VMMC VMMC Medical Solved Paper-2012

  • question_answer
    Carbohydrates are commonly found as starch in plant storage organs. Which of the following five properties of starch (I-V) make it useful as a storage material?
    I Easily translocated
    II Chemically non-reactive
    III Easily digested by animals
    IV Osmotically inactive
    V Synthesized during photosynthesis
    The useful properties are

    A)  II and III

    B)  II and IV

    C)  I, II and V

    D)  I and V

    Correct Answer: C

    Solution :

     Starch is a high molecular weight polymer of D-glucose in \[\alpha \,1\to 4\]linkage. It is synthesized in chloroplasts as it is one of the stable end product of photosynthesis. It is most abundant    and    common    storage polysaccharide in plants hence, most staple food for man and herbivores. It is a mixture  of two types of glucose homopolysaccharide, viz., amylose and amylopectin. During day time the starch synthesis in chloroplast is coordinated with sucrose synthesis in cytosol. Typically about 90% of total solute carried in phloem is the carbohydrate sucrose, a disaccharide. This is relatively inactive and highly soluble sugar playing little direct role in metabolism and so making an ideal transport sugar.


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