Experiments 11

 Experiment No. 1                                  Date: __________

Aim: To study different parts of a compound microscope.

Principle: Two convex lenses are arranged in a monocular setting to get a highly magnified, virtual and inverted image.

Material Required: A compound microscope, soft cloth, lens cleaning fluid, lens cleaning paper, a permanent slide

Procedure:

1.     Place the microscope on the working table.

2.     Clean it with a soft cloth.

3.     Clean the lenses with liquid and wipe them.

4.     Identify the various parts of the microscope.

5.     Take a permanent slide and place it on the stage.

6.     Adjust the slide; and rotate the coarse and fine adjustment knobs to focus the view.

Observation:

(A) Mechanical Parts of a Compound Microscope

1. Foot or base:

It is a U-shaped structure and supports the entire weight of the compound microscope.

2. Pillar:

It is a vertical projection. This stands by resting on the base and supports the stage.

3. Arm:

The entire microscope is handled by a strong and curved structure known as the arm.

4. Stage:

The flat and rectangular plate that is connected to the arm’s lower end is called the stage. The specimen is placed on the stage for studying and examining the various features. The centre of the stage has a hole through which light can pass.

5. Inclination joint:

It is a joint, wherein the arm is fastened to the compound microscope’s pillar. The microscope can be tilted using the inclination joint.

6. Clips:

The upper part of the stage is connected to two clips. The slide can be held in its position with the help of the clips.

7. Diaphragm:

The diaphragm is fastened below the stage. It controls and adjusts the intensity of light that passes into the microscope.

8. Nose piece:

The nose piece is circular and a rotating metal part that is connected to the body tube’s lower end. The nose piece has three holes wherein the objective lenses are embedded.

9. Body tube:

The upper part of the arm of the microscope comprises a hollow and tubular structure known as the body tube. The body tube can be shifted down and up using the adjustment knobs.

10. Fine adjustment knob:

It is the smaller knob, which is used for sharp and fine focusing of the object. For accurate and sharp focusing, this knob can be used.

11. Coarse adjustment knob:

It is a large knob that is used for moving the body tube down and up for bringing the object to be examined under exact focus.

(B) Optical Parts of Compound Microscope

1. Eyepiece lens or Ocular

At the top of the body tube, a lens is planted which is known as the eyepiece. On the rim of the eyepiece, there are certain markings such as 10X which indicates the magnification power. The object’s magnified image can be observed with the help of an eyepiece.

2. Mirror

A mirror is found attached with the pillar or the lower end of the arm. It consists of a concave mirror on one side and a plain mirror on the other side. It can be used for reflection of light rays into the microscope.

3. Objective lenses:

At the bottom of the body tube, there are two objective lenses, which are connected to the revolving nose piece. The three objective lenses are as follows:

• Low power objective – 10X
• High power objective – 45X
• Oil immersion objective – 100X

Magnification:

Here the magnification power of eye piece is 10X. If we use objective lens of 10X magnification power, the total magnification power of the microscope will be 10 x 10X = 100X.

Similarly, if we use the objective lens of 45X magnification power, the total magnification power of the microscope will be 10 x 45X = 450X.

 

 

             Experiment No. 2                                  Date: __________

 

Aim: To study and describe two locally available flowering plants one each from the families Solanaceae and Liliaceae.

 Principle: Field identification of plants is based mainly on morphological features especially of floral characters. Flowers are dissected to identify and to count the floral parts.

 Materials Required: Plant specimens of Yellow-fruit nightshade and onion, blade, forceps, needle, watch glass, dissection microscope, slide

 Procedure:

1.      Observe the roots, stem, leaves and flowers of the plant.

2.      Take a flower and observe its calyx, corolla, androecium and gynoecium.

3.      Detach each part carefully using forceps and needle and keep in a watch glass.

4.      Cut TS of the ovary and observe it under dissection microscope.

5.      Observe the stamen under dissection microscope.

Observation:

1.      Family: Solanaceae

Plant: Yellow-fruit nightshade (Solanam virginianum)

Systematic Position

            Kingdom: Plantae

Division: Phanerogamae

Sub-division: Angiospermae

Class:  Dicotyledonae

Family:  Solanaceae

Genus: Solanam

Species:  virginianum

Habitat: Grows in wild, adopted to dry conditions

Habit: Herbaceous, annual

Root: Tap root

Stem: Small, erect and branched. Creeping branches

Leaf: Lyrate, prickly, reticulate veins

Inflorescence: Raceme  

Flower:

Calyx:

Corolla:

Androecium:

Gynoecium:

Fruit:

Floral formula:

 

 

 

 

2.      Family: Liliaceae  

Plant: Onion (Alium cepa)

Systematic Position

            Kingdom: Plantae

Division: Phanerogamae

Sub-division: Angiospermae

Class:  Monocotyledonae

Family:  Liliaceae  

Genus: Alium

Species:  cepa

Habitat: Cultivated in farms

Habit: Herbaceous, annual

Root: Fibrous root

Stem: Stem is underground, enclosed in scaly leaves, forms a bulb.

