study of pollen germination experiment class 12 practical

CBSE Class 12 Biology Practical .docx

Topics Covered:- 1 Prepare a temporary mount to observe pollen germination. 2 Collect and study soil from at least two different sites and study them for texture, moisture content, pH and water holding capacity. Correlate with the kinds of plants found in them. 3 Collect water from two different water bodies around you and study them for pH, clarity and presence of any living organism. 4 Prepare a temporary mount of onion root tip to study mitosis. 5 Study the effect of different temperatures or three different pH on the activity of salivary amylase on starch. 6 Isolate DNA from available plant material such as spinach, green pea seeds, papaya. 7 Flowers adapted to pollination by different agencies (wind, insects, and birds). 8 Identification of stages of gamete development, i.e., T.S. of testis and T.S. of ovary through permanent slides (from grasshopper/mice). 9 Meiosis in onion bud cell or grasshopper testis through permanent slides. 10 T.S. of blastula through permanent slides (Mammalian). 11 Prepared pedigree charts of any one of the genetic traits such as rolling of tongue, blood groups, ear lobes, Widows peak and colour blindness. 12 Common disease causing organisms like Ascaris, Entamoeba, Plasmodium, any fungus causing ringworm through permanent slides, models or virtual images. Comment on symptoms of diseases that they cause. 13 Two plants and two animals (models/virtual images) found in xeric conditions. Comment upon their morphological adaptations. 14 Two plants and two animals (models/virtual images) found in aquatic conditions. Comment upon their morphological adaptations. 15 Appendix Read less

