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    Bio Expt Last 2

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    SUMAIRA ALTAF
    This document summarizes two experiments: 1) The first experiment aims to study symbolic association in root nodules of leguminous plants, Cuscuta parasites on host plants, and lichens. It provides background on nitrogen fixation in legume root nodules, Cuscuta parasites withdrawing nutrients from host plants, and the mutualistic relationship between algae/cyanobacteria and fungi in lichens. 2) The second experiment aims to study homology and analogy using models of animal organs. It defines homologous organs as structurally similar but functionally different, like the wings of bats and forelimbs of humans. It defines analogous organs as structurally different but functionally similar, like the

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    Bio Expt Last 2

    Uploaded by

    SUMAIRA ALTAF
    337 views4 pages
    This document summarizes two experiments: 1) The first experiment aims to study symbolic association in root nodules of leguminous plants, Cuscuta parasites on host plants, and lichens. It provides background on nitrogen fixation in legume root nodules, Cuscuta parasites withdrawing nutrients from host plants, and the mutualistic relationship between algae/cyanobacteria and fungi in lichens. 2) The second experiment aims to study homology and analogy using models of animal organs. It defines homologous organs as structurally similar but functionally different, like the wings of bats and forelimbs of humans. It defines analogous organs as structurally different but functionally similar, like the

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    This document summarizes two experiments: 1) The first experiment aims to study symbolic association in root nodules of leguminous plants, Cuscuta parasites on host plants, and lichens. It provides background on nitrogen fixation in legume root nodules, Cuscuta parasites withdrawing nutrients from host plants, and the mutualistic relationship between algae/cyanobacteria and fungi in lichens. 2) The second experiment aims to study homology and analogy using models of animal organs. It defines homologous organs as structurally similar but functionally different, like the wings of bats and forelimbs of humans. It defines analogous organs as structurally different but functionally similar, like the

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    337 views4 pages

    Bio Expt Last 2

    Uploaded by

    SUMAIRA ALTAF
    This document summarizes two experiments: 1) The first experiment aims to study symbolic association in root nodules of leguminous plants, Cuscuta parasites on host plants, and lichens. It provides background on nitrogen fixation in legume root nodules, Cuscuta parasites withdrawing nutrients from host plants, and the mutualistic relationship between algae/cyanobacteria and fungi in lichens. 2) The second experiment aims to study homology and analogy using models of animal organs. It defines homologous organs as structurally similar but functionally different, like the wings of bats and forelimbs of humans. It defines analogous organs as structurally different but functionally similar, like the

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
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    of 4

    EXPERIMENT 10

    AIM-TO STUDY SYMBOLIC ASSOCIATION IN ROOT NODULES OF LEGUMINOUS PLANTS, CUSCUTA ON


    HOST AND LICHENS.

    MATERIALS REQUIRED- Models /specimen of roots of leguminous plant, Cuscuta & Lichen.

    THEORY
    Legumes are able to form a symbiotic relationship with nitrogen-fixing soil bacteria called
    rhizobia. The result of this symbiosis is to form nodules on the plant root, within which the
    bacteria can convert atmospheric nitrogen into ammonia that can be used by the plant.
    The rhizobia are soil microorganisms that can interact with leguminous plants to form root
    nodules within which conditions are favourable for bacterial nitrogen fixation.

    Cuscuta spp. possess no roots nor fully expanded leaves and the vegetative portion appears to
    be a stem only. The parasite winds around plants and penetrates the host stems via haustoria,
    forming direct connections to the vascular bundles of their hosts to withdraw water,
    carbohydrates, and other solutes
    Lichens are organisms that arise from a mutualistic relationship between algae or
    cyanobacteria, and one or several fungal species. They come in many colors, sizes and forms,
    can survive under harsh conditions, and exist in virtually every terrestrial ecosystem on the
    planet.
    EXPERIMENT 11
    Experiment for the Study of Homology and Analogy
    Objective:
    To study homology and analogy with the help of flash card models of organs of animals

    Apparatus and Materials Required:


    Preserved specimens/Flash card models of different organs of animals, compound microscope
    Theory:
    In animals, organs that are functionally dissimilar but anatomically, or structurally, similar are
    called homologous organs. Different modes of life have created the differences, i.e, modified the
    organs to enable them to survive. Analogous organs are those which are functionally similar but
    structurally dissimilar.

    Observation:
    Homologous organs:
    If you externally examine the wings of the flying mammal bat and the forelimb of a man, you will
    not find any similarity.

    But examining the bones one by one, you will find that each of them has arm bone (humerus),
    hand bones (radius-ulna), wrist bones (carpals), palm bones (metacarpals), and fingers
    (phalanges). Of course, in terms of proportions of growth of each constituent bone, there are
    differences.

    For example, the fingers of bat are much longer. What this comparative study suggests is that
    basically the forelimbs of these two creatures are made up of the same parts, that is, they are
    anatomically similar.

    These organs need not perform the same function, as you see that bat uses it for flying and
    man uses it for handling tools. Hence, the forelimb of man and the wing of bat are homologous
    organs. Similarly, forearms of cat and man are homologous.
    Analogous organs:
    Observe the internal structure of the wings of butterfly, or see its preserved specimen, observe
    the shape and size. You will find that it is membranous and is made up of thin cuticle.

    There are veins in the wing but there is no skeleton. Now, take the preserved specimen of a bat
    and a bird, and examine their wings. You will find skeletal support. What does this type of
    comparative study indicate?

    It shows that the basic structures of wings of butterfly, bird and bat are different. In other words,
    they are anatomically different, although externally they look alike. Wings in these animals are
    used for flying. Such organs that differ anatomically and in embryonic mode of origin but
    perform similar function are said to be analogous organs.

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