8.1
Week 8
Coordination and Regulation
Area of Study 2
Detecting and Responding
Key knowledge
Coordination and Regulation:
 Plant growth hormones
Key skills
 Investigate and inquire scientifically
 Apply biological understandings
 Communicate biological information and understanding
Tasks this week relate to outcome 2.
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Describe and explain coordination and regulation of an organism's
immune responses to antigens at the molecular level.
Relevant websites – see online biology course environment. Go to the
Links section.
Glossary terms for Week 8 can be found here:
http://quizlet.com/_hvay
8.2
Introduction
Read carefully through this Week’s work before completing the tasks. Check
for any practical exercises that may require you to obtain materials and
equipment.
This is Week 8. You will need to read the information in this booklet as
well as sections from the text book – Biology VCE Units 3 and 4 by
Thomson Nelson.
The Objectives
By the end of this week you should be able to:
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Explain what a signalling molecule is.
Describe examples of the chemical factors and signalling molecules to
which organisms respond.
Explain the differing roles of nerves and hormones in communicating
messages to bring about appropriate responses.
Give some examples of illness and disease due to disruption of
detection and signalling pathways.
Explain how plant regulation pathways differ from those in animals.
List the environmental factors to which plants respond.
Describe the types and roles of plant growth regulators (hormones).
8.3
Read through pages 113 and 115 of your textbook. The information found
there is relevant to the SAC practical activity for this week. Read those pages
before attempting the practical activity.
Complete the following SAC (School Assessed Coursework) practical activity
Contact me as soon as possible if you are not able to complete this
practical.
Please note the following important instructions:
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Keep your SACs once returned, in case they are requested by VCAA.
You should make and keep copies of your SACs when completed
(particularly major ones) to protect against loss.
Read carefully through the rules of completion on the following page
before starting your SAC.
8.4
SAC Rules for Completion
Please note the following conditions for the submission of
School Assessed Coursework (SACs):
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SACs must be completed on time as indicated in the course book and SAC material
SACs received in time will be graded
SACs received after the due date will be assessed for satisfactory achievement of the
associated outcome (or part thereof) – they will receive an NA for assessment, as the student
has not fulfilled DECV assessment requirements. If an NA has been given the teacher will
explain the consequence of the NA.
Lost, stolen or damaged SAC work is governed by VCAA policy. If this happens, contact
your teacher.
A Declaration of Authenticity will be provided with SAC materials or in the course book.
You must sign this to verify that the conditions set by the teacher have been followed.
If the SAC is completed under supervision, your supervisor must sign the Supervisor’s
Certificate, attesting that the work has been done under the correct conditions.
SACs will not be assessed until the Declaration of Authenticity and Supervisor’s
Declaration (if required) have been received by the DECV.
When SACs are returned you must retain them until the results have been finalized. VCAA
may request they be submitted for moderation or verification.
Only completing SACs (Units 3 and 4) will not allow you to demonstrate achievement of
the unit outcomes. This is achieved by satisfactorily submitting all the weekly work as
specified in the course-book.
If you have enrolled late or have received materials late please contact your teacher to
establish a modified timetable. This timetable is to be followed subsequently in regards to
SAC submission. A Modified SAC Timetable will then be forwarded to you. It ensures
you know the extension arrangements and must abide by them. Once these extension
arrangements are established they become your modified timetable. SACs will then be
subject to the Rules for Completion based on your modified timetable. Students need to gain
extensions prior to the SAC submission date.
The SAC timetable and/or conditions may be varied through the processes of Special
Provision. These processes are described in the “Student Guide to Distance VCE 2005’.
Applications are the responsibility of the student or supervisor to formally apply to Year 12
Student Coordinator. All applications must be accompanied by appropriate and current
documentation
Please note: You may not resubmit work for re-grading of a SAC in Units 3 and 4. You are
only able to resubmit work in order to demonstrate the achievement of an outcome to receive
a satisfactory result for the Unit.
8.5
OUTCOME 2 SAC PRACTICAL ACTIVITY
After doing the theory from Week 7 you should be familiar with some of
the things that affect the activity of enzymes. If not, you should revise that
work if you need to, particularly the sections from the text book before
conducting this experiment.
