Cell Structure
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Cells
LI – To name the different structures of a plant and
animal cell and learn their functions
Think, pair then share – At the back of your jotter, list any parts
or functions or animal and plant cells that you can remember.
Cells are the basic units of all living organisms. Although cells
vary in shape, they do have some structures in common.
Animal Cell
nucleus
cytoplasm
What to do
cell membrane
1. Copy the diagram and label the parts of the cell.
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Plant Cell
Nucleus
Vacuole
Chloroplast
Cytoplasm
Cell wall
Cell membrane
1. Copy the diagram and label the parts of the cell.
What to do
2. Using class resources copy and complete the table
below and tick the box if the structure appears in the
named cell.
Part
Function
Animal
Plant
Nucleus
Cytoplasm
Cell Membrane
Cell Wall
Vacuole
Chloroplast
Extension
Specialised cells: Design a poster.
Choose a cell and explain how its structure relates to its function
(job). Include a diagram and where the cell would be found.
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Microscopes
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Microscopes
LI – Explain the importance of microscopes and describe
how to use a microscope properly.
The detailed structure of animals and plants cannot be seen
with the naked eye. A microscope uses lenses to magnify very
small objects.
There are two lenses on a microscope. The lens nearest to the
eye is the eyepiece lens. The lens nearest the object is the
objective lens; there may be 2 or 3 objective lenses held by
the nosepiece which rotates to allow each lens to be positioned
above the object.
The platform on which the slide is placed is called the stage.
The slide is held in place by the stage clips.
The object is made clear using the focus knobs, sometimes
there are 2 focus knobs, one for coarse adjustment and one
for fine adjustment.
The light enters the microscope from the bottom. It may be
from an electric light under the stage or reflected from a
mirror.
Parts of a microscope
1. Collect a microscope diagram.
2. Label the parts of the microscope mentioned in bold
above.
3. Your teacher will show you how to set up and use a
microscope correctly. Look at prepared slides.
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Preparing a slide for the microscope
Living material which is viewed under the microscope must be
very thin to allow light to pass through. It is therefore
necessary to look at thin piece of material. Living material must
also be kept moist; a drop of water or stain (such as iodine or
methylene blue) must be added. A stain is used to show the cell
structures more clearly.
Watch while your teacher demonstrates how to prepare a slide
using onion skin.
Collect (in pairs)
A microscope
dropper
Paper towel 2 slides 2 coverslips
iodine stain
forceps
piece of onion
Prepare a slide for viewing under the microscope.
1. Place a small, thin piece of onion on the centre of the
slide. The onion should not be folded.
2. Add ONE drop of iodine stain to the onion.
3. Carefully lower a cover slip over the onion. DO NOT
MAKE AIR BUBBLES.
4. Examine under the microscope LOW POWER FIRST.
5. Magnify the slide further.
Teacher Check!
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1. Make a drawing of your slide. (Use a PENCIL, no larger
than one third of a page).
2. Give your drawing:
a. A title
b. The magnification used
c. Label any obvious structures that you can see.
d.
3. Explain why you think it is necessary to stain living
tissue.
Magnification
To find the magnification of a microscope you have to do a
simple calculation:
Power of eyepiece lens X power of objective lens
E.g. The eyepiece power is x5 and the objective lens is x6
5 X 6 = 30
The magnification is x30
Copy the equation in the box above.
Copy and complete the table below
Eyepiece Lens
10
Objective Lens
4
10
10
Total Magnification
100
400
Extension
Make a slide using cheek cells.
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Cell Division
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Cell Division
LI – To find out the importance of cell division and the
reasons why cells must divide.
Think, pair then share – why is it important for cells to divide
and make more cells? Write your ideas on a ‘Show Me Board’.
Teacher Check!
Write down three reasons why it is important for cells to
divide.
What to do
Your teacher will show you how to inoculate agar with red
yeast, using aseptic techniques. This shows that yeast have
reproduced.
Collect:
 Agar plate
 Inoculating loop
 Bunsen
 Heatproof mat
 Stock yeast
 Disinfectant and cloth.
What to do:
1. Wipe your bench down with disinfectant.
2. Transfer the stock yeast on to the fresh sterile agar
plate, using aseptic techniques. (You might want to do a
fancy design or your initials).
3. Leave the plate at room temperature and observe the next
lesson.
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Stages of Mitosis
Mitosis is controlled by the nucleus of the cell.
Watch the presentation on the stages of mitosis.
Work with a partner to then complete the ‘card sort’ activity
– put the pictures in order and then match up the statements
with each picture.
Teacher check!
Now complete the ‘Stages of Mitosis’ diagram from your
diagram pack, by sticking the diagrams in the correct order
and then write a sentence to describe what you can see at
each stage.
