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Natural Sciences 2º ESO

Archivo de Febrero 2013

Reproduction questions

 This information has been taken from The Open Door Web Site.

The answers are in Reproduction notes.

    Reproduction notes

     This information has been taken from The Open Door Web Site.

    Summary

    Asexual Reproduction

    1. Sexual reproduction requires sex cells (sperms and eggs produced by males and females) but asexual reproduction requires no sex cells at all.
    2. Asexual reproduction is common amongst plants, single-celled organisms and simple animals.
    3. Asexual reproduction has the advantage of producing large numbers of offspring very quickly.
    4. A group of offspring produced by asexual reproduction from a single parent is called a clone.
    5. Asexual reproduction in a single-celled organism involves simply dividing into two or the budding of a small piece of the mother cell.
    6. Simple animals, such as the Hydra, may also bud off small pieces which have grown from their bodies.
    7. Green plants are quite sophisticated in their methods of asexual reproduction. Offspring may be produced by runners, bulbs, rhizomes or tubers.
    8. Gardeners have used this ability of plants to reproduce asexually. They take cuttings from plants and encourage them to grow roots and leaves. In this way large numbers of the same plant can be obtained very quickly from one parent plant.
    9. Scientists have gone one step further; they cultivate very small pieces of plants in test tubes. This is called in vitro culture and it can produce thousands of identical offspring from one plant, all grown under carefully controlled conditions.

    Sexual reproduction or Asexual reproduction?

    1. Asexual reproduction is quite rapid and requires only one parent.
    2. The offspring produced by asexual reproduction, from the same parent, are all identical to one another and they are identical to the parent.
    3. Sexual reproduction requires sex cells produced by two parents (a male and a female). Sexual reproduction is more complex and slower than asexual reproduction.
    4. Offspring produced by sexual reproduction look like their parents but they are not identical (unless they are identical twins); they show variation.
    5. Farmers breed together different varieties of animals or plants to produce offspring which show the best characteristics of both parents.
    6. Amongst populations of wild animals and plants, species show variation as a result of sexual reproduction. This variation allows them to adapt to new environments.
    7. If a species of organism which shows no variation cannot adapt it may become extinct.

    Animal Reproduction

    Reproduction in Flowering Plants

        Reproduction function videos

        Interaction function videos

        Vocabulary and pronunciation of interaction function in living things

        Study the translations and then define the words.

        Esta película necesita Flash Player 7

        Listen to the pronuncitation:
        Esta película necesita Flash Player 7

        Nervous system and endocrine system in human beings

        Acabamos de empezar la función de relación en animales y plantas. He aquí dos interesantes presentaciones sobre los dos sistemas encargados del procesamiento y coordinación en los seres humanos.

        The nervous sytem presentation from Biodeluna:

        Esta película necesita Flash Player 7

        The endocrine system presentation from Biodeluna:

        Esta película necesita Flash Player 7

        The biological significance of meiosis in reproduction and eukaryotic life cycles

        The main tasks of meiosis are:

         

        • Production of haploid gametes to maintain the diploid number of species, generation after generation. In meiosis, during the formation of gametes in animals and spores in plants, the chromosome number is reduced to half.
        • Crossing-over, which brings together new gene combination of chromosomes.
        • A mechanism for comparing the two copies of each chromosome are provided with the purpose of error correction or repairing.

        Esta película necesita Flash Player 7

        Kingdom Plantae: life cycle

        En este vídeo se resume todo lo que hemos aprendido hasta ahora sobre las plantas: sus células, su nutrición (fotosíntesis), su reproducción (alternancia de generaciones: gametofito y esporofito) y los grupos principales (helechos, musgos, gimnospermas y angiospermas o plantas con flores).

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