Biology 2004
Sample assessment instrument and student responses
Extended experimental investigation:
Coordination and control in plants
This sample is intended to inform the design of assessment instruments in the senior phase of
learning. It highlights the qualities of student work and the match to the syllabus standards.
Criteria assessed
• Understanding biology
• Investigating biology
Assessment instrument
The response presented in this sample is in response to an assessment task.
Task
Design and conduct a biological investigation on coordination and control in plants. You will be
required to keep a journal and then to write a scientific report summarising the results of the
investigation.
Instructions
• Select a topic and then develop and refine a research question. Discuss your ideas with your teacher
before finalising your experimental investigation.
• Throughout this process you should record in your journal clear links between your chosen topic and
the theory associated with the investigation to reveal interrelationships.
• When your topic has been approved, focus your research so to develop a hypothesis and experimental
investigation. Consider any safety issues and complete a risk assessment.
• Trial your proposed method and modify, if necessary, before carrying out your investigation.
• Consider the types of data that you can collect and collate the results of your investigation in
appropriate formats to identify trends and interrelationships.
• Analyse the investigation results with links to theoretical concepts to draw conclusions relating to the
question.
• Evaluate the design of the investigation reflecting on the adequacy of the data collected and propose
refinements, where needed.
• Although some work will be conducted in groups, each student must submit their own journal and
scientific report.
14363
Conditions
• You have six weeks to research, design, carry out your experiment and complete your report.
• Complete your investigation with a scientific report. The discussion and conclusion should be 800 –
1000 words.
• Your investigation must be one that can be tested safely. You will be required to submit a risk
assessment before commencing the experiment.
Instrument-specific criteria and standards
Investigating biology
Understanding biology
Student responses have been matched to instrument-specific criteria and standards; those which
best describe the student work in this sample are shown below. For more information about the
syllabus dimensions and standards descriptors, see
www.qcaa.qld.edu.au/downloads/senior/snr_biology_04_syll_standards.pdf
Standard A
Standard B
The student communicates their understanding
by:
The student communicates their understanding
by:
• making links between related ideas and
• defining and describing ideas and concepts of
coordination and control, and identifying
interrelationships.
concepts of coordination and control to
reveal meaningful interrelationships.
The student communicates investigative
processes by:
The student communicates investigative
processes by:
• formulating justified researchable questions
• identifying researchable questions
• designing, modifying and implementing an
• selecting and implementing investigations
investigation about coordination and control
• collecting and organising data to identify
about coordination and control
• collecting and organising data
trends and interrelationships
• interpreting and critically analysing results
with links to theoretical concepts to draw
conclusions relating to the question about
coordination and control
• discussing results and drawing conclusions
about coordination and control.
• evaluating the design of the investigation and
reflecting on the adequacy of the data
collected, and proposing refinements.
Key:
Cognition
words
Quality or
degree words
Note: Colour highlights have been used in the table to emphasise the qualities that discriminate between
the standards.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 2 of 12
Student response — Standard A
The annotations show the match to the instrument-specific standards.
Comments
Making links
between related
ideas to reveal
meaningful
interrelationships.
Formulating justified
researchable
questions.
The physiological and developmental effect of the hormone auxin on
tomato plants
INTRODUCTION (extract)
The natural growth of plants can be altered through the administration of many
different, naturally occurring hormones. These plant hormones, or plant growth
regulators, are produced in low concentrations and cause physiological or
developmental responses. Depending on the hormone, these responses can
be either stimulatory or inhibitory (Fauth 2009). Common examples of such a
group of hormones are auxins. Auxins are characterised by their ability to
produce cell elongation in the stems of plants (Arteca 1996).
Within plants, auxins are produced in the shoot and root tips, young,
expanding leaves, and young seeds. Where the auxins are produced is known
as the source, and where they are sent to complete their function is known as
the target. Although auxins are naturally made inside the plant, there are some
synthetically produced auxins which are used in horticulture. Synthetic auxins
are commonly used as they have such a variety of sought after effects.
Auxins have many functions within plants which either inhibit or stimulate the
growth of the plants. These functions include, but are not limited to the
following (Davies 1995):• stimulating cell elongation – when cells are new (recently divided) they are
small, and densely packed. The hormone auxin causes these new cells to
pump H+ ions (acid) into their cell walls, causing the cell to loosen and
elongate. This is caused by the higher pH, activating enzymes which break
linkages in the wall, allowing the turgidity to elongate the cells.
