MELBOURNE HIGH SCHOOL
BIOLOGY UNIT 3
PRACTICAL NOTES
Remember the importance of an Introduction section in your SAC practical reports. In
each case, be sure to consider and discuss sources of error in the practical procedure. Be
aware of all the assessment criteria and their weighting, when writing your reports.
Bring your assessment criteria sheet to the writing-up sessions, so you can refer
to the assessment criteria for each prac.
2006
PRACTICAL REPORTS
STANDARD REPORT FORMAT FOR PRACTICAL WORK

In Biology, your practical reports have to be written entirely and should follow the accepted format as shown in the
sample below.

It is important to realise the value an assessor places on the presentation of data in tables, graphs and diagrams, as
appropriate (refer to the SAC assessment criteria).
A SAMPLE PRACTICAL REPORT
top of page
12/4/69*
SAC 4–4: Studying Pond-life
 left of page
centre of page
A. Nonymous 6BIA
right of page 
INTRODUCTION
Use this section to briefly discuss the theory behind the experiment. Always cite sources of
information you include in this section.
PURPOSE
Write the Aim of the experiment, which should include to the hypothesis being tested.
MATERIALS &
EQUIPMENT
PROCEDURE
Include either reference to a published list (if available), or list the materials, chemicals and
other equipment and apparatus you used in the practical exercise.
RESULTS OR
OBSERVATIONS
This is where you record all relevant observations, readings, tables of results, etc. Be prepared
to record everything you hear, see, smell, taste, feel, etc. Practise constructing tables for the
presentation of data. In this section you would also draw diagrams and drawings, for example of
microscope slides
DISCUSSION
Here you comment on how your results and observations compare with your expectations, and
how well, or otherwise, they support your hypothesis. You would answer questions about the
procedure and could also suggest additional experimentation that might help elucidate your
hypothesis. You would also comment on problems encountered, and possible sources of error.
CONCLUSION(S)
Come to some conclusion about the exercise, in terms of how your results related to the stated
purpose of the exercise i.e. did your results support, or disprove, your hypothesis?
REFERENCES &
ACKNOWLEDGMENTS
Indicate, precisely, the title(s) of any reference(s) used, with the author(s), year of publication
and page number(s). Name anyone who assisted you, and the type of assistance they gave.
In some cases you must design your own experimental procedure. Otherwise, if you are
following a procedure from a laboratory manual or printed notes, merely quote the procedure
pages in that manual, or the title of the notes. If you change any part of a published procedure,
indicate the change(s), giving enough information for the reader of the report to be able to do
the same experiment you did, using the procedure you used.
* The date to write here is the date you began the practical work, not the date you wrote or submitted the report.

Include the references used in the References & Acknowledgments section of your report.
Melbourne High School BIOLOGY: UNIT 3
PRACTICAL NOTES
SAC 1–1: DIFFUSION THROUGH MEMBRANES
Substances move into and out of cells across the cell membrane. Some passively diffuse; others are assisted by molecules in the membrane and
others require the cell to expend energy to assist their movement.
HYPOTHESIS
It is possible to observe evidence of substance movement across cell membranes.
PURPOSE
To observe changes in the appearance of cells as evidence of the movement of substances across living cell membranes.
MATERIALS & EQUIPMENT:
Module 1: Pieces of crisp, fresh lettuce leaves; microscope slides; coverslips; forceps; mounted needle; scissors or razor blade; water; 0.9% NaCl;
2% NaCl;
Module 2: fresh potato; cork borer; Petri dish; filter paper; sucrose solutions: 1M, 0.8M, 0.6M, 0.4M, 0.2M, 0.1M or distilled water; electronic balance.
MODULE 1 PROCEDURE
1. Place 2–3 drops of 0.9% NaCl on a slide.
2. Take a small piece of crisp, fresh lettuce and bend it back on itself until it snaps, but do not break it entirely. There should be a thin layer of
epidermis holding the two sides of the bent piece together. Gently peel one side away from the other to obtain as large a piece of epidermis as
possible. Be as quick as you can, to avoid desiccation of the epidermal cells. Try to avoid touching the epidermis (use forceps instead).