You are now going to look at garlic root tip cells undergoing
mitosis. Try to identify a cell at each stage of mitosis.
Follow the method detailed below:
What to do
Preparing root tips
1. Preheat 10cm3 of 1M hydrochloric acid in a small beaker to
60oC.
2. Cut the first 2mm of root tip into the heated acid and leave
for 4-5 minutes.
3. Remove root tips from the acid and place on a clean slide
containing a large drop of water.
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4. Gently blot dry with a piece of tissue.
5. Mush up the root tip using a dissection needle and spread
over an area the size of a 5p coin.
Staining the tissue
1. Add one drop of toluidine blue to the mashed up root tip and
cover with a coverslip.
2. Turn the slide upside down and blot slide firmly.
3. View under a microscope.
Chromosome Numbers
Each new daughter cell that is produced during mitosis should
have the exact same number of chromosomes as the original
parent cell.
Why is this important? Write a short paragraph detailing
why it is important that each new daughter cell has the same
number of chromosomes are the original parent cell.
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Uncontrolled Cell Division
LI – To find out what happens when cells undergo
uncontrollable cell division.
Discuss with a partner – sometimes cells will undergo cell
division and continue to do so uncontrollably.
 What do you think will happen?
 Why do you think this has happened?
What to do
You will now watch a video clip on cancer.
http://www.bbc.co.uk/learningzone/clips/cancer-in-thedeveloped-world/5703.html
Find your diagram ‘Cancer in the Developed World’ from your
diagram pack. Listen carefully to the clip and answer the
questions on your sheet.
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Regeneration
LI – To investigate the regeneration ability in some
organisms.
What to do
Parts of some organisms can regenerate. Research one of the
following organisms.
Star fish
Liver in humans
Lizard tails
Salamander’s tails.
Once you have completed your research, make notes on the
following bullet points:
 What does regeneration mean?
 How does regeneration occur in your chosen organism?
 What is the purpose of regeneration in your chosen
organism?
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Stem Cells
LI To describe some of the ethical dilemmas of the use of
Stem cells
Your body is made of specialised cells: muscle cells, nerve cells,
skin cells, blood cells, and many more. A stem cell is a cell that
has not yet specialised. In other words, all the specialised cells
“stemmed” from this original cell. This means a stem cell could
become any kind of body cell.
Your teacher will show you a
short animation showing one
way that scientists can
collect stem cells.
Read the following passage carefully and answer the questions
below:
The use of stem cell therapy in medicine to treat serious
illness has been growing for many years. Bone marrow
transplant from one person to another is a form of stem cell
treatment. Stem cells have many uses; they could be used to
grow new organs like the liver and kidney. Growing new organs
for transplant could be used as an alternative to donation.
However, there are many ethical issues surrounding the uses of
stem cells. The main problem is that stem cells from an adult
can only specialise into a few different cells, where as
embryonic cells (from a newly fertilised embryo) can specialise
into many more different cell types. In the past, scientists
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have harvested stem cells from the cells of embryos after a
terminated pregnancy. Today scientist can harvest stem cells
from surplus embryos fertilised in-vitro that are donated to a
lab for research purposes. Unfortunately, for stem cells to be
collected, the embryo is destroyed. There is much debate
around whether or not this is ethical, some people believe
human life has already begun and scientists are “playing God”.
A more ethical way of collecting stem cells is from the
umbilical cords of newborn babies immediately after birth.
1. What kind of transplant can be performed to transfer
adult stem cells from one individual to another?
2. What would be the benefit of using organs created by
stem cells rather than donated organs in organ
transplant?
3. From the passage, give 3 ways scientists have collected
human embryos for stem cell research.
4. From the passage, suggest an ethical dilemma that
could be faced by scientists attempting to harvest
stem cells.
What to do
Your teacher will give you each a different “Stem Cell
Debate” card. Following class discussion of each
characters point of view, you will get into groups of 8 and
debate the issues of stem cell research further. To
debate you must argue why your character’s viewpoint
is right.
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Stem Cell Card Sort
What to do
Use the cards to help organise your ideas.
Group cards:
 For and against (embryonic) stem cell research.
 Discard any irrelevant or weak arguments/ facts.
After watching the video clips and completing the card sort
activities, get into groups of four, separate yourselves into two
groups of two. One group is going to present arguments ‘for’
the use of embryonic stem cells to treat diseases and the
other group is going to present arguments ‘against’.
Once you have completed your discussion, copy and complete
the table with arguments ‘for’ and arguments ‘against’ the use
of stem cells.