• the auxin supply from the apical bud suppresses growth of lateral buds –
auxin is produced in the apical bud, or the dominant growing tip, and
therefore suppresses the growth of lower lateral buds.
• mediating the tropic response in bending because of gravity or light.
AIM
To investigate the effects of varying amounts of the hormone auxin on the
development of the physiological features of tomato seedlings, and to
determine the differences in growth between seedlings with less auxin, normal
amounts of auxin and extra auxin.
HYPOTHESIS
The plants with the higher amounts of auxin (the ones watered with auxin-rich
water) will grow the tallest because auxin elongates the cells of the stem of the
plant. The seedlings which have had their apex either removed or capped, will
not grow as tall but will grow wider, because it is lacking the auxin supply from
the apical bud. This means that the growth of the lateral buds will no longer be
suppressed; resulting in a shorter plant.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 3 of 12
Comments
Designing, modifying
and implementing
investigations.
(See journal also)
METHOD
1. Fill each pot ¾ full with the potting mix. Plant two seedlings for each treatment.
2. Make a hole in the centre of each pot and then place the bean seedlings in the
indentation. Cover the roots with potting mix.
3. For Group 2, trim 2cm off the top of each plant.
4. For Group 4, cover the apical bud/s in alfoil.
5. Water the Group 1, 2 and 3 seedlings with 10mL distilled water.
6. Water the Group 4 with 10 mL of 1mg/L auxin solution.
7. Water the Group 5 with 10 mL of 0.5mg/L auxin solution.
8. Measure the size of each seedling and record heights, count each stem and
leaf.
9. Water and take measurements of the seedlings each day. Take photographs
each day to record the growth of the seedlings.
10. Repeat the experiment to confirm results.
Alfoi
Group 1- Control
Group 2- Apical
bud removed
Group 3- Apical
bud capped
Group 4- Watered
with 1mg/L Auxin
Group 5- Watered
with 0.5mg/L Auxin
Diagram One. The experimental set-up
RESULTS
Trial One
Graph One – Growth in height over 3 weeks.
The gaps are weekends when the plants weren’t measured.
Collecting and
organising data to
identify trends and
interrelationships.
Group 4 shows the greatest growth, where Group 1 and 2 also show steady
growth.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 4 of 12
Comments
Table One – total growth in each plant in Trial One.
Group
End Height
Initial Height
(cm)
(cm)
One
9.9
5.8
Two
0 (dead)
6.3
Three
0
5.7
Four
17
11.1
Five
10.4
8.4
Groups 4 and 1 show the greatest growth.
Total Growth
(cm)
4.1
- the plant died
- the plant died
5.9
2
Trial Two
Graph Two – Growth in height over 3 weeks.
Groups 4 and 5 show the greatest growth, all the other groups died.
Table Two – total growth in each plant in Trial Two.
Group
End Height
Initial Height
Total Growth
(cm)
(cm)
(cm)
One
0 (dead)
6.3
- plant died
Two
0 (dead)
5.4
- plant died
Three
0 (dead)
7.5
- plant died
Four
14.3
11.6
2.7
Five
13.1
10.3
2.8
Groups 4 and 5 show very similar amounts of growth, the other plants died
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 5 of 12
Comments
Trial Three
Graph Three – Growth in height over 3 weeks.
Groups 4 and 5 displayed the greatest growth and Group 2 showed a steady
but small growth.
Table Three – total growth in each plant in Trial Three.
Group
End Height
Initial Height
(cm)
(cm)
One
0 (dead)
11.5
Two
9.1
8.4
Three
0 (dead)
7.1
Four
11.7
8.8
Five
12.1
8.9
Total Growth
(cm)
- plant died
0.7
- plant died
2.9
3.2
Groups 4 and 5 showed the greatest growth in this trial.
Figure Five. Some of the plants displayed a
scorched like appearance. This is the Control
group at the start of week three.
The leaves appear scorched on this plant.