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• 2. KENDRIYA VIYALAYA BALLYGUNGE INDEX Sl. No TOPIC DATE REMARKS PAGE NUMBER 1 Prepare a temporary mount to observe pollen germination. 2 Collect and study soil from at least two different sites and study them for texture, moisture content, pH and water holding capacity. Correlate with the kinds of plants found in them. 3 Collect water from two different water bodies around you and study them for pH, clarity and presence of any living organism. 4 Prepare a temporary mount of onion root tip to study mitosis. 5 Study the effect of different temperatures or three different pH on the activity of salivary amylase on starch. 6 Isolate DNA from available plant material such as spinach, green pea seeds, papaya, 7 Flowers adapted to pollination by different agencies (wind, insects, and birds). 8 Identification of stages of gamete development, i.e., T.S. of testis and T.S. of ovary through permanent slides (from grasshopper/mice). 9 Meiosis in onion bud cell or grasshopper testis through permanent slides. 10 T.S. of blastula through permanent slides (Mammalian). 11 Prepared pedigree charts of any one of the genetic traits such as rolling of
• 3. tongue, blood groups, ear lobes, Widows peak and colour blindness. 12 Common disease causing organisms like Ascaris, Entamoeba, Plasmodium, any fungus causing ringworm through permanent slides, models or virtual images. Comment on symptoms of diseases that they cause. 13 Two plants and two animals (models/virtual images) found in xeric conditions. Comment upon their morphological adaptations. 14 Two plants and two animals (models/virtual images) found in aquatic conditions. Comment upon their morphological adaptations. 15 Appendix
• 4. PRACTICAL 1 Aim: To prepare a temporary a mount to observe pollen germination. Requirement: 1. Fresh seasonal flowers, Slide, Cover slip, Microscope, Sucrose, Boric acid, Magnesium sulphate, Potassium nitrate, Beaker. Procedure: 1. A nutrient solution is prepared by dissolving 10g sucrose, 10g boric acid, 30mg Magnesium sulphate and 20mg Potassium Nitrate in 100ml of water. 2. Few drops of this solution are taken on a clean slide and few pollen grains from the stamen are dusted on a mature flower. 3. The slide is observed in the microscope after 5 minutes and then it is regularly observed for about half an hour. Observation: 1. The pollen grain germinates in the nutrient medium. 2. The tube cell enlarges and comes out of the pollen grain through one of the germ pores to form a pollen tube. 3. The tube nucleus descents to the tip of the pollen tube. 4. The generative cells also pass into it. It soon divides into two male gametes. 5. Each male gamete is lenticular to spherical in outline.
• 5. Precaution: 1. Flower should be freshly plucked. 2. Clean slide is to be used to observe the pollen grain.
• 6. PRACTICAL 2 Aim:-To collect and study soil from at least two different sites and study them for texture and moisture content, pH and water holding capacity of soil. To correlate with the kinds of plants found in them. Theory: - Soil is the upper humus, containing a layer of the earth, consisting of rock and mineral particles mixed with decayed organic matter. Soil sustains plant life and contains numerous living organisms. Soil, along with air and water, is one of the three most important natural resources, which we cannot live without. A productive soil contains approximately 46% mineral matter, 4% organic matter, 25 % water and 25% air. An approximate composition of soil shown below. A. Texture of soil (From different sites:- (1) Garden, (2) Field and (3) Roadside) Aim:-To study the texture of soil (A physical property) Materials Required :-( 1) Hand lens, (2) Sieves with meshes of different sizes, (3) Soil samples collected from different sites, (4) White sheets/ plain papers. Procedure: - (a) We can determine the texture of soil by two methods. (a)Study by hand lens:-
• 7.  Dry and moist soil is taken in hand and its texture is felt by rubbing it in between the thumb and the fingers.  Observations are noted and compared.  Both the dry and moist soil is taken on a white paper and is viewed under the hand lens and results are noted and compared with the information given in table A. TABLE A Sl. No. Texture Soil as felt between thumb and fingers 1. Sand (a) Individual dry soil grains may be seen or felt. (b) They form a cast when moist soil is squeezed. 2. Sandy loam (a) Individual soil grains can be seen and felt. (b) They form a cast but fall apart when dry soil is squeezed. (c) Moist soil forms a cast that does not break. 3. Loam (a) Gentle and gritty feeling. (b) When dry soil is squeezed, forms a cast bearing a careful handling. (c) Moist soil cast is easily handled without breaking 4. Silt loam (a) Soil appears cloddy or lumpy with soft feeling. (b) Dry and moist soil forms cast that can be easily handled without breaking it. (c) If moist soil is squeezed it does not form ribbons. 5. Clay loam (a) Hard and dry soil breaks into lumps or clods. (b) Moist soil when pinched, it forms thin ribbon which breaks readily. (c) Moist soil forms cast that can bear much handling. 6. Clay (a) Dry soil forms very hard lumps or clods. (b) Wet soil is sticky. (c) Moist soil forms long flexible ribbon when it is squeezed. OBSERVATION TABLE (A) Study of soil particles by hand lens and in-between fingers (b) Study by sieving method (standard method):-  Sieves of different net sizes are used and soil samples are sieved separately.  The sieve with maximum sieve is chosen first and the soil is sieved over a white paper.  Soil particle of different sizes are separated and observations are noted and compared.
• 8. Find out the relative proportion of each fraction. Note it. Study the texture and compare it from the information table (B1 and B2) Table B1:-Texture of soil (A physical property) Sl. No Soil particle Size(diameter in mm) of particle 1. Gravel 2.00mm and more 2. Coarse sand 2mm-0.20 mm 3. Fine sand 0.2mm-0.02mm 4. Silt 0.2mm-0.002mm 5. Clay Below 0.002mm Table B2:-Texture of soil (A physical property) Sl. No Soil type textural group Main particles Percentage 1. Sandy soil Sand 85%-90%+15% clay or silt or both 2. Sandy loam Sand, loam 50%-55% 3. Loamy soil All particles In equal amount 4. Clay loam Clay, loam 50%-55% 5. Silt loam Silt, other particles 55% 6. Clay Clay 65% OBSERVATION TABLE (B) Study of soil particles by sieving method Sl. No Sample of soil Size of soil particles Main particles Inference
• 9. 1. A 2mm-0.20 mm Sand Sandy soil 2. B Below 0.002mm clay Clay 3. C 0.2mm- 0.002mm Silt, other particles Silt loam 4. D 0.2mm-0.02mm All particles Loamy soil Conclusion: - Texture of the soil is found and recorded. B. ph of soil(A physical property)  Aim:-To Study pH of Different Types of Soil  Materials Required: - Garden soil, humus rich soil, roadside soil, droppers, filter paper, riverside soil, Test tubers, distilled water, funnel  Procedure:- o First we will take a pH paper booklet. o Then we will tear pH paper strips from the booklet and will place 4 strips on the tile. o Now by using a dropper, we will take some roadside soil solution from the test tube. o We will put 1 to 2 drops of solution on the first pH strip on the tile. o Using fresh droppers, we will do the same procedure for garden soil, humus rich and riverside soil. o Now we will wait for some time for the pH paper strip to dry. o We will note the colour and compare with the colour chart given on the broad range indicator paper and get a rough estimate of pH of the sample solutions. OBSERVATION TABLE Study the ph of soil using ph paper
• 10. SL.no. Sample of soil PH of soil 1. Road side soil 7 2. Garden side soil Around 7 3. Humus rich soil 6 4. Riverside soil 8 Conclusion:-  Roadside soil is nearly neutral.  Garden side soil and humus rich soil are slightly acidic.  Riverside soil is slightly basic. C. Water holding capacity of soil  Aim:-To study the water holding capacity of soil  Materials required:-Soil sample from garden, Tin box with perforated bottom, Mortar and pestle, Filter paper, Weighing balance, Small glass rods, Petri dish, Glass rod  Procedure:- o Watch glass containing garden soil is taken and put into a mortar. o Using a pestle, the sample is grinded into fine powder. o A filter paper is taken and placed in the bottom of the tin box. o The tin along with the filter paper is weighed and noted. o The fine powdered soil sample is transferred into the tin box. o A glass rod is taken and the box is tapped gently several times, so that soil is compactly filled and forms a uniform layer at the top. o The tin box is weighed along with soil sample and its weight is noted. o A Petri dish filled with water is taken. o Two small glass rods are taken and were placed parallel to and at a small distance from each other. o The soil filled tin is placed on the two glass rods in such a manner that its bottom is in contact with water.
