^^ movement of water through the stem

Transport of Water and Minerals In

and Out of the PlantAnya Pena, Christian Solis, Jerick Bolintiam, Justine Alain Sy,

Noemi Nunez, Venus Banaag

Cell activities, such as diffusion, osmosis, imbibition, and guttation, involve the transport of water and materials

in and out of the cell membrane- which is essential for a plant to maintain equilibrium in an unstable environment.

The transport of the dissolved substances in different environments affects the plant cell in different ways. To

further understand the cell activities and the environment’s effect on the plant cell, seven different tests were

conducted. Diffusion of selected plant pigments was observed in the first experiment where Bixa orellana seeds

were placed in different test tubes containing different substances, namely: distilled water, boiled water, vegetable

oil, and heated vegetable oil. Osmosis was observed in the second experiment where small strips of the lower

epidermis of the Rhoeo spathodea was put two different slides- one with water and the other with salt solution. The

factors affecting the integrity of the cell membrane was determined in the third experiment using Pyrus Malus

peelings which was placed in different temperatures and substances. Imbibition was observed in the fourth

experiment where wood, rubber, and corn seeds were put in two beakers- one with water and the other with

kerosene. It was also noticed that each of the material had an increase in weight when placed in kerosene. The

movement of water through the stem was observed in the pechay stalk of the the fifth experiment. Transpiration was

observed in the sixth experiment which also compared four identical leaves with different applications of vasellin.

Finally, guttation was observed in rice seedlings which were covered with a wide mouth jar.

Keywords: diffusion, osmosis, cell membrane, imbibition, active transport, transpiration, guttation

The cell membrane is the biological

membrane separating the interior of a cell

from the outside environment. It is a semi-

permeable membrane surrounding all cells,

which controls the movement of substances

in an out of the cells; therefore, responsible

for maintaining a steady and stable living

condition—or a state of equilibrium—even

in the midst of a transient environment. It is

involved in a wide variety of cellular

processes, such as growth, absorption, and

respiration, and serves as the attachment

point for the intracellular cytoskeleton and,

sometimes, the extra-cellular cell wall.

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

http://en.wikipedia.org/wiki/Extracellular_space

http://en.wikipedia.org/wiki/Cytoplasm

http://en.wikipedia.org/wiki/Biological_membrane

http://en.wikipedia.org/wiki/Biological_membrane

of passive transport, moves water from

regions of high water concentration (low

solute concentration) to regions of low water

concentration (high solute concentration).

This process however, is only possible for

solutes that are readily permeable such as

nonpolar and small polar molecules. Other

processes include: bulk flow, osmosis,

imbibition, and active transport.

Through this lab exercise, the student

should have been able: (1) To determine

some factors that affect the diffusion

process; (2) To differentiate between

diffusion and imbibition; (3) To determine

some factors that affect the permeability of

cell membranes; and (4) To demonstrate the

various processes by which materials are

transported and transpired.

METHODOLOGY

Diffusion of Selected Plant Pigments –

Atsuete (Bixa orellana) seeds were weighed

by Group number 1 and placed 1g of seed

was placed into 4 test tubes. These test tubes

were labelled 1-4. In test tube number 1,

10ml of distilled water was placed. In test

tube number 2, the group put 10ml of

distilled water and then placed it in a boiling

water bath. In test tube number 3, they put

10ml of vegetable oil. In test tube number 4,

10ml of pre-heated vegetable oil was placed.

After 30 minutes, these test tubes were

shook and the color intensities in each was

compared by using +, ++, and +++.

Osmosis – Thin sections of the lower

epidermal side of Bangka-bangkaan

(Tradescantia spathacea) were cut by Group

number 3 and these were placed into a wet

mount. Using this examination under the

LPO of the microscope, a sketch of a turgid

cell was made. Next, without moving the

slide, water was drawn off using a paper

towel and was replaced with a 5% salt

solution. A sketch showing the change in the

cells was then made based on the

observations under a microscope.

Factors Affecting the Integrity of Cell

Membranes – Apple peels were acquired by

our group by using a sharp blade. 7 sections

of peels were placed in a beaker filled with

distilled water. The first three sections were

transferred into three test tubes each with

10ml of distilled water and labelled A, B

and C. Test tube A was placed under room

temperature (250C) while Test tube B was

placed inside a refrigerator (100C) and Test

tube C was placed in a water bath (600 C).

After observing for 30 minutes, each of the

three sections were placed into wet mounts

and viewed under the microscope. Color

intensity in each was compared by using +,

++, and +++. For the remaining 4 sections,

they were also placed in wet mounts and

labelled D-G. A drop of pure chloroform

was added to D. A drop of 50% acetone was

added to E. 0.1 M of NaOH and 0.1 M of

HCl were added to F and G respectively.

These four were observed under the

microscope after 15 minutes and after 30

minutes. The observations were then

recorded.

