[SPM Biology 2014 Q4 P1 Solution] Why the answer is B?

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Hi Farhaini,

SPM2014 Biology Q4

14 A slice of mustard green stem was immersed in 30 \% of sucrose solution. Which observation is correct after one hour?
Sepotong batang sawi hijau telah direndam di dalam larutan sukrosa 30 \% Pemerhatian yang manakah betul selepas satu jam?

SPM2014 Biology Q4 Solution

To understand this question, we need to refer to 2 definitions:

Hypertonic Solution
A solution that that have high concentration of dissolved particles.

water molecules in a solution tend to diffuse from a less concentrated solution into a more concentrated one

  • 30% sucrose solution has a very high concentration, hence it is a hypertonic solution.

  • By osmosis, water will always diffuse from a less concentrated solution to a more concentrated solution.

  • The concentration in sucrose solution is higher than the concentration of the cell sap / vacoule of the mustard green stem cells.

  • When the stem was immersed in a hypertonic solution, water in the cell saps (vacoule) of the stem cells will diffuse out into the sucrose solution until an equilibrium is achieved.

  • This causes the cell to become flaccid when there are less water in it (basically means become “softer” and “thinner”).

  • Epidermis is a bit like the “skin” of the cell, that wrap on top of the stem cell

  • When the plant cell become flaccid, it will bent inwards, because now the cell sap is “smaller size”, but the epidermis remains same.


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Thank you very much!:+1::+1::+1::blush:

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