Instructions for completing SAC activities
As this is part of your formal assessment it is to be done  under supervision (so ensure that your supervisor is available)
 within 80 – l00 minutes of class time. A standard practical report
(see page 0.6 at the start of this book) is to be completed by the next
day
 and sent to the DECV by the posting date shown on page 0.2.
 late enrolling students need to contact me (your teacher) to arrange
alternative dates
 extensions are available to students with extenuating circumstances
however these can only be granted by me (your DECV teacher)
 the authentication declaration sheet must be completed and sent in
with the completed practical report.
Practical activity
Do the practical activity on the following pages and write a standard
practical report in accordance with the requirements as outlined above
and on page 0.6.
Practical work
It is likely that you will have to find and prepare materials for some
practical exercises. If you think you might have problems performing a
particular practical exercise, contact your Biology teacher as soon as
possible.
8.6
OUTCOME 2
EXERCISE 8A - TEMPERATURE REGULATION
Make sure that you have read through pages 113 and 114 of your textbook before
attempting this practical activity.
Introduction
The core body temperature (internal body temperature) of some organisms
changes very little even when the temperature of the surroundings (the
ambient temperature) changes considerably. Such organisms must
therefore have mechanisms that are regulating their body temperature.
The diagram given below highlights the role that the hormonal (endocrine)
system plays in temperature regulation. Overall the regulation of human
body temperature is achieved by the nervous and hormonal systems
working together.
Figure 7.2
Thyroxine production is controlled through two negative feedback loops. Thyroxine
inhibits the secretion of thyroid-stimulating hormone (TSH) from the pituitary gland and
also the secretion of thyrotrophin-releasing hormone (TRH) from the hypothalamus.
The hypothalamus, which is found in the brain, is sensitive to a number of
different stimuli, such as temperature. In cold seasons it releases more
TRH, signalling the pituitary to secrete more TSH, thus leading to higher
levels of thyroxine and a higher metabolic rate, helping the body to
maintain a constant temperature. Humans have a ‘set point’ temperature
around 37Co. As the external temperature changes, the body employs a
number of corrective mechanisms to maintain the ‘set point’, for example
8.7
sweating removes excess heat from our skin to cool us down when the
internal temperature begins to rise above the ‘set point’.
Figure 7.3
Set points and optimum conditions are maintained through negative feedback.
The images above are courtesy of Nelson Biology VCE Units 3 and 4, second edition .
Aim/Purpose
To investigate the responses of the human body to extremes of the
surrounding temperature.
Hypothesis
Make an educated guess about what changes you think will occur in your
subjects (the participants):
a)
externally - how will their appearance, behaviour and skin temperature change?
b) internally – how will their internal temperature respond to the changes
in external temperature?
Materials and Equipment
1.
2.
3.
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5.
6.
Clinical thermometer (They usually have a kink in the end). Read
the instructions carefully if you use some other type of thermometer.
Buckets or tubs, 2-4
Hot and cold water
Stopwatch or watch with second hand.
Electric fan (optional)
Heater (optional)
Procedure/method
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Choose 5 volunteers to act as subjects and another 2 to act as
observers. Read the following paragraphs before starting the
experiment and decide what observations each observer will make.
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If you do not have enough subjects available you may need to repeat
the experiment with the same subject. Do not forget to state this in
your discussion as you will have to introduce another variable in that
you are not experimenting on these subjects at the same time.
8.8
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Before proceeding with the experiment, record the body temperature
of each subject, by placing a clinical thermometer under the tongue
for 2 minutes. If you use some other kind of thermometer, take the
reading from under an armpit and note any errors and improvements
you could comment on. Don’t forget to clean it hygienically before
moving to the next subject. Take it out, read it and record the
temperature in a table.
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Before taking the next subject’s reading, shake down the mercury in
the thermometer and put it back under the subject's tongue (only if
you use a clinical thermometer). Don’t forget about the hygiene. Make
sure the thermometer is clean.
Make two volunteers as cold as possible, by removing jumpers, etc.
Sit them in a draught if one is available and, if necessary, put their
legs in a bucket of cold water. Use the fan.
Make two other volunteers as hot as possible by moving them to a
small room, sitting them in front of a radiator, putting on extra
clothing and putting their legs in water as hot as they can stand.
The remaining volunteer is the control and so should remain at room
temperature (approx. 21Co).
