Lab Report

UFP/IFP Biology for Life Sciences: Practical Lab

Academic Year 2019-20

Student name
CEG number
Time allowed 2 hours laboratory time
Instructions  Listen carefully to instructions from the staff members and you

should stop immediately if asked to do so.
 You should work safely at all the time and wear appropriate
clothing and safety equipment.
 If you need help or any additional equipment raise your hand
up.
 Scientific Calculators are allowed.
 Dictionaries (except electronic ones) are allowed.
 Before you do your practical, your teacher will explain what
you are going to do and might carry out a demonstration – you
are advised to listen carefully and take notes.
 Your teacher will tell you the deadline to submit your lab
report.
 Your lab-report should be submitted through Turnitin (see
Assignment Brief for full details)

Information to
candidates

 Only use this paper to prepare your lab report which should be
done electronically and submitted through Turnitin. Graphs or
diagrams must be done by hand and then scanned for
submission. The originals MUST be submitted to your Tutor.
 Your Tutor can provide you with graph paper if required.

Investigating osmosis

Page 2 of 5
Investigating the water potential of celery using the weighing method.

INTRODUCTION
When the celery is immersed in a solution where there is no change in mass, there is no net
flow of water into or from the cells by osmosis, i.e. the rate at which water enters the cells =
the rate at which water enters the cells.
At this point, y CELL = y BATHING SOLUTION

Before you start work:
 Read all instructions carefully.
 Write an equipment list from the method below
 Write a risk assessment and safety precautions
 Prepare a suitable table to record your data.

Method:
1. Cut across the stem of the celery so that you a have a portion about 5 cm long.
2. Cut along the grooves so that the stem is divided into long, thin strips.
3. Dry off the cell sap from cut cells with a standard procedure.
4. Record the mass of each strip.
5. From the 1 mole solution of sucrose, prepare 10 cm 3 of each of the required
solutions:
0.2, 0.4, 0.6, and 0.8 mole.

Concentration of sucrose solution (M)
0 0.2 0.4 0.6 0.8 1.0
Volume of 1.0 M sucrose solution added (cm 3 ) 0 2 4 6 8 10
Volume of distilled water added cm 3 ) 10 8 6 4 2 0
6.

Page 3 of 5
Fill one additional test tube with 10 cm 3 of distilled water and one with 10 cm 3 of 1
mole sucrose.
7. Label each test tube with the solution it contains.
8. Leave the tubes in a constant temperature water bath for 3 minutes.
9. Add a celery strip to each test tube and cover with parafilm. Note the mass of each
celery strip in each test tube.
10. After a minimum of 15 minutes, remove the strip of celery.
11. Dry it carefully and record its mass.
12. Plot a graph of % change in mass against solution concentration.

Calculate the percentage change in mass using the formula below:
% change in mass = final mass – initial mass x 100%

Initial mass

13. Where there is no net gain or loss in mass,  CELL is equal to  BATHING SOLUTION . From your
graph read the molarity of sucrose where the percentage mass change is zero.
14. From the table below, find the water potential of a sucrose solution of that molarity
15. Hand in your table of results and graph to your tutor