Biology Presentation
Group member
1.Babjey
2.Jamyang Dorji
3.Doe Kumar Kharka
4.Ugyen Dorji
1.Aim: To check the conduction of water through
xylem
Materials required: Beaker
Stand
Knife
Water
Leafy shoot/ twig
Hypothesis: Vascular bundles in the stem,
root, leaf stalks and leaf veins are all
continuous and form an unbroken system of
tubes. Collectively, they form the transport
system throughout. Water and salt travel
upwards mainly through xylem and food
substances travel up and down in the plants
through phloem.
Procedures:
1.Take two leafy shoots (of delicate and fleshy stem)
that has been cut under water.)
2.Keep their lower ends dipping in the water
3.Remove about 3cm long, outer ring ( phloem) of
the stem ( as in the Beaker A)
4.Keep the central part intact
5.Remove an equal length of the central part (
xylem) keeping the outer part intact ( as in the
Beaker B)
6.The shoots are then fix to the stands and are
allowed to remain for sometimes with their lower
ends still immersed in the water.
Observation table
Beaker
Observations
A
The leaves of the twig remain turgid and
stand out almost normal
B
The leaves and twig get wilted and droop
down
Result/ Inference: The turgidity and normal
standing of the twig in the beaker A indicates that
water is conducted through xylem
Precautions:
The leafy shoots should be cut under the water
to prevent any air bubbles getting in.
While removing the outer ring, phloem, the
xylem should be kept intact and vice- versa.
Difficulty
It was challenging to cut the stem in the water
It was difficult to remove the inner xylem parts.
Beaker A
Beaker B
2.Aim: To prove that temperature is necessary for
germination.
Materials required:
two beakers
cotton wool
water
seeds
dropper
Hypothesis: Very low as well as very high
temperature is unsuitable for germination. A very
low temperature inhibits the growth of embryo and
a very high temperature destroys its delicate tissue.
The temperature should be optimum (i.e. 25-350C)
Procedure:
1. place the wet cotton wool in beaker
2. then place some seeds(maize) on it and marked
it ‘A’
3. place the wet cotton wool in second beaker
4. place some seeds on it and marked it ‘B’
5. place the beaker ‘A’ in normal/ordinary room
temperature
6. place beaker ‘B’ in refrigerator whose
temperature is quite low
7. then observe it
Observation table
Beaker
Observation (after 2 days)
A
Germination occurred
B
No germination occurred
Result: we conclude that temperature is
necessary for germination
Precautions: we added equal amount of water
on the cotton.
3.Aim: To prove that water is necessary for
germination
Materials required:
two beakers
cotton wool
water
seeds
dropper
Hypothesis: Water for seeds is obtained from its
environment. The seed absorbs water all over surface
through micropyle. The seeds swell and testa ruptures
to allow radical elongate and form root system
Procedure
1. place the wet cotton wool in first beakers
2. then place some seeds( maize) on it and
marked it as ‘A’
3. Place dry cotton wool in second beaker.
4. place some seeds( maize) on it and
marked it as ‘B’
5. keep both the beaker in an ordinary room
temperature.
6. observe it
Observation table
beaker
Observation
A
Germination occur
B
No germination
Result: we concluded that water is necessary for
germination.
Precaution:
The temperature should be same for both the
beakers
4.Aim: To prove that Oxygen is necessary for
germination
Materials Required:
Two conical flask
cotton wool
water
seeds
Dropper
Pyrogallic acid
Hypothesis: For the rapid cell division and cell
growth energy is required. The energy required is
available only by reparation i.e. usage of oxygen for
respiration. Hence the need of oxygen
Procedure:
1. Place the wet cotton wool in conical flask
2. Then place some seeds on it and marked it as ‘A’
3. Lower the small test-tube in the conical flask A
which it contains alkaline Pyrogallic acid, which
absorbs oxygen. (cork it tightly)
4. To second conical flask, place wet cotton wool.
Then place seeds on cotton wool and marked ‘B’
5. In the conical flask B lower the test-tube in the
same manner except the test-tube should
contain plain water.
6. Keep both the conical flask in an ordinary room
temperature.
Observation table
conical flask
Observation (after two days)
A
Germination has occurred.
B
Germination has occurred.
Result: in both the case germination take place. The result fail.
