4.1
Week 4
The Nature of Biochemical
Processes
Area of Study 1
Molecules of life
Key knowledge
 Enzymes and organic catalysts
 Energy requirements of cells
 Catabolic and anabolic reactions
Key skills
 Investigate and inquire scientifically
 Apply biological understandings
 Communicate biological information and understanding
Tasks this week relate to outcome 1.
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Analyse and evaluate evidence from practical investigation related to
biochemical processes
Relevant websites – see online biology course environment. Go to the
Links section.
Glossary terms for Week 4 can be found here:
http://quizlet.com/_gtmr
4.2
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 4. You will need to read sections from the text book –
Biology VCE Units 3 and 4 by Thomson Nelson.
The Objectives
By the end of this week you should have completed the SAC (School
Assessed Coursework) practical activity.
You should be able to:
 Distinguish between anabolic and catabolic reactions
 Understand the importance of endergonic and exergonic reactions
 Define the term catalyst
 Describe the role of enzymes in a cell
 Define the term metabolism
 Understand how enzymes work
 Give factors that affect enzyme activities
 Apply you knowledge to new situations
 Investigate the use of the enzyme renin
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.
4.3
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.
4.4
OUTCOME 1 SAC PRACTICAL ACTIVITY
After the theory and practical in week 3, you should be familiar with the
properties of differentially (semi or partially) permeable membranes.
Experiment 4A -
Demonstrating Differential Permeability (dialysis)
When making drawings make sure that:
 the outlines are clear
 they are fully labelled
 the scale of your diagrams is recorded.
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 posted to the DECV by the date given on page 0.2 unless you do
the SAC at the DECV – in which case you will have until the
following Friday to post the work.
 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.
Before beginning the prac make sure that you have completed the weekly
work in Week 3.
4.5
OUTCOME 1
EXERCISE 4A
DEMONSTRATING DIFFERENTIAL PERMEABILITY (DIALYSIS)
Aim
Observe and describe the effects of a differentially permeable membrane
on the process of diffusion.
Note/ The term ‘differentially permeable’ means semi or partially permeable
Background information
What is a control? The word ‘control’ is used as a short way of saying
the control set up or control group. A control is a standard of comparison
for checking inferences drawn from an experiment. The control part is
used to verify the experimental part. Many experiments that are made to
test an hypothesis involve the use of a control. The control establishes
what is ‘normal’ or constant. Keep all things constant except for the factor
that you are deliberately changing in the experimental set up – so that your
tests are fair. The one factor being changed is called the variable and can
be one of any number of things for example temperature, light, presence
or absence of a substance etc.
A fair scientific experiment is called a controlled experiment.
Please note
Starch (polysaccharide) is
a polymer made up of
many glucose
(monosaccharide)
monomers joined
together. This is a clue as
to the differences in size
of each molecule.
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To test for starch, add several drops of brown iodine/potassium
iodide solution to the test solution. Blue/black colour appears when
starch is present.
To test for glucose use testape or Clinstix strips
Test tape turns green in sugar.
Clinstix strip turns light purple / dark purple. – Any of the positive
colour blocks indicate presence of glucose. Use the colour guide given
below.
Dark +++
Dark purple
Hypothesis
Medium ++
Light +
Negative
light purple
Make an ‘educated guess’ about what outcomes you will expect in this
experiment. Read through the practical exercise and the aim carefully to
ensure that your hypothesis is relevant.
Equipment
1.
2.
3.
4.
5.
6.
20 cm strip of dialysis (cellulose) tubing
Test tube (needs to be wide enough to take the dialysis bag)
Rubber/elastic band
Two petri dishes (or clean saucers if you’re doing it at home)
Test-tube rack
10 mL graduated pipette
4.6
7.
8.
9.
10.
11.
Dropping pipette (eye dropper)
20 mL(approximately)of mixed glucose and starch solution in a
l00mL beaker
Iodine/potassium iodide solution in dropping bottle (or you may use
Betadine if you are doing it at home. It may be obtained from your
local chemist)
Testape/ Clinistx Reagent Strips
Supply of distilled water in 250 mL beaker.
Please note/ the dialysis bag will
probably be much larger than shown
in the diagram above.
Procedure
1. Moisten the piece of dialysis tubing and tie a very tight
knot in one end. Open the other end with your fingers so
that the end of a pipette can be inserted.
