BIOLOGY PRACTICAL CLASS XII CBSE

EXPERIMENT- 1

AIM: TO STUDY THE POLLEN GERMINATION ON SLIDE

REQUIREMENTS: fresh seasonal flowers, cover slip, slide, microscope, sucrose, boric acid, magnesium sulphate, potassium nitrate etc.

PROCEDURE:

·        A nutrient solution was prepared by dissolving 10 g boric acid, 30 mg magnesium sulphate, and 20 mg potassium nitrate in 100 ml of water.

·        A few drops of this solution were taken on a clean glass slide and a few pollen grains from the stamen of a mature flower on it.

·        The slide was observed in the microscope after 5 minutes and then it was observed regularly for about half an hour.

OBSERVATION

In nutrient medium, the pollen grain germinates. The tube cell enlarges and comes out of the pollen grain through one of the germ pores to form a pollen tube. The tube enlarges and comes out of the pollen grain through one of the germ pores to form a pollen tube. The tube nucleus descends to the tip of the pollen tube. The generative cell also passes into it. It soon divides into two male gametes. Each male gamete is lenticular to spherical in outline.

PRECAUTIONS:

·        Flowers should be freshly plucked.

·        Use clean slide to observe the pollen grains.

                                                                                                                                    

  EXPERIMENT 2.1

AIM: TO STUDY THE TEXTURE AND MOISTURE CONTENT OF DIFFERENT SOILS.

REQUIREMENTS: digger, polythene bags, hand lens, meshes of different pore sizes, measuring cylinders, water etc.

 STUDY OF SOIL TEXTURE:

The soil samples were examined by a hand lens and it was felt between fingers in dry as well as in moist state. Dried soil samples are placed on meshes of different pore sizes amount of particles that pas through them were recorded.

           About 50 gm of soil was taken from a sample in 250 ml measuring cylinder. 200 ml of water was taken and was shaken. The soil particles were allowed to settle down. Thicknesses of the layers formed by different types of particles were recorded in the measuring cylinder, and their relative percentage was calculated. Similarly relative percentage of different types f soil particle present in different soil samples was recorded.

 OBSERVATION

Heavy particles settle down first and lighter ones afterwards. Humus floats on the water surface. These layers were observed carefully and observations were recorded in tabular form.

S.NO.	Soil samples	Colour	Texture	Relative percentage			Soil class
				Sand	Silt	Clay
1.	Soil from a crop field	Dark brown	Clayey	9%	11%	80%	Fertile
2.	Garden soil	Dark Brown	Clayey	22%	40%	38%	Fertile
3.	Roadside soil	Pale Brown	Sandy	75%	12%	13%	Infertile
4.	Soil from a dried pond	Dark Brown	Clayey	12%	18%	70%	Fertile
5.	River-bank soil	Pale Brown	Sandy	2%	28%	70%	Fertile

STUDY OF MOISTURE CONTENT

Small amount of soil was taken from a sample in a dry crucible and was weighed. Weight was recorded. The crucible was heated on a burner to dry the soil and then was cooled. The crucible was weighed again to record the weight of dry soil. The process is repeated for each soil sample.

 OBSERVATION

The initial and final weights were recorded for each sample and the difference between initial and final weights was recorded. Higher difference shows higher moisture content.

S.No.	Soil samples	Initial weight           (x) gm	Final weight    (y) gm	Moisture content (y-x) gm
1.	Soil from a crop field	128.14g	152.25g	24.11
2.	Garden soil	125.23g	145.43g	20.2
3.	Roadside soil	129.02g	137.56g	8.54g
4.	Soil from a dried pond	125.42g	148.29g	22.87g
5.	River bank soil	123.59g	155.67g	32.08g

                                                                                                                                    

PRECAUTIONS

·        Soil samples should be separately packed and brought to the laboratory.

·        The thickness of layers formed by different particles in the cylinder should be carefully measured and their relative percentage should be accurately calculated.

                                                          EXPERIMENT 2.2

AIM: TO STUDY pH OF DIFFERENT TYPES OF SOIL.

REQUIREMENTS: Soil samples (from two different sites), test tubes, funnel, filter paper, pH papers of different range, distilled water, beaker.

PROCEDURE:

One tablespoon soil was dissolved from each soil sample in 100 ml of distilled water in separate beakers. The solutions were stirred well and kept for half an hour to settle down the suspended particles. Each solution was filtered off in different test tubes. A small piece of broad range pH paper was dipped in each of the soil solution. The colour of the pH paper was matched with the colour scale given on the pH paper booklet.

OBSERVATION:

The pH different soil samples were recorded in the observation table.

S.No.	Soil samples	pH
1.	Sample – A	7
2.	Sample – B	4
3.	Sample - C	10

 

PRECAUTIONS:

·        Wash the glassware thoroughly and get it oven dried before the experiment.

·        Use standard reagents.