Precautions:
The should not be a single drop of alkaline pyrogallic acid on the
seeds and cotton wool while lower with test-tube.
There should be equal amount of water spread in the cotton wool
Failure and Difficulties:
The experiment was a failure because pyrogallic acid doesn’t absorb
Oxygen. We tried the experiment for twice but the result was same
i.e. germination took place in the both beakers. We have kept
pyrogallic acid in open air to check whether it is functional or not.
The result was still the same.
5.Aim: To see the uptake of water by plant
Materials required:
Ganong’s photometer
leafy shoot
safranin
Beaker
Hypothesis: It is the device use to see the rate of
transpiration(rate at which water is absorb by plant
and send out through leaf)
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Procedure:
1. Bring the suitable plant and cut with the sharp
knife
2. Fix apparatus as shown in the diagram.
3. Air bubble is introduced in the horizontal
graduated capillary tube which is dipping into
beaker containing colour water.
4. Observe the process
(In order to bring back the air bubble to its original
position, release some water from reservoir into the
capillary tube by opening the stop-cock).
Observations: liquid in the capillary tube move very
fast. In average it took minimum 47s to complete
the capillary tube.
Results: We have observed that colour water was
moving in the capillary tube due to the transpiration
pull.
Precautions:
Entire apparatus should be filled with water so
that no air spaces are present.
Difficulties:
We face difficult to introduce air bubble
6.Aim: To prove that carbon dioxide is necessary for
photosynthesis
Materials required:
Destarched potted plant
Conical flask
KOH
Stand
Methyl alcohol or spirit
Test-tube
Petri dish
Iodine solution
Spirit lamp
Hypothesis: Photosynthesis is the process by which living
plants cells, containing chlorophyll, produce food substances
(glucose and starch), from CO2 and water by using the light
energy.
Procedures:
1. We have to destarched the plant for 48 hours
before the experiment
2. Take the destarched leaves
3. Insert one of the destarched leaves inside the
conical flask through split cork which it contains
KOH( KOH absorbs CO2 )
4. Leave the plant in the sunlight
5. After a few hours (3-4), test the leaf and any other
leaf of the plant for starch.
Starch test
Dip the that leaf in the boiling water for a minute to kill
the cells
Boil the leaf in the methylated spirit over a water bath till
it becomes pale-white due to the removal of the
chlorophyll. Now the leaf becomes hard and brittle.
Place the leaf again in the hot water to soften it.
Spread the leaf in a petri dish and pour the iodine
solution on it
The leaf which was exposed to the atmosphere should
turn blue-black and the one inside the conical flask
containing KOH should not turn blue-black.
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Result: we concluded that leave that is inside the
flask do not turn to dark blue indicating there is no
presence of starch.
Precaution: we use the soft, fleshy dicot leaf not the
rough and hard leaves of dicot.
Difficulty: it was very difficult to insert the leaf
through the cork into the flask. Not only that our
plant was lost and we have to de starch plant for
three time. And we do also realize that we must use
soft and fleshy dicot leaf
7.Aim: To check the movement of water molecules
through cells
Materials required:
Potatoes
Safrenin
pins
Knife
Water
Petri dish
NaCl solution
Hypothesis: The movement water molecules across
the semi-permeable membrane from dilute solution
to concentrated solution.
Procedures:
1. Cut the potatoes into cube shape of equal sizes.
2. Make holes at the centre of equal height, length
and breadth.
3. To the first potato cube add concentrated NaCl
solution and place it in the petri-dish containing
plain water.
4. To second potato cube add plain water and
place it in the petri-dish containing conc. NaCl
solution.
5. To third potato cube add plain water and place
it in the petri-dish containing plain water.
6. Observe.
Observation table
Petri-dish
Observations
I
The level of concentrated solution increased
and coloured water too diffused in.
II
The level of plain water inside the potato
cube decreased
III
Remain same.
Results: The diffusion of water from dilute to
concentrated solution through cells.
Precautions:
Size of the potato cube should be equal
throughout.
We struggle to cut same size of potato cube
II
I
III
We had tried to do the experiment on the osmotic
pressure. We had tried to improvise the piston in
thistle funnel but we failed to came up with idea.
So we gave up that experiment and instead we
had done on potato cubes
We had use only one type of poto meter since the
apparatus is not there
The end
Ganong’s potometer
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