Arguments For Stem Cell Use
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Arguments Against Stem Cell
Use
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My Sister’s Keeper
My Sister's Keeper is a film about an 11-year-old girl called
Anna Fitzgerald, who enlists the help of a lawyer, Campbell
Alexander, to sue her parents for rights to her own body. Anna
was conceived as a donor for her sister Kate, who is 15 and has
leukaemia. Anna donated genetic material throughout her life,
and the latest donation is for her to give a kidney to Kate. If
she wins the lawsuit, she would not have to donate.
What to do
Watch the video clip about the film and discuss the following
questions:
1. Do you feel that it's ethical to conceive a child knowing
that their genetic material will help one of your other
children? Give reasons for your answer.
2. What do you think about Anna’s decision to sue her
parents?
3. How would you feel if you were in Anna’s position?
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Inside the Nucleus
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Inside the Nucleus
LI – To revise the function of DNA, Genes and
Chromosomes
From S3, you will remember that all cells contain the genetic
information, for that species. In pairs, discuss what you can
remember about chromosomes, genes and DNA.
Then complete the card matching exercise to correctly match
the word with its definition and its diagram.
Teacher Check!
Copy and complete the table with the information you have on
your matched cards.
Term
Definition
Diagram
Chromosome
Gene
DNA
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DNA Extraction
LI – To extract DNA from a kiwi fruit
You will now extract DNA from kiwi fruit. Follow the method below:
What to do
Collect:
a kitchen knife
a stopclock
a 250cm³ beaker
a stirring rod/wire loop
detergent
salt
syringe
boiling tube
measuring cylinder
half a kiwi
blender
1. Place 10 cm³ detergent, 3 spatulas of salt, and 100 cm³ of water in
the beaker. Use the stirring rod to mix the contents.
2. Peel and cut the kiwi into small pieces, stir into the mixture in the
beaker and stand in a water bath set at 60˚C for 15 minutes. This
will break open cells and their nuclei.
3. After 15 minutes, cool the mixture in an ice bath for 3 minutes.
4. Liquidise the cooled mixture in a blender for 5 seconds. This will
separate cell walls from the rest of the rest of the cell material
which includes the DNA.
5. Filter the liquidised material. The filter paper retains the cell walls.
6. Place 5cm³ of the filtrate in a boiling tube.
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7. Measure 5cm³of ice-cold ethanol in a syringe. Carefully pour
the ethanol onto the surface of the extract by running it
slowly down the inside of the beaker.
Look for a cloudy substance forming between the extract and
the ethanol layer. This is the DNA.
8. Try to collect some DNA by slowly moving the stirring
rod/wire loop through it.
Complete a write up of this practical, including a brief outline
of the method that you used.
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Structure of a Chromosome
LI – To understand the structure of a chromosome.
centromere
genes
Chromosomes are composed of DNA.
What to do
Use the information above to label your diagram of a
chromosome.
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What to do
Using the diagram on the previous page, copy and complete the
following paragraph about the structure of a chromosome:
Chromosomes are found in the _ _ _ _ _ _ _ of a cell.
_ _ _ _ _ _ _ _ _ _ carry our genetic information on them.
Chromosomes are made up of many bands called _ _ _ _ _. Each
gene controls _ _ _ characteristic. Chromosomes and _ _ _ _ _
are composed of Deoxyribonucleic Acid (_ _ _).
Each person’s _ _ _ is unique to them.
Structure of DNA
To help you understand the structure of DNA, you will use
origami to make a model of DNA.
What to do
Collect a template from your teacher and then follow the
instructions on the handout.
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Parents and Offspring
LI – To identify the source of the chromosomes found in
the cells of a baby.
When a baby is conceived, it receives half of its genetic
information from its mother and half from its father.
Copy and complete the following diagram to show the
chromosome numbers in each nucleus in each type of cell.
Sperm
nucleus
Egg
Fertilised Egg
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Inherited Diseases
LI – To research a chosen inherited condition.
Some conditions can be passed from parents’ genetics to their
offspring.
What to do
Choose one of the following inherited diseases and use the
internet to do some research on your chosen condition.






Cystic Fibrosis
Haemophilia
Sickle cell Anaemia
Huntington’s Chorea
Red Green Colour-blindness
Down’s Syndrome
Your notes should include the following:
 How does this condition affect the sufferer?
 How is it inherited?
 Is there specialist care needed?
 Life expectancy of the sufferer?
Include any sources (web pages) that you have used.
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Genetic Engineering
LI To explain how scientists can reprogram microorganisms
by genetic engineering
Your DNA is a genetic code that is used to produce different proteins
used in the body. Scientists can alter the DNA of cells to produce
particular products. This is called genetic engineering.
Scientists can alter the DNA of organisms so that they produce new
substances that are useful to humans. They do this by a process called
genetic engineering. Useful genetic information is inserted into another
organism (like a bacteria), once reprogrammed; the organism will produce
the useful substance.