Imbibition – The weights of 2 pieces of

wood and 2 pieces of rubber were weighed

by Group number 4. 2 sets of 10g corn seed

were also weighed. In one beaker, one piece

of wood, one piece of rubber and 10g of

corn seeds was placed. Water was added

until each of the materials was completely

immersed. In the other beaker, one piece of

wood, one piece of rubber and 10g of corn

seeds was and immersed with kerosene.

After 90 minutes, all the materials from the

two beakers were taken out and dried gently.

The final weights of these materials were

then measured.

Movement of Water Through the

Stem – Pechay leaves with intact petiole

were gathered by Group number 3. 1 cm

was cut off from the base of the petiole. The

leaves were immersed in a bottle filled with

10ml of 0.01% eosin dye solution. After 15

minutes, a leaf was removed and the stalk

was split longitudinally. The length covered

by the dye was measured. From another leaf,

a thin cross section of the stalk was cut and

viewed under the LPO of the microscope.

The stained tissues were then identified

through being viewed under the microscope.

Comparison of Cuticular and

Stomatal Transpiration by Four Leaves

Method – 4 identical leaves were gathered

by Group number 4. These were then

labelled A, B, C, and D. Leaf A was the

control. Using vasellin, each of the three

remaining leaves were greased. The upper

surface of B was greased while Leaf C had

its lower surface greased. Both sides of D

were greased. These leaves were then

hanged by a thread to expose both sides to

air. The set-ups were observed after one

meeting.

Guttation – 5 rice grains were planted

on a container by Group number 1. The

lower portion of the container was immersed

with water. When the seedlings are 2-5cm

long, they were covered with a transparent

bell jar (a wide-mouthed bottle can also be

used). This set-up was observed and the

droplets that formed on the leaf surfaces

were noted.

Results

Diffusion of Selected Plant Pigments –

The diffusion of the pigments of the seeds of

Bixa orellana is relatively faster and greater

in the setups exposed to higher

temperatures. Also, the diffusion was greater

in oil than in water, heated or not.

Substance ObservationTest Tube 1(Distilled Water)

+

Test Tube 2(Hot Distilled Water)

+++

Test Tube 3(Vegetable Oil)

++

Test Tube 4(Heated Vegetable Oil)

++++

Table 1. Shows the color intensity of the different setups, + being the lightest and ++++ being the

darkest Osmosis – To observe how the cell

changes in plasmolysis, wet mounts of

Tradescantia spathacea were made and the

water was later on replaced with a 5% salt

solution.

The cells were larger and turgid when it

was exposed in water (Fig. 1). When the

water was replaced with the 5% salt

solution, the cells became flaccid (Fig. 2).

Fig. 1 Tradescantia spathacea cells in a water solution

Fig. 2 Tradescantia spathacea cells in a 5% salt solution

Factors affecting integrity of cell

membrane – The results produced from this

experiment can be divided into three parts:

temperature, pH effects, and organic

solvents.

With temperature, the peeling of Pyrus

malus that was exposed to the lowest

temperature exhibited more damage to the

cell membrane while the one that was put in

a water bath exhibited less damage.

For organic solvents, the experiment

that pure chloroform is much more

damaging than 50% acetone.

As for pH effect, the one that was

subjected to NaOH, a base, had less damage

than the one subjected to HCl, an acid.

Fig 3.1 Pyrus malus soaked in water with a temperature of 10°C

Fig. 3.2 Pyrus malus soaked in water that has a temperature of 25°C

Fig. 3.3 Pyrus malus soaked in water that has a temperature of 60°C

.

Fig 4.1 Pyrus malus subjected to 50% acetone solution after 30 minutes

Fig 4.2 Pyrus malus subjected to pure chloroform after 30 minutes

Fig 5.1 Pyrus malus subjected to 0.1M NaOH solution after 30 minutes

Fig 5.2 Pyrus malus subjected to 0.1 HCl solution after 30 minutes

Imbibition – In this experiment, the

affinity of wood, rubber, and seeds to

different solvents, kerosene and water, were

compared. Wood and rubber makes good

imbibant of water as they showed greater

significant change in weight, while rubber

showed greater change in weight when it

imbibed kerosene.

Medium Imbibant Initial Weight(Wi)

Final Weight(Wf)

% Δ in Weight{(Wf-Wi)/Wi} * 100

Water rubber 0.5g 0.7g 40%wood 19.95g 21.6g 8.27%seeds 10g 12.1g 21%

Kerosene rubber 0.4g 0.7g 75%wood 16.9g 17.9g 5.92%seeds 10g 10.6g 6%

Table 2. Compares the affinity of certain plant materials to different solvents

Movement of water through the stem

– The 10mL of 0.01% of eosin dye solution

went up through the stem in a straight line

manner through the xylem tissues.

Fig. 6.1 Cross-section of pechay stalk

Fig. 6.2 External view of stained pechay

Comparison of cuticular and stomatal

transpiration by four leaves method –

Leaf A being the control, leaf B smeared

with grease and vaselin on the upper surface,

leaf C smeared with grease on the lower

surface, and leaf D smeared with grease on

the both sides, a week of observations were

made. Leaf A was the most desiccated one

and curled on both sides. Leaf B and C were

both half-dry with leaf B curling outward

and leaf C curling inward. Leaf D remained

fresh, waxy, and moist, with no occurrence

of desiccation and curling.

