Osmosis Investigation.

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Osmosis Experiment                Biology Coursework

Osmosis Investigation

Introduction

Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration.

The ‘Semi-permeable membrane’ is a very thin layer of material (cell membranes are semi-permeable) which allow some things to pass through them but prevent other things from passing through.

The ‘Cell membranes’ allow small molecules like oxygen, water, carbon dioxide, ammonia, glucose etc. to pass through. BUT these will not allow large molecules such as starch, protein, etc. to pass through.

The ‘region of high concentration of water’ is either a very dilute solution of something like distilled or pure water. In each case there is a lot of water: there is a high concentration of water.

The ‘region of low concentration of water’ is a concentrated solution of something like sucrose. In this case there is much less water.

Reason for Experiment

In my experiment I will be discovering what happens to a plant cell (in my case a potato) when it has been put into a sugar solution.

In my experiment I will be trying to find out what would happen if we place a piece of potato into a sugar solution of different quantities, mixed with water.

So the input variable of my experiment will be how much sugar solution I am going to use in each test tube, and my outcome variable will be the mass of the potato when it has bee left in the sugar solution (after 24 hours).

Prediction

I think that in my experiment, over the 24 hours, the potatoes which have been left in the strong sugar solutions will increase in its mass and weigh more than the potatoes which have been left in the weaker sugar solutions. But they will both increase in mass after the period of time. I think this is because although they are taking in different amounts of the solution, they will still both be different to when they first started out, just as different weights. Some of the potatoes will become flaccid and some will become turgid. The temperature (°C) will stay then same.

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The Experiment

Aim

-To find out what happens when potatoes have been left in sugar solutions of different quantities and concentrates, over a 24 hour period o time.

-To measure the mass of the potato before and after the experiment, has it increased or decreased in mass?

Preliminary Work

I researched some of the work of the internet on the BBC learning website and some other websites with existing essays involving the process of osmosis, and how it is used in human cells as well as the plant cells. In class we discussed turgid and flaccid cells. Turgid cells ...

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