Transport of Water and Materials In and Out of the PlantFranclene Milla, Chanel Mirafuentes, Gianica Monteagudo, Bradley Ong

BIO 21 LAB1A MHAB1

Submitted to: Associate Professor Elena RagragioSubmitted: September 20, 2012

Transport of Water and Materials In and Out of the Plant

ABSTRACT Diffusion, osmosis, imbibitions, and guttation are directly involved in the transport of water and minerals in and out of a plant body. The cell membrane maintains and protects the plant body in the ever-changing environment. Different environments directly affect the transport of dissolved minerals into the plant cells. Our group used seven different experiments to demonstrate the transport of water and dissolved minerals in and out of a plant. Diffusion of pigments was seen in the first experiment concerning Bixa orellana, where the seeds were placed in different test tubes containing different substances. Osmosis, on the other hand, was observed using small strips of the abaxial epidermis of Rhoeo spathodea. The third experiment deals with the factors affecting the integrity of the cell membrane and was observed using apple peelings which were placed in different kinds of solvents at different temperatures. Imbibition was seen when wood, rubber and corn seeds were placed inside two beakers - one with water and the other with kerosene. It was noted that each material had an increase in weight when placed in kerosene. The movement of water through its stem was seen in an experiment involving pechay stalk; transpiration was noticed when four identical leaves where applied with petroleum jelly and were later compared. Lastly, guttation was seen in rice seedlings which was seen when rice seedlings were covered inside a container.

1. Introduction Water and mineral substances are taken up from the soil through the roots and transported upwards; on the other hand, products of photosynthesis are produced and transported throughout the plant system. In order to thrive, plants must coordinate the physiological processes that occur in the maintenance of the equilibrium of the transport of dissolved substances through the cytoplasmic membrane. The transport of nutrients and water throughout the plant body provides the framework for cell-to-cell interdependence.There are two ways in which transport can occur across a membrane, either by passive or active, depending on the energy required during the process. Simple diffusion, a kind of passive transport, moves water from regions of higher concentration to a lower one. This process is only possible for solutes which are readily permeable. Other processes include bulk flow, active transport, imbibitions and osmosis. The main objective of this experiment was to show the movement of water and minerals in and out of the plant. The specific objectives of this experiment were:I. To determine some factors that affect the diffusion processII. To differentiate between diffusion and imbibitionIII. To determine factors that affect permeability of cell membranesIV. To demonstrate the various processes by which materials are transported and transpired

2. Methodology2.1. Diffusion of Selected Plant Pigments Our group weighed the seeds of atsuete (Bixa orellana) and placed one gram of seed each into 4 different kind of test tubes. These test tubes were labelled 1-4. In test tube labelled 1, 10 ml of distilled water was placed. In test tube number 2, our group put 10 ml of distilled water and then placed it in a boiling water bath. Next, we have test tube number 3 and we placed 10 ml of vegetable oil. Lastly in test tube number 4, 10 ml of heated vegetable oil was placed. After half an hour, we shook the test tubes and recorded the color intensities in each.

2.2. Osmosis Thin sections of the lower epidermal side of Bangka-bangkaan (Rhoeo spathodea) were cut by our group. Using the LPO of the microscope, we made a sketch of the turgid cell. Next, without moving the slide, water was drawn off using a piece of paper towel and replaced it with a 5% NaCl solution. A sketch showing the change in the cells was then made based on our observations.

2.3. Factors Affecting the Integrity of Cell Membranes Apple peels were gathered by peeling it using a blade. 7 separate sections were made. The first three sections were transferred in 3 different test tubes labelled A, B, and C which contains 10 ml of distilled water. Test tube A was placed under room temperature, test tube B inside a refrigerator and test tube C in a water bath with temperature of 60C. After observing for 30 minutes, each of the three sections were placed into wet mounts and viewed using a microscope. Color intensity was noted. For the remaining 4 sections, we each placed them in separate slides and labelled them from D to G. A drop of 50% chloroform was added to D, 50% acetone for E, a drop of 0.1 M of NaOH and 0.1 M of HCl to G. These specimens were observed under the microscope immediately, after 15 minutes and after 30 minutes.

