STB 121 PRAT - Unesco

UNESC
CO-NIGER
RIA TECHN
NICAL & VOCATION
V
NAL
EDUCA
ATION RE
EVITALISA
ATION PRO
OJECT-PHA
ASE
II
NATIIONAL
L DIPLOMA IN
I
SCIENC
S
CE LABORA
ATORY
Y TECH
HNOLO
OGY
C L BIO
CELL
OLOG
GY
C
COURS
SE COD
DE: STB
B 121
YEAR
R I- SE MESTER
M
RI
P
PRACTI
ICAL
Versioon 1: Deceember 20008
PRACTICAL WEEK 1… ……………………………………………………………………………3 PRACTICAL WEEK 2………………………………………………………………………………4 PRACTICAL WEEK 3………………………………………………………………………………5 PRACTICAL WEEK 4………………………………………………………………………………6 PRACTICAL WEEK 5………………………………………………………………………………8 PRACTICAL WEEK 6………………………………………………………………………………9 PRACTICAL WEEK 7………………………………………………………………………………10 PRACTICAL WEEK 8………………………………………………………………………………13 PRACTICAL WEEK 9………………………………………………………………………………16 PRACTICAL WEEK 10……………………………………………………………………………18 PRACTICAL WEEK 11……………………………………………………………………………21 PRACTICAL WEEK 12……………………………………………………………………………23 PRACTICAL WEEK 13……………………………………………………………………………26 PRACTICAL WEEK 14……………………………………………………………………………27 PRACTICAL WEEK 15……………………………………………………………………………28 PRACTICAL 1
Title: The Living Things
Aim: To observe and draw samples of plant and animal cells from various sources under the
microscope.
Theory: The cell is the unit structural and function of life. All cells come from previously existing
cells. The observation of plants and animals cells under the microscope reveals the
arrangement and features of the cells since they cannot be seen with the naked eyes.
Materials: Cheek cells, blood cells, Allium cepa (onions) bulb, cotton wool, microscope slide, cover
slips, Methylated spirit, iodine solution, waterbiro cover.
Procedure: (A). Use a clean biro cover to scrape the inside'of your cheek. Spread this out on a slide
and mount in a little saliva. Use a cover slip and examine under low (xlO) and
high (x40) power of a microscope. Draw a few cells and label features seen.
i
(B). Sterilize the skin just below one of your fingsr nails by rubbing it with cotton wool
dipped in methylated
!
spirit. With a blood lancet, prick the skin you have Esterilized and squeeze out a small
drop of blood. Transfer a little of the blood to a clean microscope slide. Allow to dry for
five (5) minutes. Examine under low and high power of the microscope. Draw a few cells
seen.
(C). Take a scaly leaf of an Allium cepa (Onion) bulb and bend it backwards until it snaps.
Then remove an epidermal layer from it (this is only one (1) celled thick). Place it on a
slide and add a drop of water. Observe under low and high power of the microscope.
Take note of your observations. Add a drop of iodine solutions and observe again. Draw
large labeled diagrams of a few cells seen.
PRACTICAL 2
Title:
Aim:
Singled celled organisms.
To examine single celled animals and plants under the
Microscope.
Theory:
A cell can exist as a single, free and independent organism.
Singled celled (unicellular) organisms consist of a single cell
i
that can carry out all the life processes in naturej
Materials: microscope slide, cover slip, permanent slide of plasmodium parasite, pond water.
Procedure: using a dropper, take a drop water from the pond water
provided and. place on a clean microscope slide. Cover with Cover slip and
observe
under
the
microscope.
Look
out
for
unicellular animals like
amoeba, paramecium etc and unicellular plants like Chlamydomonas, chlorella, spirogyra etc.
draw large labeled diagrams of at least five (5) of these organisms. View the permanent slide of
plasmodium parasite under the microscope. Make large labeled diagram of your observation.
Questions:
1. Mention the habitat of each single celled organism you have drawn.
2. Mention
at
least
two
unicellular plants and animals.