Your teacher will explain the steps of genetic engineering,
Collect:
1.
2.
3.
4.
5.
A paper plate
A piece of red card
Selotape
Scissors
A piece of A4 paper
1. Collect the “genetic engineering” cut out in your diagram pack.
Insert the following information onto you diagram:




Bacterial DNA
Bacterial cell
“New gene”
Genetically engineered bacterial cell
2. Cut out the “steps of genetic Engineering cards” in your diagram
pack and stick these onto your diagram
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Genetic Engineering Research Task
LI To give examples of how genetic engineering provides
useful products
The following products were created by genetic engineering. Choose one
to research from the list below:



What to do
Insulin
Factor VIII
Human Growth Hormone
You will research your chosen product for 2 periods using resources in
the Library.
You will then be given 2 additional periods to produce a short 1min film
that will be shown to the rest of the class. Your film must include:
1. The name of the product of genetic engineering you are
investigating.
2. Step by step how the product is formed and the role genetic
engineering has to play in this (Hint: You might want to use
plasticine models to show this step-by-step).
3. Why it is useful to humans to create this product by genetic
engineering.
Extension Task:
If you have created your film and other members of the class are still working,
you can use your time to research:
1. What does doping mean in sport?
2. How might Human Growth Hormone be used illegally in sports?
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Important Medical Uses of Genetic Engineering
LI To explain why it is useful to use genetic engineering to
create insulin, Human Growth Hormone and Factor VIII
Insulin
Your teacher will show you a short video from BBC learning zone about
the production of insulin by genetic engineering. Answer the “Insulin
Video questions” in your pupil diagram pack.
http://www.bbc.co.uk/learningzone/clips/genetic-engineering/4200.html
Read the following information about Human Growth Hormone and Factor
VIII and complete the questions below.
Human Growth Hormone
•
Human growth hormone (HGH) is produced naturally in everyone. If
someone does not make HGH or doesn’t make enough, they may
have stunted growth. These people may be treated by injection of
HGH – produced by genetically engineered microbes.
•
In 2013, Lance Armstrong (7 times winner of the Tour de France)
admitted to using performance enhancing drugs. This is also known
as “doping”. One of the substances Lance Armstrong has admitted
to using to improve his performance is HGH – which will have
helped develop muscle mass very quickly. There is a big problem of
doping in lots of sports.
•
If HGH is taken when a person is still growing it will help to
stimulate increased growth. If taken after natural growth, it will
help develop muscle mass.
•
It has been known that parents who desperately want their
children to be elite basketball players have encouraged their
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children to take HGH. In children and young people who are still
growing this will impact on height more than muscle mass.
•
The dangers of over-use of HGH:
•
Diabetes
•
High Blood Pressure
•
Heart Muscle Damage
•
Osteoporosis
•
Menstrual changes in woman and impotence in men (sterile)
•
Fat/Lipid changes in blood
Factor VIII
•
Factor VIII is a protein that clots the blood. People who do not
produce Factor VIII have Haemophilia. This means that if they
were cut or bruised they would continue to bleed – their blood
would not clot to plug the wound.
•
Factor VIII is now produced by genetically engineered microbes
and can be injected by haemophiliacs.
1. Complete the table below:
Product
What it is used for
Insulin
Human Growth Hormone
Factor VIII
2. Write a paragraph on the problems of using HGH in doping, you must
include:
1. Why would athletes use HGH?
2. What are the dangers of doping?
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Catalysts & Enzymes
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Catalysts and Enzymes
LI – To understand what a catalyst is and what enzymes
do.
A catalyst is a chemical which speeds up a chemical reaction without
being changed itself.
An enzyme is a biological catalyst.
Enzymes are made of protein and are found in every living cell.
The chemical an enzyme acts on is called its substrate. The chemical
produced by the enzyme is the product.
We are now going to investigate how catalysts work.
1. Collect
What to do
-
Manganese Dioxide
Detergent
Test Tube
Bunsen burner
-
Hydrogen Peroxide
Spatula
Test Tube Rack
Wooden Splint
2. Instructions
a) Add a small volume of Hydrogen Peroxide (our substrate) to the
test tube.
b) Add a few drops of detergent to the Hydrogen Peroxide and mix
gently, taking care not to spill any.
c) Tip a small spatula full of Manganese Dioxide (our catalyst) into the
tube. This will trigger the breakdown reaction of Hydrogen
Peroxide into water and oxygen.
d) A glowing splint can be used to test the bubbles of foam to confirm
oxygen has been given off (oxygen will re-light a glowing splint).
e) Now add some more Hydrogen Peroxide to the tube. The reaction
should begin again, indicating that the catalyst you put in the first
time is still working.
