overview: Plastic Plants? †¢ The fanwort, an aquatic weed, demonstrates the great developmental plasticity that is characteristic of plants. o The fanwort has feathery underwater leaves and large, flat, floating surface leaves. o Both leaf types have genetically identical cells, but the dissimilar environments in which they develop cause different genes involved in leaf formation to be turned on or off. In addition to plastic structural responses of individual plants to specific environments, plant species have adaptations in morphology that benefit them in their specific environments. o For example, cacti have leaves that are reduced to spines and a stem that serves as the primary site of photosynthesis. These adaptations minimize water loss in desert environments. †¢ The form of any plant is controlled by environmental and genetic factors. As a result, no two plants are identical. †¢ Angiosperms make up 90% of plant species and are at the base of the food web of nearly every terrestrial ecosystem. Most land animals, including humans, depend on angiosperms directly or indirectly for sustenance. Concept 35. 1 The plant body has a hierarchy of organs, tissues, and cells. †¢ Plants, like multicellular animals, have organs that are composed of different tissues, and tissues that are composed of different cell types. o A tissue is a group of cells with common structure and function. o An organ consists of several types of tissues that work together to carry out particular functions. Vascular plants have three basic organs: roots, stems, and leaves. The basic morphology of vascular plants reflects their evolutionary history as terrestrial organisms that inhabit and draw resources from two very different environments. o Vascular plants obtain water and minerals from the soil. o Vascular plants obtain CO2 and light above-ground. †¢ To obtain the resources they need, vascular p lants have evolved two systems: a subterranean root system and an aerial shoot system of stems and leaves. †¢ Each system depends on the other. o Lacking chloroplasts and living in the dark, roots would starve without photosynthates, the sugar and other carbohydrates imported from the shoot system. Conversely, the shoot system depends on water and minerals that roots absorb from the soil. Roots provide anchorage, absorption, and storage. †¢ A root is an organ that anchors a vascular plant in the soil, absorbs minerals and water, and stores sugars and starches. †¢ Most eudicots and gymnosperms have a taproot system, consisting of one large vertical root (the taproot) that develops from an embryonic root. †¢ The taproot produces many small lateral, or branch, roots. o In angiosperms, taproots often store sugars and starches that later support flowering and fruit production. Taproot systems generally penetrate deeply and are well adapted to deep soils. †¢ In se edless vascular plants and most monocots, including grasses, the embryonic root dies and does not form a main root. †¢ Instead, many small roots grow from the stem. Such roots are adventitious, a terms describing a plant organ that grows in an unusual location. †¢ Each small root forms its own lateral roots, giving rise to a fibrous root system—a mat of thin roots that spread out below the soil surface. o A fibrous root system is usually shallower than a taproot system and is best adapted to shallow soils with light rainfall. Grass roots are concentrated in the upper few centimeters of soil. As a result, grasses make excellent ground cover for preventing erosion. †¢ The root system helps anchor a plant. †¢ In both taproot and fibrous root systems, absorption of water and minerals occurs near the root tips, where vast numbers of tiny root hairs enormously increase the surface area. o Root hairs are short-lived, tubular extensions of individual root epiderma l cells. †¢ Some plants have modified roots. Some arise from roots, while others are adventitious, arising above-ground from stems or even from leaves. Some modified roots provide additional support and anchorage. Others store water and nutrients or absorb oxygen from the air. Stems consist of alternating nodes and internodes. †¢ A stem is an organ consisting of alternating nodes, the points at which leaves are attached, and internodes, the stem segments between nodes. †¢ At the angle formed by each leaf and the stem is an axillary bud with the potential to form a lateral shoot or branch. †¢ The growth of a young shoot is usually concentrated at its apex, where there is an apical bud, or terminal bud, with developing leaves and a compact series of nodes and internodes. The presence of a terminal bud is partly responsible for inhibiting the growth of axillary buds, a phenomenon called apical dominance. o By concentrating resources on growing taller, apical dominan ce is an evolutionary adaptation that increases the plant’s exposure to light. †¢ In the absence of a terminal bud, the axillary buds break dormancy and give rise to lateral shoots complete with their own apical buds, leaves, and axillary buds. o This is why pruning trees and shrubs makes them bushier. †¢ Modified shoots with diverse functions have evolved in many plants. These shoots, which include stolons, rhizomes, tubers, and bulbs, are often mistaken for roots. Leaves are the main photosynthetic organs of most plants. †¢ The leaf is the primary site of photosynthetic organs of most plants, although green stems are also photosynthetic. †¢ Although leaves vary extensively in form, they generally consist of a flattened blade and a stalk, the petiole, which joins the