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Record the temperature of the hot, cold and control subjects at 2
minute intervals for 10 minutes.
Safety Warning
STOP the experiment whenever a subject shows signs of distress.
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Note as many changes in the subjects as you can. Look for changes in
the body temperature, skin (flushing or paling, appearance of sweat or
goose pimples), changes in breathing rate and pulse rate.
Continue observations until the subjects feel hot or cold 'all through',
but stop before they become really uncomfortable.
If a subject's temperature changed during the experiment, keep
recording it at two-minute intervals until it returns to normal.
Record the behaviour of the subjects at the end of the cooling and
heating period. Find out how they feel.
Results
Present the data in an appropriate form (e.g. tables, graphs etc).
Discussion
Questions
1. List all the changes observed in the hot subjects.
2. Which (if any) of these changes might reduce the body temperature?
Explain.
3. List all the changes observed in the cold subjects.
4. Which (if any) of these changes might increase the body temperature?
Explain.
5. Compare the results of the experimental set up (hot and cold
conditions) with those of the control set up. What do you notice?
8.9
6. Using Figure 7.2 above give the steps that outline how the body
responds to the temperature dropping below its ‘set point’ and the role
that thyroxine plays in that response.
7. Explain how thyroxine acts as a signal at a cellular level to cause a
response in a target cell. You may have to re-read earlier text book
information for this one.
8. Give one problem that may arise as a result of a problem occurring in
the thyroxine signal pathway.
Conclusion
9.
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12.
Was your hypothesis correct?
Referring to your results and the aim, what general conclusions
can you draw about how the body responds to extremes in the
surrounding temperature? Mention homeostasis in your
response.
What are some possible causes of error in this experiment?
What improvements could you make to this experiment so that
the results are more useful?
Standard Practical report
Write a standard practical report of the above activity. (See page 0.6 of
this booklet).
SAC Assessment Criteria Sheet
Attach the SAC Assessment Criteria Sheet provided to your standard prac report.
Use it as a guide and reference as to what you need to cover in your report.
Authentication Declaration form
Complete the declaration form provided, and attach it to the report.
8.10
Name: ……………………………………… Student Id: ……………………….
Week 8 SAC Assessment Sheet
VCE Biology Assessment Task: Unit 3 Outcome 2
Ex 8A Temperature Regulation.
Outcome Descriptors/Key
Knowledge & Skills
Very High
High
Medium
Low
Very Low
Comprehensive
Understanding,
detailed and accurate
Thorough
understanding,
detailed and
accurate
Mostly accurate
Some relevant
discussion,
understanding.
Some accuracy
Some reference,
little
understanding.
Some parts
incomplete and
inaccurate
Understanding of the terms,
concepts and theory of
homeostasis.
Q 2, 4, 5, 6 & 7
Complex
understanding
Thorough
understanding
Mostly accurate
Some relevant
discussion
Some
reference to
but little or no
discussion
Understanding of aims and
method.
Hypothesis
Q 9, 10, 11 & 12
Hypothesized
relationship
between the
variables and the
predicted results is
clear and reasonable
based on what has
been studied.
Procedures are
listed in clear steps.
Each step is
numbered and is a
complete sentence.
Hypothesis
has been
stated but not
relevant.
Procedures do
not accurately
list the steps
of the
experiment.
Professional looking
and accurate
representation of the
data in tables and/or
graphs. Graphs and
tables are labelled
and titled.
Hypothesized
relationship
between the
variables and
the predicted
results is
reasonable
based on
general
knowledge and
observations.
Procedures are
not listed in a
logical order,
steps are not
numbered and
not in complete
sentences.
Accurate
representation
of the data in
written form,
but no graphs or
tables are
presented.
Hypothesized
relationship
between the
variables and
the predicted
results has been
stated, but
appears to be
based on flawed
logic.
Procedures are
listed but are
not in a logical
order or are
difficult to
follow.
Collection and presentation
of results.
Results
Some
knowledge and
understanding
of the results.
Some accuracy.
Results
identified but
incomplete
and
inaccurate.
Evaluation of procedures
and results
Q 2, 4, 9, 10, 11 & 12
Application of theory of
homeostasis and relevant
mechanisms of
coordination, regulation,
signalling molecules and
transduction.