2. Collect approximately 60mL of glucose/starch solution in a
100mL beaker. Using the 10mL pipette, transfer enough of
this solution to two-thirds fill the dialysis bag. Take care
not to let any solution run down the outside of the bag.
3. Place the bag in the test tube and fasten with a rubber band
as shown in the diagram. Rinse the bag thoroughly by
carefully filling and emptying the test tube several times
with water. Finally, fill the tube with distilled water to
within 1 cm of the top and stand it in a rack for at least 20
min.
4. Place two or three drops of the distilled water into each of
two clean petri dishes.
a.
To one petri dish add several drops of
iodine/potassium iodide solution. Record your results
in the table below.
b. Dip one end of the testape into the water in the other
petri dish. Record your results.
Copy Table 1 below into your notes and record the results of your tests.
5. Rinse the two petri dishes and put them to one side for later use.
6. After leaving the test tube for at least 20 minutes repeat step 4 but use
samples of water collected from near the bottom of the test tube
around the dialysis bag. Use the dropping pipette to collect the
samples. Take care not to break the bag with the tip of the pipette.
Table 1
Results of tests.
Distilled water
Clinistix
test
Results
Interpretation
Iodine test
(or Betadine)
Water in test tube at end of
experiment (after 20 minutes)
Clinistix
Iodine test
test
(or Betadine)
4.7
7. Clean up all your equipment and put it away.
8. Dispose of any waste material.
Discussion
a. Of the two substances (starch and glucose) in the solution in
the dialysis bag, which was able to pass into the surrounding
liquid? By which process did that substance move through the
dialysis bag and into the surrounding liquid, osmosis OR
diffusion?
b. Suggest what differences between the glucose and starch
molecules may have enabled this to happen?
c. Which step of the procedure represents the control?
d. Why is it necessary to test for starch and sugar at the
beginning?
e. What do the results suggest about the structure of the dialysis
tubing?
f. Write down a definition of diffusion and osmosis. What are
the differences between osmosis and diffusion? Use reference
books if necessary.
Conclusion
Summarise the results of your experiment, relating them to the aim and
hypothesis of the experiment along with what you have learned and any
errors or improvements you found.
Report
Write a standard practical report of the above activity. See page 0.6 at
the start of this book for guidance.
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.
Front Cover & the Authentication Declaration Form
Complete the declaration form on the front cover for this week and make
sure you attach this to the front of your SAC for this week.
4.8
Name: ……………………………………… Student Id: ……………………….
Week 4 SAC Assessment Sheet
VCE Biology Assessment Task: Unit 3 Outcome 1
Ex 4A Demonstrating Differential Permeability
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 theory
of plasma membranes.
Q (a), (b), (e) & (f)
Complex
understanding
Thorough
understanding
Mostly accurate
Some relevant
discussion
Understanding of aims and
method.
Hypothesis, Q (c) & (d) &
Conclusion
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.
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
Conclusion & Q (a), (c),
(d) & (e)
Application of theory to
specified conditions
Conclusion & Q (b) & (f)
Comprehensive
interpretation and
evaluation.
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.
Relevant
evaluation and
interpretation.
Some
evaluation and
interpretation.
Poor
evaluation and
interpretation.
Very detailed
and relevant
Mostly detailed
and related
indirectly.
Some
knowledge of
terms, concepts
and
relationships
Knowledge
unclear and
irrelevant
Very High
High
Medium
Low
Very Low
Not shown
21-25
16-20
11-15
6-10
1-5
0
Comprehensive,
detailed and directly
relevant
Overall SAC Grade:
Some
reference to
but little or no
discussion
Hypothesis
has been
stated but not
relevant.
Procedures do
not accurately
list the steps
of the
experiment.
Not
Shown
4.9
Authentication Declaration for Outcome 1
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 ONE EXERCISE 4A Demonstrating Differential Permeability.
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 -------
4.10
1. Read through pages 70 to 81 of your text book and complete the tasks for
week 4 online at http://www.decvonline.vic.edu.au. You will find a button
in the course saying Online Tasks, click on this and answer the questions
for week 4. Use your DECV number as the username and your date of
birth in reverse order as your password (YYYYMMDD).
2. Take a screen shot or print your results and send them in
3. View the Enzymes interactive found under the Animations button.
Key Summary Points
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Metabolism is the overall chemical activity of cells, including
synthesis of organic molecules, energy transforming and recycling
processes, and breakdown of unwanted substances. These reactions
involve hundreds of enzymes working in ‘chains’.