3. Place the epidermis on the slide slide and trim it, if necessary, to fit under a coverslip.
4. Use the technique learned earlier to position a coverslip over the tissue, avoiding air bubbles.
5. Examine and draw an intact epidermal cell in as much detail as you can.
6. Now have a partner add 2% NaCl solution while you look at the cell you drew. Look for any changes in the size and position of structures within
the cell (or any adjacent cells).
7. If any changes are evident immediately, draw the appearance of the cell after the changes occurred. Otherwise, look again after 10 minutes, and
draw any changed appearance.
MODULE 2 PROCEDURE
1. Obtain a cylinder of potato and slice it into 15 cylinders each 2 mm thick.
2. Place the slices on a filter paper and weigh all slices together and record their combined mass (m1) in the table.
3. Place all the slices in a Petri dish containing your assigned sucrose solution, or distilled water. Other groups will use different solutions and you
will pool results. Keep the filter paper.
4. Cover the Petri dish with its lid and leave overnight at room temperature.
5. Next available period, place each slice on your filter paper and gently fold the paper over the slices to pat them dry.
6. Re-weight filter paper and the slices (m2).
7. Collect data from the rest of the class, complete the table and graph the results of sucrose concentration against percentage change in mass*.
* calculate % mass change as 100 X (m2 – m1)/m1
concentration of sucrose solution
water
0.1M
0.2M
0.4M
0.6M
0.8M
1.0M
starting mass (m1)
final mass (m2)
% mass gain or loss
DISCUSSION
1. By comparing the sizes of the vacuoles in the lettuce cells you drew when bathed by different solutions, what evidence did you obtain that
supports the hypothesis?
2. Name three boundaries a substance would have to cross to move from outside the lettuce cell to the interior of a vacuole?
3. By describing what you think has caused any changed appearance of your lettuce cells, explain which of those boundaries must to have been
crossed in Module 1?
4. For your solution in module 2, explain any change in mass over the course of the experiment.
5. In a case resulting in an increase in mass, in which direction did a substance move to cause the change?
6. In which of the solutions was the concentration of water molecules greatest, 1.0M or 0.1M?
7. From your graph, (a) which sucrose concentration(s) led to no mass change? (b) explain why there was no mass change.
8. How do we describe a solution outside a cell compared to the cell contents when (a) water enters the cell? (b) water leaves the cell?
9. Cut pieces of radish curl when soaked in water. From a cellular perspective, explain how and why this occurs.
Melbourne High School BIOLOGY UNIT 3
PRACTICAL NOTES
SAC 1–2: ENZYME ACTION
For nearly every chemical reaction in living organisms, there are enzymes to accelerate the rate of the reaction. The enzymes are not consumed
during these reactions and are therefore considered to be organic catalysts. For instance, starch can be broken down to maltose, a sugar, if the
starch-splitting enzyme AMYLASE is present (Greek: amylon, starch). During digestion in humans an amylase is released with saliva to begin starch
digestion in the mouth and oesophagus. Plants make a similar enzyme (usually called diastase) to digest their starch.
PURPOSE
To investigate an aspect of starch digestion to see what can be inferred about the action of a digestive enzyme from experimental evidence.
HYPOTHESES
That amylase (diastase) catalyses starch to sugars, and its activity is affected by temperature.
BACKGROUND INFORMATION
1. The presence of starch can be detected by using iodine solution. Glucose (and some other sugars, eg. maltose) can be detected using Benedict’s
solution.
2. Enzymes can be inhibited by cold and denatured by heat.
EQUIPMENT (PER GROUP OF 3 OR 4)
Seven very clean semi-micro test tubes; semi-micro test tube rack; 2 graduated test tubes & rack; watch or clock; iodine and Benedict’s solutions;
compartmented tile; 2 disposable pipettes; 0·2% diastase; starch and glucose samples; distilled water; wash bottle, Thermoline® water bath set to
90°C; ice; 100 mL beaker.