(2)
characteristics
of
plants
and
animal
of
both
PRACTICAL 3
Title:
Singled celled organism of uncertain taxonomic position.
Aim: To examine single celled organisms of uncertain taxonomic position (e.g. Euglena,
Ch.lamydQ.mon.gis) under the microscope.
Theory: Euglena is a single cell organism with uncertain taxonomic position. It shows a mixture of
plant and animal features which makes it to be included in both zoological and botanical
classification.
]
Material: Microscope, permanent slides of Euglena, and Chlamydomonas
\
Procedure: Take the permanent slide of Euglena provided and view under the microscope using low and high
power (xlO, x40). Observe
the feature and draw a large labeled diagram of'the organism.
i ,'
Question:
i
1. State the function of three (3) features you have labeled.
2. Mention
three
(3)
plant
Chlamydomonas.
3. Name the organ of locomotion for the animals.
characteristics
I
of
Euglena
and
PRACTICAL 4
Title: The effect of hypertonic, hypotonic and isotonic solutions on the cell wall.
Aim:
To describe experimentally the effects of hypertonic, hypotonic
and isotonic solution on the cell plasma.
'
i
Theory: When a living plant cell is placed in a salt or sugar solution that is more concentrated or
stronger than the cell sap (hypertonic solution) water is lost from the cell to the stronger
solution.
The cytoplasm shrinks and plasmalemma gets detached from the cell wall. A cell placed in a less
concentrated solution absorbs water and becomes turgid.
Materials: Distilled water, Nacl solution pond water containing spirogyra cells, microscope slide, and
microscope.
Procedure: From the Nacl provided, prepare molar solutions in the
following concentrations; 0.2m.0.4m, 0.6m,0;8m and 0.10m. put a drop of the greenish part of
your pond water on each of the five slides provided and examine under the microscope. Once
you have observed spirogyra cell add each of the molar solutions one at a time on the five (5)
slides respectively.
Leave for a few minutes and examine under the microscope. Note which of the concentrations is
hypertonic, hypotonic and isotonic to the spirogyra cells. Make diagrams of the cell from each of the five
(5( concentrations you observed under the microscope. Copy and complete the table below
Nacl concentrations
(1) 0.2m
Changes observed.
Questions:
1.
Which of the concentration of Nacl
solution is hypertonic, isotonic and
hypotonic to the cell plasma?
2.
what
are
the
effects
of
hypertonic
and hypotonic solutions on the cell
plasma
PRACTICAL 5
Title:
Mitotic cell division.
Aim:
To observe and identify the various stages of mitotic cell division from
projected permanent slide..
Material: Slide projector and permanent slides of different stages of Mitotic cell division.
Theory: Mitosis is a cell division following the duplication of the
Chromosomes. Each daughter cell produced has exactly the same number of
chromosomes as in the parents' cell. Mitosis produces two diploid cells. It occurs in
the somatic cells, during growth, development and in asexual reproduction.
Procedure: Carefully observe each of the projected slides and identify and draw each stage of
the cell division observed.
Questions:
1. Define cell division
,
i
2. What type of cell division have you observed?
3. Where does this type of cell division occur specifically in plants
and animals?
4. State two significances of this type of cell division.
8
PRACTICAL 6
Title:
Meiotic cell division.
Aim:
To observe and identify the various stages of meiotic cell division from
projected slides.
Materials:
Slide projector and permanent slides of various stages of meiotic cell division
Procedure:
Observe carefully each of the projected slides and identify each of the stages
of the cell division observed and draw a well labeled diagram of each stage.
Questions:
1. Define meiosis.
2.
what type of cell have you observed?
3.
where does this types of cell division take place? Mention the specific
places in both plant and animals where this type of cell division occurs.
4.
state in a tabular form five differences between the two types of cell
divisions observed.
9
PRACTICAL 7
Title:
Extraction and separation of photosynthetic pigments.