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3. Prepare a short report of what happened. Include the following
line: The catalyst remained unchanged at the end of the reaction
and could be re-used.
Copy and complete the following statements about catalysts.
A catalyst is a chemical which _ _ _ _ _ _ _ _ a chemical reaction.
A catalyst remains _ _ _ _ _ _ _ _ _ at the end of a reaction.
An _ _ _ _ _ _ is a biological catalyst.
Enzymes are made of _ _ _ _ _ _ _ and are found in every living _ _ _ _ .
The chemical an enzyme acts on is called its _ _ _ _ _ _ _ _ .
The chemical produced by the enzyme is the _ _ _ _ _ _ _ .
Word Bank
Substrate
Enzyme
Unchanged
Cell
Product
Speeds up
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Protein
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Types of Enzyme Reactions
LI – To understand some of the enzymes that are present
in living cells.
Enzymes control two types of reactions:
 synthesis
 breakdown.
During synthesis reactions lots of small molecules are joined together to
make a large molecule. During breakdown reactions large molecules are
broken down into smaller molecules.
Breakdown Reactions
Enzymes are required in cells to speed chemical reactions and to control
the cell. If an enzyme is present the reaction happens; if not, it doesn't.
The catalyst in living cells which breaks down hydrogen peroxide into
water and oxygen is called CATALASE.
What to do
We are now going to investigate the presence of catalase in living cells.
1.
Collect
- Hydrogen Peroxide
- Cooked Liver
- Cooked Potato
- Test Tube Rack
- Wooden Splint
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Fresh Liver
Fresh Potato
4 Test Tubes
Bunsen Burner
33
Instructions
a)
b)
In a similar way to the previous experiment, add a small volume
of Hydrogen Peroxide to each test tube.
To each of the 4 test tubes, add a sample of the 4 different
tissue samples, as shown in the diagram below:
A
B
C
D
Fresh
Liver
Cooked
Liver
Fresh
Potato
Cooked
Potato
c)
Watch for the production of oxygen gas in each tube and
record your results.
d)
Again, you can use a glowing splint to test for any oxygen coming
from the test tubes.
4. Write a brief report of the experiment, including a labelled
diagram.
5. Copy and complete the following results table for the experiment.
Test tube
Oxygen produced?
Catalyst
present?
A
B
C
D
6. Include in your report what conclusion you can draw about enzymes
and living cells.
Catalase acts on its substrate hydrogen peroxide to make the products
oxygen and water.
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Extension Activity
Enzymes are found in the human body and are very important in the
digestion of food.
Our saliva contains an enzyme called AMYLASE that is made by cells in
the salivary glands and which breaks down starch into sugar (called
maltose).
1. Collect
What to do
-
Starch Solution
Iodine Solution
Clinistix
Test Tube Rack
Dropper
-
Amylase
Water
2 Test Tubes
Measuring Cylinder
Dimple Tile
2. Instructions
a)
b)
c)
d)
e)
f)
g)
Label your two test tubes, A and B.
Add 5ml of Starch Solution to each tube.
Add 2ml of amylase to tube A and stir gently.
Add 2ml of water to tube B and stir gently.
After 20 minutes, remove two drops of each tube and place into
a dimple tile.
Test one drop from each tube for starch by adding a drop of
iodine solution and observing the colour change (if any).
Test one drop from each tube for sugar by dipping a clinistix in
and observing the colour change (if any).
A
amylase
+
starch
B
water
+
starch
Reminder:
Test for starch = adding iodine solution (blue/black colour appears)
Test for sugar = using clinistix (paper square turns pink/purple)
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3. Write a short description of this experiment. Include 3 things:
- a labelled diagram of what you set up
- a table of results (shown below)
- what conclusion you can draw from the results.
Test tube
Starch present
after 20 mins?
(yes/no)
Sugar present after
20 mins? (yes/no)
1 - with amylase
2 – without amylase
You can do a similar experiment with amylase using your own saliva!
Chew bread (a starchy food) for long enough and the amylase in your
saliva will break it down into sugar, making the bread start to taste
sweet.
Amylase acts on its substrate starch to make the product maltose.
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Synthesis Reactions
So far all the enzymes you have met have been involved in breaking down
large chemicals into smaller ones. In some places in nature, it is necessary
to BUILD UP larger chemicals from smaller ones. There are enzymes that
speed up these reactions too. For example, potatoes contain the enzyme
PHOSPHORYLASE that acts on its substrate GLUCOSE-1-PHOSPHATE
to make the product STARCH.
Potato phosphorylase acts on its substrate glucose-1-phosphate to make
the product starch.