                                                         

EXPERIMENT 3

   REQUIREMENTS: garden soil, roadside soil, measuring cylinders, funnels,

   Filter papers, balance, oven etc.

PROCEDURE:

Two funnels were taken and were line with filter paper. They were labeled as A and B. They were placed on measuring cylinders. 100 gm oven dried sample each of garden soil and roadside soil were taken. Garden soil was placed in funnel A and roadside soil in funnel B. 100 ml of water was poured in each funnel. The volume of filtered out water in the measuring cylinder was recorded when the dripping of water stops from the funnel.

OBSERVATIONS AND RESULTS:

The observations and results were recorded in the observation table.

S.No.	Soil types	Weight of soil    (X)	Volume of water poured   (Y)	Volume of water collected in measuring cylinder(Z)	Volume of water retained  the soil (Y-Z)	Water holding capacity of the soil in % (Y-Z)/X*100
1.	Garden soil	50 g	50 ml	26 ml	24 ml	48%
2.	Roadside soil	50g	50 ml	40 ml	10 ml	20 %

CONCLUSION:

Garden soil has a higher water holding capacity than the roadside soil, because the roadside soil has larger quantities of sand and silt.

PRECAUTIONS:

·        Weighing of soil samples should be done accurately.

·        Pour water slowly and gently on the soil in the funnel.

·        Record the volume of collected water in the measuring cylinders carefully.

EXPERIMENT 4.1

AIM: COLLECT WATER FROM TWO DIFFERENT WATER BODIES AROUND YOU AND STUDY THEM FOR pH.

REQUIREMENTS: water samples from two different sites, test tubes, pH papers.

PROCEDURE

Different water samples were taken in different test tubes. A small piece of broad range pH paper was dipped in each of the water samples. The colour of the pH paper was matched with the colour scale given on the pH paper booklet.

OBSERVATIONS

pH of different water samples were recorded in the observation table.

S.No.	Water samples	pH
1	Pond water	6.5
2	Tap water	7

PRECAUTIONS

·        Take clean and dried test tubes.

·        Dry the pH papers before comparing the colour with the colour scale.

·        Match the colour carefully and determine pH accurately.

Experiment 4.2

Aim: TO STUDY THE CLARITY AND PRESENCE OF PARTICULATE MATTER (SUSPENDED POLLUTANTS) IN DIFFERENT SAMPLES OF WATER.

 Requirements: cardboard box, electric bulb or torch, different samples of water.

Procedure:

·        We took a cardboard box and prepared a tyndal set up from it to test turbidity. Tyndal setup can be prepared by making a pencil size hole in the cardboard box and fixing a light source on the other side of the box.

·        We placed the beaker containing the samples of water one by one.

·        We made the laboratory dark and light the bulb or the torch.

·        We observed the sample of water through the hole and compared the turbidity of different water samples.

Observation: Suspended particulate pollutants such as clay particles, organic matter, bacteria, unicellular organisms etc. are observed.

Precautions:

·        The hole in the cardboard box should not be large.

·        The light source should be of sufficient intensity.

Experiment 4.3

Aim: To study different water samples for the presence of living organisms.

Requirements: water samples, microscope, glass slides, dropper, methylene blue, spirit lamp etc.

Procedure:

·        We took a clean slide and put a few drop of water separately from different water samples and spread it to make a thin film of water on the slide and allowed it to dry.

·        We passed the lower side of the slide through the flame of spirit lamp 2- 3 times to fix the living organisms present in the water.

·        Then we added a few drops of methylene blue on the slide and left it for 2 minutes.

·        We washed the slide and observed the slide under the microscope.

Observations: A number of types of microorganisms such as bacteria, protozoa, diatoms, some algae, cyanobacteria are observed.

Conclusion: Presence of large number of microorganisms indicates the presence of organic pollutants in water.

EXPERIMENT  5

OBJECTIVE: TO STUDY POPULATION DENSITY AND PERCENTAGE FREQUENCY OF DIFFERENT PLANT SPECIES OF A GIVEN AREA.

REQUIREMENTS:  Metre scale, strong or cord, nails ,paper, pencil etc.

PROCEDURE:

(a)   Determination  of the  size of Quadrat:  A  L shaped structure was prepared  in the field of 1mX 1m by using 3 nails and  a string was tied with it .Then 10cm was measured on one side of the arm of L and then the other.  A 10X10sq cm area was prepared using another piece of sting .The number of species was counted  occurring in this  area. Then  the area was  increased  to 20*20sq.cm and similarly recorded additional species occurring in this area .It was  repeated the same  till 1*1sq.m area  was covered.