• 11. o The set up is left undisturbed till water appears on the upper surface of the soil (till entire soil surface is wet). o The tin is removed and allowed all the gravitational water to flow out from the bottom. o When no more water percolates, the bottom is wiped and was dried with a filter paper. o Again they are weighed and noted. OBSERVATION TABLE Study the water holding capacity of soil Soil Sample Weight of tin + filter paper (X) Weight of the tin with soil.(Y) Weight of tin after taking out from the Petri dish.(Z) Weight of the soil (Y- X) Weight of the water retained by the soil. (Z- Y) Water holding capacity (Z-Y)/(Y- X) * 100 Garden Soil 39.48 246.85 280.37 207.37 33.52 16.16 Roadside Soil 39.5 340.83 360.64 301.33 19.81 6.57 Conclusion:-  Garden soil has more water holding capacity than roadside soil. D. Moisture content of soil  Aim: - To study moisture content of soil
• 12.  Materials required: - Garden soil, Roadside soil, Wire gauge, Weighing balance, Burner, Crucibles.  Procedure: - o A watch glass containing garden soil is taken and put into a crucible. o The crucible with soil sample is weighed on a weighing balance. The crucible is placed over the burner. o The soil is heated for some time till the soil becomes dry. o The crucible is again weighed to record the weight of dry soil. o Watch glass containing roadside soil is taken and put into a crucible. o Weigh the crucible with the soil sample on a weighing balance. o The crucible is taken and is placed it over the Bunsen burner. o The soil is heated again for some time till the soil becomes dry. OBSERVATION TABLE:- Study the moisture content of soil Soil sample Initial weight (x) gm Final weight (y) gm Moisture content (y-x) gm roadside soil 208.21 206.35 1.86 garden soil 183.2 178.21 4.99 Conclusion:-  Garden soil has more moisture content than roadside soil. Precautions:-  Collect soil from different locations.  Collect soil in a poly bag (small) or a paper or aluminum foil or pouches.  Separate soil samples must be collected separately.
• 13. PRACTICAL3 (A) Aim: To test the clarity of water samples. Theory: Turbidity is the measure of the relative clarity of a liquid. Turbidity of the water body determines the depth to which light can penetrate and thus affects the distribution and photosynthesis of phytoplankton and macrophytes. The more turbid the water body, the less is the thickness of its photic zone (the layer of a body of water that is penetrated by sufficient sunlight for photosynthesis). Materials Required: Water from different sources, beaker, torch, one sided open wooden box Procedure:  A wooden box is taken with one side open and two holes on opposite walls of the box.  Little water sample is poured in a beaker and put inside a box.  A beam of light is flashed with the help of torch from one of the holes.  The clarity is observed carefully from the other hole.  The experiment is repeated for different water samples.
• 14. Observation: A large number of particles can be seen moving in Water. The water is called turbid water and the phenomenon is called Tyndall effect. Conclusions: Turbidity is the measure of clarity and amount of suspended particles in the water column. Pond water has fewer suspended particles, so it has a low turbidity level. Bore well water and backwater have more suspended particles, so they have a high turbidity level. Precaution:  The two holes in the box should lie on a straight line  The turbidity is to be measured carefully without disturbing the sample PRACTICAL 3(B) Aim: To study the pH of water. Materials Required: Pond water, beakers, bore well water, pH indicator papers, dropper, tap water, backwater, and tile. Theory: The pH is a measure of the relative amount of free hydrogen and hydroxyl ions in an aqueous solution. Solutions with a pH less than 7 are said to be acidic and with a pH greater than 7 are basic. The pH of pure water is 7 at 25°C. The pH value of a water sample can be determined by indicator dye method and electrometric method using a pH meter. For routine purposes, the indicator dye method, using universal pH indicator solution or paper strips containing the pH indicators, is used. Procedure:  The four water samples are taken in the beakers  Four pH papers are wetted and kept on the tile  The water from each source is dropped on the pH papers using a dropper
• 15.  The pH paper is left for a while to let it dry  The colour is noted and compared with the colour chart given on the broad range indicator paper to get a rough estimate of pH of the sample solutions Observations: Sl. No. Water samples Colour pH(Approx) 1. Pond Water Light blue 8 2. Tap water greenish 6 3. Backwater Light blue 8 4. Waste water yellowish 3 Results: Hence different sources of water have different pH. Precautions:  Beakers should be cleaned well to remove any dirt from it.  pH paper should be allowed to dry and it should not be contaminated. PRACTICAL 3 (C) Aim: To study different organisms found in different water bodies. Materials required: Water samples, glass slides, cover slips, dropper, filter paper, compound microscope, needle, test tube. Theory: A productive water body has high nutrient concentrations and has a very high density of phytoplankton. These bodies have high amounts of nutrients and dissolved oxygen and bear large number of organisms at various trophic levels. The status of health of a water body can be determined by analyzing water samples for the number and type of organisms present in it.
• 16. Procedure:  A beaker containing pond water is taken and poured into a test tube.  The water sample is left undisturbed for some time till the sediment settles to the bottom of the test tube.  The clear water is decanted off leaving the concentrated sediment at the bottom of the test tube.  With the help of a dropper, a drop of water is transferred from the test tube to the center of a glass slide.  A cover slip is taken and gently placed on the slide with the aid of a needle.  The extra water is removed using a filter paper.  This glass slide is placed on the stage of the compound microscope and observed.  Repeat the procedure with different sources of water. Observations: We can observe a large number of different organisms in the water samples. .
• 17. Conclusion: Ponds are small and shallow water bodies. The biota consists of phytoplankton and zooplanktons. Well water contains only few organisms like viruses and bacteria. Permanent ponds and lakes possess microscopic phytoplankton such as diatoms, Chlorella, Chlamydomonas, etc. The consumers in small ponds include Daphnia, Cyclops, amphibians, fish etc. Common water birds are ducks, herons, kingfishers etc. Rivers are systems where algae, diatoms, water grasses are found. Consumer animals include fish, minks etc. Variety of organisms is pH sensitive. Result: Number and type of organisms differ according to type of aquatic habitat. Precautions:  Carefully use the compound microscope  Always use a clean slide. Slide should be cleaned well to remove dirt from it.  Each sample should be well labeled according to the collection site.
• 18. PRACTICAL 4  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, acetocarmine strain, hydrochloric acid blade, F.A.A fixative, ethyl alcohol, carnoy’s fluid, blotting paper etc.   Procedure:  We take a root tip on a clean slide and add a drop of acetocarmine stain on it.  Next, we touch the acetocarmine stain with hot rusted needle to make the stain specific for nuclear materials.  Then, we warm it, and the stain evaporates.  After that, we squash the needle tip with a needle or forceps.  Lastly, we take the slide in the folds of a blotting paper and apply pressure our hands. We then observe the slide under the microscope.