leaf to a stem node. o Grasses and other monocots lack petioles. In these plants, the base of the leaf forms a sheath that envelops the stem. Monocots and eudicots differ in the arrangement o f veins, the vascular tissue of leaves. †¢ Most monocots have parallel major veins that run the length of the blade, while eudicot leaves have a branched network of major veins. †¢ Plant taxonomists use floral morphology, leaf morphology, the branching pattern of veins, and the spatial arrangement of leaves to help identify and classify plants. o For example, simple leaves have a single, undivided blade, while compound leaves have several leaflets attached to the petiole. o Many large leaves are compound, which allows them to withstand strong winds without tearing. The structural adaptation of compound leaves also confines pathogens that invade the leaf to one leaflet. †¢ Most leaves are specialized for photosynthesis. †¢ Some plants have leaves that have become adapted for other functions, including tendrils that cling to supports, spines of cacti for defense, leaves modified for water storage, and brightly colored leaves that attract pollinators. Plant organs a re composed of three tissue systems: dermal, vascular, and ground. †¢ Each organ of a plant has three tissue systems: dermal, vascular, and ground tissues. Each system is continuous throughout the plant body. †¢ The dermal tissue system is the plant’s outer protective covering. †¢ In nonwoody plants, the dermal tissue system is a single layer of tightly packed cells, or epidermis. †¢ The epidermis of leaves and most stems secretes a waxy coating, the cuticle, which helps the aerial parts of the plant retain water. †¢ In woody plants, protective tissues called periderm replace the epidermis in older regions of stems and roots. †¢ The epidermis has other specialized characteristics consistent with the function of the organ it covers. For example, the root hairs are extensions of epidermal cells near the tips of the roots. o Trichomes, outgrowths of shoot epidermis, reduce water loss and reflect light. They protect against insects with sticky secret ions of insecticidal biochemicals. †¢ The vascular tissue system is involved in the transport of materials between roots and shoots. o Xylem conveys water and dissolved minerals upward from roots into the shoots. o Phloem transports sugars, the products of photosynthesis, to the roots and sites of growth, such as developing leaves and fruits. †¢ The vascular tissue of a root or stem is called the stele. In angiosperms, the root stele forms a solid central vascular cylinder, while the stele of stems and leaves consists of vascular bundles, separate strands of xylem and phloem. †¢ Both xylem and phloem are complex tissues with a variety of cell types. †¢ The ground tissue system is tissue that is neither dermal nor vascular. †¢ Ground tissue is divided into pith, internal to vascular tissue, and cortex, external to the vascular tissue. †¢ The functions of specialized cells within ground tissue include photosynthesis, storage, and support. Plant tissues ar e composed of three basic cell types: parenchyma, collenchyma, and sclerenchyma. Plant cells are differentiated, with each type of plant cell possessing structural adaptations that make specific functions possible. o Cell differentiation may be evident within the protoplast, the cell contents exclusive of the cell wall. o Modifications of cell walls also play a role in plant cell differentiation. †¢ The major types of differentiated plant cells are parenchyma, collenchyma, sclerenchyma, water-conducting cells of the xylem, and sugar-conducting cells of the phloem. †¢ Mature parenchyma cells have primary walls that are relatively thin and flexible; most lack secondary walls. The protoplast of a parenchyma cell usually has a large central vacuole. †¢ Parenchyma cells are often depicted as â€Å"typical† plant cells because they generally are the least specialized, but there are exceptions. o For example, the highly specialized sieve-tube elements of the phloem ar e parenchyma cells. †¢ Parenchyma cells perform most of the metabolic functions of the plant, synthesizing and storing various organic products. o For example, photosynthesis occurs within the chloroplasts of parenchyma cells in the leaf. o Some parenchyma cells in the stems and roots have colorless plastids that store starch. The fleshy tissue of most fruit is composed of parenchyma cells. †¢ Most parenchyma cells retain the ability to divide and differentiate into other cell types under special conditions, such as the repair and replacement of organs after injury to the plant. †¢ In the laboratory, it is possible to regenerate an entire plant from a single parenchyma cell. †¢ Collenchyma cells have thicker primary walls than parenchyma cells, although the walls are unevenly thick. †¢ Grouped into strands or cylinders, collenchyma cells help support young parts of the plant shoot. Young stems and petioles often have strands of collenchyma just below the epi dermis, providing support without restraining growth. †¢ Mature collenchyma cells are living and flexible and elongate with the stems and leaves they support. †¢ Sclerenchyma cells have thick secondary walls usually strengthened by lignin; they function as supporting elements of the plant. †¢ Sclerenchyma cells are much more rigid than collenchyma cells. †¢ Unlike parenchyma cells, sclerenchyma cells cannot elongate. †¢ Sclerenchyma cells occur in plant regions that have stopped lengthening. Many sclerenchyma cells are dead at functional maturity, but