Diffusion and Osmosis Lab Report-3

 

 

Diffusion and Osmosis Lab Report  Nicole Mackey AP Biology  November, 2019

 

 Nicole Mackey Formal Lab Report, 2019 Introduction Osmos osiis and  diffusion in ce cellls is cruc uciial beca cau use of how the act ctiions of both help the ce celll func functi tion on prop proper erly ly..  Diff Diffus usio ion n tran transp spor orts ts subs substa tanc nces es in an and d ou outt of th thee ce cell ll ei eith ther er th thro roug ugh h pass passiv ivee or  act active ive tran transspor port,  and and osmo osmosi siss sp spec eciifica ficallly deal dealss with with the di diff ffus usiion of wat water er.. Pota Potato toes es ar aree a for orm m of tuber  that grows from the ground, and it utilizes diffusion for growth and other actions. Potatoes will  react to different environments it is placed in, and when exposed to a new environment, it  may shrink or grow. This all correlates to the idea of osmosis because of its reaction. The three  types of solutions substances can be placed in are isotonic, hypertonic, or  hypo hypoto toni nic. c. Isoton otoniic  cr crea eate tess no net net move moveme ment nt bet between ween the wate waterr in th thee cell cell and and th thee wate waterr the ite tem m is plac placed ed  in. in. Hyper yperttoni onic ca caus uses es cell cellss to shri hrivel vel and and di diee beca becaus usee th thee wate waterr le leav aves es th thee cel cell. Last Lastly ly,, hypotonic causes cells to swell and burst b urst because water moves into the cell. By usin using g  dif diffe ferren entt co conc ncen entr trat atio ions ns of sucr ucrose ose so solu luttio ions ns,, the pot potat atoe oess ar aree goi going to rea eact ct to eac ach h one  in a dif different way. The net movemen ementt of the water in each solut utiion will determine the new weight  and size of the potato sticks. The experiment that was used determined the water   potential of  the potato sticks, and factors of this include the weight and change in the look of the st stic icks ks.. The The rate rate of osmo osmosi siss was was depe depend nden entt on the begi beginn nnin ing g size size of the pota potato to an and d the sol olut utio ion n th thee  potatoes were  placed in. The potato aided in the understanding of water potential and osmosis in  plants.

Prelab Questions 1. What happen happen if you you applied applied saltwater saltwater to the roots roots of of a plant? plant? Why? a. The plant  will shrivel and wilt if it was placed in salt water. It would shrivel  because salt  is a hypertonic solution, and this will cause the water to move out of  the ce celll.  It is also a new envir vironment for the pl plaant that isn’t us usee to salt water, so it will shrivel. 2. What are  two different ways a plant could control turgor pressure, a name for internal water potential within its cells? Is this a sufficient definition for turgor pressure?

 

a. Plants maintain  their turgor pressure by moving proteins in and out of the cell. They Th ey al alsso  obt obtai ain n wat water to incr increa ease se thei theirr tu turrgor gor pres pressu surre beca becaus usee wi with thou outt wat ater er,, it will wilt.  The de deffinition; however er,, is inac acccurate be beccaus usee turgor pres esssur uree is the  pressure of  the cytoplasmic membrane over the cell wall, which will then change the water potential in plants. 3. Will water  move in or out of a plant cell if the plant cell has a higher water potential than its surrounding environment? a. Water will  leave or move out of the cell if the cell has a higher concentration on the inside.  The cell is trying to reach an equilibrium, so it will try to create an equilibrium by leaving the cell and entering the new environment. 4. Where is the cell membran membranee in relation relation to the cell cell wall? wall? Can you see the the two structur structures es easily? Why or why not? a. The membrane membrane is is found between between the cell cell wall and cytoplasm cytoplasm.. You cannot cannot see the the two structures with a naked eye but bu t with a microscope, the two structures are easily visible. 5. What parts parts of the cell cell that you see control control the water water concentrat concentration ion in the the cell? a. The semi semi permeable permeable membrane membrane and the large large water water vacuole vacuole control control the the water water concentration in the cell. 6. What changes changes do you expect expect to see when the the cells are exposed exposed to the the solutions solutions?? a. The cell cell will not change change in the the freshwater freshwater.. A hypotonic hypotonic solutio solution n will keep the cell rigid and healthy. However, Howeve r, in salt water, the cell will plasmolyze and wilt. 7. How will will you know if a partic particular ular treatmen treatmentt is increasing increasing turgor turgor pressur pressure? e? If it is reducing turgor pressure? a. Turgor pressure pressure is the pressure pressure of the cell cell wall wall against against the rest rest