• 19. PRACTICAL 5 Aim: Study the effect of different temperatures and three different pH on the activity of the salivary amylase. Principle: Chewing of food stimulates the secretion of saliva by salivary gland in our mouth. Saliva mixes to the food and helps in digestion. The enzyme ptyalin or salivary amylase present in human saliva hydrolyse the big molecules of food into small molecules called maltose .the activity of enzymes gets affected by certain factors like ,temperature and Ph . Effect of temperature : All enzymes are protein in nature. At a lower temperature, the enzyme salivary amylase is deactivated and at high temperature the enzyme gets denatured .Therefore, more time would be taken by the enzyme to digest starch at lower and higher temperatures .Optimum temperature for enzymatic activity ranges from 32 C TO 37 C. The optimum temperature means that the temperature at which a enzyme shows it maximum activity .At this optimum temperature , the enzyme is the most active and shows the maximum activity and takes less time to digest the starch . Effect of pH : The optimum pH for the enzymatic activity ranges from 6 to 7. Above and below this range, the reaction rate reduces as enzyme gets denatured. The enzyme salivary amylase is most active at pH 6.8. Our stomach has high level of acidity which causes the enzyme to denature and change its shape. Achromatic point: The effect of temperature and ph on the activity of salivary amylase on starch can be studied by using the iodine test. If we add saliva on starch, the salivary amylase present in saliva gradually acts on starch and converts it into maltose. Starch keeps giving blue color with iodine until it is completely converted into maltose .at this point no blue color is formed. This point is called achromatic point .Hydrolysis of starch can be verified by the iodine test .Starch forms blue color complex with iodine. If starch is not present in the food then it will not give blue color to the food. Preparation: Collection of saliva:
• 20. Rinse mouth thoroughly with cold water and ensure that it does not contain any food particles. Now take 20 ml of lukewarm water in the mouth and gargle so that the saliva mixes well with the water and then spit it in the beaker .Filter if there is any suspended particle present .filtrate is saliva solution and contains enzyme ptyalin. [Alternatively you can use readymade amylase powder (fungal diastase) .Prepare 1:20 dilution of this enzyme with distilled water and as salivary amylase solution] Preparation of 1% of starch solution: take about 0.5 g of starch and add enough water to make it a paste and then dilute it with adding 50ml of water and heat up for 5 minutes. Preparation of 1% NaCl solution: dissolve of 1g of NaCl into 100 ml of water. Preparation : 1. Take three test tubes and label these as A, B and C .and prepare these in the following way. 2. Set A: Add 5ml of 1% of starch solution + 1ml of 1% NaCl solution +2ml of saliva solution in test tube A .Now keep these test tube in ice water bath (2C TO 4C). Set B: Add 5ml of 1% of starch solution + 1ml of 1% NaCl solution +2ml of saliva solution in test tube B .Now keep it in a hot bath at room temperature 25to 30 C. Set C: Add 5ml of 1% of starch solution + 1ml of 1% NaCl solution +2ml of saliva solution in test tube C. Keep this solution in hot boiling water. 2. Take a white tile and mark it as shown in figure. Time Set-A Set-B Set- C 2 * * * 4 * * * 6 * * * 8 * * * 10 * * * 12 * * * 14 * * * 16 * * * Marking on White Tile 3. After 2 minutes of preparation, take 1-2 drops from each test tube and put it on the tile at respective places. Put one drop of Iodine solution on each spot. 4. Now observe change in colour of test solution with Iodine (Dark Blue-black to Orange- brown) if any, and note it in the observation table.
• 21. 5. Repeat the step 3 and 4 after every 2 minutes till achromatic point reached i.e. no Blue- black colour is formed and the colour of Iodine does not changed. Observation: Time Interval Set-A (5degree C) Set-B (27 degree C ) Set-C (70 degree C) 2 BLUE BLUE BLUE 4 BLUE BLUE BLUE 6 BLUE NO CHANGE IN COLOUR BLUE 8 BLUE BLUE 10 BLUE NO CHANGE IN COLOUR 12 NO CHANGE IN COLOUR It takes 5 minutes (less time) to reach achromatic point at 37-degree C, as the enzyme is maximum active at this temperature, while at higher and lower temperatures 12 minutes and 10 Minutes (more time) is taken to reach the achromatic point. Conclusion All enzymes are protein in nature. At lower temperatures, the enzyme salivary amylase is deactivated and at higher temperatures, the enzyme is denatured. Therefore, more time will be taken by enzyme to digest the starch at lower and higher temperatures. At 37-degree C, the enzyme is most active, hence, takes less time to digest the starch.
• 22. Procedure: (Study of effect of PH on Salivary Amylase) 1. Test tubes are taken and are marked as A, B and C. 2. Set-A: Add 5ml of 1% starch solution + 1ml of 1% NaCl solution + 2ml of the saliva solution + 2ml of dil. HCl/ tablet of known pH in test tube A. Now keep this test tube in ice water bath (2-degree C to 4-degree C) Set-B: Add 5ml of 1% starch solution + 1ml of 1% NaCl solution + 2ml of the saliva solution + tablet of known pH7 in test tube B. Set-C: Add 5ml of 1%starch solution + 1ml of 1% NaCl solution + 2ml of the saliva solution + 2ml of dil. NaOH/ tablet of known pH 9 in test tube C 1. Keep all the test tubes in the water bath at room temperature at 37 C for 10 minutes. 2. Take a white tile and mark it as shown in the figure. 3. After 2 minutes of preparation, take 1-2 drops of each test tube and put it on the tiles at respective places. Put one drop of iodine solution on each spot. 4. Now observe change in color of test solution with iodine ( dark blue – black to orange - brown ) if try ,and note it in the observation . 5. Repeat the step 3 and 4 after every 2 min till schematic point reached i.e. no blue black is formed and the color of iodine does not change. Time interval Color intensity Of solutions At different temp. Set –A (Ph 5) Set –B (Ph 6.8) Set –C (Ph 8) 2 Blue blue blue
• 23. 4 Blue blue blue 6 Blue No colour changed blue 8 Blue blue 10 Blue blue 12 Blue blue 14 No colour changed No colour changed It takes 4 minutes (less times ) to reach achromatic point at ph 6.8 as the enzyme is maximum active at this ph , while at higher and lower ph 14 minutes and 14 minutes (more time ) to reach the achromatic point . Conclusion: Ph 4 and is acidic and ph 9 is alkaline, therefore salivary amylase did not act in these tubes. Whereas it acted in the tube of ph 6.8 (that is slightly acidic) and digested the starch. Precaution:  Always use clear and dried glassware for the experiment.  All the measurements must be accurate.  Different droppers should be used to pour different solutions.  Do not mix the drops on the tiles.  Maintain uniform temperature throughout the experiment. PRACTICAL 6
• 24.  Aim: Isolate DNA from available plant material such as spinach, green pea seeds, papaya, etc.  Materials required: Plant materials (spinach, pea, banana, and strawberry), Mortar and pestle, Test tubes, Beakers, Ethanol, Spool, Enzymes (Cellulase, ribonuclease, lipases, and protease).  Procedure: Plant material was grinded in pestle and mortar and a fine paste was made by adding some distilled water. The paste was taken in a test tube. Then the paste was treated with Cellulase to break down the cell wall. Then it was treated with protease to hydrolyze the peptide bonds of proteins, i.e. the intertwined histone proteins from the DNA were removed. Then it was treated with lipase to dissolve the lipid molecules. Then the mixture was treated with ribonuclease to dissolve any RNA molecules that were remaining. Then chilled ethanol was added slowly to separate out the DNA as precipitate. Then spooling was done on the surface to separate DNA completely.  Observation: The DNA appears as white precipitates of fine thread on the spool. Precautions: Do not pour chilled ethanol directly in the test tube, but add slowly with the help of glass rod so that the layers separate out properly. Do not stir the mixture while spooling. PRACTICAL 7
• 25. Aim: 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/Osmium and Brassica (Mustard) forceps, hand lens, slide, needle etc. Procedure: The given flower was placed on a slide and observed with the help of hand lens. The adaptation of the flower meant for pollination by the external agencies was noted down. 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  Axillary inflorescences. o Flowers are small and inconspicuous. o The flowers are colorless, odourless, nectar less. o Flowers are produced above the foliage or placed in hanging position. o Both the stigmas and anther are exerted. o Anthers are versatile, and pollen grains are small and dusty. The pollen grains are produced in very large numbers. o Stigma is hairy, feathery or branched to catch wind born pollen grains. Salvia flowers (entomophilous or insect pollinated flowers)  The flowers of salvia show following adaptations for pollination by insects.