they produce rigid secondary cells walls before the protoplast dies. o In parts of the plant that are still elongating, secondary walls are deposited in a spiral or ring pattern, enabling the cell wall to stretch like a spring as the cell grows. †¢ Two types of sclerenchyma cells, fibers and sclereids, are specialized entirely for support. o Fibers are long, slender, and tapered, and usually occur in group s. ? Fibers from hemp are used for making rope, and fibers from flax are woven into linen. o Sclereids are irregular in shape and shorter than fibers.They have very thick, lignified secondary walls. ? Sclereids impart hardness to nutshells and seed coats and the gritty texture to pear fruits. †¢ The water-conducting elements of xylem, the tracheids and vessel elements, are elongated cells that are dead at functional maturity. o The thickened cell walls remain as a nonliving conduit through which water can flow. †¢ Both tracheids and vessels have secondary walls interrupted by pits, thinner regions where only primary walls are present. †¢ Water moves from cell to cell mainly through pits. †¢ Tracheids are long, thin cells with tapered ends. Because their secondary walls are hardened with lignin, tracheids function in support as well as transport. †¢ Vessel elements are generally wider, shorter, thinner-walled, and less tapered than tracheids. †¢ Vessel e lements are aligned end to end, forming long micropipes or xylem vessels. †¢ The ends are perforated, enabling water to flow freely. †¢ In the phloem, sucrose, other organic compounds, and some mineral ions move through tubes formed by chains of cells called sieve-tube elements. †¢ Sieve-tube elements are alive at functional maturity, although a sieve-tube element lacks a nucleus, ribosomes, and a distinct vacuole. The end walls, the sieve plates, have pores that facilitate the flow of fluid between cells. †¢ Each sieve-tube element has a nonconducting nucleated companion cell, which is connected to the sieve-tube element by numerous plasmodesmata. †¢ The nucleus and ribosomes of the companion cell serve both that cell and the adjacent sieve-tube element. †¢ In some plants, companion cells in leaves help load sugar into the sieve-tube elements, which transport the sugars to other parts of the plant. Concept 35. 2 Meristems generate cells for new organs. A major difference between plants and most animals is that plant growth is not limited to an embryonic or juvenile period. †¢ Most plants demonstrate indeterminate growth, growing as long as the plant lives. †¢ In contrast, most animals and certain plant organs, such as flowers, leaves, and thorns, undergo determinate growth, ceasing to grow after they reach a certain size. †¢ Indeterminate growth does not mean immortality. †¢ Annuals complete their life cycle—from germination to flowering to seed production to death—in a single year or less. o Many wildflowers and important food crops, such as cereals and legumes, are annuals. The lives of biennials span two years, with flowering and fruiting in the second year. o Radishes and carrots are biennials that are harvested after the first year. †¢ Plants such as trees, shrubs, and some grasses that live many years are perennials. o Some buffalo grass of the North American plains has been growing fo r 10,000 years from seeds that sprouted at the end of the last ice age. o Perennials do not usually die from old age but from an infection or some environmental trauma, such as fire or drought. †¢ A plant is capable of indeterminate growth because it has perpetually embryonic tissues called meristems. Apical meristems, located at the tips of roots and in the buds of shoots, supply cells for the plant to grow in length. †¢ This elongation, primary growth, enables roots to extend through the soil and shoots to increase their exposure to light and carbon dioxide. †¢ In herbaceous plants, primary growth produces almost all of the plant body. †¢ Woody plants also show secondary growth, progressive thickening of roots and shoots where primary growth has ceased. †¢ Secondary growth is produced by lateral meristems, cylinders of dividing cells that extend along the lengths of roots and shoots. The vascular cambium adds layers of vascular tissue called secondary xyle m and phloem. o The cork cambium replaces the epidermis with thicker, tougher periderm. †¢ The cells within meristems divide to generate additional cells, some of which remain in the meristematic region, while others differentiate and are incorporated into the tissues and organs of the growing plant. o Cells that remain as sources of new cells are called initials. o Cells that are displaced from the meristem, called derivatives, continue to divide until the cells they produce become specialized within developing tissues. At the tip of a winter twig of a deciduous tree is the dormant apical bud, enclosed by scales that protect its apical meristem. †¢ In the spring, the bud sheds its scales and begins a new spurt of primary growth. †¢ Along each growth segment, nodes are marked by scars left when leaves fell in the autumn. †¢ Above each leaf scar is either an axillary bud or a branch twig. †¢ Farther down the twig are whorls of scars left by the scales that en closed the apical bud during the preceding winter. †¢ Each spring and summer, as primary growth extends the shoot, secondary growth thickens the parts of the shoot that formed in earlier years. Concept 35. Primary growth lengthens roots and shoots. †¢ Primary growth produces the primary plant body, the parts of the root and shoot systems produced