Q 2, 4, 6, 7, 8.
Comprehensive
interpretation and
evaluation.
Comprehensive,
detailed and directly
relevant
Hypothesized
relationship
between the
variables and
the predicted
results is
reasonable
based on
general
knowledge and
observations.
Procedures are
listed in a
logical order,
steps are
numbered but
not in complete
sentences.
Accurate
representation
of the data in
tables and/or
graphs. Graphs
and tables are
labelled and
titled.
Well developed
evaluation and
interpretation.
Very detailed
and relevant
Relevant
evaluation and
interpretation.
Mostly detailed
and related
indirectly.
Some
evaluation and
interpretation.
Some
knowledge of
terms, concepts
and
relationships
Poor
evaluation and
interpretation.
Knowledge
unclear and
irrelevant
Very High
High
Medium
Low
Very Low
Not shown
21-25
16-20
11-15
6-10
1-5
0
Overall SAC Grade:
Not
Shown
8.11
Authentication declaration for outcome TWO
This document must be posted or, if being sent by E-mail, scanned with your actual signature on it.
Student Declaration of Authentication of Coursework
Name of student:----------------------------------------DECV Student No.------------Return the signed Declaration to:
Name of Teacher: ----------------------------------------
AUTHENTICATION OF SCHOOL ASSESSED COURSE WORK
The VCAA requires that the student sign a declaration at the time of submitting the completed common
assessment task stating that all unacknowledged work is the student's own. The student must
acknowledge all resources used. This will include text and source material used and the name(s) and
status of the person(s) who provided assistance, and the type of assistance received. Accordingly,
students must sign and return the declaration below when they submit the common assessment task to
their teacher at the Distance Education Centre, Victoria. Without this completed declaration their work
cannot be assessed.
STUDENT DECLARATION OF AUTHENTICITY
NAME OF STUDY:------------------------------------------------NAME OF STUDENT: ---------------------------------------------
OUTCOME TWO EXERCISE 8A – TEMPERATURE REGULATION
I declare that all unacknowledged work on Outcome 1 above is my own and that I have completed this
Outcome 1 practical in a period of not more than 100 minutes for the practical activity itself. The formal
write up of the practical was completed by the next day.
Student's signature ---------------------------------------
Date:-----------
TEACHER/PARENT DECLARATION OF AUTHENTICITY
I declare to the best of my knowledge the unacknowledged work signed for above is the work of
the student identified. OR I cannot attest to the authenticity of the student’s work.
*Teacher's/Parent’s signature: -----------------------------------------------(* delete as appropriate)
Date -------
8.12
Read through the following information as well as pages 132 to 135 of your
text book on "Communication in plants" and complete the tasks or questions
that follow. Use your own A4 paper or send work as MSWord documents
attached to an email.
Plant Responses
Plants do not have highly specialised receptors like those found in
animals, yet they respond to a variety of changes in their environment.
The stimuli they respond to include:
 Physical factors such as day/night length (photoperiodism),
light (phototropism), gravity (geotropism) as well as
temperature and touch.
 Chemical factors such as water, carbon dioxide and ethylene
gas (which ripens fruit).
These responses are mediated chemically by hormones and can best be
described by the response model:
Detection
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Effect  Response  Transmission
Tropism
Growth in plants is triggered by environmental factors.
When the direction of growth is related to the direction of the stimulus,
the responses are called "tropisms". For example: Positive phototropism
is when plants grow towards a source of light. The growth is controlled by
a plant hormone, an auxin, called indoleacetic acid (IAA). In the
presence of light, this hormone is unevenly distributed in the growing tip.
Because there is more IAA on the side away from the light, more growth
takes place on that side. This causes the plant to grow towards the light.
See the plant hormones interactive animation in the online environment
for Unit 3 Biology. Have a look at the animation of auxin for an easy way
to remember how it acts on plants.
Positive geotropism is when plant roots grow towards the pull of gravity.
Photoperiodism
What makes some plants flower during winter and others during summer?
What makes the leaves of some trees fall in autumn?
Why do seeds germinate during Spring?
Plants respond to the length of day/night - this is called photoperiodism.
The receptor that is stimulated by photoperiod is a pigment ion the leaves
that responds to red light.
