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?
To understand this question, we need to refer to 2 definitions:
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.
Thank you very much!