by apical meristems. o Herbaceous plants and the youngest parts of woody plants represent the primary plant body. †¢ Apical meristems lengthen both roots and shoots. However, there are important differences in the primary growth of these two systems. †¢ The root tip is covered by a thimble-like root cap, which protects the meristem as the root pushes through the abrasive soil during primary growth. o The cap also secretes a polysaccharide slime that lubricates the soil around the growing root tip. Growth in length is concentrated just behind the root tip, where three zones of cells at successive stages of primary growth are located. †¢ These zones—the zone of cell division, the zone of elongation, and the zone of differentiation—grade together. †¢ The zone of cell division includes the root apical meristem and its derivatives. o New root cells are produced in this region, including the cells of the root cap. †¢ The zone of cell division blends into the zone of elongation, where cells elongate, sometimes to more than ten times their original length. It is this elongation of cells that is mainly responsible for pushing the root tip, including the meristem, into the soil. o The meristem sustains growth by continuously adding cells to the youngest end of the zone of elongation. †¢ In the zone of differentiation, cells complete differentiation and become distinct cell types. †¢ The primary growth of roots produces the epidermis, ground tissue, and vascular tissue. †¢ Water and minerals absorbed from the soil must enter the plant through the epidermis, a single layer of cells covering the root. Root hairs greatly increase the surface area of epidermal cells. †¢ Most roots have a vascular cylinder of xylem and phloem. o In eudicot roots, xylem radiates from the center like a star, with phloem developing between the arms of the xylem â€Å"star. † o In monocot roots, the vascular tissue consists of a central core of parenchyma surrounded by alternating xylem and phloem. The central region, called pit, is distinct from stem pith. †¢ The ground tissue of roots consists of parenchyma cells that fill the cortex, the region between the vascular cylinder and the epidermis. Cells within the ground tissue store sugars and starches, and their plasma membranes absorb water and minerals from the soil. †¢ The innermost layer of the cortex, the endodermis, is a cylinder one cell thick that forms a selective barrier between the cortex and the vascular cylinder. †¢ Lateral roots may sprout from the outermost layer of the vascula r cylinder, the pericycle. o A lateral root pushes through the cortex and epidermis to emerge from the established root. o The vascular tissue of the lateral root is continuous with the vascular cylinder of the primary root. The apical meristem of a shoot is a dome-shaped mass of dividing cells at the shoot tip. †¢ Leaves arise as leaf primordia on the flanks of the apical meristem. †¢ Axillary buds develop from islands of meristematic cells left by apical meristems at the bases of the leaf primordia. †¢ Within a bud, leaf primordia are crowded close together because the internodes are very short. †¢ Most of the elongation of the shoot occurs by growth in length of slightly older internodes below the shoot apex. †¢ In some plants, including grasses, internodes continue to elongate all along the length of the shoot over a prolonged period. These plants have meristematic regions called intercalary meristems at the base of each leaf. o This explains why grass c ontinues to grow after being mowed. †¢ Unlike its central position in a root, vascular tissue runs the length of a stem in strands called vascular bundles. o Because the vascular system of the stem is near the surface, branches can develop with connections to the vascular tissue without having to originate from deep within the main shoot. †¢ In most eudicots, the vascular bundles are arranged in a ring, with pith inside and cortex outside the ring. The vascular bundles have xylem facing the pith and phloem facing the cortex. †¢ In the stems of most monocots, the vascular bundles are scattered throughout the ground tissue rather than arranged in a ring. †¢ In both monocots and eudicots, the stem’s ground tissue is mostly parenchyma. †¢ Many stems are strengthened by collenchyma cells just beneath the epidermis. †¢ Sclerenchyma fiber cells also provide support. †¢ The epidermal barrier of leaves is interrupted only by stomata, tiny pores that regulate gas exchange between the surrounding air and the photosynthetic cells inside a leaf. Each stomatal pore is flanked by two specialized epidermal cells called guard cells. o The term stoma can refer to either the stomatal pore or the entire stomatal complex, the pore and two guard cells. †¢ The stomata are also the major avenues of evaporative water loss from the plant—a process called transpiration. †¢ The ground tissue of the leaf, the mesophyll, is sandwiched between the upper and lower epidermis. †¢ The mesophyll consists mainly of parenchyma cells specialized for photosynthesis. †¢ In many eudicots, a layer or more of columnar palisade mesophyll lies above spongy mesophyll. CO2 and oxygen circulate through the labyrinth of air spaces around the irregularly spaced cells of the spongy mesophyll. †¢ The air spaces are particularly large near stomata, where gas exchange with the outside air occurs. †¢ The vascular tissue of a leaf is cont inuous with the vascular tissue of the stem. †¢ Leaf traces, connections from vascular bundles in the stem, pass through petioles and into leaves. †¢ Vascular bundles in the leaves are called veins. Each vein is enclosed in a protective bundle sheath consisting of one or more layers of parenchyma. o Bundle-sheath cells are prominent in leaves that undergo C4 photosynthesis. Within a leaf, veins subdivide repeatedly and branch throughout the mesophyll. †¢ The xylem brings water and minerals to the photosynthetic tissues, and the phloem carries sugars and other organic products to other parts of the plant. †¢ The vascular infrastructure also functions to support and reinforce the shape of the leaf. Concept 35. 