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9th Class Science The Fundamental Unit of Life Question Bank Cell-The Fundamental Unit of Life

  • question_answer
    Four strips are cut from a fresh potato. The length of each strip is measured. One strip is placed in water and others in different concentrations of sugar solution. After an hour, the strips were measured again. The results are shown in the table. Which of the liquids P, Q, R and S is water?
    Liquid Original length of strip (mm) Final length of strip (mm)
    P 75 75
    Q 78 80
    R 82 80
    S 86 85

    A)  P                    

    B)         Q                   

    C)  R                    

    D)         S

    Correct Answer: B

    Solution :

    Sugar solution is hypertonic to cell sap of potato, whereas water acts as a hypotonic solution to it. When the potato strip is placed in water, its cells will gain water by osmosis, resulting in increased in size of potato strip. When the potato strips are put in sugar solution of different concentrations, the cells will lose water resulting in decrease in the size of strip. As only potato strip placed in liquid 'Q' shows increase in length, this shows that liquid 'Q' is water.


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