 

of the cell. If the membrane and the cell wall aren’t able to be seen separated, turgor  pressure is high. If the membrane and cell wall are visibly separate, then turgor pressure is low. low. 8. How could could you determin determinee which soluti solution on is isotoni isotonicc to the cells? cells? a. In isotonic isotonic soluti solutions, ons, the the cell might might become become flaccid flaccid and and limp because the cell cell doesn’t have enough turgor pressure to keep the cell have a high water content. 9. How could could you measure measure the the plant pieces to determine determine the rate rate of osmosis osmosis?? a. By measuring measuring the plant's plant's pieces pieces mass, mass, or the surface surface area area to volume volume ratio ratio you can can determine the rate of osmosis. The measure of the plant’s mass before and after it is placed in the solutions also determines the rate of osmosis. If the surface area to volume ratio decreases that also means that osmosis has occurred. 10. How could you calculate water potential in the cells? a. By using using the water water potential potential equation equation and measuri measuring ng the weight weight of the cells cells over time. 11. Which solution has a water potential equal to that of tthe he plant cells? How do you know? a. The sucrose sucrose soluti solution on with the molarity molarity of .2. We We concluded concluded this this because because the  potato had little to no change in mass after being put in the solution. 12. Was the water potential in different different plants the same? a. Since we didn’t didn’t experimen experimentt on different different plants, plants, we we weren’t weren’t able to conclude conclude this. this. Compared to the other potatoes in other people’s labs. The water potential was different between groups. 13. What would your results be if the potato were placed in a dry area for several days before your experiment?

 

a. The potato potato would would lose mass mass because because it is place place in an area area that has has less less water. water. The  potato would try to reach an equilibrium by releasing water into the environment, and this causes it to lose mass. 14. When potatoes are in the ground, do they they swell with water when it rains? If not, how do you explain that and if so, what would be the advantage or disadvantage? a. The potato’s potato’s skin acts acts as a cell cell membrane membrane.. This means means when when the potato potato is in the ground and it rains, the potato won’t swell because the skin protects it from gaining too much water. The advantage is that the potato is protected from its outside environment.

Question Which potato  would uld be able ble to have the highest percent chang ngee over the cou ourrse of thr hreee days and how would that be possible?

Hypothesis If the  size and sha hap pe of the po pottato ato has a better surface to volume rat atiio than the othe herrs and is plac aceed  in a sucrose soluti ution of 1.0 molarity, the po pottat ato o stick will swell and have a hi hig gh water   potential because it has the driving force to move.

Variables ●

Indep ndepen ende dent nt Vari Variab ablle  – The The indep ndepen ende dent nt var varia iabl blee is th thee su sucr cros osee sol olut utiions ons and and th thei eir  r  concentrations.

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Depe De pend nden entt Var Varia iabl blee  – The The amou amount nt of days days the pota potato to is pl plac aced ed in the sol olut utiion an and d the weight of the potatoes are the dependent variable.

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Cont Co ntrrol Var Varia iabl bles es  – The The cont contro roll var varia iabl bles es ar aree th thee pot potat ato o sti tick ckss, but but not not th thee si size zess, th thee cups, and amount of solution each potato is placed in.

 

  Materials ●

Potato, peeled, cut into fries

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Balances

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Rulers (metric)

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Cups

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Unlabeled, color coded sucrose solutions of different concentrations

Methods 1.

Obtain cut  potato sticks from our teacher and cut them in half again so that they would fit in  each cup we have. Record each weight and length of the potatoes that you will  place in each cup.

2.

There are  5 cups, and in each one, a different concentration of the sucrose solution is  placed in  it. The main focus is to cover the potato so that it would have the ability to change in size and weight rather than drying out from being in the open air.

3.

Set each  cup aside in a place that was easy to access; Wait one day for the reweighing of the potatoes

4.