4 Secondary growth adds girth to stems and roots in woody plants. †¢ The stems and roots of most eudicots increase in girth by secondary growth. †¢ The secondary plant body consists of the tissues produced by the vascular cambium and the cork cambiu m. The vascular cambium adds secondary xylem (wood) and secondary phloem, increasing vascular flow and support for the shoot system. o The cork cambium produces a tough, thick covering consisting of wax-impregnated cells that protect the stem from water loss and invasion by insects, bacteria, and fungal spores. †¢ Primary and secondary growth occur simultaneously but in different regions. o Elongation of the stem (primary growth) occurs at the apical meristem, but increases in diameter (secondary growth) occur farther down the stem. †¢ All gymnosperms and many eudicots have secondary growth, but it is rare in monocots. The vascular cambium is a cylinder of meristematic cells that may be one cell thick. †¢ The vascular cambium forms successive layers of secondary xylem to its interior and secondary phloem to its exterior. †¢ The accumulation of this tissue over the years accounts for most of the increase in diameter of a woody plant. †¢ The vascular cambium d evelops from parenchyma cells that retain the capacity to divide. o In a typical woody stem, the vascular cambium forms as a continuous cylinder outside the cortex and primary xylem and inside the pith and primary phloem. In a typical woody root, the vascular cambium forms in segments between the primary phloem, the lobes of primary xylem, and the pericycle. †¢ Viewed in cross section, the vascular cambium appears as a ring of initials. o As these cells divide, they increase the circumference of the vascular cambium, adding secondary xylem to the inside of the cambium and secondary phloem to the outside. †¢ Some initials are elongated, with long axes parallel to the axis of the stem or root. o These initials produce cells such as tracheids, vessel elements, and fibers of the xylem. They also produce sieve-tube elements, companion cells, parenchyma, and fibers of the phloem. †¢ Other initials are shorter, oriented perpendicular to the axis of the stem or root. o These initials produce vascular rays that transfer water and nutrients laterally within the woody stem, store sugars and starches, and aid in wound repair. †¢ As secondary growth continues over the years, layer upon layer of secondary xylem accumulate, producing the tissue we call wood. †¢ Wood consists mainly of tracheids, vessel elements (in angiosperms), and fibers. These cells, dead at functional maturity, have thick, lignified walls that give wood its hardness and strength. †¢ The first tracheid and vessel cells formed in the spring (early wood) have larger diameters and thinner walls than the cells produced later in the summer (late wood). o The structure of the early wood maximizes delivery of water to new, expanding leaves. o The thick-walled cells of later wood provide more physical support. †¢ In temperate regions, secondary growth in perennial plants ceases during the winter. †¢ This pattern of growth—cambium dormancy, early wood production, and late wood production—produces annual growth rings. Dendrochronology is the science of analyzing tree ring growth patterns. o Scientists can use ring patterns to identify climate change. †¢ As a tree or woody shrub ages, the older layers of secondary xylem, known as heartwood, no longer transport water and minerals. o Heartwood contains resins and other compounds that protect the core of the tree from fungi and insects. †¢ The outer layers, known as sapwood, continue to transport xylem sap. †¢ Because each new layer of secondary xylem has a larger circumference, secondary growth enables the xylem to transport more sap each year, supplying more leaves. Only the youngest secondary phloem, closest to the vascular cambium, functions in sugar transport. †¢ The older secondary phloem dies and is sloughed off as part of the bark. †¢ Early in secondary growth, the epidermis produced by primary growth splits, dries, and falls off the stem or root. †¢ The e pidermis is replaced by two tissues produced by the first cork cambium, which arises in the outer cortex of stems and in the outer layer of the pericycle of roots. †¢ The first tissue, phelloderm, is a thin layer of parenchyma cells that forms to the interior of the cork cambium. The cork cambium also produces cork cells, which accumulate at the cambium’s exterior. †¢ Waxy material called suberin deposited in the cell walls of cork cells before they die acts as a barrier against water loss, physical damage, and pathogens. †¢ A cork cambium and the tissues it produces make up a layer of periderm, a protective layer that replaces the epidermis. †¢ Because cork cells have suberin and are compacted together, the periderm is impermeable to water and gases. †¢ In most plants, water and minerals are absorbed in the youngest parts of the roots. The older parts of the roots anchor the plant and transport water and solutes between roots and shoots. †¢ In a reas called lenticels, spaces develop between the cork cells of the periderm. o These areas within the trunk facilitate gas exchange with the outside air. †¢ The thickening of a stem or root splits the first cork cambium, which loses its meristematic activity and differentiates into cork cells. †¢ A new cork cambium forms to the inside, resulting in a new layer of periderm. †¢ As this process continues, older layers of periderm are sloughed off. o This produces the cracked, peeling bark of many tree trunks. Bark is all tissues external to the vascular cambium, including secondary phloem (produced by the vascular cambium), the most recent periderm, and all the outer layers of periderm. Concept 35. 