To see metaphase I animated, click the Play button. The centrioles are at opposite poles of the cell. The pairs of homologous chromosomes (the bivalents), now as tightly coiled and condensed as they will be in meiosis<span>, become arranged on a plane equidistant from the poles called the metaphase plate.</span>
<span>The distinct evidence of climate change in the O’Higgins glacier is proven by the measurement of the area that it covers. About 11.5 kilometers of glacier land has melted within the twentieth century. Satellite images reveal the retreat of glaciers where they compared early 1900s images from the present.
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Answer:
The answer is <em><u>D.
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Explanation:
Viruses can evade the processing and presentation of antigens, for example by interfering with the expression of MHC class I proteins, although this increases their susceptibility to be detected by natural killer cells (NK). However, some members of the herpesvirus, papillomavirus, retrovirus, poxvirus and flavivirus families have also developed strategies to escape the attack of NK cells and promote their survival, inhibiting cell apoptosis. Finally, some pathogens often change surface antigens frequently, as in the case of influenza viruses (orthomyxovirus).
The human immunodeficiency virus (HIV) affects CD4 + T cells and degrades the host's ability to counterattack with a strong cell-mediated immune response. There are so many tactics of immune evasion used by HIV, which have so far hindered the development of an effective vaccine.
