Think Work VM Knowledge

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 2. Separation of plant (photosynthetic) pigments by paper chromatography Aim:  Separation of plant (photosynthetic) pigments by paper chromatography.  The plants show the presence of many pigments.  The different photosynthetic pigments present in the leaf cells are chlorophylls, carotenes, and xanthophylls.  These photosynthetic pigments can be separated using the technique of paper chromatography.  Principle The separation of solutes (chloroplast pigments) is based on the liquid-liquid partitioning of pigments in paper chromatography.  The partitioning takes place between the solvent (water) molecules (static phase) adsorbed to the cellulosic matter of the paper (capillary action organic (mobile) phase.)  Requirements -  Chromatography chamber, chromatography paper (Whatman's filter no.1), pestle - mortar, capillary tube, muslin cloth, suitabl

Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII  Class-12th science Click here download in PDF 15. To study various syndromes and their karyotypes in human beings.   Alm -  To study the various syndromes and their karyotypes.  A karyotype is a name given to the whole group of characteristics that allow the identification of a particular chromosome set.  It includes the number and size of chromosomes that are constant for a species.  Chromosomes are arranged in a series of decreasing lengths representing what is called an idiogram.   The characteristics of chromosomes in making an idiogram are a number, length, position of the centromere, secondary constrictions, length of chromosome arms, arm ratio, banding pattern, etc.  The position of the centromere is different in different chromosomes but it is always constant for a particular chromosome.  You have already studied four different shapes of chromosomes based on the position of the centromer

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 1. To detect the presence of starch added as an adulterant to the milk.   A Biter-proof starch added adulterants to the milk.  come animal source cow/buffalo), etc.  The pipettes,  1 iodine solution, milk samples (minimum 3, preferably will They Addition of much increases the SNF (Solid Not Fat) content of milk. Wheat flour, I flour can be added for increasing the SNF (Solid Not Fat) content.  Starch proper synthetic milk, which is, then added to natural milk. This is commonly used opposite for the added water. Since the starch powder is easily and cheaply available, it is the adulterant to milk, after water. Procedure Measure out 3ml milk into a  test tube/container.  2. Keep the test tube for incubation in a boiling water bath for 5 minutes.  3. After incubation, cool the test tube, add a few (2-3) drops of 1% iodine solution and mix the contents

  Practical Notebook Biology Standard XII Biology  Answered. Practical Notebook Standard XII Class-12th science Click here download in PDF 12. To examine the presence or absence of Barr body in the given sample.   Alm:  To observe Barr bodies in squamous epithelial cells obtained from the inner lining of the check (Buccal smear).  Requirements: Cotton buds, slide saline solution, 70% alcohol, Giemsa / Methylene blue stain compound microscope, etc  Procedure:  Clean the mouth by rinsing and gargling with water, several times.   Take a sterile cotton bud and in normal saline solution   Rub it on the inner lining of the cheek several times.   Smear the bud on a clean slide and allow it to dry.   Place the slide in a Petri dish.  Layer it with a fixative (70% alcohol).    Allow it to stand for a few minutes.    Drain off the extra fixative.    Stain the smear with Giemsa / Methylene Blue and wait for 10 minutes.    With the help of a dropper gently wash off the excess stain with water.  

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 13. Detection of commonly used adulterants in milk   The most common adulterants found in milk are urea, insecticides, NallCO,, vegetable oil, sucrose, starch, etc.   Aim:  To detect the presence of excess water added to the milk by using a lactometer.  Requirements: Lactometer, measuring cylinders (500 ml capacity), thermometer, and milk samples (minimum 3, preferably raw milk, of the same animal source cow/buffalo)  Theory:  Animal husbandry plays a major supporting role in the rural economy.  Milk collection centers and cooperative societies play an integral role in delivering the milk from the cowsheds to the customers.  The addition of water to milk can be a big problem.  Hence water content of the milk is checked at any level before it reaches the customer.  Pure milk has a specific gravity of 1-032; the addition of water to it reduces this va

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 9. Isolation of DNA from Given Sample  Aim:  To extract and isolate DNA from a fruit sample.   Requirements: -  Fleshy berry fruits like banana, Zizyphus, grapes, etc, can be used.  Fleshy fruits of banana, liquid soap, distilled water, salt (NaCl), 1000 ml ice-cold isopropyl alcohol i.e.  IPA (Chill the alcohol (IPA) by placing the test tube in a beaker containing ice cubes and some water] measuring spoons, glass stirring rod, test tubes, glass beakers, plastic cups, strainer or coffee filter, funnel, etc. Principle:  All plants' DNA extraction protocols comprise the basic steps of disruption of a cell wall, cell membrane, and nuclear membrane to release the DNA into solution followed by precipitation of DNA and ensuring removal of the contaminating biomolecules.  A figure is separated by physical means such as grinding,  to form a mash  The ce

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 10. Dissect and display floral whorls.  Dissect another and take T.S.  or V.S.  of the ovary to show pollen grains and locules of the ovary, respectively.    Aim:  To dissect given flowers to study and display different whorls.  Dissect anther and ovary to show a number of locules (chambers).   Requirements: -  Flowers such as Brassica or Hibiscus.  Forceps, razor blade, slides, two needles, coverslips, dissecting microscope, paper, etc.  Ced  Procedure: -  Observe different floral whorls such as calyx, corolla, androecium, and gynoecium.  Take out each floral whorl carefully and arrange them in proper ascending order on white paper.  Count the members of each whorl and also note down, if there is cohesion or adhesion between the members of the same whorl or different whorls.  Mount the anthers on the slide and observe them under a lens or dissectin

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 11. To study wing shape and eye color in Drosophila.   Aim:  To study the genetic variation of traits in Drosophila melanogaster.  Requirements: Glass jar, petri dish, banana pieces, muslin cloth, bell jor, slide, coverslips grated series of school, fine, DP%, etc. Procedure L Preparation of culture beds:  Peel the ripe banana fruit.  Discard the skin and mash the fruit into a soupy pulp.   Take a clean sterilized glass jar or Petri dish and place the banana pulp in it.   Add a few grains of yeast.   Keep a small blotting paper to absorb excess moisture from the pulp and also to provide a substratum for the pupation of the larvae.   Many culture beds can be prepared by the above method for the different varieties of a fruit fly.  II The culturing of Drosophila  The pulp in the culture beds attracts the Drosophila.  Cover the culture beds with a bell

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 8. Study of population density and frequency of different plant populations, by quadrat method.   Aim:  To study population density and frequency of plant population by quadrat method.   Principle:  All the different types of individual plants growing at a particular space or geographical area at a particular time, form (constitutes) the plant population of that area.    It changes from time to time and may increase or decrease due to many different factors.   The number of individuals of a species present per unit area at a given time is called population density.  6. Population density = 4.  The population density (D) can be calculated as D = N / S.  where N Number of individuals of a species and S- Units of space or area (no. of quadrats).  MS  The population density can be determined by marking quadrats of suitable size and recording the number