Biosc&0150:&Foundations&of&Biology&I.& & Review&8:&Chapters&37&and&39& &!Adel,&Anthony,&Kathleen,&Megan,&Dr.&Swigonova& & Page&1&of&16&Review&Chapter&37:&&Water&and&sugar&transport&1. What&is&transpiration?&Water&loss&due&to&evaporation&a. What&two&conditions&must&be&met&for&transpiration&to&occur?&Stomata&must&be&open,&and&the&air&surrounding&the&leaves&is&d rier&than &the &air&insid e&the &leaves&b. How&does&water&move&up&a&tree?&Does&it&require&ATP?&Which&direction&does&it&move?&Water&always&moves&passively!&It&requires&no&ATP,&it&moves&by&differences&in&water&potential&from&high&to&low&c. If&a&plant&has&a&high&s olu te &co nc en tra tio n ,&it&ha s &a&( hig h&/ &low)&solute&potential.&Low&d. How&do&solute&potential&and&water&potential&combine&to&make&up&water&potential?&When&selectively&permeable&membranes&are&present,&water&tends&to&move&by&osmosis&from&areas&of&high&solute&potential&to&areas&of&low&solute&potential.&However,&when&no&membranes&are&present,&water&moves&from&areas&of&high&pressure&potential&to&low&pressure&potential.&&&e. Why&are&solute&potentials&always&negative?&Because&they&are&measured&relative&to&that&of&pure&water,&which&has&0&Mpa.&Since&there&is&always&some&solutes&inside&a&cell,&the&water&inside&always&has&a&solute&po tentia l&low er&th at&tha t&of&pu re&w ater&&f. How&do&the&terms&flaccid&and&pressure&potential&relate&to&one&another?&A&cell&that&is&flaccid&means&it&has&no&turgor&pressure&and&thus&a&pressure&potential&of&0.&&g. Application:&Why&don't&red&blood&cells&pop&in&the&bloodstream?&Red&blood&cells&don't&pop&because&the&blood&provides&an&isotonic&environment&for&the&cells.&&2. Work&with&Water&Potential&a. If&a&cell&with&a&solute&po te nt ial&o f&–&0.2&MPa&and &a &pr e ssu re &p o te nt ia l&o f&0 . 4&MPa&is&placed&in&a&chamber&filled&with&pure&water&that&is&pressurized&with&0.5&MPa,&what&will&happen?&Water&will&flow&into&the&cell&b. You&place&a&piece&of&potato&weighing&0.3&grams&with&a&water&pot en ti a l&o f&1 &MPa&in&a&beaker&of&Pepsi.&After&10&minutes,&you&remove&the&potato&piece,&and&it&now&weighs&0.25&grams.&What&can&you&conclude&about&Pepsi’s&water&potential?&Pepsi’s&water&potential&was&less&than&1&MPa&c. If&you&could&turn&a&p la nt&u ps ide&d ow n &w itho ut&affe ctin g&the &fun ctio n&of&th e&m ajo r&orga ns &(roots,&shoots,&and&leaves),&wou ld&tran sp ort&of&w ate r&in&xyle m&m o ve&up w ard s&tow a rd&the &roots,&or&would&it&still&move&towa rd&the &leave s? & Would&transport&of&sugar&in&phloem&chan g e&as&a&result&of&this&inversion?&Water&would&still&move&towards&the&leaves&in&the&xylem&of&your&inverted&plant.&Roots&don't& have&stomata&for&water&t o &m o ve &th ro u g h&a n d &th er e &is&n o t&a &mechanism&for&water&to&move&from&the&ground&into&leaves&and&then&exit&through&the&roots&via&transpiration.&Transpiration&would&still&move&water&out&through&the&leaves,&but&this&would&stop&as&the&roots&dried&out.&Transport&in&the&phloem&would&not&be&altered.&Sugars&would&still&move&from&the&source&to&the&sink&as&described&by&the&pressure&flow&model&for&phloem&transport.&d. Compare&and&Contrast&i. The&pressure&potential&of&wet&soils&vs.&dry&soils.