During the  next day, obtain the new weights of the potatoes by using a balance. Make sure the  po pottato ato isn’t sop opp ping wet when it’s on the balance bec ecaause this is supp ppo osed to record the  weight of the potato and not the water around it. Record the observations down in a notebook. Place the potatoes back in the solution.

5.

After waiting  another day, take the potatoes out to weigh them again. Record the observations

6.

After gathering  the data ata from weig eighin hing the potatoes, calculate the water potential of the  potatoes by using the formula:

 

  7.

Also calculate  the percent changes from day to day weighing of the potatoes. (this will  be used in the graph that will be created)

8.

Create a  graph that presents the data that was found: this includes the way the weights changed over the course of three days and the percent changes

Data

 

The collection of data began began on day zero when they weren’t placed in the solution. Each day, they were weighed again to see the change over time. The total amount of days that they were weighed was three. The data was used to calculate the mean percent change of the  potatoes in the different solutions. The sucrose solution of .2 molarity had a percent change of 8.1%. The .4 molarity had a change of 1.3%. The 0.6 molarity had a change of -10.1%. Lastly, the 1.0 molarity had a percent change of -12.2%. The calculated water potential of the potato is -11.1 bars.

Analysis Thee data Th data  that that is sh show own n abov abovee help helped ed to det deter ermi mine ne the osm osmot otic ic chan change ge of each each pota potatto sti tick  ck  in the  soluti utions. The slope shows a downwar nward d trend, an and d as the mol olaarity inc ncrrea easses es,, the pe perrce cen nt decreases. Each  potato stick reacted differently to the solutions, however if placed in a .45 soluti ution, the  potato would be plac aceed in an isotonic solut utiion be beccaus usee it wouldn’t show ch chaange. ge. Thee othe Th others rs wer were plac placed ed in so sollutio utions ns that hat sh show owed ed ch chan ange ge.. In th thee .6, .6, .8, .8, an and d 1.0 1.0 mol olar ariity ty,, th they ey wer were  placed in  a hypertonic solution because of how the potatoes lost water and mass. In the .2 and .4 molarity, the  mass and water increased making it placed in the hypotonic solution. In the .45 molarity solution, the potato’s water potential would be -11.1 bars.

Analyzing Results: 1. Cell ells are  small becau ausse they must have a large surface relative to their volume in able to functi ction ade deq quate ately.  This allows the cell ell to fun uncction at a faster rate tha han n if they larger. Thee cell Th cell  can can al alsso tran transspor port su subs bsta tanc nces es fas aste terr than than if it were were to be ex exha haus usti ting ng mor more ener energy gy  because the  cells volume is too big. The cell membrane has many convolutions in order  to be  able to have a high surface to volume ratio. The surface to volume ratio helps to manage the cell and how many resources it needs and how much energy to use. 2. The The mitoc itocho hond ndrria has has many many conv convol olut utio ions ns in or orde derr to in incr crea ease se its sur urffac acee ar area ea.. Thi This al alllows ows it to  crea creatte mor more ener energy gy an and d prod produc ucee ever everyt ythi hing ng mor oree ef efffic iciient ently ly.. Its sur urfa face ce to vol volume ume

 

ratio is  high gheer on the surf urfac acee area side, so this mea ean ns it has many folds inside in orde derr to create more energy. The energy that is created is ATP. 3. No diffusion  or os osm mosis will occ ccu ur within a cel elll placed in an isotonic solution. Sinc ncee it is  placed in  a solution that is the same as the inside environment, no net movement will occur. The environment and the cell are at an equilibrium.

Conclusion The hypothesis  was correct for the molarity, but it wasn’t that much for the size of the  potato. We  believed the factor would play a bigger role in the experiment, but the percent changes over  time was what was mainly focused on. If taking account for the sizes, then the hypo hypoth thes esis is coul could d  have have been been fur further ther eval evalua uate ted, d, but but in th thee end end th thee mola molarrit ity y part part of our our dat data. It had had a high  water po potten enttial beca cau use of its driving force to move to a different place was high gheer than the the res rest.  Thes Thesee mean meanss that hat ev even en thou though gh the the firs firstt part part di didn dn’’t pl play ay a bi bigg gger er fa fact ctor or in our our expe experi rim men entt and data  like we thought it would, we were still able to obtain data from the molarities of the solutions.