8.13
SEND…
Questions
1. What is the difference between phototropism and geotropism?
2. Why do plant cells need to communicate?
3. What is a plant growth regulator? List five plant growth regulators.
See the five plant hormones given in the animation section of the
online biology course environment.
4. The fruits available to us at supermarkets are often out of season in
our local area. We rely on having them transported long distances,
often from as far away as Queensland. For example, apples may have
been harvested many weeks, even months ago, yet they appear fresh
and ripe on supermarket shelves. Use your knowledge of "ripening
hormones" and a little research to find out how such fruits are
managed between picking and purchasing. (Hint: When are they
harvested? In what kind of environment are they stored? For how
long? How can fruit merchants ensure their fruits are ripe at the time
of sale to supermarkets?)
Activity 8B – Phototropism in Plants
Aim
To demonstrate phototropism in
wheat seedlings.
Background information
Positive phototropism is when
plants grow towards a source of
light. The growth is controlled
by a plant hormone, an auxin,
called indoleacetic acid (IAA).
In the presence of light, this
hormone is unevenly distributed in the growing tip. Because there is more
IAA on the side away from the light, more growth takes place on that side.
This causes the plant to grow towards the light. See also the plant
hormones – auxin animation online (go to the DECV website – VCE Unit
3 Biology site – Animations link).
Hypothesis
What do you predict will be the outcome of this experiment?
Materials and Equipment
The pictures on pages 8.13 and 8.14
Procedure
1. Some wheat seedlings are grown on moist cotton wool in two Petri
dishes or two saucers. The seedlings are grown straight up in both
clumps. See the diagram below.
8.14
When there are plenty of young green shoots:
2. One group (Group A) of seedlings is placed in a darkened room (or
enclose the seedlings in a box with a hole in one end) with a lamp to
illuminate the seedlings from one side.
3. One group (Group B) will act as the control and so should be left in a
well lit area..
Results
4. After two or three hours record any changes in the seedlings
After 2 – 3 Hours:
Group A
Group B
Discussion
Using your knowledge of the course concepts in addition to the results of
your experiment answer the following questions:
8.15
1.
2.
3.
4.
5.
What was the stimulus in this demonstration?
What was the response and how is this brought about by the plant. In
other words what happens in the plant to bring this about?
Explain the term phototropism.
How could phototropism help a plant to survive?
What plant hormone is responsible for phototropic responses?
Conclusion
What conclusions can you draw from this experiment?
If the results do not come to your expectations, explain the reasons
SEND…
Practical Activity Ex 8B – Phototropism in Plants: Write a
standard practical report of the above activity.
Key Summary Points
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Many complex animals use a variety of chemical and electrical signals
in a communication network involving two systems - the nervous
system and the endocrine system. These systems are integrally related.
Signalling molecules are chemicals that are released by cells such as
neurotransmitters and hormones.
Most of the chemical signals produced by animal cells are hormones
There are two main types of hormones - steroid hormones and amino
acid and polypeptide-based hormones.
Hormones travel throughout the body via the bloodstream.
Hormones bind to specific receptor proteins found only in target cells.
Integrated responses to environmental change usually involve a large
amount of sensory information received from different parts of the
body.
Glands in the endocrine system secrete hormones which are important
in homeostasis, such as regulating blood glucose levels in the
bloodstream, in growth and development and many other processes.
The nervous system is composed of specialised cells called neurons,
which are organised in the central nervous system (CNS) - the brain
and spinal cord- and the peripheral nervous system - which extends
out to the rest of the body. The CNS coordinates the information
received from stimuli and coordinates the best response.
Neurones transmit messages between receptor organs effector organs
and the CNS in the form of electrical impulses.
A neurotransmitter is a chemical substance that can control and
coordinate responses.
Many physiological disorders can be attributed to a breakdown at
some stage in these regulatory mechanisms and some novel
technologies are being developed to treat them.
8.16
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Pheromones are chemicals emitted by living organisms to send
messages to individuals of the same species.
Plants have no nervous system; internal coordination is controlled by
hormones (or growth regulators)
Plant growth and reproduction are synchronised with seasonal
changes, and with local physical and climatic conditions. Plants also
respond to light, gravity and temperature.
Plants are sensitive to a number of environmental factors, both
physical and chemical, that contribute to hormonal regulation.