 OBSERVATION

S.NO	AREA	TOTAL  NO. OF SPECIES
1	10X10 sq.cm	1
2	20X20sq.cm.	1
3	30X30sq.cm.	1
4	40X40 sq.cm	1
5	50X50 sq.cm	1
6	60X60 sq.cm	1
7	70X70 sq.cm	1
8	80X80 sq.cm	1
9	90X90 sq.cm	1
10	100*100 sq.m	1
S.NO	AREA	TOTAL  NO. OF SPECIES
1	10X10 sq.cm	0
2	20X20sq.cm.	1
3	30X30sq.cm.	2
4	40X40 sq.cm	3
5	50X50 sq.cm	9
6	60X60 sq.cm	10
7	70X70 sq.cm	14
8	80X80 sq.cm	16
9	90X90 sq.cm	16
10	100*100 sq.m	16

Y-AXIS: No. of species .

X-AXIS: Size of the Quadrats.

(b)   Determination of population density and percentage frequency

A quadrat of 50cmX50cm size was taken, it was laid  randomly at  3 places. The number of plants of three species was counted in all the three quadrat separately and recorded.

Population   Density=Total no. individuals in all the quadrats studied

                                              Total no. of quadrats studied   

Percentage   Frequency  =  Total no. of quadrats in which species occurred            100

                                                           Total no of quadrats studied

OBSERVATION   AND RESULTS

 Different plant species  ,their population density and percentage frequency occurring in a given area .

s. no	Plant species	No. of individuals per Quadrat   1         2           3	Total no of individuals in all the quadrats studied (N)	Total no. of quadrats in which species occurred  (A)	Total no. of quadrats studied (B)	Population density N/B	Frequency percentage A/B      100
1.	X	3            6            4	13	3	3	13/3	3/3X100
2.	Y	6            0            2	8	2	3	8/3	2/3X100
3.	Z	7            3            5	15	3	3	15/3	3/3X100
4	M	72         24         18	114	3	3	114/3	3/3X100

PRECAUTIONS

1. The measurement of quadrats should be accurate.                         

2. The string or cord used should not be very thick.

3. One individual of a species should be counted only once in the Quadrat.

                                                              EXPERIMENT NO.  6

AIM- TO MAKE A TEMPORARY MOUNT OF THE ONION ROOT TIP FOR STUDY OF VARIOUS STAGES OF MITOSIS.

 Materials required- Onion root tips, needles, brush, burner, microscope, aceto-carmine stain, hydrochloric acid blade, F.A.A fixative, ethyl alcohol, Carnoy’s fluid, blotting paper, etc.

Procedure:

·        A root tip is taken on a clean slide on & a drop of aceto-carmine stain is added on it.

·         Aceto-carmine stain is touched with hot rusted needle making the stain specific for nuclear materials. Then it is warmed. On warming, the stain evaporates.

·        The root tip is squashed with the help of a needle or a forceps.

·        Now the slide taken in the folds of a blotting paper & pressure is applied with hands. The slide is observed under microscope.

Observations:

Resting cells: It is a non- dividing cell. Nucleus is small & occupy a small space in a cell. Genetic material is in the form of chromatin granules.

 Interphase: Nucleus is large, distinct & occupies most of the space of cell. Nucleous is well pronounced. Genetic material is in the form of chromatin threads & their ends are not visible. Duplication of genetic material takes place during this phase.

 Prophase: The chromatin network begins to coil & appears as long thread-like structures called chromosome. Each chromosome consists of two chromatids that are joined at a pointe called centromere. The nuclear membrane also starts disappearing in late prophase.

 Metaphase: It starts with the complete disappearance of nuclear membrane. The chromatids become shorter & thicker due to dehydration & condensation & they acquire a specific shape & size. Fine fibrils appear in the cell cytoplasm & are organized to form spindle fibres.

 Anaphase: The centromere of each chromosome is divided into two so that each chromatid gets its own centromere. At pole, each chromatid now behaves as an independent chromosome; so the chromosome number of the daughter nuclei is maintained the same. The spindle fibres get attached to the centromeres of their side.

Telophase: At each pole, the chromatids become uncoiled, thin & invisible. Chromosomes are again re-organized into network of chromatin threads. The two daughter nuclei formed are qualitative & quantitatively similar to the parent nuclei. The nucleolus & nuclear membrane reappear again. Thus two daughter nuclei are formed at the two pole of a cell.

Precautions-

·        Root tips should be taken early in the morning hours.

·        Slide should be warmed gently much above the burner.

EXPERIMENT NO. 7.1

AIM- TO STUDY THE EFFECTS OF TEMPERATURE ON THE ENZYMATIC ACTIVITY OF SALIVARY AMYLASE ON  STARCH.

 Materials required- Test tubes, beakers, pipettes, funnels, thermometer, cotton, starch, iodine, potassium iodide, sodium chloride, thermocol box, buffer solution of pH 6.8 & match box.

Preparations:

·        1% Starch solution: to 10ml of distilled water 1g of soluble starch is added to make it into a thick paste. 90 ml of distilled water is boiled and added to 10ml of the starch paste already prepared, gradually by stirring. The solution is left overnight and then filtered to get 1% starch solution.