&Wet&soils&have&almost&no&pressure&potential,&while&dry&soils&have&a&highly&negative&pressure&potential&because&the&few&water&molecules&present&cling&to&soil&particles&ii. The&solute&potential&of&salty&soils&vs.&typical&soils.&Salty&soils&have&extremely&low&solute&potentials&compared&to&typical&soils&because&the&concentration&of&solutes&is&high&&3. The&initial&molar&concentration&of&the&cytoplasm&inside&a&cell&is&2M&and&the&cell&is&placed&in&a&solution&with&a&concentration&of&2.5M.&&a. True&or&False.&If&false,&explain.&Biosc&0150:&Foundations&of&Biology&I.& & Review&8:&Chapters&37&and&39& &!Adel,&Anthony,&Kathleen,&Megan,&Dr.&Swigonova& & Page&2&of&16&i. Initially,&solute&concentra tio n &is&gre at er&o u tsid e&t he &ce ll&th an &in sid e. &True&ii. Water&will&enter&the&cell&because&solute&potential&is&lower&inside&the&cell&than&outside.&False,&water&will&leave&the&cell&because&solute&potential&is&higher&inside&the&cell&than&outside&iii. The&cell&will&become&flaccid&because&the&pressure&potential&is&greater&outside&the&cell&than&inside.&False,&the&cell&will&become&more&flaccid&because&the&solute&pote ntia l&is&greater&inside&the&cell&than&outside&iv. Initially,&the&cytoplasm &is&h yp ert on ic&t o &th e&su rro un d in g&so lu tio n .&False,&the&cell&is&hypotonic&to&the&surrounding&solution&v. Initially,&the&numerical&va lue &of &the&solute&potential&is&more&negative&inside&the&cell&than&outside.&False,&it&is&more&negative&outside&the&cell&than&inside&vi. Net&diffusion&of&water&will&be&from&inside&the&cell&to&outside&the&cell.&True&vii. At&equilibrium,&the&molarity&of&the&cytoplasm&will&have&increased.&True&viii. At&equilibrium,&the&pressure&potential&inside&the&cell&will&have&increased.&False,&the&pressure&potential&inside&the&cell&will&remain&zero&&&4. When&the&pressure&potential,&Ψ,&is&negative,&there&is &a &n e t &w a t er &fl o w&____________ _ _ _ .&When&Ψ&is&positive&there&is&net&flow&of&water&________________.&When&Ψ&=&0,&___________ _.&Into&the&cell;&out&of&the &cell;&t he re&is&n o &n et&w a te r&flo w &in to &or&o u t&o f&t he &cell&&5. What&is&the&advantage&of&transpiration&being&a&passive&process?&&What&is&the&disadvantage?&It&is&advantageous&for&plants&to&m o ve&w ater&th rou gh &a&pas sive &proc ess &like&trans pira tion &bec au se&water&in&a&tree&needs&to&move&great&distances&in&order&to&get&to&where&it&is&needed,&especially&in&the&top&leaves&of&very&tall&trees.&&There&is&no&ene rgy&exp en diture&for&this ,&whic h&free s&en ergy &for&us e&in&other&processes.&&The&disadvantage&of&this&is&that&transpiration&can&occur&rapidly&in&dry&climates&and&result&in&a&high&water&loss&for&the&tree,&risking &deh yd ratio n.&&6. The&Cohesion&Tension&Theory&a. Explain&the&theory&in&your&own&words.&It&is&the&regulation&of&long&distanc e&w a te r&m o vement.&It&all&starts&with&the&tran sp ira tio n&f ro m &lea f&s urf a ces &as &w at er&is &pu lled &u p&o u t&o f&t he &m e nis ci&from&all&the&way&down&in&the&ro ots.&It&is&a&con sta nt&pu llin g&as&lo ng&as &the&atm o sphere&is&drier&and&the&stomata&are&open.&&b. What&is&most&responsible&for&creating&the&steep&concentration&gradients&between&the&leaf&interior&and&its&surroundings ?&Alo n g&the &wa ter&tran spira tion &co ntin u um ,&wh ere &is&the&w ate