1. Collect
What to do
- Potato extract (containing phosphorylase)
- Distilled Water
- Glucose-1-phosphate solution
- Dimple Tile
- Droppers
- Stopwatch or Timer - Iodine Solution
2. Instructions
a)
Set up the dimple tile as shown below:
Row A = glucose-1-phosphate + potato
phosphorylase
Row B = glucose-1-phosphate + distilled water
Row C = potato phosphorylase + distilled water
b) Add iodine solution to one dimple in each row at
intervals of 3 minutes.
c) After 9 minutes, note the colour changes (if any) and in what rows they
occurred.
3. Under the heading ‘Potato Phosphorylase’, copy a diagram of the
dimple tile, showing what was put into each row, and shaded to show
the colour changes that occurred.
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The Right Enzyme for the Job
LI– To understand that enzymes are specific and why.
When an enzyme is described as SPECIFIC this means that it will only act
on ONE substrate. Enzymes do just one job. Each type of enzyme (and
there are thousands of types) only carries out one type of reaction e.g.
amylase will only change starch into maltose - nothing else. It is for this
reason that an enzyme is said to be SPECIFIC.
The LOCK AND KEY theory explains why enzymes are specific to one
substrate. This is shown below:
This enzyme would not be able to break down any other type of food
particle because the enzyme is shaped only to fit that particular
substrate and no other.
In the lock and key model the substrate is the lock and the enzyme is the
key. Just like the lock, the substrate becomes changed and just like the
key, the enzyme remains unchanged during a reaction.
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1.
Copy and complete the following passage:
The substance upon which an enzyme acts is called the
.
The substance produced as a result of a reaction is called the
__________.
Each enzyme acts on only one type of __________ . An enzyme is
therefore said to be
.
2.
Copy the labelled diagram of the lock and key mechanism. Your
teacher might put this on the board with a short explanation or you
can use the diagram on the previous page.
The lock and key theory explains why enzymes are specific to one
substrate. In the lock and key model the substrate is the lock and the
enzyme is the key. Just like the lock the substrate becomes changed and
just like the key, the enzyme remains unchanged during a reaction.
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Optimum Temperature
LI – To understand the optimum temperature in relation to enzymes.
Enzymes are made of protein and as a result have an
OPTIMUM temperature and at which they work best. The
optimum temperature for enzymes found in the body is 37 oC,
body temperature.
The optimum temperature and pH of an enzyme is the
temperature and pH at which it will work best.
This graph show that the optimum temperature of this enzyme
is 37oC
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1. Collect
What to do
- Amylase solution
- Starch Suspension
- 4 Test Tubes
- Fridge
- Water Bath @35oC
- Water Bath @60oC
2. What to do:
a. Set up the test tubes as shown below:
1)
Test the samples for starch at different time intervals
(0,1,5,10,15,20 mins).
b. Copy and complete the following results table:
o
0 min
1 min
5 min
10 min
15 min
20 min
A (2 C)
B (20oC)
C (35oC)
D (60oC)
3. For a conclusion answer the following questions in sentences:
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4. At which temperature did the enzyme work best? Explain how you
know this.
5. How well did the enzyme work at low temperature?
6. How well did the enzyme work at high temperature?
Enzymes also have an optimum pH at which they work best.
This graph shows that the optimum pH of pepsin, salivary amylase and
alkaline phosphatase are 2, 6 and 9 respectively.
The following experiment demonstrates the optimum pH of pepsin.
Some glass rods, all 50mm long, containing albumen were placed in
solutions of pepsin and buffer for 24 hr at 37 oC. Each beaker had a
different pH as shown below:
pH = 2.5
3.7
4.9
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7.0
8.4
9.0
42
When the rods are removed, the lengths of albumen remaining were
measured.
The
results are shown in the table below:
pH
2.5
3.7
4.9
7.0
8.4
9.0
What to do
Initial
length
(mm)
50
50
50
50
50
50
Final
length
(mm)
29
38
43
47
50
50
Decrease in
length (mm)
21
12
7
3
0
0
1. Draw a line graph of ‘decrease in length of albumen (mm)’ against
‘pH’. Use graph paper and add it to your notes.
2. At which of the pH values was pepsin most active, and how do you
know?
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Understanding Enzymes
LI – To make your own enzyme and show your understanding
of how enzymes work.
What to do
To show how well you now understand how enzymes work you are going to
make your own enzyme and show the class how this enzyme works.
You can demonstrate this by choosing one of the following activities;



Make a cartoon strip showing enzyme action;
Make a plasticine model showing enzyme action;
Make an animation showing enzyme action.
To be successful you need to show;




That you understand the action of enzymes
Show substrates, enzymes and products.
Show how enzymes are specific.
Explain the term optimum.
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Everyday Uses of Enzymes
LI – To understand an everyday use of enzymes.
BIOLOGICAL WASHING POWDERS contain enzymes.
