The Effect of Osmosis in Plant Cells

The Effect of Osmosis in Plant Cells

Introduction

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Osmosis is the diffusion of water molecules across a partially

permeable membrane, from a region of high concentration to a region of

low concentration. The partially permeable membrane contains a series

of small holes, allowing only water molecules to pass through, as

shown in the diagram below. The glucose molecules (represented by red

circles) are too big to fit through the membrane. As there are a

greater number of water molecules (represented by blue circles) on the

left side, there is a steady net flow into the right side with fewer

water molecules, i.e. into the stronger solution.

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Water moves into and out of plant cells by osmosis, depending on the

concentration of the surrounding solutions. When water moves into a

plant cell, the vacuole increases in size, pushing the cell membrane

against the cell wall. The cell wall makes sure that too much water

doesn't enter, which would cause the cell to burst. The cell becomes

turgid or firm when the cell membrane pushes against the cell wall. It

gives the cell support and keeps the plant upright. Plant cells which

do not receive enough water cannot stay turgid and so wilting occurs.

Cells which are not turgid are described as flaccid. If a plant cell

loses too much water by osmosis, plasmolysis occurs, and plasmolysed

cells are unlikely to survive.

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Aim of investigation

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In my investigation, I aim to investigate what factors would have most

effect on osmosis in plant cells. There are several factors which

could have an impact on osmosis in plant cells, which include:

· Surface area of the plant

· Sucrose concentration of the water

· Age of the plant

· Type or variety of plant

· Atmospheric temperature

· Mass of the plant

From these options, the option I will be investigating is the sucrose

concentration of the water. I can have full control over this factor.