Aim:
To extract, separate and identify photosynthetic pigments by
adsorption chromatography using a column of icing sugar.
Materials:
5g of dried nettle powder, 90% acetone, measuring cylinder, filter paper,
funnel, retard stand, 2 stoppered flasks, 100ml beaker, water bath, petroleum ether,
distilled water and anhydrous sodium Sulphate.
Materials
For
chromatography:
Petroleum
ether,
glass
,column,
rubber
cork, small bore rubber tubing, adjustable clip, glass rod, glass wool, icing sugar,
teat pipette, beaker and stand, filter paper.
j
Theory: In order to live, plants need various food substances. 'Majority of
plants manufacture their own food substances from carbon
;
dioxide and water from their surroundings.
Plants synthesize their own food by a process known ias
photosynthesis. Some plants part contains a'green pi
jment
called chlorophyll in chloroplast cells which assist in absorbing
light energy for photosynthetic process.
(a) Procedure for extraction of pigments.
:
- Weigh out about 5g of dried nettle powder
- Extract with 35ml of 90% acetone for 15 minutes in a stoppered
container
- Shake the bottle gently during the extraction
- Filter into a measuring cylinder
- Note the volume of the filtrate.
- Put into a separating funnel a volume of petroleum ether twice ihe
10
volume of the extract.
- Add the extract.
-
Stopper the flask and shake well
-
The petroleum ether will take up most of the dissolved pigments from the acetone.
-
Pour equal volume of distilled water (equal in volume to the original extract) slowly
down one side of the funnel.
-
Slowly gently. Run out and discard the lower layer (water + acetone)
-
Repeat with three more portions of water to remove all the acetone
-
Leave the extract to dry over a table spoon of anhydrous sodium sulphate in a
stoppered flask for at least 15 minutes.
-
It is essential that the extract be kept dry other wise future experiment involving its
use will be spoilt.
-
Pour the extract into a 100ml beaker and evaporate it over a water bath, to few
millimeters.
Note: The water bath should be heated and the busen flame extinguished before the
petroleum ether is evaporated because it is highly flammable.
b.
procedure for the preparation of the column.
-
Place cotton wool at the bottom of a glass column fitted with a cork through which
passes a short length of small bore glass tubing.
-
To the glass tubing fit a short length of rubber tubing.
-
To make the joint between the glass and rubber tubing secure, it may be wired.
-
Attach an adjustable clip to the rubber tubing
-
Pour a little petroleum ether into the column and adjust the clip on the tubing so the
liquid drips through slowly.
-
Mix some icing sugar in a small beaker with some petroleum ether and pour it into the
column.
11
-
The mixture should not be too thick
-
As the sugar settles in the column, leaving a clear layer of petroleum ether above it,
pipette off some of the liquid using a teat pipette and pour in more sugar suspension.
-
Repeat this process gently tapping the column to help the sugar settle until it is evenly
filled to within a few centimeters to top; close the tap until you are ready to add your
pigment extracts.
c.
Procedure for the chromatography of the extract.
-
When the pigment has been concentrated sufficiently
-
Remove the excess petroleum ether from above the column, using a pipette.
-
Gently add the extract to the top of the icing sugar column.
-
Open the clip at the bottom of the column and allow the liquid to run through slowly.
-
When the extract has moved into the column, gently add more petroleum ether to the
top of the column.
-
As the extract moves down through the column, it separated into distinct bands of
pigments.
-
Observe the progress of the bands down the column and add more petroleum ether as
needed to prevent the column from running dry.
-
Close the clip when the pigments have separated sufficiently.
Note: Do not allow the column to run dry. Always keep some petroleum ether above the
column.
-
Make well annotated diagram of the column.
Questions.
1.
Define photosynthesis.
2.
List the conditions necessary for photosynthesis to take place.
3.
Mention the types of chlorophyll pigments present in plants and state the functions of
each type.
