Answer the following questions.                                                                   a) Plants generally store carbohydrates in the form of starch but not in the form of glucose. Give one reason in support of such storage. Name the form in which human beings store carbohydrate also mentioning the place where it is stored.                                                     b) Explain why the plants growing in deserts take carbon di oxide at night and utilize it during the day in the synthesis of carbohydrates?   c) Give reason, why the milk teeth in children are replaced by permanent teeth.                                                                                             d) Plants generally wilt in the afternoon and regain their freshness in the next  morning. State the logical reason for this process.