·        1% NaCl solution: 1g of NaCl is dissolved in 100ml of distilled water.

·        Collection of saliva: a thin film of cotton is made and dipped into water. The water of the cotton is drained off and spread over the mouth of funnel in such a way that it acts as filter. The funnel is kept over a thin test tube. Now saliva is poured into the funnel. To 1 ml of saliva 19 ml of water is added for dilution of the enzyme.

Procedure:

·        In each experimental tube 1ml of diluted enzyme is added.

·         Immediately with the help of a dropper, a drop each from these tubes is taken & added to the tubes having iodine.

·         The time reading is noted as 0 minute reading.

·         After an interval of 2 to 4 min, again a drop from each tube is taken & added to the iodine tubes & the change in the color of iodine is noted.

·         The experiment is repeated after every 2 to 4 min till the color of iodine does not change any further.

Observation table:

Temperature	Time taken to reach the achromic point
5±2° C	20 min
37±2° C	14 min
50±2° C	23min

Result: It takes less time to reach achromic point at 37° C as the enzyme is maximum active at this temperature while at higher & lower temperatures more time is taken to reach the achromic point.

Precautions

·        All the glassware used must be thoroughly cleaned & dried.

·        Always filter the saliva through a wet cotton film & not through a filter paper.

·        Maintain approximately the same temperature of the water bath throughout the experiment as far as possible.

EXPERIMENT NO. 7.2

Aim-  TO STUDY THE EFFECT OF Ph ON THE ACTIVITY OF SALIVARY AMYLASE ON STARCH.

Materials required- Test tubes, beakers, pipettes, funnels, sodium chloride, potassium iodide, iodine, cotton, match box, etc.

Preparations:

·        1% Starch solution: to 10ml of distilled water 1g of soluble starch is added to make it into a thick paste. 90 ml of distilled water is boiled and added to 10ml of the starch paste already prepared, gradually by stirring. The solution is left overnight and then filtered to get 1% starch solution.

·        1% NaCl solution: 1g of NaCl is dissolved in 100ml of distilled water.

·        Collection of saliva: a thin film of cotton is made and dipped into water. The water of the cotton is drained off and spread over the mouth of funnel in such a way that it acts as filter. The funnel is kept over a thin test tube. Now saliva is poured into the funnel. To 1 ml of saliva 19 ml of water is added for dilution of the enzyme.

Procedure-

·         Iodine indicator tubes & reaction mixture tubes are taken and 1ml of diluted enzyme is added.

·         A drop from each of these test tubes is taken and added to the test tubes having iodine.

·         The time of adding is taken as 0 min reading.  Both the test tubes are kept in water bath maintained at 370 C throughout the experiment.

·        After an interval of 2 to 4 min covered by thermocol box again a drop from each test tube is taken and added to the iodine tubes & the change of color in iodine is noted.

·         The experiment is repeated after every two minutes.

Observation table

TIME	REACTION WITH IODINE
	EXPERIMENTAL TUBE	CONTROL TUBE
0	Blue colour	Blue colour
2	Blue colour	Blue colour
4	Greenish blue	Blue colour
6	Green blue	Blue colour
8	Greenish yellow	Blue colour
10	Yellow	Blue colour
12	Yellowish orange	Blue colour
14	orange	Blue colour

Result- It takes 14 minutes for 1 ml of diluted enzyme to digest completely 5 ml of 1% starch solution to the achromic point

At achromic point experimental tube shows a positive Benedict’s test indicating the presence of simple sugars and absence of starch

Precautions

·        All the glasswares used must be thoroughly cleaned & dried.

·        Always filter the saliva through a wet cotton film & not through a filter paper.

·        Maintain approximately the same temperature of the water bath throughout the experiment as far as possible.

EXPERIMENT 9

Objective:

TO STUDY THE FLOWER ADAPTED TO POLLINATION BY DIFFERENT AGENCIES (wind, insect and birds).

Requirements:

Fresh flowers of maize or any other serial/grass, Salvia/Ocimum and Brassica (mustard) forceps, hand lens, slide, needle etc.

Procedure:

Place the given flower on a slide and observe it with the help of hand lens. Note down the adaptation of the flower meant for pollination by the external agencies.

Maize flowers (anemophilous or wind pollinated flowers)

The flower of maize shows following adaptations for pollination by wind.

·        The maize plant is monoecious and bears unisexual flowers. The male flowers are born in terminal inflorescence while the female flowers are born in axillaryinflorescences.

·        Flowers are small and inconscipicous.

·        The flowers are colorless, odorless, nectar less.

·        Flowers are produced above the foliage or placed in hanging position.

·        Both the stigmas and anther are exerted(i.e. hang out side the perianth).

·        Anther are versatile, and pollen grains are small and dusty.

·        The pollen grains are produced in very large numbers.