12
PRACTICAL 8
Title:
Extraction and separation of photosynthetic pigment
Aim:
To extract and separate photosynthetic pigments (chlorophyll) by paper
chromatography, using ascending technique.
a.
b.
c.
Apparatus for extraction of the pigments.
•
5g of dried nettle powder
•
90% acetone
•
Measuring cylinder
•
Filter paper
•
Stand
•
2 stoppered flasks
•
100ml beaker
•
Water bath
•
Petroleum ether
•
Distilled water
•
And anhydrous sodium sulphate
Apparatus for the chromatography
•
Chromatography tank (or large sweet jar)
•
What man No 1 grade chromatography paper and capillary pipette
Developing solvent
•
Acetone
•
Petroleum ether (5ml : 45ml)
•
White petroleum jelly
•
Paper clips
13
a.
Procedure for extraction of the pigments:
•
Weigh out about 5g of dried nettle powder
•
Extract with 35ml of 90% acetone for 15 minutes in a stoppered container
•
Shake the bottle gently during the extraction
•
Filter the extract into a measuring cylinder
•
Note the volume of the filtrate
•
Put into a separating funnel a volume of petroleum ether twice the volume of
the extract.
b.
Preparation of the paper
•
Draw a thick pencil mark across the paper to ensure that the sample spots are
not immersed in the solvent and also allow maximum development
•
Make series of pencil marks along this starting line, indicating where the
samples for analysis are to be placed this marks should be 3cm apart and
should begin not less than 4cm from the edges of the papers
c.
Application of the sample to the paper.
•
Using capillary pipette draw some quantities of the sample.
•
Put a drop of the sample on marled starting line
•
Allow the solution to flow onto the paper
•
Care should be taken to ensure that the diameter of the resultant spot does not
exceed 7-8mm.
•
Allow the spots to dry
•
Avoid overloading the chromatogram by putting too much of the sample on
the line as this results in poor separations.
d.
Development of the chromatogram
•
After allowing the sample spots to dry.
•
Roll the paper or the chromatogram into a cylinder shape
14
•
Using linked paper clips, hold the edges so as to prevent the edges from
touching
•
Add suitable amount of solvent (acetone : petroleum ether) to the tank or jar.
•
Place in the chromatography tank with the end carrying the sample spots
dipping into the solvent
•
Replace the lid sealing it with white petroleum jelly and leave the
chromatogram to develop.
•
Detect and identify the separated compounds after careful observation.
Questions:
1.
Make a large well labeled diagram of the chromatography showing the positions of
the separated pigments on the paper.
2.
Determine the RF value using the equations.
RF = Distance moved by the compound
Distance moved by the solvent
Or RF = Distance traveled by the compound
Distance traveled by the solvent
3.
Then identify the separate compounds.
15
PRACTICAL 9
Title:
Separation and identification of photosynthetic pigments using thin layer
chromatography.
Aim:
To demonstrate the separation of the photosynthetic pigments by thin layer
chromatography.
Apparatus:
Grease free microscope slide
Cellulose MN300 powder or silica gel
Distilled water
Petroleum ether
Acetone
2 beakers
Foil
Petri-dishes or watch glass
Extract of photosynthetic pigments
Fine capillary pipette.
a.
Procedure for the preparation of the thin layer chromatogram
•
Prepare a thick cream from about 1g of the cellulose powder and a few drops
of distilled water
•
Carefully pour some of the prepared cream onto a glass slide so that it forms a
pool across the end of the grease free.
•
Heat the slide in an oven at 1000C for 10 minutes to obtain a better separation.
•
Spread the layer of adsorbent over the slide by holding a second slide loosely
between the fore finger and thumb, dipping the end of the slide into the pool of
adsorbent on the first slide.
•
Draw it very tightly along the length of the slide.
16
•
Make sure the spreading slide hinges very slightly between the thumb and the
fore finger as it is drawn along
•
Allow the prepared slide to dry for 15-20 minutes at room temperature.