• 26. o The flowers are showy or brightly colored for attracting, pollinating insects. o The flowers are born in verticillate inflorescence to become conspicuous. o Flowers secret nectar to feed visiting insects. Nectar gland are placed in such  A position that an insect must touch both the anthers and stigmas. o The flowers have landing platform for the insects. o The flowers are protandrous with bilipid corolla and have turned pipe or liver mechanism. o Each stamen has long connective which bears a fertile anther lobe at the upper  End and sterile plate like anther lobe at the lower end. The two sterile anther plates  Block the path of insects. o 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. o In older flowers the style brings the stigma in such a position that it brushes  Against the back of insects and collect pollen grains brought by the insects from a young flower.  Begonia flowers (ornithophlious or bird pollinated flowers)  The flowers of Begonia show the following adaptations for pollination by birds.  >The flowers are usually brightly colored red, orange, yellow or blue. o The floral parts are commonly leathery. o In some cases, the corolla is leathery. o The flowers secrete abundant watery nectar or have edible parts o The nectar is secreted in such abundance that drops of it can be brought down by shaking branches o The flowers are generally odourless or without fragrance.
• 27. PRACTICAL 8(A)  Aim : Identification of stages of gamete development, i.e. t.s. of ovary through permanent slides (from grasshopper, mice)  Requirements: Permanent slide of TS of ovary ,microscope  Procedure :  (1)Fix the permanent slide under the microscope  (2)First observe it under the low power and then high power  Observations :( 1) Outermost layer of the ovary is germinal epithelium.  (2)Inner to germinal epithelium is a layer of fibrous tissue call tunica albuginea.  (3) Stroma includes cortex and Central medulla cortex contain ovarian follicle.  (4)A graphical follicle consists of an ovum surrounded by a group of follicular cell.  (5)Follicle cell of Graffian follicle secretes estrogen and cells of Corpus luteum secrete estrogen.  (6)Follicle mature and migrate to the ovum surface where these burst to release.  (7)Ovum degenerating of Corpus luteum is known as Corpus albicans.   Precautions: (1) First focus the slide under low power and then under the high power of the microscope.  (2) Use fine adjustment while focusing the slide under high power of the microscope.
• 28. PRACTICAL 8(B)  Aim:– to study and identify the stages of gamete development on T.S of testis  Requirements: – slide of T.S of testis, microscope.  Procedure: - (1) Fix the permanent slide under the microscope.  (2) First observe it under the low power and then is high power.  Observations: - (1) The mammalian testis is covered by a thick fibrous tissue called tunica albuginea.  (2) Outermost layer of testis is tunica verginalis.  (3)Testis have 250 compartments of testicular lobules, each contains 1to 3 highly coiled seminiferous tubules.  (4)Spermatogonia are formed from germinal epithelium of seminiferous tubules.  (5)Long cells known as Sertoli cells are present in testis which nourishes the Spermatogonia.  (6)Sperms can be observed collected in the centre of seminiferous tubules.  (7) Interstitial tissue also contains leydig cells which provide sex hormone – testosterone, dermal cells are in the sequence.  SPERMATOGONIA > SPERMATOCYTES >  SPERMATIDS>SPERMATOZOA > SPERMS  PRECAUTION: - (1) Try not is touch the slide with our naked figure.  (2)Slide should be first focused in low power then in high power.  (3)Use fine adjustment while focusing the slide under high power of microscope.
• 29. PRACTICAL-9  Aim- To study meiosis in onion bud cells through permanent slide.  Requirements- 1. Permanent slide of different stages of meiosis in bud cells. 2. Microscope. Observations - Under the high power of microscope following stages of meiosis were distinctly observed:  MEIOSIS- I 1. Prophase - It was of long duration and had five sub-stages: (a)Leptotene  Chromatin fibres were condensed and formed thick thread like structures called chromosomes.  Nuclear envelope nucleolus was distinct. (b)Zygotene  Homologous chromosomes were formed in pairs called bivalent. This pairing was called synapsis.  The individual of a pair were similar in length and in position of their centromere. (c)Pachytene  The two chromatids of each chromosome became visible, so that a bivalent would become a tetrad.
• 30. Crossing over (exchange of chromatids segments between homologous chromosomes had taken place between non-sister chromatids of homologous chromosomes.) (d)Diplotene  The two chromosomes of each bivalent moved away and homologous were held together at one or more points called chiasmata. (e)Diakinesis  Homologous chromosomes appeared were thick and ring shaped.  Nucleolus and nuclear envelope were disappeared and spindle began to be formed. 2. Metaphase I–  The bivalent (homologous chromosomes) arranged themselves at the equator of the spindle  The spindle got attached to the centromere of the chromosome. 3. Anaphase I i) The two chromosome of each bivalent moved to the opposite pole. ii) Each pole has half the number of chromosomes with two chromatids each. 4. Telophase I i) The chromosome at each pole uncoils, and nucleolus and nuclear envelope reappeared. ii) Cytokinesis taken place to form two haploid daughter cells.
• 31. Interkinesis A very short interphase might have been intervened between meiosis I and meiosis II. B. Meiosis II It include following four stages --- 1. Prophase II (i) The chromosomes of daughter cell began to condense and become thick. (ii) Nuclear envelope and nucleolus started disappearing.. 2. Metaphase II (i) The chromosomes were arranged on the equator of the spindle. (ii) Each chromosome was held by the spindle at the centromere to both the poles. 3. Anaphase II (i) The sister chromatids (daughter chromosomes) of each chromosome got separated and started migrating towards the opposite poles. (i) Each pole, thus received haploid number of chromosomes. 4.Telophase II (i) They began to uncoil and became thin. (ii) The nuclear envelope and nucleolus were reconstituted. Cytokinesis occurred and four daughter cells are formed, each with haploid number of chromosomes.
• 32. Precautions 1. Floral buds have been fixed between 8 to 10 AM. 2. Slide was warmed gently to avoid overheating. PRACTICAL 10
• 33.  Aim: To study the t.s of blastula through permanent slide.   Apparatus required: Permanent slide of blastula, microscope.   Procedure: 1) We fix the slide of t.s blastula under the microscope. 2) We observe the slide under low power and the high power microscope.  Observations: 1) It is a spherical, mass of 64 cells. 2) It is composed of an outer envelope of cells, the trophoblast and the inner cell mass, embryo blast. 3) Within the envelope there is a fluid filled space called blastocoel. 4) The inner cell mass is the precursor of embryo. Precaution: adjust the power of the microscope very careful and finely.
• 34. PRACTICAL 11  Aim: -To study the prepared pedigree charts of genetic traits such as rolling of tongue, widow’s peak, colour blindness.  Requirements: -Prepared pedigree chart of the genetic traits.  Procedure: -The given pedigree charts were observed and comments were written on it.   Problem 1 (Inability to roll the tongue) Inability to roll the tongue appears in the progeny due to recessive gene. So the possible genotype of the family members was found through the following pedigree.
• 35. Analysis:- The trait is present in the father parent due to presence of two recessive genes [I- 2 (aa)].The trait can appear in the progeny only when it becomes homozygous recessive. Since only one of their progeny carries the trait, the mother parent must be heterozygous (test cross- Aa × aa = 50% heterozygous, 50% recessive). So I – 1 is (Aa ), II -1is (aa ) and II-2,II-3, II-4 are heterozygous and therefore( Aa). The cross between II-1 and her husband also produces one homozygous recessive [III-2 = (aa)]. This is possible only if the outsider is heterozygous (Aa). Naturally III-1 is also a heterozygous (Aa). II-3 is heterozygous (Aa). Her husband can either be heterozygous (Aa × AaAA,2 Aa, aa) or homozygous dominant (Aa × AA 2AA, 2Aa). Since none of the progeny is with recessive rolling tongue the possibility is that the new entrant in the pedigree is homozygous dominant (AA). Therefore III-3, III-4, III-5, are either AA or Aa.  Problem 2 ( Widow’s Peak)) In the pedigree below, it was determined whether the shaded symbols belonged to dominant or recessive trait. The genotype of the whole pedigree was also analyzed.