Leaf: Simple, linear, parallel veins

Inflorescence:

Flower:

Perianth:

Androecium:

Gynoecium:

Fruit:

Floral formula:

 

Experiment no. 3                               Date: __________

Aim: To study the distribution of stomata on the upper and the lower surfaces of a dicot leaf.

Principle: Stomata are tiny openings that are located in the young shoots of plants and epidermis of the leaves. If slides of the peels of the upper epidermis and the lower epidermis are prepared, the number of stomata can be counted.

Materials Required: A fresh leaf of Hibiscus, compound microscope, 2 slides, 2 cover slips, blade, forceps, safranin stain, glycerine, 2 watch glasses, water, needle

Procedure:

1.      Take a fresh leaf of Hibiscus leaf and wash it.

2.      Slit the leaf in an oblique manner so that the epidermis can be peeled off. Take the upper epidermis in a watch glass with water.

3.      Cut a small piece of the peel using blade and forceps.

4.      Put it in safranin stain in another watch glass.

5.      Pick up the peel and wash it in water in watch glass.

6.      Place the peel onto a clean slide and put two drops of glycerine.

7.      Using a needle, place the cover slip over it carefully.

8.      Examine it under a microscope; and count the number of stomata seen.

9.      Similarly, repeat the steps to prepare a slide of the lower epidermis of the leaf; and examine it under the microscope; and count the number of stomata seen.

Observation:

Several stomata are seen on both the surfaces of the epidermis of the leaf.

No. of stomata on the upper surface	No. of stomata on the lower surface

Result:

The number of stomata is much more in the lower epidermis while a few are found in the upper epidermis of the leaf of a dicot plant.

 

             Experiment No. 4                                Date: __________

Aim:  To study the effect of salivary amylase on digestion of starch

Principle:  Saliva contains ptyalin or amylase enzyme which partially digests starch present in food into maltose sugar.  

Materials required: 3 test tubes, test tube holder, starch solution, iodine solution, Fehling’s solutions A and B, spirit lamp

Procedure:  

1.      Collect some saliva in a clean test tube.

2.      Perform the following tests:  

Sr no.	Test	Observation	Inference
Test 1.	Take about 2 ml of starch solution in a test tube and add one or two drops of iodine solution in it.	Solution turns blue.	Starch is present.
	In the above mixture, add 2 ml of saliva. Stir it. Heat the mixture of the test tube.	Blue colour becomes fade.	Amylase converts starch into maltose sugar.
Test 2.	Take about 2 ml of starch solution in a test tube and add some amount Fehling’s solution A and B (in equal amount) Heat the mixture of the test tube.	No precipitate is found	Starch does not react with Fehling’s solutions
	In the above mixture, add 2 ml of saliva into it. Stir it. Heat the mixture of the test tube.	Red yellow precipitate is formed.	Sugar is present (maltose). (Amylase converted starch into maltose.)

 

Results: In presence of amylase enzyme, starch is converted into maltose sugar.

 

             Experiment No. 5                                 Date: __________

Aim:  To test the presence of sugar and albumin in urine sample.

 Principle:  Presence of the substances can be ascertained using some confirmatory tests.

Materials required: 4 test tubes, test tube holder, Fehling’s solutions A and B, Conc nitric acid, 30% Sulphosalicyclic acid, measuring cylinder, dropper, spirit lamp

 Procedure:  

GLUCOSE

Sr no.	Test	Observation	Inference
1.	Fehling’s Test: Take about 2 ml of the sample solution in a test tube; and add some amount of Fehling’s solution A and B (in equal amount) Heat the mixture of the test tube.	Red coloured precipitate is formed.   Or   Red coloured precipitate is not formed.	Glucose is present   Or       Glucose is absent.
2.	Benedict’s  Test: Take about 2 ml of the sample solution and add some amount of Benedict’s solution. Stir it. Heat the mixture of the test tube.	Red coloured precipitate is formed.   Or   Red coloured precipitate is not formed.	Glucose is present   Or       Glucose is absent.

Result: The given urine sample has glucose / has no glucose in it.

 

 

ALBUMIN

 

Sr no.	Test	Observation	Inference
1.	Heller’s Test: Take 5 ml of conc nitric acid in a test tube. Using a dropper, add some drops of urine sample in the test tube along the inner side of the test tube while keeping it in inclining position.	Urine drops cover the nitric acid. At the intersection of two layers, a white ring is formed.   Or No white ring is formed.	Albumin is present.           Or Albumin is absent.
2.	Sulphosalicylic Acid Test: Take 2 ml of the urine sample in a test tube. Using a dropper, add some drops of sulphosalicylic acid in it. Gently heat the mixture.	Cloudy turbid solution or whitish solution is formed.   Or Cloudy turbid solution or whitish solution is not formed.	Albumin is present.       Or     Albumin is absent.