Enzymes are proteins that act as biological catalysts to control the
metabolism of the cell.
Catalysts make a reaction take place more easily. They do not change
the direction of a reaction, are needed in small amounts and remain
unchanged at the end of the reaction.
Each enzyme usually catalyses only one type of reaction. This
specificity is related to the three-dimensional structure of the
molecules.
Activation energy is the energy required to get a reaction started, even
if the reaction eventually releases energy.
Enzymes act by reducing the amount of activation energy required for
a reaction to occur.
The affinity of an enzyme for a substrate can be regulated to alter the
rate of a reaction.
Factors affecting enzyme action include temperature, pH, other
chemicals, amount of reactants and products, and the presence of
coenzymes and cofactors.
Enzymes are important in both traditional modern medicine.
Enzymes play critical roles in metabolic pathways in living
organisms.
Lack of a particular enzyme can result in disease.
Anabolism is the building of larger molecules from smaller molecules.
It requires energy to construct the new bonds and often involves
dehydration.
Catabolism is the breakdown of macromolecules into smaller
molecules. The breaking of bonds releases energy and often involves
hydrolysis.
4.11
Challenging Activity: Mnemonic Activity
Choose one or more terms from the list given on page 96 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!
For an example see the Enzymes animation found under the
Animations button in the DECV online Biology course environment.
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 4.
Make sure you check out the other Mnemonics left by your classmates and
leave them a comment.
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.
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 1-18 online / screen shot or printed
 SAC Practical activity 4A Demonstrating differential permeability
 At least one mnemonic of a biological term online
 Your online Personal Reflection for week 4
 The front cover for this week signed by your supervisor
Exam Practice Exercise
Past Exam Questions
4.12
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.
Each of the following multiple choice questions is worth one mark.
Question 3 (2000 Exam paper – 1 mark)
Enzymes are:
A. carbohydrates that have the ability to catalyse reactions.
B. proteins that speed up chemical reactions.
C. carbohydrates that are denatured at very high temperatures.
D. proteins that are used up in chemical reactions.
Question 25 (2002 Exam paper– 1 mark)
The rate of reaction of a typical human enzyme was compared with the
rate of reaction of a typical enzyme taken from bacteria that live in hot
springs. The rates of reaction were measured over the same range of
temperatures. The data obtained is shown in the following figure.
It is reasonable to conclude that
A. typical human enzymes fail to act at temperatures above 50ºC.
B. the optimal temperature for enzymes for both organisms is about 37ºC.
C. a denatured bacterial enzyme would resume activity if reincubated at
40ºC.
D. enzymes from bacteria that live in hot springs withstand temperatures
up to 100ºC.
Question 17 (2003 Exam paper– 1 mark)
The following graph illustrates the effect of different concentrations of a
substrate on the rate of a cellular reaction.
4.13
In this series of experiments, the amount of enzyme, the pH and the
temperature remain constant.
The limiting factor at point X is the
A. pH.
B. temperature.
C. amount of enzyme.
D. substrate concentration.
Don’t forget to drink plenty of water!
ONLINE DISCUSIIONS
Get to know your fellow students!
Go to our Ning at http://vcebiology.ning.com/ to access our online
community. Start a Forum post of your own or add to one that is already
there called Introductions.
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.
END OF WEEK 4
Answers to Past Exam Questions
Question 3 B is the correct answer.
Question 25 A is the correct answer.
Question 17 C is the correct answer. Point X on the graph shows that as
the substrate concentration increases the rate of the reaction remains
constant. A limiting factor is one that prevents the rate of reaction from
increasing. The substrate concentration is increasing and the amount of
enzyme is constant so the limiting factor is the amount of enzyme.
4.14
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.
64804
[64804]
STUDENT NUMBER ___________________
SCHOOL NAME _______________________
STUDENT NAME ______________________
SUBJECT
Biology Unit 3
YEAR/LEVEL
TEACHER
12
WEEK
4
________________________
[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
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Please check that you have attached:
SAC Practical activity 4A Demonstrating Differential Permeability
 This Coversheet and the declaration and authentication
I declare that, except where indicated, the attached SAC is solely the work of the student
 has been completed according to the following requirements:
named above, and
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Within
 80 – l00 minutes of class time
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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.)

4.15
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