·        Stigma is hairy, feathery or branched to catch wind born pollen grains.

Salvia flowers (entomophilous or insect pollinated flowers)

The flowers of salviashow following adaptations for pollination by insects.

·        The flowers are showy or brightly colored for attracting, pollinating insects.

·        The flowers are born in verticellaster inflorescence to become conspicuous.

·        Flowers secretnectar to feed visiting insects. Nectar gland are placed in such aposition that an insect must touch both the anthers and stigmas.

·        The flowers have landing platform for the insects.

·        The flowers are protandrons with bilipped corolla and have turned pipe or liver mechanism.

·        Each stamen has long connective which bears a fertile antherlobe at the upper end and sterile plate like anther lobe at the lower end. The two sterile anther plates block the path of insects.

·        As the insect moves toward in a young flower in search of nectar, its head pushes, the anther plates and forces the fertile anther lobes to strike against its back.

·        In older flowers the style brings the stigma in such a positions that it brushes against the back of insects and collect pollen grains brought by the insects from a young flower.

EXPERIMENT 10

Objectives:

TO STUDY THE POLLEN GERMINATION AND GROWTH OF POLLEN TUBE IN A POLLINATED PISTIL (in portulaca/grass or any other suitable flower.)

 Requirements:

Fresh pollinated flowers of portulaca/grass or any other suitable flower, glass slide, coverslip, needles, forceps, brush, dropper, safranin, glycerin, Petri dish, water, blotting paper, microscope, etc.

Procedure:

·        Take out the pollinated carpel from the flower of portulaca/grass or any other suitable flower and place it on a glass slide in a drop of water. Gently tease it with the help of needle or pick up the carpel from the flower and cut a longitudinal section of it. Place the section on a glass slide in a drop of water.

·        pour a drop of safranin on the teased carpel of its section and wash it with water.

·        Put a drop of glycerin and cover the teased carpel of its section with coverslip. Remove the extra glycerin with blotting paper. Observe the preparation under the high power of microscope and draw the diagrams of different stages of pollen germination.

Observation:

Different stages of germinating pollens are observed in the stigma and style region of the carpel. Some pollens are in their initial stage of germination other have quite long pollen tube containing tube nucleus and two male nuclei.

Precautions:

·        Only pollinated carpel should be selected for the experiment.

·        Teasing should be done gently, so that the pollen tubes are not ruptured.

·        Excess of glycerin /water should be removed by blotting paper.

EXPERIMENT 11

Objectives:

 TO STUDY AND IDENTIFY THE STAGE OF GAMETE DEVELOPMENT IN MOUSE(MAMMAL) i.e, T.S OF TESTIS AND L.S OF OVARY THROUGH PERMANENT SLIDE.

 Requirements:

Permanent slide of T.S of testis and L.S ovary, microscope

Procedure:

 Fix the permanent slide under the microscope. First observe it under the low power and then under the high power.

Observations:

T.S of testis

·        the testis of a mouse is covered by a thick fibrous tissue called tunica albuginea.

·        The testis consists of seminiferous tubules embedded in the interstitial tissue.

·        Various type of germinal cells is present from outside towards lumen in the following sequence.

Spermatogonia

Spermatocytes

Spermatids

Spermatogoa

Sperms

·        Between the germinal cells, pyramid shape cells called sertoli cells are present.

·        A large number of spermatozoa with their heads embedded in sertoli cells are present in lumen of seminiferous tubule.

·        The intestinal tissue also contains leydigs cells, which produce male sex hormone testosterone

V.S. of Ovary

·        A mouse ovary is a solid structure bounded by germinal epithelium followed by a thick layer of fibrous tissue, the tunica albuginea.

·        The ovary consists of outer cortex and inner medulla.

·        The medulla contains many rounded or oval bodies called ovarian or Garaafian follicles at various stages of development.

·        The medulla also contains blood vessels, nerves fibres and some smooth muscles.

·        Each follicle contains a large ovum surround by many layers of follicles cells.

·        The cortex contains young and mature follicles.

·        The cortex may also contain a large mass of yellow cells termed corpus luteum, formed in an empty Graafian follicle after the release of its ovum.

Precautions:

·        First observe the slide under low power and then under high power of the microscope.

·        Use fine adjustment of the microscope for focusing the slide under high power.

EXPERIMENT   12.1

OBJECTIVE: TO STUDY MEIOSIS IN ONION BUD CELLS THROUGH PERMANENT SLIDE.

REQUIREMENTS :- 1.Permanent  slide of different stages of meiosis in onion bud cells.

                                  2.Microsope.

OBSERVATIONS

Under the high power of microscope ,following stages of meiosis are distinctly observed:

A. Meiosis I

1.Prophase I. It is of long duration and has five sub-stages:

(a)Leptotene

(i) chromatin fibres condense and form thick threads like structures called chromosomes.

(ii)Nuclear envelop nucleolus are distinct .