5 Growth, morphogenesis, and differentiation produce the plant body. †¢ The development of body form and organization is called morphogenesis. †¢ During plant development, a single cell, the zygote, gives rise to a multicellular plant of a particular form with funct ionally integrated cells, tissues, and organs. †¢ Each cell in the plant body contains the same genomes, but different patterns of gene expression cause cells to differentiate. The three developmental processes of growth, morphogenesis, and cellular differentiation act to transform the fertilized egg into a plant. Molecular biology is revolutionizing the study of plants. †¢ Modern molecular techniques enable plant biologists to investigate how growth, morphogenesis, and cellular differentiation give rise to a plant. †¢ Much of this research has focused on Arabidopsis thaliana, a small weed in the mustard family. o Thousands of these small plants can be cultivated in a few square meters of lab space. o With a generation time of about six weeks, Arabidopsis is an excellent model for genetic studies. Arabidopsis also has one of the smallest genomes of all known plants. †¢ Arabidopsis was the first plant to have its genome sequenced, in a six-year multinational proje ct. o More recently, rice and poplar trees have had their entire genomes sequenced. †¢ Arabidopsis has a total of about 26,000 genes, with fewer than 15,000 different types of genes. †¢ Now that the DNA sequence of Arabidopsis is known, plant biologists are working to identify the functions of every one of the plant’s genes. †¢ To aid in this effort, biologists are attempting to create mutants for every gene in the plant’s genome. Study of the functions of these genes has already expanded our understanding of plant development. †¢ By identifying each gene’s function, researchers aim to establish a blueprint for how plants develop, a major goal of systems biology. †¢ One day it may be possible to create a computer-generated â€Å"virtual plant† that will enable researchers to visualize which plant genes are activated in different parts of the plant during the entire course of development. Growth involves both cell division and cell expansion. †¢ Cell division in meristems increases the cell number, thereby increasing the potential for growth. However, it is cell expansion, especially cell elongation, that accounts for the increase in plant mass. †¢ The plane (direction) and symmetry of cell division are important determinants of plant form. o If the planes of division by a single cell and its descendents are parallel to the plane of the first cell division, a single file of cells will be produced. o If the planes of cell division of the descendent cells vary at random, an unorganized clump of cells will result. †¢ Although mitosis results in the equal allocation of chromosomes to daughter cells, cytokinesis may be asymmetrical. Asymmetrical cell division, in which one cell receives more cytoplasm than the other, is common in plant cells and usually signals a key developmental event. o For example, guard cells arise from an unspecialized epidermal cell through an asymmetrical cell division to fo rm a large unspecialized epidermal cell and a small guard cell â€Å"mother cell. † o Guard cells form when the small mother cell divides in a plane perpendicular to the first cell division. †¢ The plane in which a cell will divide is determined during late interphase. †¢ Microtubules in the outer cytoplasm become concentrated into a ring, the preprophase band. Although this ring disappears before metaphase, its â€Å"imprint† consists of an ordered array of actin microfilaments that remains after the microtubules disperse and signals the future plane of cell division. †¢ Cell expansion in animal cells is quite different from cell expansion in plant cells. o Animal cells grow by synthesizing a protein-rich cytoplasm, a metabolically expensive process. †¢ Growing plant cells add some protein-rich material to their cytoplasm, but water uptake by the large central vacuole accounts for 90% of a plant cell’s expansion. o This enables plants to gro w economically and rapidly. For example, bamboo shoots can elongate more than 2 m per week. †¢ Rapid expansion of shoots and roots increases plants’ exposure to light and soil, an important evolutionary adaptation to the immobile lifestyle of plants. †¢ In a growing plant cell, enzymes weaken cross-links in the cell wall, allowing it to expand as water diffuses into the vacuole by osmosis. †¢ The wall loosens when hydrogen ions secreted by the cell activate cell wall enzymes that break the cross-links between polymers in the wall. †¢ This reduces restraint on the turgid cell, which can take up more water and expand. Small vacuoles coalesce to form the cell’s central vacuole. †¢ The greatest expansion of a plant cell is