• 36. Analysis: - Since the shaded symbol appears in all the offspring, father must be homozygous dominant while the mother homozygous recessive (AA × aa= all Aa) because in all other cases this possibility is absent (Aa × aa = 2Aa+2aa; aa × AA = all Aa; aa × Aa = 2aA + 2aa). All of theII generation will, therefore, be heterozygous (Aa). This is further confirmed by marriage of II- 1 with homozygous recessive (Aa × aa = aa + Aa) bears children of both the parental types. Marriage of II- 3 with the homozygous recessive can produce both recessive and heterozygous.  Problem 3 (Colour Blindness ) Colour blindness is a sex linked recessive disorder of humans. The pedigree chart given below shows the inheritance of colour blindness in one family. So the possible genotype of the members of 4, 5 and 6 in the pedigree chart was found. Analysis: - The allele for colour blindness is present on X chromosome (Xc), while the chromosome Y does not bear corresponding allele for this character. A male has only one X chromosome, which he receives from his mother. He is colour blind if his mother is carrier. A female becomes colour blind, when her mother is a carrier and father is colour blind. Thus, in the above case the genotype of number 4 will be XX, that of member 5 will be XcY and that of member 6 will be XY. Thus the possibility of 1st child to be colour blind will be ¼ = 25% if a carrier woman marries a normal man.
• 37. PRACTICAL 12  Aim: To identify common disease causing organisms like Ascaris, Entamoeba, Plasmodium, any fungus causing ringworm through permanent slides, models or virtual images. Comment on symptoms of diseases that they cause.  Principle: There are a large number of organisms which are pathogenic /parasitic to humans. These organisms substantially damages human body and cause diseases, which may be fatal sometimes. Characteristic morphological features are identified in these organisms and the symptoms are carefully observed to study the proper behavior of the organisms.  Materials required: preserved specimen / permanent slide / photographs of Ascaris, Entamoeba, Plasmodium, ring worm fungus (Trichophyton), compound microscope  Procedure : 1. The preserved specimens/permanent slides /photographs of the organisms are observed. 2. Their characteristic features are noted in the record book 3. Carefully the diagram of the pathogen is drawn and labeled.  Observation
• 38.  Ascaris The following features are observed:-  Body long (20 to 40 cm), cylindrical (5 to 6 mm diameter), no segmentation is seen.  Sexes are separate; the females are longer than the males.  Both the ends are pointed; posterior end of male is ventrally curved.  Mouth is situated at the anterior end and is surrounded by three lips.  Excretory pore is present on the ventral Surface slightly behind the anterior end. Systematic position: Phylum: Nematoda Class: Chromadorea Type: Ascaris lumbricoides  Disease caused by Ascaris lumbricoides: Ascaris is the common intestinal multicellular organism which causes Ascariasis. Symptoms:  Symptoms increase with the number of worms present and may include shortness of breath, fever, abdominal pain and diarrhea in the beginning of the disease.  Irregular bowel  Occasional vomiting  Anaemia
• 39.  Entamoeba The following features are observed:-  It is unicellular  Shape is irregular and presence of pseudopodia is seen.  Eccentrically located single nucleus is seen.  In the nucleus a peripheral ring of granule of nucleoprotein and central karyosome are observed. Rest of the space in the nucleus looks empty.  Contractile vacuoles are absent but many food vacuoles can ob observed. (Mature quadric nucleated cysts may be present. Systematic position: Phylum: protozoa Class: Tubulinea (Superclass: Rhizopoda) Type: Entamoeba histolytica  Disease caused by Entamoeba: Entamoeba is an intestinal parasite in humans and causes amoebic dysentery. Symptoms:  frequent loose  mucus filled watery stools  abdominal pain and spasms  Plasmodium vivax
• 40.  The following features are observed-  It is an intracellular endo parasite seen easily within the RBC of the infected person.  It is unicellular.  The most diagnostic stage of the parasite is "signet ring" stage in the erythrocytes, within which it appears as a rounded body.  It has a big vacuole inside, and the cytoplasm is accumulated at one place containing the nucleus. Because of the above mentioned features, the parasite appears as a ring. Systematic position Phylum – Protozoa Class – Sporozoa Type – Plasmodium vivax  Disease caused by Plasmodium vivax : Malaria Symptoms:  Intermittent high fever with chills which is followed by profuse sweating at an interval of alternate days.  Trichophyton (Ringworm Fungus) The following features are observed:-  It is a complex multicellular organism.  Circular shape of the ring worm is observed.  Texture of hyphen is waxy, glabrous to cotton like can be detected.
• 41.  Unstained hyphae (white), yellowish Brown to reddish Brown in colour can be seen. Systematic position: Kingdom: Fungi Class: Deuteromycetes Type: Trichophyton rubrum  Disease caused by Trichophyton: Ringworm is a contagious fungal infection of the skin. Symptoms:  It typically begins as rash with a clearly defined border.  Infected area of the skin is itchy, red, raised, scaly patches.  It is redder on the periphery than in the centre creating a ring like appearance.
• 42. PRACTICAL 13 Aim:-To study the morphological adaptations of two plants and two animals (models/virtual images) found in xeric conditions. Requirements:-Virtual images or models of two plants and two animals found in xeric conditions. Observation:- 1. Capparis decidua Comments  It is a drought enduring non-succulent xerophyte.  The leaves do not open completely and remain on the plant for very short period to reduce transpiration.  The stipules are modified into slightly curved spines to reduce transpiration and check grazing.  The function of photosynthesis is mainly carried out by green stem.  2. Acacia arabica Comments  It is a xerocoles rodent, which avoid heat by adapting nocturnal habits ( i.e active in the nights ).  It conserves water by excreting solid urine and can live from birth to death without drinking water.  It seal its burrow by day to keep its chamber moist.  It obtains water from its own metabolic processes and from hygroscopic water in its food. 3. Kangaroo Rat Comments  It is a xerocoles rodent, which avoid heat by adapting nocturnal habits (i.e active during night).  It conserves water by excreting solid urine and can live from birth to death without drinking water.
• 43.  It seal its burrow by day to keep its chamber moist.  It obtains water from its own metabolic processes and from hygroscopic water in its food. 4. Camel Comments  It is a 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 upto 25% of its body weight.  It accumulate its fat in the hump rather than all over the body. This speeds heat flow away from the body and its thick coat prevents the flow of the heat inwards to 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 wind blow sand.
• 44. PRACTICAL 14  Aim: study of two plants and two 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 water bodies containing fresh water.  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 petioles of the leaves are inflated that keep the leaves out of water.  The emerged leaves have waxy and cuticular coating to keep it waterproof. 2. Nelumbo nucifera (Sacred lotus) Comments  The leaves are very wide and disc shaped which allows the lotus to float on water and absorb large amount of sunlight.  The stem and leaf surfaces are coated with a wax which is hydrophobic in nature.  Heat is produced from the flower, stem, roots and leaves which regulate the surrounding water temperature.  Birds and insects are attracted towards them due to their brilliant colors.  The seeds are distributed through water. A hard nut-like fruit is formed after blooming and fell in water after it is dried out.
• 45. 1. A Freshwater Fish (Rohu or Carp) Comments  Its body is compressed laterally to reduce friction and to allow it swift passage in the water while swimming.  It has fins that help in swimming.  It has an air bladder which maintains buoyancy.  It has gills as organs of respiration for the exchange of gases underwater.  The body is covered with impermeable scales to prevent the osmotic entry of water inside the body. 2. Scyphozoa(True Jellyfish) Comments  Its tentacles bear nematocysts which helps them in their defense and to capture their prey.  It has umbrella-shaped bells which pulsate to provide propulsion and highly efficient locomotion.  It exhibits two morphological body plans, the polyp which is sessile and the medusa which is mobile.  Gases are diffused through the epidermis of the jelly fish.
• 46. APPENDIX