PROCEDURE
Validation tests


Testing for starch Place the compartmented tile on a flattened piece of absorbent paper, and add 1 drop of starch from the room
temperature test tube to one tile compartment, and add 1 drop of iodine to that compartment. Record any colour change occurring in the iodine.
Label this compartment and keep the result on the tile for later comparison. Be careful to record any subtle changes that occur over the time of
the experiment.
Testing for glucose/maltose Add about 1 mL of glucose solution to a semi-micro test tube and add 5 drops of Benedict’s reagent.
Place 1 mL of starch solution into another semi-micro test tube and add 5 drops of Benedict’s solution. Place the test tubes in the Thermoline water
bath for 2 minutes, noting the grid references for your tubes in the water bath. Record any colour change(s) occurring in the Benedict’s solution, and
keep these tubes for later comparison.

Testing for starch digestion
1.
2.
3.
4.
5.
For the digestion, pour starch to a height of about 1 cm in each of the two graduated test tubes. Put one of these test tubes in ice water in
the 250 mL beaker. Keep the other in the large test tube rack at room temperature.
Using a semi-micro test tube, test a drop of the diastase solution using the Benedict’s test. Add 5 drops of Benedict’s reagent and 1 cm of
water and place in the Thermoline water bath for 2 minutes. If it tests positive for glucose, keep this test result for comparison with later
tests.
As quickly as possible, get from your teacher 1 mL of diastase solution for each of the large, starch digestion test tubes; then return one
tube to the ice water. Keep the other in the test tube rack at room temperature.
At intervals of 5 minutes, use one disposable pipette to take out a drop of mixture from each test tube, place it on a tile with a drop of iodine,
and record any colour changes. Do this for five samples taken 5 minutes apart, using the same pipette but a different tile compartment in
each case. Arrange the test samples sequentially in the tile compartments and label them.
Also, after 10, 20 and 30 minutes, use the other disposable pipette to transfer a 10-drop sample from each digest to semi-micro test tubes
containing 2 drops of Benedict’s solution and 1 mL of water and test for glucose (like you did above), each time recording the outcomes.
Keep these for colour comparisons. Use the same pipette for each sample.
DISCUSSION
1. This experiment was conducted on the assumption that there is amylase in saliva, and that diastase was similar to
amylase. Discuss the outcomes of your experiment in terms of your expectations, explaining what evidence you
think you obtained for the presence of a starch-digesting enzyme.
2. If you observed evidence for the disappearance of starch, and/or the appearance of glucose/maltose, what
alternative explanation(s) (other than diastase activity) can you suggest that could account for your observations?
3. What was the reason for keeping one enzyme–starch solution at 0°C?
4. Explain why it was necessary to test the starch solution for starch, and for glucose/maltose.
5. Explain why it was necessary to test the diastase for glucose/maltose.
6. In this exercise you tested the effect of temperature on enzyme activity. Design an alternative procedure you could
have used to test the effect of variation in pH on the enzyme’s activity (NB the first assessment criterion).
Make sure you have addressed ALL the assessment criteria for this SAC before submission of your report. 
Melbourne High School BIOLOGY UNIT 3
PRACTICAL NOTES
SAC 2–1: GLUCOSE IN THE BLOOD
INTRODUCTION
Cells in a multicellular organism require a relatively stable internal environment for normal functioning. This internal environment is provided by the
tissue fluid and plasma that bathe the body cells. Many substances are exchanged between cells and their internal environment. Glucose is a major
nutrient and is usually maintained in the blood at a level between 3.6 and 6.8 mmol/L. Some people have diabetes mellitus, a condition in which
there is a deficiency of the hormone insulin. These people are unable to maintain their blood sugar levels within normal limits without medical
treatment.