(b)Zygotene

(i)Homologus chromosomes form pairs called bivalent.This pairing is called synapsis.

(ii)The individual of a pair are similar in length  and in position of their centromere.

(c)Pachytene

(i)The two chromatids of each chromosome  become visible, so that a bivalent becomes a tetrad.

(ii)Crossing over (exchange of chromatid segments between homologus chromosomes )takes place between non-sister chromatids  of homologus chromosomes .

(d)Diplotene

(i)The two chromosomes of each bivalent move away and homologus are held together at one or more vpoints called chiasmata .

(e)Diakinesis

(i)Homologus chromosomes appear thick and ring shaped.

(ii)Nucleolus and nuclear envelope disappear and spindle begins to be formed.

2. Metaphase I

(i)The bivalent (homologus chromosomes) arrange themselves  at the equator of the spindle.

(ii)The spindle get attached  to the centromere of the chromosome.

3.Anaphase I

(i) The two chromosomes of each bivalent move to the opposite pole.

(ii)Each pole has half the number of chrosomes with two chromatids each.

4. Telophase I

(i)The chromosome at each pole uncoil , and nucleolus and nuclear envelope reappear .

(ii)Cytokinesis  occurs to form two haploid daughter cells.

Interkinesis

A very short interphase may intervene between meiosis I and meiosis II.

B.Meiosis  II

 It include  following  four stages :

1.Prophase II

(i)The chromosomes of daughter cell begin to condense  and become thick.

(ii)Nuclear envelope and nucleolus begin to disaapear .

2.Metaphase II

(i)The chromosomes are arranged on the equator  of the spindle .

(ii)Each chromosome is held by the spindle at the centromere to both the poles

3.Anaphase II

(i)The sister chromatids (daughter chromosomes ) of each chromosomes separate  and migrate towards the opposite poles.

(ii)Each pole ,thus receives haploid number of chromosomes .

4.Telophase II

(i)The begin to uncoil and become thin .

(ii)The nuclear envelope and nucleolus are reconstituted .

Cytokinesis  occurs and four daughter cells are formed ,each with  haploid number of chromosomes .

PRECAUTIONS

1.Floral buds should be fixed between 8 t 10 A.M.

2.Slide should be warmed gently to avoid  overheating.

EXPERIMENT 12.2

OBJECTIVE:  TO STUDY MEIOSIS IN GRASSHOPPER TESTIS THROUGH PERMANENT SLIDE.

REQUIREMENTS

1. Permanent slide of different stages of meiosis in grasshopper testis.

2. Microscope.

PROCEDURE

1. We have fixed the permanent slide under the microscope .

2. Then we observed the slide under the low power of the microscope and then high power of the microscope.

OBSERVATIONS

1. Spherical cells with various stages of meiosis can be observed .

2. Located  different stages of meiosis with the help of diagram  .

PRECAUTIONS

1. Grasshopper should be dissected from dorsal side .

2. Preserved testis should be properly washed before use .

3. Do not heat the testis tubules .

4. Proceed for squash preparation only when testis has taken sufficient  stain.

EXPERIMENT 13

OBJECTIVE:  TO STUDY T.S OF BLASTULA THROUGH PERMANENT SLIDE.

REQUIREMENTS

1. Permanent slide of blastula.

2. Microscope.

PROCEDURE

1. We fixed the slide of T.S. of blastula under microscope .First we observed the slide under low power and then under high power of the microscope.

OBSERVATIONS

1. It is a spherical mass of about sixty four cells.

 2. It is composed of an outer envelope of cells, the trophoblast or trophoetoderm and inner cell mass (embryoblast).

3. Within the envelope there is a fluid filled cavity called blastocoel.

4. The side of the blastocyst to which the inner cell mass is attached is called the embryo.

5. The inner cell mass is the precursor of the embryo.

 PRECAUTIONS

1. First focus the slide under low pressure  and then under the hogh poewer of the microscope.

2. Use fine adjustment while focusing the slide under high power of the  microscope. 

EXPERIMENT 14.1

AIM: - TO STUDY MENDELIAN INHERITANCE USING SEEDS OF DIFFERENT COLOUR/SIZE OF ANY PLANT.

REQUIREMENTS: - Pea seed sample, enamel tray, Petri dishes, notebook, pencil/pen

PROCEDURE:-

·        A lot of about 100 pea seeds are taken in an enamel tray.

·        The round and wrinkled seeds are separated out and are put in two different petridishes.

·        The number of the round and wrinkled seeds are noted and their approximate ratio is calculated.

·        The process is repeated for the other contrasting trait of the seed i.e, yellow and green colour.