•
Touch the thin layer with the pipette containing the sample of the extract,
holding the pipette at an angle of 450C or less.
•
Avoid an over flow of the sample from the pipette.
•
Allow it to dry
•
Place the slide with the sample spot lower most in a beaker containing a few
millimeters of a mixture of petroleum ether and acetone. (75 parts to 25
parts)>
•
Draw a line across the plate a few centimeters from the upper end before
placing the chromatogram in the tank.
•
Cover the top of the beaker with foil paper or a Petri dish or lid to prevent the
escape of solvent vapour.
•
Allow to develop for about 30 minutes
•
Observe the separation of the pigment as it takes place remove the plate and
dry in a stream of cod air.
Questions:
1.
Compare the speed of separation and sensitivity with that of ascending technique of
paper chromatography.
2.
List the advantages of thin layer chromatography over the rest other forms of paper
chromatography.
3.
Differentiate between thin layer chromatography and paper chromatography
4.
why is it necessary to draw a line a few centimeters from the upper end before putting
the chromatogram into the tank..
17
PRACTICAL 10
Title:
Respiration in plants.
Aim:
To demonstrate that carbon dioxide is produce by green plants during
respiration.
Apparatus:
•
Green pea seedling (or barley grains)
•
15% potassium hydroxide solution
•
Water
•
2 glass beakers
•
2 retorts stand
•
2 Clamps and stands
•
Sticky tapes.
Theory:
All living things (plants and animals) take part in gasous exchange, in which
gases are exchanges between the living organisms and its environment. This
referred to as external respiration. In the cell of living organisms, complex
food substances are as well broken down to simper substances with release of
energy. This is known as internal respiration. Gaseous exchange occurs at the
respiratory surface such as gills in fish, lungs in plants. During respiration
oxygen is taken in and carbon dioxide is given off.
Procedure:
•
Place some green pea seedlings in each of the retorts.
•
Fill one of the beakers with water and the other potassium hydroxide solution
•
Label them A and B
•
Invert them, one over beaker A containing water and the other over beaker B
containing potassium hydroxide solution.
18
•
Arrange them is such a way that the open ends are below the level of the liquids in
both beakers.
•
Leave the set up to stand for some days.
•
Cover the retorts with dark/black clothes to prevent the seedlings from
photosynthesizing
•
Observe the set up after a few days and record you observations.
QUESTIONS
1.
Define respiration
2.
What is the use of the potassium hydroxide solution in beaker B
3.
Account for the rise in the level of the liquid in B and explain what happen in the
set up in beaker A.
4.
Differentiate between internal or tissue or cellular respiration and external respiration.
Alternative experiment to demonstrate that carbon dioxide is produce by green plants during
respiration
Materials: 5 capillary tubes, 2 stoppered conical flasks, 2 beakers sodium hydroxide solution
and lime water.
Procedure:
•
Put potassium hydroxide solution into one of the conical
•
Insert one end of a capillary tube through a hole in the cork
•
Put some quantity of lime water into both beaker
•
Connect one of the beakers to the conical flask containing potassium hydroxide
solution by inserting one end of the capillary tube into the
•
Conical flask and the other end to the beaker through an opening or hole in the
stoppers or corks.
•
Into another conical flask, put germination pea seed or seedling, and connect it to the
first beaker containing lime water and insert another capillary tube to the first
19
through the other end into the second beaker with a capillary tube. Insert another
capillary into the beaker and connect the open end to an aspirator and vacuum pump.
A small animal such as rat may be used.
•
Draw in air through apparatus using the vacuum pump or aspirator.
•
The potassium hydroxide solution in the first beaker removes any carbon dioxide in
the air entering the apparatus and this is checked by the limewater in the first beaker.
•
Leave the set up for some days and observe
•
Record your observation
•
Account for the change in the lime water in the last beaker.
•
What does this experiment show?
20
PRACTICAL 11
Title:
Transpiration Rate
Aim:
To demonstrate that water vapor is given off by a leafy shoots of
plants.