YOUR TASK
Data from 3 different people with diabetes are presented. Examine the data provided and answer the associated questions.
DATA
Module 1
These data were collected by a nurse while the patient was in hospital. The patient received intravenous, short-acting insulin (by continuous infusion
into a vein). Insulin is mixed with saline and infused into the patient at a rate dependent on the level of glucose in the blood. The level of sugar in the
blood is measured at regular intervals. Information about the insulin delivered and blood glucose measurements are given in Table 1.
Table 1
DAY 1
Time
2400
0400
0800
1200
1400
1600
1900
2300
Infusion
(units of insulin)
6
10
6
Blood sugar
(mmol/L)
Time
16.0
17.9
17.1
21.6
16.7
16.7
23.6
16.1
0600
0800
1000
1400
1800
2200
0200
0600
DAYS 2/3
Infusion
Blood sugar
(units of
(mmol/L)
insulin)
6
16.0
16.7
6
16.6
10
20.6
6
15.4
6
16.0
8.6
10.0
Module 2
The data for this person were also collected by nurses while the patient was in hospital. This patient received injections of insulin subcutaneously
(under the skin). Information is given in Table 2.
Table 2
Time
0100
0400
0730
0830
1120
1345
1600
1730
2000
2100
2400
DAY 1
Infusion
(units of
insulin)
30
14
Melbourne High School BIOLOGY: UNIT 3
Blood sugar
(mmol/L)
6.7
7.7
8.8
7.0
12.5
9.8
5.1
4.8
2.2
5.1
9.5
Time
0730
1100
1215*
1315*
1525*
1615
1730
2000
2100
0700
PRACTICAL NOTES
DAYS 2/3
Infusion
(units of
insulin)
30
6
12
Blood sugar
(mmol/L)
4.7
2.5
1.8
1.6
2.6
3.5
4.9
4.5
7.1
6.6
Module 3
This person was an out patient at a hospital and brought records that had been collected in the previous weeks. The form has the headings, as
shown in Table 3. The person had circled the words TABLETS and BLOOD in the top line. Blood glucose tests were carried out at bedtime (missing
a day or two every so often) and these results over a few weeks were as shown in Table 4.
Table 3
DATE
WEIGHT
kg
INSULIN OR TABLETS
Type
Dose
URINE/BLOOD TESTS
TEST
breakfast lunch tea
BEFORE
URINE
BLOOD
URINE
BLOOD
URINE
bed
COMMENTS
hypos thirst diet exercise
Table 4
blood
glucose
(mmol/L)
12
14
16
14
13
15
15
date
13 July
14 July
15 July
16 July
17 July
19 July
20 July
date
22 July
23 July
25 July
26 July
27 July
28 July
29 July
blood
glucose
(mmol/L)
13
18
14
12
11
11
11
date
30 July
31 July
1 Aug
2 Aug
3 Aug
4 Aug
6 Aug
blood
glucose
(mmol/L)
11
12
11
10
11
11
11
date
7 Aug
10 Aug
11 Aug
12 Aug
13 Aug
14 Aug
15 Aug
blood
glucose
(mmol/L)
16
8
11
12
8
10
11
DISCUSSION QUESTIONS
These will be provided when you come to the double period allocated for this SAC.
EXTENSION
 Before the discovery of insulin it was suspected that the pancreas contained an anti-diabetic factor, but an experiment
in which a chemical extract of whole dog pancreas was injected into diabetic dogs had no noticeable effect on their
blood glucose levels.
 A glucose tolerance test gives information about a person’s ability to regulate their blood glucose levels, and is used to
diagnose diabetes. A person fasts from midnight before the test first thing in the morning. The person eats a high
carbohydrate diet for 3 days prior to the test and, if possible, does not take any medication prior to the test.
 For the test, a person is given 75g of glucose. The blood level is measured 10 minutes before the glucose is given, at
the start of the test and at half hour intervals after the ingestion of the glucose.