OBSERVATIONS:-

S.NO	Characters / Traits of seed	Total no. of seeds observed	No. of seeds showing contrasting form of the trait	Approximate Ratio
1.	Seed shape (round/wrinkled)	106	80(R):26 (W)	3.07:1
2.	Seed colour(yellow/green)	110	83(Y): 27(G)	3.07:1

CONCLUSION;-

The contrasting forms in both the traits of the pea seed (i.e, seed shape and seed colour) show an approximate ratio of 3 : 1. The ratio is exactly the same as obtained by Mendel for monohybrid crosses and indicate that the dominant and recessive forms of seed shape and seed colour exist in the ratio 3 : 1 in the population of pea seeds.

PRACAUTIONS:-

·        Large number of seeds should be taken to minimize the error in the analysis.

·        The contrasting form of the trait should be observed carefully.

                                                          EXPERIMENT 14.2

AIM: - TO ANALYSE SEED SAMPLE OF PEA FOR MENDELIAN DIHYBRID RATIO OF  9 : 3: 3: 1.

REQUIREMENTS: - Pea seed sample, enamel tray , petridishes, notebook pencil/pen.

PROCEDURE:-

·        A lot of about 250 pea seeds are taken in a enamel tray.

·        The yellow round , yellow wrinkled , green round , green wrinkled seeds are separated and put in separate petridishes.

·        The number of seeds in each dish is noted and their approximate ratio is found out.

OBSERVATION:-

Total no. of seeds observed	No. of yellow round seeds	No. of yellow wrinkled seeds	No. of green round seeds	No. of green wrinkled seeds	Approximate     Ratio
257	145	48	48	16	9.06:3:3:1

CONCLUSION:-

The ratio of yellow round, yellow wrinkled, green round , green wrinkled approximately

9 : 3 : 3 : 1, which is exactly the same as obtained by Mendel for a dihybrid cross. This indicates that the contrasting genes for seed colour and seed shape show an independent assortment in the population of pea seeds.

PRECAUTIONS:-

i)    Large number of seeds should be taken to minimize the error in the analysis.

ii)  The contrasting form of the trait should be observed carefully.

EXPERIMENT 15

AIM:-  TO STUDY THE PREPARED PEDIGREE CHARTS OF GENETIC TRAITS SUCH AS ROLLING OF TONGUE, BLOOD GROUPS, WIDOW’S PEAK, COLOUR BLINDNESS etc.

REQUIREMENTS:- Prepared pedigree chart of the genetic traits.

PROCEDURE:- Observe the prepared pedigree charts and write the comment on it.

PROBLEM 1:- (Inability to roll the tongue)

Inability to roll the tongue appears in the progeny due to recessive gene. Find out the possible genotype of the family members in the following pedigree.

          

PROBLEM 2:- (Widow peak)

In the pedigree given below, indicate whether the shaded symbols belong to dominant or recessive trait. Also give the genotype of the whole pedigree.

               

EXPERIMENT 16

AIM: - TO COMMENT ON THE EXERCISE OF HYBRIDISATION (emasculation,tagging and bagging) THROUGH  MODELS / CHARTS.

1. EMASCULATION

Identification. Forceps or scissors method of emasculation.

Comment

·        This method is employed in the crops having flowers of sufficiently large size lint cotton.

·        The instrument used in this method includes pocket lens, forceps, needle, scissors, scalpel, camel hair brush etc.

·        In this process anthers are removed from the flowers before their maturation.

·        The anthers are cut with the help of sterilized forceps and scissors.

Identification. Hot or cold and alcohol emasculation.

Comment

·        This method of emasculation is employed in the crops having small flowers like paddy, sorghum etc.

·        In this method the penicles (cluster of flowers) are dipped In hot water for 1-10minutes to kill the anthers.

·        In the same way emasculation is done with cold water or alcohol.

2. Identification. Bagging, tagging and labeling.

Comment

·        After emasculation, the flowers are covered with small bags to prevent pollination.

·        The bags are made up of polythene, paper, and muslin cloth or parchment paper.

·        These bags are punctured or perforated to provide aeration to the flowers.

·        The flowers of male parents are also protected in bags to prevent mixing of their pollen grain with foreign pollens.

·        After dusting of the desired pollen grains on the emasculated flowers, the bags are retagged.

·        A label of paper is tagged on the plant which displays the date of emasculation, crossing and brief account of the parents.

                           

EXPERIMENT 17

AIM:-STUDY OF COMMON DISEASE CAUSING ORGANISMS

1. Entamoeba

    Identification - Entamoeba histolytica.

    Disease caused- Amoebiasis or Amoebic dysentery

    Comments-

·        It is a human parasite that resides in the upper part of the large intestine .

·        It causes the disease called amoebic dysentry or amoebiasis.

·        The symptoms of the disease include abdominal pain, repeated motions with blood and mucus.

·        The parasite is unicellular and has one pseudopodium.

·        There is a single nucleus and a number of food vacuoles.

·        It feeds on red blood corpuscles by damaging the wall of large intestine and reaches the blood capillaries.

·        It produces ulcers and can also reach other body organs.

