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Core Experiments :
Unit - 3
In this unit experiments to study animal and plant cells will be performed. For this
purpose you will make temporary slides of various plant and animal material to study
them. According to curriculum, in the following pages instruction are given for the following
excercises.
1.
To make a temporary mount of root apex to study the steps of mitosis.
2.
To make a slide of flower bud to study the steps of meiosis.
3.
To study cyclosis in Hydrilla and Paramaecium.
4.
To make a slide of onion peel to study structure of plant cell.
5.
To make a slide of cheek epithelial cell of frog / man to study structure of animal cell.
6.
To study the presence of cell wall components cellulose, lignin, suberin, mucilage in
plant cell.
Since to study the above phenomena, temporary slides have to be made, therefore the
procedure of making temporary slides will be explained first.
Temporary Slide Mounting
Temporary slides are made to study
microscopic organisms and the cells and
tissues of plants and animal since these slides
cannot be preserved for long, they are called
temporary slides.
(3)
Stain the given tissue by the given method
and place it on the centre of slide.
(4)
To find the centre of the slide place the slide
on a paper, and draw its outline. Now join
the opposite corners of the slide by drawing
a line. Where the two lines intersect, it is
the centre of the slide. Place the slide back
on the figure and since the glass slide is
transparent the centre point will be easily
visible.
(5)
Now put a drop of glycerine on the tissue
placed on the centre of the slide and with
the help of a needle slowly lower the
cover slip on the material. Avoid entry
of air bubbles (fig 3.2).
(6)
Blot the excess glycerine with cloth or
blotting paper .
To make any temporary slide the following
materials are required :
Microslide
Cover slip
Needles with handles
Forceps & dropper
Watch glass
glycerine
Necessary stains such as eocin, methylene
blue saffranine, haemotoxylin acetocarmine etc.
Instructions for making a temporary slide:
(1)
Dip the given slide in water and then clean
it with a cotton cloth followed by a silk
cloth.
(2)
Clean the cover-slip lightly with a silk cloth
only
Fig. 3.1 To find centre of slide
35
36
(7)
PRACTICAL BIOLOGY - XI
Stuck a lebel on one slide of the slide
bearing name of tissue and your name.
4.
Press the cover slip lightly and observe the
slide under the microscope.
nuclear
membrane
Aster
nucleolus
Chromatid
chromatin
thread
centriole
cellmembrane
Fig. 3.2 Placing cover slip
(a) Interphase
centromere
(b) Prophase
(c) Metaphase
centriole
nucleolus
Cell Division
chromatin
thread
nuclear
membrane
6. Mitosis
Aim of Exeperiment : To study various
steps of mitotic cell division in the root tip.
Materials required : Root tips of onion,
FAA solution, IN HCl, spirit lamp,
acetocarmine stain, needle, slide, cover slip,
watch glass, foceps, droppers etc.
To perform this experiment, first take 23 onion and place them on a glass of water
without dipping in the water. Place the glass
in slightly dark place and study it daily when
the young roots are about 2-3 mm long, then
in the morning at around 8.00 a.m. cut 2-3 mm
of the root apex and transfer in a small bottle
in which FAA solution is present.
FAA solution is made from formaline,
acetic acid and 90% alcohol are mixed in equal
proportions FAA solution is ready for use.
Procedure :
1.
Take out 2-3 piece of root tips kept in FAA,
place them in watch glass and wash them
with water.
2.
Now place the root tips on a slide and add
few drops of IN HCl on them. Heat the
slide on a low flame with a needle, it can
also be teased.
3.
Now put a few drops of acetocarmine stain
on the material and heat the slide. After
sometime cover the material with a cover
slip.
(d) Anaphase
(e) Telophase
Fig. 3.3 Different stages of Mitotic Cell Division
Observation : Observe the slide first under
low power and then under high power, Find the
stages of prophase, metaphase, anaphase and
telophase and compare them with the given figures.
Note : Observe permanent slides of the
various phases also.
