Biology test 1
Section A: Structured questions (30 marks)
1. Use a ‘✓’ and a ‘✕’ to indicate the presence and absence of the following
subcellular structures in prokaryotic cells and eukaryotic cells.
(5 marks)
Sub-cellular structure
Prokaryotic cell
Eukaryotic cell
Cell membrane
✓
✓
Nuclear membrane
✕
✓
Cytoplasm
✓
✓
Endoplasmic reticulum
✕
✓
Ribosome
✕
✓
2. The image below shows a part of an onion epidermis observed under a light
microscope. The magnification of the eyepiece and the objective are both 10X.
MN = 6cm
a. What is the magnification of the above image?
(1 mark)
Magnification: 10 X 10 = 100X
b. Using the diameter of the image, MN, and calculate the average actual width of an
onion epidermal cell. Express your answer in μm and show your working. (2 marks)
Average width of onion epidermal cells in image: 6 cm/12 = 0.5 cm
Average actual width: 0.5cm /100 = 0.005 cm = 50 μm
c. If the same onion epidermis is observed with a 40X objective instead of a 10X
objective, how will the image be different from the one above?
(2 marks)
More details of cellular structure.
Dimmer image.
3. The table below summarizes some of the subcellular structures of a cell and their
functions.
Subcellular structures
Functions
Mitochondrion
(i) provides energy for cellular activities.
(ii) Chloroplast
Converts solar energy into chemical energy.
Nucleus
(iii) control cellular activities.
(iv) Cell wall
Protects the inner structures.
a) Complete parts (i) to (iv) in the above table.
(2 marks)
b) Give two reasons to explain why the cell described above cannot be an animal
cell.
(2 marks)
Animal cells doesn’t contain cell wall and chloroplasts.
c) Name the process that takes place in the structure described in part (ii) of the
table.
(1 mark)
Photosynthesis.
4. In 1935, Davison and Danielli proposed the “sandwich model” to illustrate the
structure of cell membrane. The model is shown in the diagram below.
a) The “fluid mosaic model” proposed by Singer and Nicolson has been the most
accepted model of cell membrane. Compare and contrast the structure of cell
membrane as illustrated by these two models.
(3 marks)
similarities: both contain a phospholipid bilayer.
differences: “sandwich model”: phospholipid bilayer sandwiches between two layer
of protein molecule.
“fluid mosaic model”: protein molecules embedded halfway or span through the
phospholipid bilayer.
b) Base on the “fluid mosaic model”, account for the selective permeability of the
cell membrane.
(3 marks)
The differentially permeable membrane (phospholipid bilayer) is impermeable to
polar molecules. Hydrophilic substances have to be transported by transport protein.
Hydrophobic molecules can pass through phospholipid bilayer freely.
c) Which aspect of the nature of science is shown in the development of the cell
membrane model?
(1 mark)
Scientific knowledge is tentative/ subject to changes.
4. In an experiment to investigate the effect of water potential gradient on the rate
of osmosis, a series of sucrose solutions of various concentrations were prepared
and a series of osmometers were constructed as shown in the following diagram.
The increased in height of the liquid column in the capillary tube of each osmometer
after two hours was measured and recorded in the table below:
Concentration of sucrose solution (%)
Time taken for the liquid to rise 10cm (min)
5
105
10
84
15
58
20
32
a) Account for the rise in the liquid levels in the capillary tubes of the osmometers.
(2 marks)
The water potential of distilled water is higher than that of the sucrose solution.
Water enters the dialysis tubing by osmosis
forcing the liquid level up.
b) State two precautions that should be taken when setting up the osmometers to
ensure fair comparison.
(2 marks)
the length/size of dialysis tubing should be the same.
The volume of sucrose solution in dialysis tubing of each set up should be the same.
The bore size of capillary tubes should be the same.
c) What conclusion can be drawn from the results about the effect of water potential
gradient on the rate of osmosis?
(1 mark)
Steeper the water potential gradient, higher the rate of osmosis.
d) If the 20% sucrose solution were replaced by glucose solution of the same
concentration, what would happen to the rate of ascent of the liquid level? Explain
your answer.
(3 marks)
The ascent of liquid level would decrease.
Glucose would diffuse out of the dialysis tubing.
The water potential gradient across the dialysis tubing will be reduced.
Section B: Multiple choice questions – Circle your answers (8 marks)
1.
A student is designing an experiment to investigate whether heavier female rats
produce more offspring than lighter female rat. In the experiment, what are the
independent and dependent variables?
Independent variable
Dependent variable
A.
age of female rats.
weight of female rats
B.
number of offspring.
weight of female rats
C
weight of female rats
number of offspring
D.
weight of female rats
age of female rats
2.
Which of the following comparisons between the light microscope and the
electron microscope is incorrect?
Light microscope.
A. light is used to form images
B. specimens must be dead
C. images are of lower magnifications
D.
images show less details
Electron microscope
electron beams are used to form images
specimens can be alive
can produce images of higher
magnifications
images show more details
3.
A.
B.
C.
D.
Which of the following are organic substances found in organisms?
(1) nucleic acids (2) minerals (3) proteins (4) fats (5) carbohydrates
(1), (2), (3) and (4) only
(1), (2), (3) and (5) only
(1), (3), (4) and (5) only
(2), (3), (4) and (5) only
4.
Which of the following is not a function of water in plants?
A.
To provide a medium for chemicals to take place.
B.
C.
D.
To provide a transport medium.
To prevent overheating by sweating.
To provide turgidity to support young seedlings.
5. Which of the following statement about cellulose in plant cells is correct?
A. It stores energy for plant cells.
B. It can be stained blue-black with iodine solution.
C. It helps to maintain the shape of the plant cells.
D. It regulates the movement of water in and out of the plant cells.
6. What is the maximum number of fatty acids that can be condensed with a
glycerol molecule?
A. one
B. two
C. three
D. four
7. Which of the following statements about proteins is incorrect?
A. The building blocks of proteins are amino acids.
B.
C.
D.
Proteins are a structural component of cell membranes and the cytoplasm.
Proteins can be used to release energy.
Proteins contain carbon, hydrogen, oxygen and nitrogen only.
8. Which of the following combinations of compounds are made up of the same
elements?
A. fatty acid and amino acid
B. triglyceride and phospholipid
C. DNA and RNA
D.
cellulose and protein