Materials:
Potted plants, thick polythene bag, 2 bell jars, 2 glass plate white
petroleum jelly and a string.
Theory:
Transpiration is the loss of water in form of vapour from the aerial
parts of the plant. The main site for transpiration is the surface of the
leaves. It can also occur from any point surface which is permeable to
water and is in contact with the surrounding air. There are three forms
of transpiration namely cuticular, lenticular and stomata transpiration
respectively.
Procedure:
•
Wet the potted plants with enough water
•
Place the potted plants in a thick plythene bag such that it completely covers the pot
and the base of the plant.
•
Using a string, tie firmly the mouth of the polythene bag around the base of the
shoot of the plant.
•
Air tight the joint between the neck of the bag and the base of the shoot by sealing it
with white petroleum jelly.
•
Place it on a glass and cover it with a bell jar.
•
Seal the joint between the bell jar and the glass plate with white petroleum jelly.
•
Place the second bell jar on the second glass plate and seal in the same way as the
first.
•
Place both set ups in a warm sunny place for 2-3 hours.
•
Observe the set ups and note any change within the bell jars
21
•
Record your observations.
Note: A potted plant with all the leaves removed may be places on the second glass plate
and covered with a bell jar as a control
Questions:
1.
List the advantages of transpiration to a plant
2.
Explain the following (a) stomata transpiration (b) lenticular transpiration and (c)
cuticular transpiration.
22
PRACTICAL 12
Title:
Transpiration
Aim:
To measure the rate of transpiration of a leafy shoot using a
photometer
Materials:
Photometer, freshly cut leafy shoot, a beaker filed with water, a stop
watch, a sharp knife or razor blade.
Theory:
A photometer is a piece of apparatus designed to measure the rate of transpiration of a leafy
shoot. This is done by measuring that ate of water uptake by the shoot. As water is lost from
the shoot by transpiration, an equivalent quantity of water is taken up by the shoot to replace
that which is lost. Thus by calculating the transpiring surface area of the leaf and measuring
the amount of water taken up by the shoot, the rate of transpiration per unit area of a leaf
surface can possibly be calculated. There are various types of photometer, all of which
function in a similar manner but vary in their accuracy. None is 100% accurate, each has its
own standard error which can be calculated.
Procedure:
•
Cut a leafy shoot from a branch of a plant. The diameter of the stem should be
slightly greater than the diameter of the hole of the cork into which it is going to be
placed.
•
Put the cut end into a beaker containing water. Care should be taken not to wet the
leaves of the shoot.
•
Fill the reservoir of the photometer
•
Open the clip and allow water to flow into the various arms of the potometer
•
Care should be taken not to trap air bubbles.
•
Insert the stem of the shoot into the cork and fix it into the arm of the cork of the
photometer.
23
•
Ensure that water flows from the reservoir to the end of the capillary tube.
•
Air tight all the joints of the photometer by sealing with white petroleum jelly
•
Place the apparatus in a warm well aerated position and leave for about 15 minutes
to adjust to the conditions of the surroundings.
•
Before the reading is taken, open the clip and allow water to move the meniscus
back to the end of the capillary tube
•
Using the stop watch start timing
•
The take the reading of the movement of the meniscus at the end of water in the
capillary tube
•
Return the meniscus again to the open end of the capillary tube.
•
Time the movement of the meniscus again and take the reading
•
Take several readings
•
Now move the apparatus to a position in which the atmospheric conditions contrast
as much as possible with the original conditions
•
Allow it to get adjusted it its new surrounding
•
Return the meniscus again to the open end of the capillary tube
•
Start timing the movement of the meniscus and after some minutes take the reading
•
Repeat this several times and compare the rate of transpiration under different
conditions.
•
Remove all the leaves
•
Cut at random from the leaves square of size 1cm.