DISCUSSION
As can be seen in Graphs and Tables 1–3, the amount of auxin available to
each plant had an effect on the growth of the plant. The group which is
supplied with the highest amount of auxin-1mg/L, (Group 4) had the highest
average total growth of the three trials (3.8cm). Group 5, the only other group
which showed any consistent growth, and in which all the plants survived, was
the other group given extra auxin, 0.5 mg/L IAA, had an average total growth
of 2.7cm, over one centimetre less than the average of Group 4.
Identifying trends.
Interpreting and
critically analysing
results (throughout).
This demonstrates that plants which have access to higher amounts of auxin
grow taller in a shorter time as a result of the elongating effect of this particular
hormone. These findings were in line with the information from Cartage 2008
who says that cells in plants are elongated when supplied with higher amounts
of auxin, therefore higher concentrations of auxin results in greater plant
growth.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 6 of 12
Comments
Links to theoretical
concepts.
Identifying trends
and
interrelationships.
Interpreting and
critically analysing
results (throughout).
Modifying an
investigation.
Tables 1–3 show the plants in Group 2 and 3 (cut or capped by alfoil) died or
showed very little growth. They could not produce auxin which is produced in
the plant tip and were prevented from photosynthesising, which stopped them
from being able to produce energy to live off, and died as a result.
The tomato seedling in Trial 3, Group 2 which had its uppermost leaf cut off
survived as it could continue photosynthesis. However, it showed very little
growth (0.7cm) as it was unable to produce auxins to elongate the cells of the
plant. Although only one result was obtained over the three trials, this
modification of only cutting the very top leaf off shows that a reduced amount
of auxin leads to a shorter plant.
The ‘cut’ group had the smallest growth recorded. The control group showed
the next lowest average growth then 0.5mg/L group and finally the 1mg/L
showed the most growth. This order of growth (smallest to largest) is
proportional to the amount of auxin available to each seedling.
Although the withering and dying of the plants in groups 2 and 3 was a result
of a lack of photosynthesis, the two seedlings that died from the control group
are both anomalies. It was noticed at the start of the second week that they
had developed a scorched appearance possibly as a result of the sun burning
them through the glass windows they were situated next to.
The plants were then put under artificial lighting so they would no longer be
burnt. For the plants in Groups 4 and 5 this seemed to solve the problem.
However, for the other three groups the plants still remained burnt-looking.
Control trial two was brown all over.
As the plants overall didn’t benefit from the artificial light, the light was not the
factor which was destroying the plants. It was hypothesised that the acidity of
the soil was not at an optimum level so an acidity test was undertaken.
Link to theoretical
concepts.
The soil had a pH 5-6, which leads to an excess absorption of boron and a
deficient absorption of phosphorous. An excess of boron resulted in necrosis
occurring, and plant leaves yellowing and developing a scorched appearance.
Necrosis is death of plant tissue in spots. This is a possible cause for the death
of control trials 2 and 3. The yellowing and scorched appearance on the leaves
can be seen in Figure Five.
It does not explain all the anomalies as all the plants were planted in the same
soil and some of the seedlings did recover under the artificial lighting.
The experiment did return the expected results, however the accuracy of data
collection was low. If the experiment was to be repeated these would all have
to be modified to ensure better results:
• the plants should be as close as possible to the same height at the start of
Evaluating the
design of the
investigation and
reflecting on the
adequacy of the data
collected and
proposing
refinements.
•
•
•
•
•
•
the experiment
the dilution of the auxin solution could have been performed with a more
accurate measuring instrument
the soil pH should have been between 6 and 7 as that is the range where the
absorption of elements is at an optimum for most elements
the seedlings should have been kept in one place and an artificial light
should be used for the duration of the experiment
the plastic ruler used for measuring was too wide to fit in the pot, so the zero
could not line up with the base of the plant. Measurements were very
subjective as the plants did not come to a point.
only the very top leaf or stem should be cut off or capped in groups 2 and 3
a larger sample size.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 7 of 12
Comments
For farmers growing produce it is important to know whether, and to what level
the use of synthetic auxins will help their produce grow. The experiment
shows that higher levels of auxin results in taller plants. As these results show
a substantial difference in a short period of time, this experiment could be the
deciding factor as to whether or not the expense of indole-acetic acid is
beneficial.
CONCLUSION
Drawing
conclusions.
The findings indicate that the amount of auxin available to a plant affects the
height. The hypothesis was supported by the findings as the plants with the
highest availability of auxin were the plants which showed the most vertical
growth, and the seedlings with less auxin result in shorter plants. This is
because auxin elongates the cell, resulting in a taller plant.