(7) Meiosis
For observing meiotic cell division the above
N
membrane
Pair of
homologous
chromosomes
Prophase
A
Leptotene
B
Zygotene
Tetrad
C
Pachytene
Crossing
over
D
Diplotene
E
Dikinesis
Spindle
fibres
Centromere
F
Metaphase-I
G
Anaphase-I
H
Telophase-I
I
Interphase-I
4
daughter
cells
J
Prophase-11
K
Metaphase-11
L
Anaphase-1
M
Telophase-1
Fig. 3.4 Different stages of Meiotic Cell Division
CORE EXPERIMENTS
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Chloroplast
procedure is adopted but as this kind of division
takes place in the reproductive organ cells
therefore instead of root tip cells, cells from young
buds are preserved in FAA
When experiment has to be performed the
anthers from the preserved buds are taken and
the same procedure is adopted as in mitosis. In
this addition of IN HCl is not necessary.
Observe the permanent slides of meiosis
also under the guidance of the teacher.
(8) Study of cell movement :
To study cells and cellular movements the
following two activities can be performed:
(a)
Movement of peotoplasm and chloroplasts
in the cells of Hydrilla plant.
(b)
Movement of Paramaecium (a unicellular
protist) and study of its ciliary movement.
Study of cells and movement of protoplasm
and chloroplast in Hydrilla :
Hydrilla is an easily available aquatic plant.
It is commonly kept in fish aquarium also. Take a
Hydrilla leaf and take out its peel. Keep the peel
in few drops of water
in the centre of the
slide. Cover it with
cover slip and abserve
it
under
the
m i c r o s c o p e
immediately.
You will observe
rectangular cells of
Hydrilla and a large
vacuole in the cells
with the cytoplasm and
green
coloured
chloroplast moving
around the vacuole in
a circular manner
(cyclosis) as shown in
Fig. 3.6
Fig. 3.6 Movement of protoplasm and
chloroplant in Plant Cell
(B) Movement in Paramaecium :
Bring water from a pond and place a few
drops of it on a slide and observe under the
microscope. You will observe many microscopic
organism moving in the water. Among them there
may be a slipper shaped paramaecuim visible.
Paramaecuim is a unicellular organism which
moves due to the constant beating of cilia present
on its body surface.
If paramaecuim is not visible then observe
many other cellular plants and animals moving
around. You can study cellular movement by
observing them also.
Upper edge
Upper
contractile
vacuole
Micro
Nucleus
Macro
nucleus
Mouth
Notch
Protoplasm
Post end
Cell Mouth
lower contractile
vacuole
Cilia
Fig. 3.5 Branch of a
Hydrilla Plant
Fig. 3.7 Paramaecium
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(9)
PRACTICAL BIOLOGY - XI
Slide of Human / Frog cheek epithelial
cells :
Materials required : Slide, cover slip,
tooth pick, dropper, water, watch glass, methylene
blue, needle, glycerine etc.
Cell group
Nucleus
Fig. 3.8 Method of removal of onion peel
cyto
plasm
Fig. 3.10 Epithelial cell of cheek
Procedure :
peel and place it on the centre of the slide
(4) Put a drop of iodine solution on the peel
and then wash it gently with a few drops of water.
(5) Now put a drop of glycerine on the peel
and carefully place a cover slip on it so that air
bubble don’t enter.
(6) Observe the slide under the microscope.
Wash the mouth throughtly and with the help
of tooth pick scrape the inner side of your cheek.
Take the scraping on a slide and put a few drops
of water on it. Add two to three drops of methylene
blue on it. Cover it with a cover slip after a few
minutes.
Observation :
Observe the slide under the microscope.
Try to locate the nucleus in the cell.
The same experiment can be done using
a chloroformed frog to get scraping from the
cheek.
(i)
In the simple microscope rectangular cells
are clearly visible. Nucleus is also visible.
(ii)
Each cell has a nucleus and large vacuoles
are visible.
