Download Homework Exercise 4 The diagram below represents differences in

Cell Biology Homework – Transport across cell membranes
Homework Exercise 4
1
The diagram below represents differences in the concentration of molecules
inside and outside an animal cell, together with the direction of movement of
the molecules.
Identify the arrow (A, B, C or D) on the diagram that would represent the
diffusion of oxygen into the cell.
(1)
2. The diagram below shows the appearance of a cell from an onion.
Pieces of onion were placed in three different solutions:
a 10% salt solution, 2% salt solution and pure water.
The following diagrams show the appearance of the cells after 10 minutes
Solution X
Cells swell
solution Y
cells unchanged
solution Z
cell content shrinks
Identify the other two solutions
(i) 10% salt solution _______
2% salt solution
pure water
Y
_______
(2)
(ii) Look at the diagrams of the plant cells drawn above and state which cell
Is plasmolysed and which cell is turgid.
8
(2)
Cell Biology Homework – Transport across cell membranes
(iii) Give a definition of osmosis.
(3)
3. The diagrams below represent red blood cells in different solutions as
they would appear under a microscope.
(a)(i) Use the information in the diagrams to predict the percentage water
in a red blood cell.
(1)
(ii) Explain your answer
(1)
(b) The cells in diagram B are smaller in size. Explain the change in terms of
water concentration.
(2)
(C ) State what would happen to red blood cells bathed in pure water.
9
(1)
Cell Biology Homework – Transport across cell membranes
4. A student cut five similar cylinders from the same potato, dried them with
a paper towel and weighed them.
Each cylinder was placed in a different concentration of sugar solution
as shown in the diagram below.
After three hours, the student removed the cylinders from the solutions, dried
and weighed them as before.
The results are shown in the table below.
Test
Concentration
Initial mass
Final mass
Change in mass
Percentage
tube
of sugar
of potato
of potato
of potato
change in mass
solution (M)
cylinder (g)
cylinder (g)
cylinder (g)
of potato
A
0.1
2.0
2.2
+0.2
+10
B
0.2
2.0
2.1
+0.1
+5
C
0.3
2.0
1.8
-0.2
-10
D
0.4
2.0
1.7
-0.3
E
0.5
2.0
1.5
-0.5
-25
(a) Calculate the percentage change in mass of the potato cylinder
in 0.4M sugar solution.
(1)
(b) Name the variable altered in this investigation.
(1)
(c ) Suggest one way in which the reliability of the results could be
improved.
(1)
(d) Predict the appearance of the cells in potato cylinder E after
three hours.
(1)
(e) At the end of the experiment, identify one tube that would contain
turgid cells.
(1)
10
Cell Biology Homework – Transport across cell membranes
5. Active transport involves the movement of molecules or ions aross a cell
membrane.
(a) Which of the digarams below shows the direction of movement of
the molecules by active transport into the cell?
(1)
molecules
(b) Name the type of molecule found in the cell membranes that is
required for the process of active transport.
(1)
(c) The movement of molecules in or out of a cell can be by passive or
active transport. Describe one difference between passive and active
transport.
(1)
11