BIBLIOGRAPHY
Arteca, R. (1996). Plant Growth Substances: Principles and Applications.
New York: Chapman & Hall.
Davies, P. J. (1995). Plant Hormones: Physiology, Biochemistry and Molecular
Biology. Dordrecht: Kluwer
Fauth, P 2009, Hartwick, viewed 31 January 2010,
http://users.hartwick.edu/fauthp/HORTHormone.ppt
Mendipweb, Plant-hormones Info 2009, viewed 31 January 2010
http://www.plant-hormones.info/auxins.htm
Cartage 2008, Plant regulation and response, viewed 12 March 2010
http://www.cartage.org.lb
Graig, P 2008, Mid Wales-Trees, viewed 12 March 2010
www.midwales-trees.co.uk
EXTRACTS FROM JOURNAL
Making links
between related
ideas to reveal
meaningful
interrelationships.
Hypothesis: The plants with the higher amounts of auxin (the ones watered
with auxin-rich water) will grow the tallest because auxin elongates the cells of
the stem of the plant, whereas the seedlings which have had their apex either
removed or capped, will not grow as tall but will grow wider because they are
lacking auxin from the apical. This means that the growth of the lateral buds
will no longer be suppressed, resulting in a shorter plant.
Materials:
Designing
investigations.
•
•
•
•
•
•
•
•
•
bean seedlings (tomatoes instead)
soil (potting mix)
auxin solution of two different concentrations, 1mg/L and 0.5mg/L
scissors (scalpel)
alfoil
pots
ruler
water
measuring cylinder
Method
1. Plant seedlings in the same amount of soil, two seedlings for each trial (6 in
total). The control group will be named Group 1, the group with the apical bud
will be named Group 2, and the group being watered with auxins will be named
Group 3.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 8 of 12
Comments
Modifying
investigations.
2.
3.
4.
5.
For Group 2, trim their tops off. How much?
Water the Group 1 and 2 seedlings with x mL distilled water.
Water Group 3 seedlings with x mLs of the auxin solution.
Measure the size of each seedling and record heights, widths and internodal
heights.
6. Water and take measurements of the seedlings each day. Take photographs
each day to record the growth of the seedlings.
7. Repeat and modify the experiment to confirm results.
Changes may need to be made later on.
[…]
Modification
As it appeared that the plants were turning brown (or burning) so they were
moved under artificial light to stop this from happening. The plants now have
24 hour light so can photosynthesise all the time but without the heat to burn
them.
Although at first it didn’t seem to make a difference – the plants did eventually
revive and start growing under the artificial light.
[…]
Acidity test
Because the plants were dying I did an acidity test on the soil that they are
planted in, the auxin solutions and the distilled water.
[…]
From the research it seems that either an excess of boron or deficiency of
phosphorous are causing this as these symptoms are the same as what
appears in the plants being grown. This would be a pH of around 6 because
that is where a lot (:. Excess) of boron is absorbed and where not much (:.
Deficient) amount of phosphorus is absorbed.
[…]
If the pH is around 8, then either of these problems could be behind this. Most
likely the boron excess.
[…]
Conclusion
Because the pH of the soil was 5-6 the problems seen in the plants could be
caused by either an excess of boron being absorbed or a deficiency of
phosphorous. It can be assumed it was more likely to be the boron because
the symptoms were more evident.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 9 of 12
Student response — Standard C
The annotations show the match to the instrument-specific standards.
Comments
Ethylene and Fruit Ripening Experiment
Introduction:
Describing ideas and
concepts and
identifying
interrelationships.
Identifying
researchable
questions.
The aim of this experiment was to test if the hormone ethylene, produced in
banana’s, would affect the ripening rate of certain fruits. Ethylene is unlike
other plant hormones as it is a gaseous hormone. Ethylene is used for fruit
ripening at a fruits last maturing stages. The ethylene slowly reaches to 0.1 to
1.0ppm while the fruits ripening, and once it’s ready to mature, the ethylene
has reached it’s right amount of ppm to expose it’s gas and start the maturing
process. What is being tested is if allowing the ethylene from the ripening fruit
and extended ethylene from an already ripened banana will ripen the fruits
faster.
