How does the concentration of sucrose affect the weight

How does the concentration of sucrose affect the weight

of pieces of potato after osmosis has taken place?

Aim

The aim of this is experiment is to investigate how much sucrose is in

a potato. We are going to investigate the effect of different

concentrations of sucrose on the weights of pieces of potato after

osmosis has taken place.

Prediction

I predict that the less concentrated the solution of sucrose is, the

greater the weight of the potato will be. I predict this because

osmosis is the movement of water from a region of high water

concentration to a region of low water concentration through a

semi-permeable membrane i.e. the cell wall of the potato. If the

concentration of water inside the potato is high then the water will

pass out through the cell wall, decreasing the weight of the potato.

If the concentration of water outside of the potato is high then the

water from outside of the potato will pass through the cell wall into

the potato, thus increasing the weight of the potato. A low

concentration of sucrose will have a greater ratio of water to

sucrose, so more water will pass thorough into the potato in an

attempt to even up the amounts of water and sucrose on both sides. If

the concentration of sucrose outside of the potato is high then there

will be less water to pass through into the potato and the potato will

therefore lose water from inside in an attempt to even up the

concentrations of sucrose and water on both sides. If the cell has

lost water then it will not weigh as much as a cell full of water as

the cell will be flaccid. If the cell has gained water then it will be

turgid and will weigh more. The higher the concentration of the sugar

solution, the faster osmosis will take place. I think this because the

more sugar in the water, the longer it will take for it to balance

out.

Some background information

Osmosis is the movement of water from an area of high concentration

(lots of water particles) to an area of low concentration (few water

particles). It is only the movement of water, as only water particles

are small enough to pass through the semi-permeable cell membrane of

the plant. Osmosis makes plants cells swell up if they are surrounded

by a weak solution i.e. a lot of water, and they therefore become

turgid. This is useful in giving support for cells and opening

stomatal guard cel...

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...in that will affect the next measurement. Our

results were also left by a window, so the temperature could have been

affected if the window was open or the weather outside was hot. To

improve this experiment next time we can also make sure that we leave

the test tubes in the test tube racks nowhere near anything that will

affect the temperature i.e. a heater or a window.

The conclusion may only be valid only within a certain range, if we

were to use even more precise concentrations of sucrose solution then

we can eventually find out the precise concentration that provides the

correct answer. The concentrations used were slightly too vague as I

had to say that the answer must lie between two amounts. However, if

we were to improve the experiment by narrowing down the concentrations

we will use even more then this will be time-consuming and very

tedious. Therefore, it will not be a good idea to try and improve the

experiment in this way.

To extend this investigation we can also experiment changing the

following variables:

Þ Temperature of the experiment

Þ Surface area of the pieces of potato

Þ Weight of the potato

Þ How long the experiment is left for.