•
Weigh these squares
•
Takes the average weight to be the weight of one square centimeter of leaf surface
•
Weigh the square together with all the leaves
•
Divide the total weight by the one taken to be the weight of one square centimeter
of leaf surface. This gives the total area of leaf surface.
24
Calculation
Weight of ncm2 of leaf = w grams
Therefore average weight of 1cm2 = w/n grams
Let the total weight of the leaves = T grams
Then the total area of transpiring leaf surface = T/W x n/1 = Acm2
Let the distance moved by air bubble along capillary tube = Lmm.
The tine taken to move this distance = t seconds.
The diameter of capillary tube = dmm
Volume of water taken up by shoot = πd2L/4 = Vmm3
In t seconds this volume was transpired by Acm2 of leaf surface
In 1 seconds, the volume of water transpired = Vmm3/cm2 of leaf surface
tA
Therefore volume of water transpired = V/1000tA ml/cm2s
Questions:
1.
Calculate the volume of water transpires under various atmospheric conditions during
the experiment, using the reading obtained.
2.
List 5 conditions that can affect the rate of transpiration.
25
PRACTICAL 13
Title:
Phototropism
Aim:
To demonstrate phototropism on plants
Materials:
3 pots containing 3 day old cowpea seedlings, a box with a slit and a
cupboard.
Theory:
Phototropism is the response of plant parts to the stimulus of light. The
shoots of plants grow towards the direction of light. They are therefore
said to be positively phototropic while the root grow away from the
direction of sunlight and are said to be negatively phototropic.
Procedure:
•
Label the three pots A, B and C each containing 3 day old cowpea seedlings.
•
Place pot A in dark box or cupboard
•
Place pot B in direct sunlight and
•
Pot C in a box with a slit on one side or by a side of a window
•
Leave the set up for a few days
•
Observe each of the set up and record your observation
Questions:
1.
Define trpism
2.
List 5 types of tropism you know
3.
Account for the curvature in the shoot.
26
PRACTICAL 14
Title:
Geotropism
Aim:
To demonstrate geotropism in plants root.
Materials:
Beans seeds, 2 beakers, filter papers and a flat board
Theory:
Plant roots grow towards gravity and are said to be positively geotropic
while the shots grow away from gravity and are said to be negatively
geotropic
Procedure:
•
Sow some beans seeds between moist filter papers in each of the beakers
•
Carefully remove the young seedling from one of beakers as soon as the radicals and
plumules emerge
•
Place them on a flat board in the dark with both the radicles and plumules lying
horizontally.
•
Leave the seedlings in the second beaker to remain in a vertical position.
•
Leave the setup for some days
•
Make sure the filter papers are adequately wet
•
Observe the seedlings from both set ups
•
Record your observation.
Questions:
1.
Account for the bent in the seedlings lying horizontally on the board
2.
Why is there no bent observed in the control seedling in the second beaker
3.
Define geotropism
4.
Draw and label a seedling from each of the set up.
27
PRACTICAL 15
Title:
Hydrotropism
Aim:
To demonstrate hydrotropism in plants
Materials:
A porous pot containing eater places in a glass trough, saw dust, bean
seeds.
Theory:
Plants roots do not only grow downwards towards the force of gravity,
they also grow in the direction of source of water in the soil. They are
therefore said to be positively hydrotropic. While the shoots grow
away from water source and are said to be negatively hydrotropic.
Procedure:
•
Fill the glass trough with saw dust
•
Place the porous pot in the glass trough
•
Fill the porous pot with water
•
Plant some bean seeds 5cm away from the pot, and water daily until the plumuele
appears. Stop watering
•
Leave the set up for few days
•
Carefully up root the seedling after some days
•
Observe the roots and shoots
•
Set up a control in a similar way without a porous pot
•
Uproot the seedlings from the control set up and observe the root and shoot
•
Record observation
•
Draw out your conclusion
Questions:
1.
What is hydrotropism
2.
Discuss your observation in the experiment just carried out
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3.
List other forms of response in plants apart from tropism and explain two.
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