Aim: Investigating membrane structure including the effect of temperature on membrane
permeability
Hypothesis: The beetroot exposed to liquids at 0 degrees will keep the membranes
unharmed & intact. When exceeding to high temperatures e.g., 50 degrees the membrane of
the beetroot will become unstable and the fluidity will change. This may be because the
lipids lose their structure and become weak. When the membrane has a break, the red
pigment will leak out. Whilst the temperature increases the membrane will break at rapid
pace.
Independent variable Temperatures 0,10,20,30,40,50,60,70. At
different temperatures the amount of
betalain pigment released from the
vacuoles of beetroot cells will change,
meaning the permeability of the cell
membrane will be affected. The rate of the
movement of the oxygen particles entering
the cell via simple diffusion will also be
affected.
Dependent variable Permeability of the membranes, the data
can be taken from using a colorimeter to
determine light transmission within the
water samples at different temperatures.
Control Variables How will the variable be controlled, what
impact does it have?
Temperature (degrees) of the water baths The energy of the particles would differ
when different amounts of temperature is
used, which can cause the rate of simple
diffusion to change and the permeability of
the cell membranes in the beetroot cell. Put
a thermometer in each of the test-tubes and
make sure they are checked throughout the
investigation.
Sizes of the beetroot slices A ruler and a cork borer can be used to
measure the length and width of the slices
and use a knife for precision of cuts. If you
do not control this variable then the number
of cells would vary causing variation in
oxygen absorbency level via diffusion and
the amount of pigment released
Amount of diluted water in the test tube The amount of oxygen particles would vary
(5cm^3) causing variation in the amounts of of
oxygen which would be absorbed by
diffusion, it is measured by measuring
cylinders.