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  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 8. Study of plants found in xerophytic and aquatic conditions/habitats.  And comment on their adaptations  Introduction:  Adjustment (acclimatization) of plants and animals for their survival and perpetuation, to their environment by means of special structures or functions, is known as adaptation The plants that can grow and survive in deserts, dry conditions of soil, and high temperature, are called xerophytes.  All xerophytes show adaptations to reduce the loss of water due to transpiration.  Some xerophytes show the presence of stored mucilage in the plant parts that help in retaining water.  Some plants have latex, that helps retain water and seal the place of injury.  E.g.  Euphorbia, Calotropis, Acacia, Opuntia.   The plants that grow in abundance of water are, called hydrophytes.  They are generally adapted to remain buoyant and avoid the dec

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF https://drive.google.com/file/d/10NrtEg6k0Hh8ttkenvZvI2EzFqZN8vPr/view?usp=sharing 7. Study of meiosis in onion flower bud with the help of permanent slides.  Aim:  To study and identify different stages of meiosis.  Principle 1 Meiosis is a special type of cell division that occurs in the diploid reproductive or germ tissue (cells).  It is a reduction division that results in the formation of four haploid daughter cells each receiving half of the total number of chromosomes than those present in the mother cell from which it is produced Observation For the preparation of meiosis slides, generally, anther of Lily or Onion is used.  Meiosis can be studied with the help of stained permanent slides of T. S. of the anther.  Permanent slides should be observed under the high power of a compound microscope.  Meiosis is a process that occurs in two steps vi

Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF T.S.  Testis: Date Internal structure of testis shows the presence of tunica albuginea and seminiferous tubules.  Testis 6. Study of T. S. testis, T. S. ovary, and V. S. of blastula, through permanent slides.  Is externally covered by fibrous connective tissue called tunica albuginea.  It is internally covered by tunica vascularis formed by capillaries and externally by an incomplete covering called tunica vaginalis.  Seminiferous tubules are lined by cuboidal germinal epithelial cells.   It shows different stages of spermatogenesis lic spermatogonia, primary and secondary spermatocytes, spermatids, and sperms.  Few large pyramidal cells are present interrupting germinal epithelia are nurse cells or Sertoli cells.  Sperm bundles get attached to Sertoli cells with their heads.  The function of Sertoli cells is to provide nourishment to the sperms till

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF 5. Study of V. S. of anatropous ovule through a permanent slide / relevant chart.   Ovule (megasporangium) is enclosed in the ovary.   There may be one or many ovules in an ovary.   Alm:  Study of anatropous ovule and functions of its various parts.  .  The ovule in which micropyle, chalaza, and funicle are not in one straight line and integuments run parallel to funicle is called as anatropous ovule.  It is also called an inverted ovule and is the most common type of ovule, in angiosperms, The ovule shows two main parts - body and funicle.  Body The body shows two integuments originating from the base of the ovule reaching up to the tip of the ovule.   The tip shows a small cleft, left by two integuments called a micropyle.  The integuments enclose a mass of fertile, parenchymatous, diploid cells called nucellus.  There is only one fertile cell loc

  Practical Notebook Biology Standard XII Biology  Answeres Practical Notebook Standard XII Class-12th science Click here download in PDF B. DEMONSTRATION EXPERIMENTS 1. Comparative study of rates of transpiration in the upper and lower surfaces of the leaf, using four-leaf experiment.  7 Loss of excess water in the form of vapor through the aerial parts of the plant is called transpiration.  Aim: To study the comparative rate of transpiration in the upper and lower surfaces of a leaf by conducting four-leaf experiments.   Requirements: -  Two stands, thread, four leaves of Calotropis / banyan tree, Vaseline (petroleum jelly), etc.  Fig.  Comparison of transpiration, a demonstration by four-leaf experiment Apply Vaseline to leaf surface in the following manner,  1. Leaf A: - Petroleum jelly is applied on both surfaces  Figure: Procedure:  The leaves selected should be healthy preferably of the same size and showing growth.  Tie the different leaves of the same plant with thread in suc

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.