Guttation – The appearance of xylem

saps happened at the tip of the leaf blades

after the plant was covered with a wide

mouth jar.

DISCUSSION

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. The opposite is

also true. Another factor affecting the rate of

diffusion is the size of the particles. The

smaller the size of the particle, the faster it

would be diffused.

For the Bixa orellana seeds, the

carotenoids diffused more quickly when it

was submerged in the heated vegetable oil

solution. Generally, increases in temperature

speeds up the movement of molecules and

faster movements of molecules means faster

rates of diffusion. This is why the heated

distilled water and the heated vegetablle oil

had the fastest rates of diffusion.

As for the competition between oil and

water, faster rates of diffusion happened in

oil because the pigments of the Bixa

orellana seeds are insoluble in water.

Osmosis – When the Trandescantia

spathacea was immeresed 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 a turgid cell, the water

will continually move into the cell until the

concetration of the impermeable solutes

equals to that of the hypotonic solution.

When the water was replaced with a

5% salt solution, the water bacame

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

concetration of the impermeable solutes

equals to that of the hypertonic solution.

Factors affecting the integrity of cell

membrane – In this experiment, the apple

peelings exhibited diffecrent intensities of

the color of their pigments. The darker ones

indicate more damage and stress to the cell

membrane while the lighter ones indicate

less stress and damage.

The ones with the damaged cell

membranes exhibited darker colors because

when the cell membrane gets destroyed, the

pigments from inside the cell leak out.

Temperature – 3 test tubes containing

immersed apple peelings in water were

subjected to different temperatures. In this

experiment, we have arrived with a

conclusion that lower temperatures inflict

more damage to the cell membrane and that

normal and high temperatures did not do

much damage.

pH effects – Wet mounts of 0.1M NaOH

solution and 0.1M HCl solution were

observed for 30 minutes. The results show

that the more acidic a solution is, the more

damage it can inflict to the cell membrane.

The more basic it is, the less damage.

Organic solvent – Chloroform inflicted

more damage in the membrane than the

acetone. In this one, the pH again got

involved. Chloroform is more acidic than

acetone.

Imbibition – Woods and seeds imbibed

better in water while rubber imbibed better

in kerosene. Water is composed of 2

molecules of hydrogen and a molecule of

oxygen, hence H20. Kerosene is an oil

distillate commonly used as a fuel or

solvent. It is a thin, clear liquid consisting of

a mixture of hydrocarbons and is primarily

derived from refined petroleum.

Imbibition occurs with or without the

help of living cells. According to Ferdinand

Sachs’ imbibition theory, water moves in

tubes in the walls of plants without the

cooperation of living cells and not within the

cell cavities.

There are no living cells in the veneer.

Veneer comes from the peeling of tree

trunks and these are secondary xylem, which

are dead cells.

Living cells are involved in the

imbibition of the seed. This is because the

entry of water takes place in the testa, which

may be actively dividing.

The swelling effect of imbibition in

seeds is important in seed germination

because imbibition in water can burst the

seed coat, which would signal the start of

germination.

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 spread the 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.

Comparison of the cuticular and

stomatal transpiration – Too much

transpiration can cause the dessication of the

leaves. Cuticle helps in preventing this. The

control set-up, leaf A, where nothing was

applied, desiccated while leaf D which was

smeared with grease on both sides remained

fresh and waxy without any occurrence of

desiccation.

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 release of water from

plants the hydathodes, which is induced by

root pressure, mainly because of the high

moisture content of the soil while

transpiration is the process of water vapor

loss from the internal atmosphere of the

plant.

Another difference is that in

transpiration, water vapor is released while

in guttation, xylem saps are released.

LITERATURE CITED

ANTHOCYANIN. (2009, September 23). In

Wikipedia, The Free Encyclopedia.

Retrieved 14:25, September 23,

2009, from http://en.wikipedia.org/

w/index.php?

title=Anthocyanin&oldid=31571458

1

CAROTENOID. (2009, September 18). In



2009, from

http://en.wikipedia.org/w/index.php?

title=Carotenoid&oldid=31476936

GUTTATION. (2009, May 15). In


Retrieved 16:21, May 15, 2009, from


title=Guttation&oldid=290118315

IMBIBITION. (2009, June 8). In Wikipedia,

The Free Encyclopedia. Retrieved

02:19, June 8, 2009, from


title=Imbibition&oldid=295094135

LYCOPENE. (2009, September 21). In



2009, from


title=Lycopene&oldid=315268969

STERN, K. R. 1997. Introductory Plant

Biology

TONICITY. (2009, September 23). In



2009, from


title=Tonicity&oldid=315700881

TRANSPIRATION. (2009, September 16).

In Wikipedia, The Free

Encyclopedia. Retrieved 10:18,

September 16, 2009, from http://

en.wikipedia.org/w/index.php?

title=Transpiration&oldid=31431491

3

^^ movement of water through the stem

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