Evaluation This lab  experience attempted to explain water potential in a more hands on way. We were able  to see the cha han nge in size of the potatoe oess ov oveer the course of the day. The first day wen entt our way,  but I was absent when the rest of the testing went on for the potato. I got my research from my  other lab partners, but it didn’t help that I was absent for it. The methods we used were we ren’ n’tt out out  of the the box box beca becaus usee it was was just ust tes esti ting ng osmo osmoti ticc chan change gess in pota potattoes oes th that at were were pl plac aced ed in su sucr cros osee solut olutiions ons.  Th Thee equi equipm pmen entt we used used was al alll reg egul ular ar an and d up to dat date, so noth nothiing went went wron wrong g ther theree eit either her. If this this expe experi rime ment nt were were to happ happen en agai again, n, I woul would d want want to be th ther eree meas measur uriing the data data myself so  I wouldn’t have to rely on someo eon ne to get all the informat atiion from. I wou oulld improve the experiment  by adding more time to the potato in the solution to see a bigger change over   time.

 

Future Research The change gess  I would tak akee would be no nott only nly addi din ng more trials, but I woul uld d also switch up the the  vari variab ablles and and mate materria ials ls.. I woul would d try diff differ eren entt pl plan antts and and see th thee react eactiions ons to th thee so sollut utio ions ns over over tim ime. e.  Temp Temper erat atur uree ch chan ange ges, s, sunl unlight ight ex expo posu surre, an and d ai airr ex expo posu surre woul would d al alsso be a chan change ge in va vari riab able less that that I woul would d te test st.. To ex expa pand nd on va vari riab able les, s, the the solu soluti tion onss co coul uld d be more more th than an ju just st sucr sucros ose. e. They Th ey coul could d  also also incl nclude ude sal altt too. too. The The ques questi tion onss that that I woul would d ch chan ange ge woul would d to see its chan change ge over  over  a longer  period of time rather than just a day or two. This would allow me to create a bigger   graph that would really show its change over time. References Understanding Water Potential - Diffusion and Osmosis Investigation 4

 

Thompson Formal Lab Report Rubric v08.2017  Name: ______________________ __________________________ ____

Aspect Formatting

Introduction

Question Hypothesis

Variables

Materials

Methods

Data

Analysis

Conclusion

Criterion Formatting follows guide perfectly: Title page, running head, page number, headings, font, indentation, bullet, spelling, grammar,  punctuation, appropriate tense, spacing, writing convention Advanced written strategies. Includes context and relevance, in-text citation as appropriate, personal engagement, contribution to the experiment, pre-lab observations, purpose of lab Clear, specific, focused, measurable. Written as a question or  problem. Uses the general concept if y is done ,then z will occur because…,   because statement is justified in the introduction, predicts a measurable and quantifiable relationship, actually answers the question proposed, each independent variable is addressed Uses full sentences, IV is the manipulated variable, IV includes the compare value, DV is the measured value, DV may include what the DV actually measures, CV identifies all controllable factors Bullet format, two columns if long list, includes images of equipment set-up as appropriate, all material is referenced in methods section, includes key information* Clearly written, present tense, avoids first person and unnecessary transitions, number format, provides protocols as necessary, addresses controls, safety, potential errors, trials, & key information*, includes all relevant steps, addresses data collection, all material is included in the materials section Clearly presents raw data, correctly processes the data (percent, totals, mean, captions, standard deviation, labels, sequence), tables, graphs, and/or diagrams, annotations, includes uncertainty unce rtainty and significant figures, uses an appropriate number of trials Provides an in depth analysis of the data, discusses: trends, compares data among trials and variables, significance of data  points (meaning of the data or the reason for outliers); includes sample calculations (i.e. percent, mean, median, mode, standard deviation, +  uncertainty, etc.), does not draw conclusions, addresses all processed data, may include sources of error Confirms or rejects the proposed hypothesis, is according to the data, written in third person, compares analyzed data to proposed hypothesis, compares analyzed data to accepted scientific literature, provides an answer to the initial question

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Evaluation

Future Research References Feedback

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Reflects on the strengths and weaknesses of experimental methods, material and apparatus, time management, sources errors, and suggestions for improvement Proposes multiple and specific ways to expand the experiment, leads the reader to consider new questions for investigation Provides references according to APA convention

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