The enzymes in washing powder are made by BACTERIA.
Enzymes in washing powders are used to digest (break down) large
molecules that make stains into small molecules, allowing them to be
washed away.
Different enzymes digest different things. For example, fat stains (such
as butter) are digested by special fat-only digesting enzymes. Special
starch-only digesting enzymes digest starch stains (such as grass).
Biological detergents work best at LOW temperature (about 30-40oC),
unlike traditional powders which work best at high temperatures (85 oC 100oC). This means that biological powders save energy.
We are going to demonstrate the effectiveness of biological and nonbiological detergents at different temperatures.
1. Collect
What to do
-
4 Test Tubes
Test Tube Rack
Water Bath @40oC
4 Pieces of Fabric
-
Biological Detergent Solution
Non-Bio Detergent Solution
Water Bath @70oC
Source of Stain
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2. Instructions
a)
b)
Stain 4 pieces of the same fabric with the same stain.
Set up the test tubes as detailed below:
A
B
C
D
Material with same stain
c)
d)
e)
f)
g)
Place 5ml of biological detergent solution into tubes A and B.
Place 5ml of non-biological detergent solution into tubes C and D.
Place tubes A and C into a water bath at 40oC.
Place tubes B and D into a water bath at 70oC.
After 30 minutes (or longer if possible) observe what is left of the
stains on each piece of fabric.
3. Copy and complete the following table, by ticking each description
as ‘BIO’, ‘NON-BIO’ or ‘BOTH’:
BIOLOGICAL
DETERGENT
NON-BIO
DETERGENT
BOTH
Cleans clothes
Requires more energy to
be effective
Contains enzymes
Works better at lower
temperatures
Designed to act on specific
stains
4. Research the use of enzymes in everyday life. Choose one of the
following topics and prepare a flow chart/one page
document/spider diagram of how enzymes help with this;
a. Pulp and paper industry
b. Producing soft centered sweets
c. Baby food
d. Textiles
e. Producing bread
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Immobilisation
LI – To understand the process of enzyme immobilisation
and why it is used.
Immobilisation techniques involve trapping whole cells or enzymes and
using them to carry out chemical reactions.
Enzyme immobilisation has a number of advantages:
- the end product is EASILY SEPARATED from the enzyme or
cells.
- the cells or enzymes can usually be USED MANY TIMES (which is
good because they are expensive).
- there is LESS WASTE PRODUCED so the problem of disposal is
reduced.
- immobilised cells and enzymes can be used in a CONTINUOUS
FLOW PROCESSING (detailed below).
In continuous flow processing, reactants are continuously fed into a
reaction chamber and products are continuously removed with no need to
stop production except for essential maintenance.
Setting up a
continuous
flow
process is
complex but
it also has a
number of
advantages
over making
individual
batches of
product:
- the raw materials are supplied steadily to ensure a maximum rate
for the reaction.
- the product is easily separated from the enzyme or cell.
- the enzyme or cells can be used repeatedly saving on costs.
- valuable time is saved by not having to stop the process and set it
up again.
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We are going to set up a miniature version of a continuous flow process.
1.
Collect
- Syringe
- 2 Beakers
- Milk
What to do
- Sodium Alginate Solution
- Calcium Chloride Solution
- Lactase Solution
2. Instruction
a) Draw up 2ml lactase enzyme into your syringe.
b)
Draw up 8ml sodium alginate into syringe.
c)
Mix the liquids in the syringe.
d)
Add mixture (drop by drop) to 100ml calcium chloride.
e)
f)
g)
h)
i)
j)
k)
Leave for 3mins to set.
Filter the immobilised enzyme beads and rinse them in water.
Place the beads into a beaker and add a small volume of milk.
Using a Clinistix, immediately test the milk for sugar using a
clinistix (will turn from pink to purple if sugar is present)
Leave the milk to mix with the beads for 10-15 minutes. The
lactase in the beads will break the lactose in milk down into small
sugars.
Now test the milk with Clinistix again. A purple colour will
indicate that product has formed.
The beads can now be easily removed from the product and used
again.
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Immobilisation involves trapping whole cells or enzymes and using them
to carry out chemical reactions.
3. Make a list of the advantages of using enzyme immobilization.
4. Use the informaiton in the read section above to produce a table
comparing continuous flow processing over batch processing. Your
teacher can help with this informaiton.
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Microbes & Industry
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Yeast
LI – To understand what yeast is and what it can be used
for.
YEAST is a single-celled (unicellular) fungus. It divides by budding (cell
division) and is shown below:
Cell Wall
Like all living cells, yeast survives on the energy made during
RESPIRATION. Respiration in the presence of oxygen is called aerobic
respiration. Respiration in the absence of oxygen is called ANAEROBIC
respiration.