Directionality is often an important aspect in plant sensing and
responding, particularly of light (phototropism) and gravity
(geotropism).
Photoperiodism is a plant's ability to measure seasonal changes by the
length of day and night. Short -day plants require long nights to
trigger flowering. Long-day plants flower if the nights are short or if
the plants are continuously illuminated.
Many commercially available synthetic substances that mimic natural
plant hormones have been developed to control the development and
growth of plants.
Challenging Activity: Mnemonic Activity
Choose one or more terms from the list given on page 137 of your
textbook and create a memory aid to help you remember the definition
of that term. You may use drawings, poetry, song, sound, whatever
works for you! Share your ‘mnemonic’ (memory aid) with the other
students of your class via the chat room. Feel free to discuss your ideas
with me.
See the mnemonic for "plant hormones" given online in the Biology
Unit 3 section of the DECV website. Click on the Animation button
found on the left hand navigation bar and then click on the "Plant
hormones interactive" link.
Log on to the www.decvonline.vic.edu.au check out the back of your
DECV book for your login details if you have forgotten.
Click on the link to the Unit 3 Biology course.
Click on the button “Discussion Room”
Place your Mnemonic as a comment to the Discussion post titled
Mnemonics Week 8.
Challenging Activity: Personal Reflection
Log on to the VCE Biology Course. Place your Personal Reflection in the Biology
Blog as outlined on 0.7 in the introduction of this book.
8.17
Exam Practice Exercise
Past Exam Questions
Each week you will get a least one question that relates to the weeks
work, that comes from a past VCE exam paper.
The purpose of this task is to familiarize yourself with the type of
questions you will encounter during the exam and the timing you should
devote to each.
Timing
You should allow 1 minute and ten seconds per mark assigned to the
question.
Below you will find two multiple choice questions and one short answer
question taken from past exam papers. The answers given at the end of
this week come from the examiner’s report put out by VCAA after the
exams were conducted.
Each of the following multiple choice questions is worth one mark.
Multiple Choice Section
Question 10 (2000 Exam paper – 1 mark)
Large nerves contain a large number of sensory and motor neurons. The
sensory neurons
A. synapse directly with motor neurons in glands.
B. form part of the autonomic nervous system.
C. transmit impulses from the central nervous system to muscles.
D. transmit impulses from receptors to the central nervous system.
Question 16 (2003 Exam paper – 1 mark)
The nervous and endocrine systems are the two major regulatory systems
of the body. Both systems
A. take the same time to respond to a stimulus.
B. have the same duration of response to a stimulus.
C. use the blood for the transport of their chemical signals.
D. release chemical signals that act on tissues they control.
Short Answer Section
Question 2 (2004 Exam paper– 4 marks)
You should spend 4 minutes and 40 seconds on this question
Three experiments were carried out to investigate the control of growth in
oat coleoptiles. In addition to the oat coleoptiles, materials used included
8.18
• agar, a jelly-like substance
• juices from ground-up oat coleoptiles.
Experiment 1
Three groups of oat coleoptiles were treated as follows:
Group 1 – no treatment
Group 2 – tip of coleoptile cut off and replaced in same position
Group 3 – tip of coleoptile cut off at same level as in group 2 and
removed
The coleoptiles were incubated for four hours in darkness. The set-up and
results are shown below.
a. Explain why group 2 coleoptiles grew and group 3 coleoptiles did not.
1 mark
Experiment 2
Three groups of oat coleoptiles were treated as follows:
Group 4 – no treatment
Group 5 – tip of coleoptile cut off and replaced by a piece of agar that had
been soaking in juices from ground-up oat coleoptiles
Group 6 – tip of coleoptile cut off at same level as in group 5 and
replaced by a piece of plain agar.
The coleoptiles were incubated for four hours in darkness. The set-up and
results are shown below.
8.19
b. Explain why there is growth of coleoptiles in group 5 but no growth of
coleoptiles in group 6.
1 mark
Experiment 3
Four groups of coleoptiles (shown in the diagram below) were treated as
follows:
Group 7 – no treatment
Group 8 – tip of coleoptile cut off and replaced, in the position shown, by
a piece of agar that had been soaking in juices from ground-up oat
coleoptiles
Group 9 – tip of coleoptile cut off and replaced, in the position shown, by
a piece of agar that had been soaking in juices from ground-up oat
coleoptiles
Group 10 – tip of coleoptile cut off and replaced, in the position shown,
by a piece of plain agar.