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Biology practicals class xii, study of pollen germination :.

Our Objective

What is pollination ?

Learning outcomes:, students understand the term pollination., students understand how pollen germinates., students do the experiment better in the lab if one has gone through the animation and written text of theory & biological phenomena behind it., materials required.

 Lab Procedure

Prepare the pollen germination medium by dissolving 10 grams sucrose, 10 milligrams boric acid, 30 milligrams magnesium sulphate and 20 milligrams potassium nitrate in 100ml of distilled water.

Using a glass rod, stir the solution to mix it well., using a dropper, take some nutrient solution and put two drops on a clean glass slide., take a mature flower and dust a few pollen grains from its stamen on to the drop on the slide., after 5 minutes, place the glass slide on the stage of the compound microscope., observe the slide through the microscope regularly for about half an hour..

Observations

Viva-Voce [Study of Pollen Germination]

Additional Resources / Sources :

Laboratory Manual Biology for class XII - Published by NCERT.

https://en.wikipedia.org/wiki/Pollination   http://sciencelearn.org.nz/Contexts/Pollination/Science-Ideas-and-Concepts/Pollination-and-fertilisation   http://www.britannica.com/science/pollination   https://en.wikipedia.org/wiki/Pollen_tube   https://en.wikipedia.org/?title=Pollen   http://www.nuffieldfoundation.org/practical-biology/observing-growth-pollen-tubes

Significance & Overview Of Biology Class XII Practicals 

There are altogether twenty-five exercises in the present manual which are based on Biology curriculum for Class XII.

• CBSE Class 12
• CBSE Class 12 Biology Practical

Study Pollen Germination On A Slide

To study pollen germination on a slide.

Necessary Materials & Apparatus

Freshly plucked seasonal flowers, beaker, boric acid, sucrose, microscope and cavity slide.

The first step involves the preparation of a nutrient solution. This is done by dissolving 10g of sucrose as well as 10mg of boric acid in 100ml of water.

Pour a few drops of this solution onto the cavity slide. Then, use a brush or fingers to gently dust a few pollen grains from the stamen of mature flowers.

Let the slide set for 5 mins. Then, use the microscope to view the slides in 30-minute intervals.

Observation

The pollen grains will germinate when submerged in the nutrient-rich medium. This is characterized by the enlargement of the vegetative/tube cell. It emerges through one of the germ pores, eventually forming a pollen tube. The generative cell nucleus grows into the pollen tube and makes two male gametes (sperm nuclei). The male gamete is either spherical or lenticular in outline.

Precautions

• Ensure that the flowers are freshly picked
• The observation slide should be a cavity slide, meaning that it has a depression in the centre.

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

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BIOLOGY, EDUCATION

EX- PGT (BIO) OF KENDRIYA VIDYALAYA & DENOBILI MUGMA DHANBAD

BIOLOGY PRACTICAL CLASS XII CBSE

can we edit it as per requrment to look it better

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As already mentioned some experiments are missing,I would like to ask should we write principle as well? My teacher is asking to write principle also ,so what to do?I m waiting for your precious answers. Thanks and regards Bhupender Singh

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To Prepare a Temporary Mount to Observe Pollen Germination

CBSE Biology Experiment - Prepare a Temporary Mount to Observe Pollen Germination

Do you know some pollen grains are thousands of years old? But how are these pollen grains still alive? These pollen grains have a hard sporopollenin layer resistant to all environmental changes. Pollen grains are the male gametophyte of flowering plants. Initially, pollen grains are uninucleated, but later they become multinucleated by dividing into vegetative and generative cells. Pollen grains germinate on the stigma and divide into two types of cells. Vegetative cells convert into pollen tubes, and generative cells convert into male gametes.

Table of Content

Apparatus required, observations.

Precautions

Lab Manual Questions

Viva questions, practical based questions.

To prepare a temporary mount to observe pollen germination. 

Freshly plucked flower

Boric acid(10mg)

Sucrose(10g)

Magnesium sulfate 

Calcium nitrate

Pollen germination is defined as the physiological or chemical changes in the pollen grains. Various events occur during pollen germination. Some of the events are described below: 

Pollen Attachment 

Pollen after shedding from the flower is attached to the stigma (only if the stigma allows pollen to attach).

Pollen Tube Growth 

After attachment, the intine layer gets hydrated and ruptures the exine layer and the stigma releases various nutrients such as boron and calcium for pollen grains. Then vegetative cells convert into a pollen tube inside a pistil and make way for male gametes. The entire content of the pollen grain goes into the pistil through the pollen tube.

Pollen-Pistil Interaction 

Pollination does not always ensure the transfer of the right type of pollen. Sometimes incompatible pollen may reach some flowers. So, there is a mechanism to identify whether the right type of pollen is transferred or not. That mechanism is known as pollen-pistil interaction. Only compatible pollen can germinate and produce a pollen tube. It is a dynamic process and involves pollen recognition followed by approval or denial. If it is the right type and compatible pollen it will be accepted by the stigma, if it is incompatible or the wrong type of pollen, it will be rejected by the stigma.

First, we will prepare a nutrient solution for pollen grains,

For this, we have to dissolve 10g sucrose and 10 g boric acid in water. 

After dropping this mixture on a cavity slip using a dropper,

Then brush off a few pollens grains on this mixture using a brush and keep the solution untouched for 5 minutes,

After 30 minutes place this slide under a microscope to see pollen germination, and then observe it regularly for about half an hour.

The pollen grain will germinate after submerging sometimes in nutrient media.

During germination, pollen grain divides into two cells- a vegetative cell and a generative cell. Later on, this vegetative cell converts into a pollen tube through which male gametes come out of the pollen grain. Two male gametes are formed by the division of a generative cell. Male gametes may be lenticular or spherical. Pollen germination under a microscope can be seen for about half an hour. 

Pollen germination can be observed when a slide is placed under a microscope.

Precautions 

Following precautions must be taken while experimenting.

Always use a new slide for dusting pollen grains.

Flowers used for the experiment must be freshly plucked,

Only a few drops of nutrient media  should be used,

Mounting should be free from air bubbles.

Staining should be proper and moderate.

1. What is the shape of a pollen grain?

Ans: Pollen grains are of various shapes. Some are circular, globular, lenticular, etc. 

2. What is the composition of the wall of pollen?

Ans: Pollen grain has two layers: intine and exine. Intine is made of cellulose and pectin, whereas exine is made of sporopollenin.

3. What is the importance of tectum to taxonomists?

Ans: I t helps taxonomists to identify the type, nature, and family of the pollen grain.

4. What is a tectum?

Ans: Tectum is the innermost layer of the microspore.

1. What is palynology? 

Ans:  study of pollen grains of plants, spores, and some microscopic organisms..

Ans: The outer wall of the pollen grain is composed of sporopollenin, and the inner wall is composed of cellulose and pectin. 

3. What is a tectum?

Ans: Tectum is like protrusion on a pollen grain's outer surface or spore.

4. What is the shape of the pollen grain?

Ans: There are a variety of shapes of the pollen grain; some are spherical, some are cylindrical, and some are oval. 

5. What are the different types of cells of pollen grain? 

Ans: There are two types of cells in pollen grain - one is vegetative and another type is generative cell.

6. What is the importance of tapetum?

Ans: Tapetum is the innermost layer that provides nutrition to developing pollen grains.

7. Why does pollen survive for many years?

Ans: Pollen grains can survive for many years because of the presence of the sporopollenin layer, which is the hardest substance.

8. What is the importance of germ pores?

Ans: Germ pore helps male gametes to come out of pollen grain, it makes a pollen tube through which male gametes come out of pollen grain.

9. Why do some athletes use pollen as an energy source?

Ans : Pollen grains are a very rich source of nutrients, they contain large amounts of nutrition, and that's why athletes use pollen as a source of energy.

10. What is the meaning of viability?

Ans: Viability Means the ability to survive in adverse conditions.

Q1. Name the area of the pollen grain where the tube arises.

Sporopollenin

None of the above

Ans: (1) Germ pore

Q2. Which solution is used for pollen germination?