Hypothesis: Ripening of unripe fruits is unaffected by storing it with a banana.
Prediction: The fruits won’t change their ripening rate after being exposed to
more ethylene.
Procedure:
Selecting and
implementing an
investigation.
1. Label bags clearly from 1-3
2. Put fruit in bags.
− Bag One-1 Banana, 1 Pear
− Bag Two-1 Banana, 1 Pear
− Bag Three-1 Pear
3. Fold the tops of the bags down twice so that it’s not fully concealed but not
much air is entering or escaping.
4. Place all bags in a constant room temperature area (independent variable)
5. Check all bags every day for 5 days and record results accordingly e.g. photos,
tables, etc.
6. After the 5 days are complete, cut the pears in half and put cover one half in
Iodine and leave the other to compare how much starch is in the pears. The
lighter the colour goes, the riper the pear is. The darker the colour stays, the
more likeliness that the pear is still unripe.
Results:
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 10 of 12
Comments
Collecting and
organising data.
Discussion:
Before the experiment was tested with pears, it was tested with mandarins.
By the end of the five days of the experiment, the mandarins were brown and
mouldy. No one in the group could figure out why this happened as none of
it was in our background research. So we looked into why this may have
happened. We found that ethylene is a base, like the pear. And on the pH
scale, mandarins aren’t on the same level as ethylene as they are acidic.
So mixing the ethylene with the acidic mandarins wouldn’t have any affect as
mandarins are form 7 on the pH scale, meaning it’s neutral. And the acidic
fruits, like mandarins, release glycol ethylene, not normal ethylene. So the
ethylene was stronger in the bananas and the proteins were all wrong so the
two fruits just reacted against each other, and that’s why it went all mouldy.
Selecting, modifying
and implementing an
investigation (B
standard)
We decided to conduct the experiment again but with a different fruit. So
further research was made to see what fruits were essential for the ethylene
test. We chose to use pears as they are easier to notice when it’s ripening as
the colour goes from dark green to light yellow/green. And the fruit goes from
hard to soft and appetizing.
From the results above and in the journal, you can evidently see in the photos
and tables provided that there were some unsuspected results. The prediction
of this experiment was that ethylene would not contribute to the ripening rate of
pears. The results prove otherwise.
Discussing results.
Identifying
interrelationships.
From day one to day three of the experiment, the pears in bags one and two
were clearly lighter than the pear in bag three. By day five, the pears in bags
one and two were softer than the pear in bag three and also had brown bruises
on them as they started to spoil. This links us back to the background
research. It verifies that the research was legitimate and appropriate when
saying that adding a fruit already with the high amount of ethylene needed to
start the ripening process, fastens the process.
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
Page 11 of 12
Comments
Discussing results.
Drawing
conclusions.
You can see in the table and photos, that day five of the ripening, we have
named ‘Iodine Day.’ At the end of the experiment, we cut the pears in half and
covered the flat surface of one half in iodine and left the other one to compare
colour. The iodine started off as a dark colour from the pears in bags 1 and 2
but then slowly turned lighter; meaning the pears were ripe. The pear from bag
3 was also lighter but was not overripe like the other two pears. This was
concluded that the bananas were left in the bags for too long, leaving the
pears to spoil. So linking back, we were proven wrong when predicting that
ethylene had nothing to do with ripening fruits faster than their normal ripening
rate.
Conclusion:
In conclusion, testing if ethylene ripens fruit faster than it ripens by itself is a
limited experiment. The fact that we didn’t know that there were limited fruits
for this experiment proves that we didn’t do enough background research.
This has been noted for future experiments. Our results and data proved that
ethylene can ripen specific fruits if given the right ppm level. Therefore our
prediction and hypothesis were proven wrong. Ethylene can help fasten the
ripening rate of fruits such as pears. It contributes to the ppm level needed to
start the ripening process, but earlier. And that’s why the pears from bags 1
and 2 were overly ripe by the pear from bag 3 was ripe.
Bibliography
http://www.plant-hormones.info/ethylene.htm
http://www.catalyticgenerators.com/whatisethylene.html
http://www.biology-online.org/11/10_growth_and_plant_hormones.htm
Biology 2004
Sample assessment instrument and student responses
Queensland Curriculum & Assessment Authority
July 2014
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