2. Plasmodium

    Identification- Plasmodium vivax

    Disease caused – Malaria.

    Comments-

·        Plasmodium enters human body in sporozite stage by the bites of female Anopheles mosquito.

·        The sporozoite is spindle shaped and uninucleate organisms capable of wriggling movement.

·        The sporozoites infect liver cells and produce cryptomerozoites. The later enter new liver cells and produce metacryptomerozoites.

·        The metacryptomerozoites enter RBCs and passes trophozoite signet ring stage and amoeboid stage and produce schizont and merozoites .

·        The merozoites enter fresh RBCs and produce merozoites.

·        The gametocytes reach into mosquito stomach, when the later sucks the blood of infected human host.

·        The gametocytes produce male and female gametes in the stomach of mosquito.

·        The male and the female gametes fuse to form zygote. The later becomes worm like called ookinete, which penetrate in the wall of stomach and form oocyte.

·        The oocyte produce sporozoites which are released in the haemocoel of the mosquito and reach into the salivary gland and make the mosquito infective.

    Symptoms

·        the symptoms of malaria fever starts appearing 14 days after the infectious bite.

·        Symptoms include restlessness, less apetite, slight sleeplessness follwed by muscular pain, headache and feeling of chilliness.

·        The patient sweats a lot and the temperature rises.

3. Ascaris

    Identification- Ascaris lumbricoides

    Disease caused- Ascariasis.

    Comments

·        It is an endoparasite of the small intestine of the human beings and is more common in children.

·        The animal shows sexual dimorphism. The female is longer than the male.

·        The posterior end of the male is curved ventrally.

·        In female, the genital aperture is present on the mid – ventral line at about one third of the lenth from the anterior end.

·        In male from the cloaca two equal chitinous spicules or pineal setae project which help in copulation.

    Symptoms

·        Generally a large number of adult Ascaris wirm infest a single host, and obstruct the intestinal passage and thereby cause abdominal discomforts like colic pains.

·         The patient may also suffer from impaired digestion , diarrhoea and vomiting.

·        In children mental efficiency is affected and body growth is retarded.

4. Microsporum

    Identification- Microsporum andaouini

    Disease caused- Ring worm of scalp in children or Dermatomycosis

    Comment

·        The fine mycelium of the fungus occurs in break in the dermis.

·        It infects hair, where hyphae emerge from the sheath and grow up and down them.

·        The hyphae in the hair put out to the surface fine filaments on which spores are born.

·        The spores are very small and are produced in great numbers . They are readily detached and spread infection.

EXPERIMENT 18

AIM:- STUDY OF PLANTS AND ANIMALS FOUND IN XEROPHYTIC CONDITIONS AND COMMENT UPON THEIR ADAPTATIONS / MORPHOLOGICAL FEATURES.

1. Opuntia dillenii (Nagphani)

    Comments

·        It is a succulent or drought resisting xerophyte , which grows wild in arid areas.

·         The leaves are caduceus. They fall down soon after their formation to reduce transpiration.

·        The stem is jointed, flattened and green phylloclade.

·         The stem becomes fleshy due to storage of water. The stored water is used throughout the unfavorable periods.

·        The stem possesses abundant mucilage, which helps in retaining water.

2. Camel

Comments

·        It is xerocoles animal adapted to the desert conditions.

·        It is able to tolerate wide range of temperature fluctuations and is able to maintain blood moisture even during hot period.

·        It excretes concentrated urine and can withstand dehydration up to 25% of its body weight.

·        It accumulates its fat in the hump rather than all the body.

·        Its feet has two toes each with fleshy pad below which spread the load on sand enable it to move on hot and slippery sand.

·        Its slender snout bears a cleft upper lip, long eye lashes and muscular nostrils which can be closed for protection from windblown sand.

                                                              EXPERIMENT 19

AIM:- STUDY OF PLANTS AND ANIMALS FOUND IN AQUATIC CONDITIONS AND COMMENT UPON THEIR ADAPTATIONS/ MORPHOLOGICAL FEATURES.

1.Eichhornia( water hyacinth)

Comments

·        It is a free floating hydrophyte that grows in ponds lakes and water bodies containing freshwater.

·        When the level of water is low, the plant gets rooted in the soil.

·        The stem is offset that grows prostrate below the surface of water. It is spongy and stores air.

·        The leaves arise at the nodes in clusters. The petiolesof the leaves are inflated that keep the leaves out of water.

·         The emerged leaves have waterproof, waxy and cuticular coating to prevent wetting.

2. A freshwater fish( Rohu or Carp)

Comments

·        Its body is ccompressed laterally to reduce friction and to allow swift passage in water while swimming.

·        It possesses fins that helps in swimming.

·        It has a air bladder or swim bladder which maintains buoyancy.

·        It possesees gills as organs of respiration for the exchange of gasses in water .

·        The body is covered with water impermeable scales to prevent osmotic entry of water in the body.