2.4. Imbibition The 2 pieces of rubber and 2 pieces of wood were individually weighed. 2 sets of 10 grams of corn seeds were also weighed. In a beaker, we placed 1 piece of wood, a piece of rubber and 10 grams of corn seeds and water was added until the materials were completely immersed. In another beaker, a piece of wood, a piece of ruber and 10 grams of corn seeds were placed and kerosene was added until the materials were immersed. After 90 minutes, these materials were taken out and gently dried and their final weights were measured.

2.5. Movement of Water Through Stem Pechay leaves with intact petiole was used. 1cm of the base of the petiole was cut off. The leaves were immersed in a bottle containing 10ml of 0.01% of eosin dye solution. After about 10-15 minutes, a leaf was removed and the stalk was split longitudinally. The length covered with dye was measured. From another leaf, a thin cross section of the stalk was cut and viewed under a microscope in LPO. The stained tissues were identified through being viewed under the microscope.

2.6. Comparison of Cuticular and Stomatal Transpiration by Four Leaves Method 4 identical leaves were gathered. These were then labelled A, B, C, and D. Leaf A was assigned as the control. Using vasellin, each of the three remaining leaves were greased. Leaf B was greased on the upper surface. Leaf C was greased on the lower surface. Leaf D was greased on both sides. These leaves were then hanged by a thread to expose both sides to air. The set-ups were observed after one meeting.

2.7. Guttation 5 rice grains were planted on a container. The lower portion of the container was immersed with water. When the seedlings are 2-5cm long, they were covered with a transparent wide mouth jar. The set-up was observed and the droplets that formed on the leaf surfaces were noted.

3. Results3.1. Diffusion of Selected Plant Pigments The diffusion of the pigments of the seeds of Bixa orellana is relatively higher when the concentration is also high. More so, the higher the temperature, the greater the rate of diffusion. Table 1. Intensities of the Rate of DiffusionSubstanceObservation

Test Tube 1 (Distilled Water)+

Test Tube 2 (Hot Distilled Water)+++

Test Tube 3 (Vegetable Oil)++

Test Tube 4 (Heated Vegetable Oil)++++

3.2. Osmosis The cells were larger and tugid when it was exposed with water; however, when it was replaced with 5% NaCl solution, the cells became flaccid and plasmolyzed.

3.3. Factors Affecting the Integrity of Cell MembranesThe results produced from this can be divided into 3 parts: temperature, pH effects, and organic solvents. With temperature, the outside of the normal physiological range would disrupt membrane integrity causing pigments to leak out of the cells. For organic solvents, nonpolar ones would cause damage to the membrane since the outer membrane is nonpolar and hydrophobic. Lastly, extreme pH causes protein membranes to denature.

Table 2. Color Intensity of Various SolutionsTest TubeIntensity of ColorTest TubeIntensity of Color

A (C) room temperature+++D (chloroform)+

B (C) - refrigerated++E (acetone)++

C (C) heated to 60C+F (NaOH)+

--------G (HCl)++

3.4. Imbibition In this experiment, the affinity of the wood, rubber and seeds to different solvents were compared. Wood and rubber makes good imbibant of water as they showed significant change in weight; on the other hand, rubber showed greater change in weight when it is imbibed in kerosene.

Table 3. Weight Before and After ImbibitionMediumImbibantInitial weightFinal weight% in Weight

WaterRubber0.5 g0.7 g40%

Wood19.95 g21.6 g8.27 %

Seeds10 g12.1 g21%

KeroseneRuber0.8 g1.35 g80.57%

Wood5.55 g7.25 g44.68%

Seeds10 g10.3 g3%

3.5. Movement of Water Through Stem After 15 minutes of being immersed in a bottle with 10mL of 0.01% eosin dye solution, the dye solution went up through the stem of the pechay in a straight line manner through the xylem tissues.

3.6. Comparison of Cuticular and Stomatal Transpiration by Four Leaves MethodAfter 3 days of observation on the leaves, leaf A being the control was the most desiccated and curled on both sides, leaf B smeared with grease and vasellin on the upper surface and leaf C smeared with grease on the lower surface are both half-dry with leaf B curling outward and leaf C curling inward, and leaf D smeared with grease on both sides remained fresh, waxy, and moist, with no occurrence of desiccation and curling.