Result: The given urine solution has albumin / has no albumin in it.

 

Experiment No. 6                                  Date: __________

Aim: To show experimentally that carbon dioxide is released during respiration.

Materials Required: A conical flask, a beaker, a cork with a hole, a glass tube bent at right angles at two places, a small test tube, KOH solution, thread, coloured water.

Procedure:

1. Take the conical flask and place some germinating gram or pea seeds in it.

2. Insert the shorter end of the glass tube through the hole in the cork and fix it on the conical flask.

3. Before fixing the cork, hang a test tube containing KOH solution inside the conical flask with the help of a thread.

4. Take coloured water in the beaker and keep the longer end of the glass tube dipped inside it.

5. Make the conical flask airtight by applying Vaseline on its rim.

6. Note the initial level of water in the tube.

7. Observe and note the rise in the water level after an hour, without disturbing the apparatus.

Observation:

Water level rises up in the bent tube.

Result:

The rise in the level of water indicates that CO₂ is produced by germinating seeds during respiration. Actually, the germinating seeds respire and produce CO₂, which is absorbed by KOH solution. This creates a vacuum in the conical flask. The air present in the bent glass tube moves into the conical flask. This pulls the water in the bent tube further up.

 

             Experiment No. 7                                  Date: __________

Aim: To separate the pigments of a leaf using paper chromatography

 

Materials Required: Two fresh green leaves, mortar and pestle, acetone, petroleum ether, a long strip of filter paper, a broad test tube, glass rod.

Procedure:

1.      Take two fresh leaves, wash them and then cut into small pieces.

2.      Put them in a mortar and crush them using a pestle. Mix acetone to crush into a fine paste.

3.      Using a glass rod, take a drop of this paste and put it on one end of a paper strip, about three centimetres away from the end.

4.      Allow the green drop spot to dry. Then put one more drop over the spot. Allow to dry. In this way, form a thick green spot.

5.      Take a broad test tube and fill some petroleum ether into it, approximately up to two centimetres.

6.      Dip the end of the filter paper strip with green spot in the test tube in such a way that the paper end dips in the solvent but the spot remains outside it.

7.      Keep the paper strip vertically erect.

8.      Allow the set up to remain undisturbed for some 25 or 30 minutes.

Observation:

The particles of the green spot move upwards along with the solvent petroleum ether; and get separated into regions of several colours like blue-green, yellow-green, yellow and orange.

Result: The pigments of a leaf can be separated into several colours like blue-green, yellow-green, yellow and orange.

 

 

             Experiment No. 9                                 Date: __________

Aim: To study mitosis in onion root tip and in animal cells (grasshopper) from permanent slides.  

 

Materials Required: Permanent slides of onion root tips and animal cells of grasshopper.

Observation:

Many cells with chromosomes in their nucleus are seen. They are all in different stages of mitosis.

The various stages of mitosis are:

1. Prophase

• The process of mitosis is initiated at this stage wherein coiling and thickening of the chromosomes occurs
• Shrinking and hence the disappearance of the nucleolus and nuclear membrane takes place
• The stage reaches its final state when a cluster of fibres organizes to form the spindle fibres.

2. Metaphase

• Chromosomes turn thick in this phase. The two chromatids from each of the chromosomes appear distinct
• Each of the chromosomes is fastened to the spindle fibres located on its controller
• Chromosomes align at the centreline of the cell

3. Anaphase

• Each of the chromatid pair detaches from the centromere and approaches the other end of the cell through the spindle fibre
• At this stage, compressing of the cell membrane at the centre takes place

4. Telophase

• Chromatids have reached the other end of the cell
• The disappearance of the spindles
• Chromatin fibres are formed as a result of uncoiling of daughter chromosomes
• The appearance of two daughter nuclei at the opposing ends due to the reformation of the nucleolus and nuclear membrane
• At this phase, splitting of the cell or cytokinesis may also occur.

 

             Experiment No. 9                                 Date: __________

Aim: To study imbibitions in seeds or raisins.   

Materials Required: A few dry and a few swollen seeds/raisins

Observation:

1.       When seeds / raisins are soaked in water for some time, they adsorb or imbibe water.

2.       The seeds / raisins are called imbibant and the water that is imbibed is called adsorbent.

3.       Imbibition is the process of adsorption of water by substances without forming a solution.

4.       Imbibition is the temporary increase in the volume of the cell.

5.       Imbibition is a passive transport of materials.

6.       The process of imbibition occurs mainly due to the presence of hydrophilic colloids.