AS BIOLOGY 1 October 2008
Methods of Transport within and
between cells
three investigations
Things that you find inside the cell,
Knowledge is not simply another
don’t always stay inside the cell, and commodity. On the contrary.
sometimes things you find outside a Knowledge is never used up. It
cell, you really don’t want inside the increases by diffusion and grows by
cell, so the methods of controlling dispersion.
what comes in and what comes out is Daniel J. Boorstin
as important in your cells as it is in a sheet possible but with no ventilation
trendy nightclub. We’re going to look holes. If there are no holes in the bag
at three experiments that tell us a littlethe complete bag can be used.
about these transport methods. 2 Spread the plastic over the top of a
beaker or your cupped hand and pour
One the starch solution into the centre of
the plastic. Hold the sides of the plastic
You need... up and twist them together to make a
About 20 cm3 thick starch solution closed bag. Tie a knot in the bag or use
Warm water a rubber band to tightly seal the bag of
Iodine (dissolved in KI) starch solution.
Medium sized (200–300 cm3) 3 Half fill the beaker with warm water.
beaker Add enough iodine to make a light
Clear plastic bag (the thin ones used yellowy brown solution.
for vegetables at the supermarket work 4 Place the plastic bag of starch
well) solution into the iodine and observe for
Safety: about 15 minutes
view information sheet for iodine
Procedure Questions to answer
1 Cut a section from the plastic bag. Describe and explain the changes you
You need the largest roughly square saw. Why did we use warm water?
Iodine
What colour is iodine?
What does it react
with? What colour will
it turn?
1

AS BIOLOGY 1 October 2008
What is different about the cells of a grape
to the cells in your own body? Will they
cope better with more water or less well?
What is different about the skin of a grape
to the inside of a grape?
two
You need 5 Leave for at least 24 hours. Then observe and
4 grapes of similar size feel the fruit
50 cm3 water
50 cm3 strong sugar solution Questions
2 small beakers Write a description and explanation of the
changes or lack of changes in your pieces of
Safety fruit
Write a safety risk assessment for this
practical What limits the change in size of
a. The unpeeled fruit?
Procedure b. The peeled fruit
1 Pour approximately 50 cm3 of strong sugar
solution into a small beaker.
2 Pour approximately 50 cm3 of water into
another small beaker.
3 Label the beakers clearly.
4 Peel two of the grapes and add one peeled
and one un-peeled grape to each beaker.
2

AS BIOLOGY 1 October 2008
three
You need
Homework
2 thin slices of potato (about 0.5 cm
one
wide)
2 thin slices of cucumber (about 0.5 Create a template for all practical
cm wide) investigations that you can use
Water throughout the year
Saturated salt solution two
2 Petri dishes
Make sure all of the questions on
Safety: this sheet have been thoughtfully
Write a risk assessment for this answered - including all risk
investigation assessments for the investigations
carried out (remember the format
1. Risk 2. What could happen 3.
Procedure How would you prevent this?)
1 Place a slice of cucumber and a slice
of potato in each Petri dish. three
What would happen to blood if you
2 Fill one Petri dish with water and the placed it in a hypertonic or
other with saturated salt solution, hypotonic solution? illustrate your
being careful to cover the slices and answer. If you did the same to an
making a note of which is which. onion cell would you expect to see
the same? What is different about
3 Remove and examine the slices after the two cells. Again, illustrate your
10 minutes. answer.
Question
Due: October 6th 5pm
Describe and explain the changes
Cucumber
Are cucumbers water
based? How could
you find out? what
observations can you
make about
cucumbers? Can you
eat them without
dribbling?
3