 Two people, one normal and one with type 1 diabetes mellitus, were tested and the results are shown in the graph
(Figure 1).
glucose tolerance test
blood glucose level
(mmol/L)
patient 1
patient 2
12
normal BGL
9
6
3
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.3 4.0 4.3 5.0
time (hours)
Figure 1
Melbourne High School BIOLOGY: UNIT 3
PRACTICAL NOTES
DISCUSSION QUESTIONS
EXTENSION QUESTIONS
Melbourne High School BIOLOGY: UNIT 3
PRACTICAL NOTES
SAC 2–2: PLANT RESPONSES TO STIMULATION
INTRODUCTION
After seeds germinate and the seedlings emerge from the soil, their stems usually seek a light source and grow towards it; they also
could be considered to be growing away from gravity. On the other hand, the roots grow downwards, towards gravity (or away from
light).
HYPOTHESES
1. That the stems of germinated seeds will grow towards a light source and away from gravity.
2. That the roots of germinated seeds will grow away from a light source and towards gravity.
YOUR TASK
To germinate some seeds and then test the seedlings’ responses to light and gravity, in two different experiments. Some
groups will do Module 1, the rest will do Module 2 and you will combine results.
MATERIALS & EQUIPMENT (PER GROUP OF 4)
1 growing tube with cap and liner; probe; pipette; tweezers; 1·5 mL measuring spoon and 10 mL measuring cylinder; gel powder; 3 bean
seeds
PROCEDURE
 In both modules, you first have to germinate some seeds. Pour 20 mL tap water into a growing tube and soak the absorbent paper
liner. Using the spoon, add ¼ spoon of gel powder to the water in the bottom of the tube.
 Do not add too much gel powder!
 The powder will begin to swell as it absorbs water, and will form a clear gel. If it does not set within 4 hours, add a little bit more
powder.
 Use a probe to open a small gap between the wall of the tube and the blue absorbent paper liner, then use tweezers to place a seed
in the gap about 3 cm below the top of the liner. The idea is to place a seed so the paper holds it against the clear plastic wall of
the growing tube.
 Repeat the seed placement with 2 more seeds, placed evenly around the tube.
 Loosely place the cap on the tube to retain humidity. Once germination has occurred, the cap will be removed during the day, and
replaced loosely during the night, until the growing plant tip reaches the top of the tube.
 If the liner seems to be drying out, add 1–2 mL water to the gel, as required.
MODULE 1: DEALING WITH GRAVITY
1. When the plant roots are 3–5 cm long place one tube on its side in an evenly lit position; use a small piece of sticky tape to prevent
the tube from rolling.
2. Set a second tube on a clinostat at an angle of 45° to the vertical; switch on the clinostat.
3. Set a third tube on a clinostat at 45°, but do not turn on the clinostat.
4. Check the tubes after a couple of days, looking for signs of change in the root growth; compare the root growth with root growth in
the tubes kept vertically in the dark.
5. After 4–5 days, restore all tubes to the vertical in uniform light; check the subsequent root growth.
MODULE 2: MOVING TO THE LIGHT
1.
2.
3.
4.
When the plant stems are 3–5 cm high place two tubes vertically in a poorly-lit position facing a window.
Place a third tube vertically on a rotating clinostat near the first two tubes.
Place the remaining tubes in uniform light.
Check the plants frequently and note any differences in stem growth.
DISCUSSION
1. What was the control in this experiment?
2. In what way(s) did your results support the hypotheses?
3. What effect, if any, would masking the seedling tips have on their subsequent growth?
4. If this experiment demonstrated a stimulus–response control mechanism
a. What was/were the stimulus/i?
b. What was/were the response/s?
c. Explain the internal hormonal changes that enabled the response/s.
5. What is the scientific name for a plant growth response to light?
6. What advantage would a plant that grows towards light have over others that could not, or which grew more
slowly?
7. Why should a plant stem grow away from gravity?
Melbourne High School BIOLOGY: UNIT 3
PRACTICAL NOTES