(iii)
Each cell is surrounded by a cell wall.
(11) Tests for various components in cell
wall of plant cells :
Nucleus
(10) Study of plant cell in an onion peel
Materials required : An onion, Blade or
knife, watch glass, water, forceps dropper, iodine
solution, slide and cover slip.
Rectangular
cells
Procedure :
(1) Cut long pieces of onion with the help
of knife or blade
(2) Take a fleshy scale leaf from one of
the pieces and fold it on the concave surface.
On doing so a then peel will come out. Keep
the peel in water in a watch glass.
(3) Now cut a 0.5 cm square piece of the
Fig. 3.9 Cells in Onion peel
As you know the plant cells are surrounded
by a rigid cell wall there are many chemical
components present in the cell wall - the chief
among them being cellulose, lignin, suberin and
mucilage. Carry out the follow tests to study them.
(A) Test for Cellulose :
CORE EXPERIMENTS
Materials required : Microscope, glass
slide, cover slip, iodine solution, 75% conc.
H2SO4, water paper or cotton fibres.
Procedure :
Place a few fibres of cotton and study them
under the microscope. Now add a few drops on
the fibres and put a few drops of iodine solution.
The fibres turn brown in colour. Now add drop
of 75% H2SO4 and a drop of water.
Observation :
The fibres turn yellow in colour, which
shows the presence of cellulose (The presence
of cellulose can be observed in a section of
the stem of tomato plant. For that place a thin
T.S. of stem in iodine solution. After a minute
blot out the iodine solution with a filter paper
and add 1 drop of 60-70% H2SO4. Place a
coverslip and observe under the microscope
immediately. The cell wall of the cells swell
and become blue in colour.
(B) Test for Lignin :
This can be tested by any of the following
two methods :
(A) Materials required : Microscope,
stem of tomato / sunflower, match stick, 1%
alcoholic phloroglucin, conc. HCl etc.
Procedure :
Cut thin section of stem of tomato /
sunflower or take small segments of match
stick on a slide. Put a drop 1% alcoholic
phloroglucin on it. Cover with cover slip and
add drops of conc. HCl along the sides of the
coverslip with the help of a dropper.
Observation :
Red purple colour in the cell walls indicate
the presence of lignin in them.
(b) Material required : Stem of tomato /
sunflower, match stick, 1% potassium
permanganate solution in water, dil 2% HCl
and sodium bicarbonate.
Procedure :
Cut thin sections of the stem or match stick
and place them in 1% KMnO4 solution in a watch
glass for 15-20 mins. After that remove the
KMnO4 solution and wash the sections in dil 2%
39
HCl. Now trnasfer the sections in another watch
glass and wash them several times with water. After
that add a few drops of Sodium bicarbonate on
them.
Observation :
Deep red colour in the sections indicate the
presence of lignin in their cell walls.
(C) Tests for Suberin :
Material required : Cork, Sudan IV
(aloholic) 50% alcohol, slide, cover slip, water,
glycerine etc.
Prodecure :
Cut thin sections of cork and place them in
alcohol Sudan IV solution for 20-25 minutes in a
watch glass. When the sections are well stained,
then wash the sections in 50% alcohol, two to
three times to remove the excess stain. Finally
wash them in water and place them on a slide in a
drop of glycerine. Place a cover slip on it and
observe under the microscope.
Observation :
Red coloured suberin is observed in the cell
walls of the cork cells.
(D) Tests for Mucilage :
Materials required : Testa of linseed 10%
CuSO4 solution, 10% NaOH, water, slide, cover
slip, glycerine etc.
Procedure :
Take thin sections of linseed and place them
for about 20 minutes in 10% CuSO4 solution.
After 20 minutes wash them with water and
place a section on a slide. Wash the slide once
again with two drops of 10% CuSO4 and put
glycerine and cover with a cover slip. Observe
under the microscope.
Observation :
Cells having mucilage give a shiny
appearance.