To investigate the effects of sucrose concentration on osmosis in potato tissue.

Authors Avatar

PHILIP XIU 11SK                                                                                        BIOLOGY COURSEWORK

To investigate the effects of sucrose concentration on osmosis in potato tissue

PLANNING

We have been asked to research the effects of sucrose concentration on osmosis in potato tissue. Osmosis is the spontaneous movement of a solvent (-in this case water) from a place where its chemical potential is higher to another place where it is lower, through a semi-permeable membrane (-such as a cell membrane). A cell membrane lets smaller molecules such as water through but does not allow bigger molecules to pass through. The smaller molecules will continue to diffuse across the membrane until the area in which the molecules are found reaches a state of equilibrium, meaning that the molecules are in a steady state, with molecules moving in and out of the membrane, however with no net loss or gain.

Plant cells always have a rigid cell wall and cell membrane surrounding them. When they take up water by osmosis the cells start to swell up, but the cell wall prevents them from bursting, (-which is what animal cells, who have no cell walls would do), the plant cell is then said to be turgid. When turgid, the pressure inside the cell rises and eventually the internal pressure of the cell is so high that no more water can enter the cell. This hydrostatic pressure works against osmosis, even when the plant cell’s water potential is greater than that of the outsides. Turgidity is very important to plants because this is what makes the plant “stand up” and acts as a form of support.

The opposite of turgidity is plasmolysis, this is the retraction of the cytoplasm from the wall of a vacuolated plant cell as a result of osmotic withdrawal of water from the vacuole. They are said to become flaccid and limp.

For this particular investigation we are allowed, a bench solution of 1 molar sucrose (-this will be the sugar solution) solution and potato cylinders.

FAIR TEST

To find the effect of sucrose solution on osmosis, I will have to keep all the other factors the same, these are:

Join now!

-Temperature

-Water potential of potato initially

-Size of potato

-Mass of potato

-Volume of solution potato is in

-Type of potato

-Time left in solution

-Surface area of potato

-Using same balance to measure potato

-Light intensity

-Potato cut at the same time, and left the same time

If I am going to conduct a fair test then I will have to keep these factors the same, this is so that I can achieve reliable results to test out my hypothesis. The temperature will be at a constant room temperature, this is so that it won’t affect ...

This is a preview of the whole essay

Here's what a teacher thought of this essay

Avatar

This is a good start to a report on this investigation. 1. The planning section has a good level of detail and includes relevant information. 2. The fair test section also has a good level of detail but lacks structure. 3. The scientific knowledge section shows good research but should be at the beginning of the report. 4. The tables of results are well presented. 5. During the method section of the preliminary test the structure breaks down. Use subheadings to divide methods and findings. 6. The report needs to be finished. *** (3 stars)