Periosteum is the thin yet tough outermost layer of bones. Its many collagen fibers support the bone and firmly connect it to the surrounding structures. Osteogenic cells in the periosteum play a vital role in the growth and repair of bony tissue.
Answer:
About 95 percent of the skin cells in the epidermis are devoted to creating new skin cells in the lower two levels of the epidermis, which then cycle to the top layer to help form the stratum corneum. Eventually the dead cells of the stratum corneum flake off as new keratinocytes move up, and the cycle repeats itself.
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A dihybrid cross is defined as a breeding experiment involving parental generation chromosomes that have two contrasting traits. The individual organisms involved in this can be either homozygous or heterozygous.
This kind of cross pollination experiments led to the development of George Handel's Law of Independent Assortment.
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The
first observation was that, natural selection might itself be variable because
it is dependent with the different seasons the environment have. Second, the
frequency of small-beak depth Geospiza fortis became lesser on an island when a
large-beak-depth was introduced because the large-beak-depth species has
greater survival rate especially during dry season were they can eat larger and
harder seeds as compare to the small-beak-depth birds.