8.20
The set-up is shown on below:
The coleoptiles were incubated for four hours in darkness and then each
group was examined to determine whether growth or bending had
occurred in the coleoptiles.
c. Predict the growth result for each of the four groups of coleoptiles.
Record your answers in the table below by placing one tick in each of the
four columns. Place your tick against the result you predict for each of the
four groups.
Experimental group
7
8
9
10
No growth
Vertical growth
Bending to left
Bending to right
2 marks
Total 4 marks
Checklist
This week you should have submitted the following work to me.
Please tick the items you have sent, and keep this as your record.
 Responses to Questions 1 – 4
 SAC Practical activity 8A – Temperature Regulation
 Activity 8B : Phototropism in Plants
 At least one mnemonic of a biological term left online
 Your Personal Reflection of week 8
Don’t forget to drink plenty of water!
8.21
Feedback
What, if anything needs to be improved, corrected, cleared up or
presented better from the materials presented in this week? Your honesty
is appreciated. Write your comments on the back of the cover sheet.
Answers to Past Exam Questions
Answer to Multiple Choice Section
Question 10: D is the correct answer.
Question 16: D is the correct answer.
Answers to Short Answer Section
Question 2
a. The growth hormone (auxin) is produced in the tip of coleoptiles.
Although group 2 coleoptiles were cut, the tip remained and auxin was
available to diffuse down the stem and stimulate growth. In group 3, the
removal of tips meant no auxin was available and hence no growth.
Students are reminded to carefully read the stem of the question. Some
students referred to light receptors in their answers. The stem of the
question states that the coleoptiles were incubated for four hours in
darkness.
b. Coleoptile juices in agar contain a growth hormone (auxin) that diffuses
from the agar into group 5 coleoptiles whereas the agar on group 6
coleoptiles contains no juices therefore no hormone to stimulate growth.
When a question requests a comparison be made between two groups the
response should make mention of both groups.
Student responses such as ‘group 5 coleoptiles have auxin’ could not be
awarded a mark as no mention of what happened to group 6 was made.
Some students incorrectly referred to the presence of nutrients in the juice
as the cause of the growth.
c.
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The most common mistakes made by students when filling in this table
were predicting the growth result for groups 8 and 9. Many incorrectly
stated that group 8 would bend to the left and group 9 to the right.
END OF WEEK 8
8.23
315 Clarendon Street, Thornbury 3071
Telephone (03) 8480 0000
FAX (03) 9416 8371 (Despatch)
Toll free (1800) 133 511
Fix your student barcode
label over this space.
SCHOOL NO.
64808
[64808]
STUDENT NUMBER ___________________
SCHOOL NAME _______________________
STUDENT NAME ______________________
SUBJECT
Biology Unit 3
YEAR/LEVEL
TEACHER
12
WEEK
8
________________________
[ZX]
PLEASE ATTACH WORK TO BE SENT.
NOTE: Please write your number on each page of your work which is attached to this page.
SEND
Please check that you have attached

SAC Practical activity 8A – Temperature Regulation

Responses to Questions 1- 4

Activity 8B : Phototropism in Plants

At least one mnemonic & your Personal Reflection left online
I declare that, except where indicated, the attached SAC is solely the work of the student
named above, and has been completed according to the following requirements:


Within 80 – l00 minutes of class time
It was completed under the supervision of the Supervisor named below.
Student's signature: ___________________________________ Date: ______________
Supervisor's signature: ________________________________ Date: ______________
Name of Supervisor: _______________________________________
Relationship to Student: ____________________________________
(Teacher, Employer, Parent, etc.)
8.24
YOUR QUESTIONS AND COMMENTS
Please provide the following information:
Were you able to complete the tasks in the time frame allocated? ____________________
Roughly how long did it take for you to complete this week of work? _____________
Use this space for any queries or comments you have, (or maybe errors you’ve found).
DISTANCE EDUCATION CENTRE TEACHER’S COMMENTS
DISTANCE EDUCATION CENTRE TEACHER