3.7. Guttation The appearance of the xylem saps happened at the tip of the leaf blades after the plant was covered with a wide mouth jar.

4. DISCUSSION4.1. Diffusion of selected plant pigments The greater the concentration gradient between the outside and the inside of the membrane, the greater the diffusion. If the concentration of the pigments outside and inside the membrane were greater, then it would diffuse more quickly and vice versa. The other factor that affects the rate of diffusion is the size of the particles. The smaller the particle, the faster it would be diffused.Increase in temperature speeds up movement of molecules and faster movement of molecules means faster rates of diffusion. This is why the heated distilled water and heated vegetable oil had the fastest rates of diffusion. Faster rate of diffusion was observed in oil than water because the pigments of the atsuete seeds are insoluble in water.4.2. Osmosis When the bangka-bangkaan was immersed in a hypotonic solution, the cells became turgid. The water was moving from a smaller concentration of solutes than the solution on the other side of the membrane. In the turgid cell, the water will continually move into the cell until the concentration of the impermeable solutes equals to that of the hypotonic solution.When the water was replaced with a 5% salt solution, the water became hypertonic. The water then moved from a larger concentration of solutes than the solution on the other side of the membrane. In a plasmolyzed cell, the water would continually move out of the cell until the concentration of the impermeable solutes equals to that of the hypertonic solution. 4.3. Factors affecting the integrity of cell membrane The apple peelings exhibited different intensities of the color of their pigments. The darker parts indicate more damage and stress to the cell membrane while the lighter ones indicate less damage and stress. The damaged cell membranes exhibited darker color because the pigments from inside the cell leak out.In this experiment, 3 test tubes containing immersed apple peelings in water were subjected to different temperatures. Results show that lower temperatures inflict more damage to the cell membrane and normal to high temperatures inflict less or no damage.In terms of the effect of pH, wet mounts of 0.1M NaOH solution and 0.1M HCl solution were observed for 30 minutes. The results show that the more the acidic a solution is, the more damage it inflicts to the cell membrane and the more basic a solution is, the less damage. Results also show that chloroform inflicted more damage in the membrane than the acetone. It is because chloroform is more acidic than acetone.4.4. Imbibition Wood and seeds imbibed better in water while rubber imbibed better in kerosene. Imbibition is the process by which a substance absorbs a liquid and, as a consequence, swells in volume but does not dissolve. Imbibition, which is usually reversible, is exhibited by many biological compounds, particularly by cell-wall constituents such as pectin, celluloses, and lignin. The swelling effect of imbibitions in seeds is important in seed germination for imbibition in water can burst the seed coat, which signals the start of germination.4.5. Movement of water through the stem The 0.01% of eosin dye solution rose up through the stem into the leaves. This only shows that water moves through the xylem elements in the stem to transport water.The eosin dye stain reached up to the cross section of the leaf which means that the water is diffused all throughout the plant through the stem.4.6. Comparison of the cuticular and stomatal transpiration Too much transpiration causes dessication. Cuticle helps in preventing dessication of the leaves. The control set-up, leaf A, where nothing was applied dessicated while leaf D which was smeared with grease on both sides remained fresh and waxy without any occurrence of dessication.

4.7. Guttation Since the jar was closed, there was an excess of moisture in the environment of the rice seedlings, hence, it could not undergo transpiration, which why guttation was induced. Guttation is the exudation of liquid water onto a plant surface. It occurs under conditions of high humidity when the saturated atmosphere prevents transpiration. The increase in root pressure forces water out of special hydathodes. The secreted water may contain calcium salts, which dry as a white crust at the leaf margins. Morning 'dew' on grass is often the product of guttation, as the lower temperatures at night provide ideal conditions for the process to occur. In transpiration, water vapor is released while in guttation, xylem saps are released.

REFERE NCES1. Committee on Biology 21 Laboratory Manual FS AY 2008-2009. (2008). Biology 21: General Botany Laboratory Manual.1. Mauseth, J. (2009). Botany: An Introduction to Plant Biology, 4th edition. Sudbury, MA: Jones and Bartlett Publishers.