Methylene blue

Ans: (2) Sucrose

Q3. If there are 20 pollen grains, then how many meiotic divisions will occur?

Ans: (1) 5 meiotic division 

Q4. Which of the following is not a layer of microsporangium?

Endothecium

Middle layer

Epithelial layer

Ans: (3) Epithelial layer

Q5. Who induces pollen germination?

Ans: (3) Boron

Q6. Which stain is used for pollen fertility?

Saccharine 

Ans: (3) Iodine 

Q7. Why is potassium nitrate used for pollen germination?

To Slow metabolism

To increase metabolism

Both of the above

Ans: (2) To increase the metabolism 

Q8. Who is responsible for pollination?

All of the above

Ans: (4) All of the above

In this article, we have studied pollen germination class 12 practical experiment. Pollen germination can be studied by dusting pollen grains on the slide and observing them under a microscope. We can see pollen grains dividing into vegetative and generative cells

We can also observe the growth of the pollen tube.

FAQs on To Prepare a Temporary Mount to Observe Pollen Germination

1. Why do some pollen grains fail to germinate?

There are many reasons for not germinating all pollen grains. Some of the reasons are given below:

Sometimes the right type of pollen does not transfer to the stigma, so it is an incompatible type of pollen grain, and the stigma rejects it and does not let it germinate 

All pollen tube length is not of the same size. Sometimes the length of the pollen tube is too short, so it can't germinate

Even in our experiment, some pollen grains have not germinated because of the improper nutrient mixture.

2. What factors affect pollen tube growth?

There are various factors affecting pollen tube growth: 

Enzymes - Various enzymes such as cellulose and pectinase affect the growth of pollen tubes while pollen germination 

Carbohydrates - A little sugar is also used for pollen growth. Because sugar prevents the bursting of pollen grains while landing on the stigma 

Boron - Boron is an important element for pollen tube growth. Stigma secretes large amounts of boron while pollen germination because pollen grains are deficient in this element.

Calcium - calcium is also an essential element for pollen tube growth

3. Explain about different types of entries of pollen tube into the ovule

After germination on the stigma pollen tube reaches the ovule. Now depending on the entry of the pollen tube into the ovule, it is of three types.

Chalazogamy - In this pollen tube enters through the chalazal end. This type of entry occurs in the casuarina flower.

Porogamy - In this entry, pollen tube occurs through a micropyle pore. This type of entry takes place in a lily flower. 

Mesogamy-. In this type, entry of the pollen tube into the ovary occurs through funicles or integuments. This type of entry takes place in Cucurbita.

Notes For Free

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Study Pollen Germination on a Slide

Aim :  To study pollen germination on a slide.

Apparatus and materials required : Fresh seasonal flower slides, microscope, beaker, cavity slide, boric acid, sucrose.

Procedure :

Prepare a nutrient solution by dissolving 10g sucrose and 10 mg boric acid in 100 ml water.

Take a few drops of this solution on a clear slide, dust a few pollen grains from the stamen of a mature flower in it.

Obverse the slide under the microscope after 5 minutes. Keep observing the slide regularly after intervals of half an hour.

Observations :

In a nutrient solution or nutrient-rich medium, the pollen grains germinate. The tube/vegetative cell enlarges and comes out the pollen grains through one of the germ pores to form a pollen tube. The generative cell nucleus soon passes into it and dives to make 2 sperm nuclei (male gametes). Each male gamete is lenticular to spherical in outline.

Precautions :

Flowers should be freshly picked

Use a clear cavity slide to observe pollen grain

You can also get Class XII Practicals on  Biology ,  Physics , and  Physical Education .

33 Replies to “Study Pollen Germination on a Slide”

Please post the clear pictures please

Also give result and conclusion of the experiment

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Haan Arshan darna nahi hai ham tumhare saath hai ……

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😈😈😈👻👻👻💀💀💀💀💀💀💀💀💀💘💘😈😈😈😈😈😈👻💯💯😡😡😡😡😡😡👿👺👺👺👺👺👺👹👹👹👹👹👽👽👽👽👽👾👾👾👾💪💪☁☁☁☁☁☁☁ ☀ 🐦 🐧 🐤 🐦 🐤 🐧 🐦 🐔 🐥 🌻🌻🌹🌷🌷🌳🌳🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🔌🔋🔋📲🎂🎁🎉👑🎉🎉🎉🎊🎊🌞🌴🏄🎇🎂🎁🎉👑🌞🌴🏄🎇🌞🌴🏄🎇📮 ___ 💌👨💓👩😊👍✨🏡🚗💨😊👍✨👨💓👩👨💓👩👨💓👩😊👍✨〰〰〰〰〰 〰〰🍒〰〰 〰🍰🍰🍰〰 🍥🍥🍥🍥🍥 🍰🍰🍰🍰🍰 🍥🍥🍥🍥🍥 〰〰〰〰〰 〰〰〰〰〰❕🔥❕🔥❕🔥❕ ❕📍❕📍❕📍❕ 🍰🍰🍰🍰🍰🍰🍰 🍥🍥🍥🍥🍥🍥🍥 🍧🍧🍧🍧🍧🍧🍧 🍰🍰🍰🍰🍰🍰🍰 ❕➖➖➖➖➖❕❕🔥❕🔥❕🔥❕ ❕📍❕📍❕📍❕ 🍰🍰🍰🍰🍰🍰🍰 🍥🍥🍥🍥🍥🍥🍥 🍧🍧🍧🍧🍧🍧🍧 🍰🍰🍰🍰🍰🍰🍰 ❕➖➖➖➖➖❕ 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗🐝🐝🐝🐝🐝🐝 🌼 Hi, honey! 🌼 🍯🍯🍯🍯🍯🍯 🌼🌼🌼🌼🌼🌼 🌱🍃🌱🌱🍃🌱💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗💗✉✉💗✉✉💗 💗✉✉💗✉✉✉ 💗💗💗💗✉✉💗 💗✉✉💗✉✉💗 💗✉✉💗✉✉💗🐝🐝🐝🐝🐝🐝 🌼 Hi, honey! 🌼 🍯🍯🍯🍯🍯🍯 🌼🌼🌼🌼🌼🌼 🌱🍃🌱🌱🍃🌱 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🍥 🌰 🍥🍓 🌰 🍥🍥🍥🌰 🍥🍓🍥🍥 🍥🍥🍥🍥🍥 🏉🏉🏉🏉🏉 🏉🏉🏉🏉🏉 🏉🏉🏉🏉 🏉🏉🏉 🏉🏉🏉 🏉🏉🏉

op bhay op 😜😜🤣😜🤣

Please give the conclusion

Plz give the clear pic

Send me plz clear picture

Why Boric acid is added?

Thanks!! This is really very helpful 😊😊

THANKS !! THIS IS REALLY VERY HELPFUL 😊😊

Thanks!! This is really helpful 😇😇

This helped a lot thanks for posting

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Biology 2023

• Multiple Choice

Subject : Biology Class 12

School : delhi public school, damanjodi.

• Discover more from: Biology Class 12 150   documents Go to course

• More from: Biology Class 12 150   documents Go to course

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