usually oriented along the plant’s main axis. o The orientation of cellulose microfibrils in the innermost layers of the cell wall cause this differential growth, as the cell expands mainly perpendicular to the â€Å"grai n† of the microfibrils. o The orientation of microtubules in the cell’s outermost cytoplasm determines the orientation of cellulose microfibrils, the basic structural units of the cell wall. Arabidopsis mutants confirm the role of cytoplasmic microtubules in cell division and growth. Studies of Arabidopsis mutants have confirmed the importance of cytoplasmic microtubules in both cell division and expansion. †¢ For example, fass mutants have unusually squat cells, which follow seemingly random planes of cell division. †¢ The roots and stems of fass mutants lack the ordered cell files and layers. †¢ Fass mutants develop into tiny adult plants with all their organs compressed longitudinally. †¢ The organization of microtubules in fass mutants is abnormal. o In interphase cells, the microtubules are randomly positioned. Preprophase bands do not form prior to mitosis. o Therefore, the cellulose microfibrils deposited in the cell wall cannot be arranged to determine the direction of the cell’s elongation. †¢ Cells with a fass mutation expand in all directions equally and divide in a haphazard arrangement, leading to stout stature and disorganized tissues. Morphogenesis depends on pattern formation. †¢ Morphogenesis organizes dividing and expanding cells into multicellular tissues and organs. †¢ The development of specific structures in specific locations is called pattern formation. Pattern formation depends to a large extent on positional information, signals that continuously indicate each cell’s location within an embryonic structure. †¢ Within a developing organ, each cell responds to positional information by differentiating into a particular cell type. †¢ Developmental biologists are accumulating evidence that gradients of specific molecules, generally proteins or mRNAs, provide positional information. o For example, a substance diffusing from a shoot’s apical meristem may â€Å"in form† the cells below of their distance from the shoot tip. A second chemical signal produced by the outermost cells may enable a cell to gauge its position relative to the radial axis of the developing organ. o Developmental biologists are testing the hypothesis that diffusible chemical signals provide plant cells with positional information. †¢ One type of positional information is polarity, the identification of the root end and shoot end along a well-developed axis. †¢ Axial polarity results in morphological and physiological differences. †¢ The unidirectional movement of the hormone auxin causes the emergence of adventitious roots and shoots from the appropriate ends of plant cuttings. The establishment of axial polarity is a critical step in plant morphogenesis. †¢ The first division of a plant zygote is normally asymmetrical and may initiate the polarization of the plant body into root and shoot ends. †¢ Once this polarity has been induced, it i s very difficult to reverse experimentally. o In the gnom mutant of Arabidopsis, the first division is symmetrical, and the resulting ball-shaped plant lacks roots and leaves. †¢ Other genes that regulate pattern formation and morphogenesis include master regulatory genes called homeotic genes, which mediate many developmental events, such as organ initiation. For example, the protein product of the KNOTTED-1 homeotic gene is important for the development of leaf morphology, including the production of compound leaves. o Overexpression of this gene causes the compound leaves of a tomato plant to become â€Å"supercompound. † Cellular differentiation depends on the control of gene expression. †¢ The diverse cell types of a plant, including guard cells, sieve-tube elements, and xylem vessel elements, all descend from a common cell, the zygote, and share the same DNA. The cloning of whole plants from single somatic cells demonstrates that the genome of a differentiated cell remains intact and can dedifferentiate in tissue culture and give rise to the diverse cell types of a plant. †¢ Cellular differentiation depends, to a large extent, on the control of gene expression. †¢ Cells with the same genomes follow different developmental pathways because they selectively express certain genes at specific times during differentiation. †¢ The activation or inactivation of specific genes involved in cellular differentiation depends on positional information—where a particular cell is located relative to other cells. For example, two distinct cell types in Arabidopsis, root hair cells and hairless epidermal cells, develop from immature epidermal cells. o Cells in contact with one underlying cortical cell differentiate into mature, hairless cells, while those in contact with two underlying cortical cells differentiate into root hair cells. o The homeotic gene GLABRA-2 is normally expressed only in hairless cells. If it is rendered dysfu nctional, every root epidermal cell develops a root hair. Clonal analysis of the shoot apex emphasizes the importance of a cell’s location in its developmental fate. In the process of shaping an organ, patterns of cell division and cell expansion affect the differentiation of cells by placing them in specific locations relative to other cells. †¢ Thus, positional information underlies all the processes of development: growth, morphogenesis, and differentiation. †¢ One approach to studying the relationship among these processes is clonal analysis, mapping the cell lineages (clones) derived from each cell in an apical meristem as organs develop. †¢ Researchers use mutations to distinguish a specific meristematic cell from the neighboring cells in the shoot tip. For example, a somatic mutation in an apical cell that prevents chlorophyll production produces an â€Å"albino† cell. o This cell and all its descendants appear as a linear file of colorless cells running down the long axis of the green shoot. †¢ To some extent, the developmental fates of cells in the shoot apex are predictable. o For example, clonal mapping has shown that almost all the cells derived from division of the outermost meristematic cells become part of the dermal tissue of leaves and stems. It is not possible to pinpoint precisely which cells of the meristem will give rise to specific tissues and organs, however, because random changes in rates and planes of cell division can reorganize the meristem. o For example, the outermost cells usually divide in a plane parallel to the surface of the shoot tip. o Occasionally, however, an outer cell divides in a plane perpendicular to this layer, placing one daughter cell beneath the surface, among cells derived from different lineages. †¢ In plants, a cell’s developmental fate is determined not by its membership in a particular lineage but by its final position in an emerging organ.Phase changes mark majo r shifts in development. †¢ In plants, developmental changes can occur within the shoot apical meristem, leading to a phase change in the organs produced. o One example of a phase change is the gradual transition from a juvenile phase to an adult phase. o In some plants, the result of the phase change is a change in the size and shape of leaves. o The leaves of juvenile and mature shoot regions differ in shape and other features. o Once the meristem has laid down the juvenile nodes and internodes, they retain that status even as the shoot continues to elongate and the meristem changes to the mature phase. If axillary buds give rise to branches, those shoots reflect the developmental phase of the main shoot region from which they arise. o Although the main shoot apex may have made the transition to the mature phase, the older region of the shoot continues to give rise to branches bearing juvenile leaves if that shoot region was laid down when the main apex was still in the juven ile phase. o A branch with juvenile leaves may actually be older than a branch with mature leaves. †¢ The juvenile-to-mature phase transition points to another difference in the development of plants versus animals. o In an animal, this ransition occurs at the level of the entire organism, as a larva develops into an adult animal. o In plants, phase changes during the history of apical meristems can result in juvenile and mature regions coexisting along the axis of each shoot. Genes controlling transcription play key roles in a meristem’s change from a vegetative to a floral phase. †¢ Another striking phase change in plant development is the transition from a vegetative shoot tip to a floral meristem. †¢ This transition is triggered by a combination of environmental cues, such as day length, and internal signals, such as hormones. Unlike vegetative growth, which is indeterminate, the production of a flower by an apical meristem stops primary growth of that shoo t. †¢ This transition is associated with switching â€Å"on† floral meristem identity genes. †¢ The protein products of these genes are transcription factors that help activate the genes required for the development of the floral meristem. †¢ Once a shoot meristem is induced to flower, positional information commits each primordium arising from the flanks of the shoot tip to develop into a specific flower organ—a sepal, petal, stamen, or carpel. Viewed from above, the floral organs develop in four concentric circles, or whorls. o Sepals form the fourth (outermost) whorl, petals form the third, stamens form the second, and carpels form the first (innermost) whorl. †¢ Organ identity genes, or plant homeotic genes, regulate positional information and function in the development of the floral pattern. o Mutations in these genes may lead to the substitution of one type of floral organ for the expected one. †¢ Organ identity genes code for transcript ion factors. †¢ Positional information determines which organ identity genes are expressed in which particular floral-organ primordium. In Arabidopsis, three classes of organ identity genes interact to produce the spatial pattern of floral organs. †¢ The ABC model of flower formation identifies how these genes direct the formation of four types of floral organs. †¢ The ABC model proposes that each class of organ identity genes is switched â€Å"on† in two specific whorls of the floral meristem. o A genes are switched on in the two outer whorls (sepals and petals), B genes are switched on in the two middle whorls (petals and stamens), and C genes are switched on in the two inner whorls (stamens and carpels). Sepals arise in those parts of the floral meristems in which only A genes are active. o Petals arise in those parts of the floral meristems in which A and B genes are active. o Stamens arise in those parts of the floral meristems in which B and C genes are a ctive. o Carpels arise in those parts of the floral meristems in which only C genes are active. †¢ The ABC model can account for the phenotypes of mutants lacking A, B, or C gene activity. o When gene A is missing, it inhibits C, and vice versa. o If either A or C is missing, the other takes its place.