Yeast will convert glucose into CO2 and alcohol in an anaerobic process
called FERMENTATION. The two products of this reaction are very
useful to us, as you will see later.
What to do
We are now going to look at live yeast cells and explore some of the
properties of yeast that make it incredibly useful to humans.
1.
Collect
- Dried Yeast
- Glucose
- Glass Slide
- Warm (not hot) water
- Microscope
- Dropper
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2
Instructions
a)
b)
c)
Prepare a dilute suspension of yeast by mixing a few dried yeast
pellets with a small volume of warm water and a spatula of
sugar. Your teacher may have prepared a stock solution for the
class to use.
Using a dropper, take a single drop of suspension and place it on
to a glass microscope slide.
Use the microscope to view the drop. Under high magnification,
you may be able to make out the tiny yeast cells floating about
in the suspension.
3. Draw a sketch of the yeast cells as you saw them under the
microscope. Don’t forget to label your drawing and include the
magnification you were using at the time.
Copy the diagram of yeast from the previous page and complete the
following summary of yeast:
Yeast is a unicellular _ _ _ _ _ _ .
Yeast will respire anaerobically (without _ _ _ _ _ _) in a process known
as _ _ _ _ _ _ _ _ _ _ _ _ .
During this process, yeast will convert glucose into
_ _ _ _ _ _ _ _ _ _ _ _ _ and _ _ _ _ _ _ _ .
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Making Bread
The CO2 produced during the fermentation of yeast can be used in the
process of making bread. The bubbles of gas produced are trapped in the
dough and make the bread rise, making the bread less dense when it is
baked.
Today we are going to investigate the effect of yeast on dough.
What to do
1.
Collect
- Live yeast / Yeast suspension
- 2 Small Beakers
- Sugar
- Water
- Marker Pen
2.
-
Flour
1 large beaker
2 Labels
Spatula
Instructions
a)
b)
c)
d)
e)
f)
Mix flour, sugar and water together in the large beaker using a
spatula.
Once the mixture is forming a soft dough (you may need to add
more flour or water to make this happen) split the dough equally
into two balls and place one in each small beaker.
Label one beaker A.
Label the other beaker B, add a small amount of yeast or yeast
suspension and knead together.
Place both beakers in a warm place.
After about 30mins, observe any changes that have occurred in
the balls of dough.
3. Write a short report on the experiment you did, including a labelled
diagram and what happened.
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Making Alcohol
The ALCOHOL produced during the fermentation of yeast (sometimes
called ETHANOL) can be used in the process of BREWING and
WINEMAKING. Live yeast cells are added to a suitable source of sugar,
and if conditions are kept anaerobic, the sugar is converted to alcohol and
CO2.
Different alcoholic drinks are produced by using different sources of
sugar. Some examples are shown below:
Alcoholic Drink
Wine
Beer
Vodka
Cider
What to do
Source of Sugar
Grapes
Barley
Potatoes
Apple
We are going to produce a batch of our own alcohol using the
fermentation of fruit sugars.
1.
Collect
- Fruit
- Sugar
- Clean Beaker
- Clean Spoon
2.
- Yeast suspension
- Small Bottle with Lid
- Distilled Water
Instructions
a)
b)
c)
d)
e)
f)
Crush the fruit into the beaker using the spoon.
Add a spoonful of sugar and a small amount of distilled water.
Stir until you get a sugary, fruity mixture.
Add this mixture to your bottle.
Add to the bottle a small amount of yeast suspension.
Place the lid loosely on the bottle. This will prevent too much
oxygen getting in but will allow the release of CO2 gas.
3.
Why did we crush the fruit into the beaker?
4.
Why did we add the sugary mixture to the bottle?
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5.
What is the purpose of the yeast?
6.
What did you observe?
7.
a. Why did this happen? b. What process is taking place?
Research - Extension
What to do
You may have time to investigate the production of different alcoholic
drinks.
The misuse of alcohol can have a very negative effect on people, their
family and friends. Research the negative effects of alcohol abuse and
produce a poster warning people of these effects.
Your teacher may like you to present the findings of your research into
alcohol abuse to the rest of the class.
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Brewing Beer
LI – To understand what yeast is and what it can be used
for.
The fermentation of sugar using yeast can be done COMERCIALLY (i.e. on a
large scale to make profit). The next 2 pages show this detailed process stepby-step.
You will see the process is complex, and every stage must be carried out
properly for the beer to be made correctly.
The following 3 notes relate to a diagram over the page about commercial beer
making:
Note 1: In commercial beer making, the first step is the MALTING of
barley. During this process, barley grains are watered to make them
start to GERMINATE. During germination the starch inside the barley
grains turns into a sugar called MALTOSE. Malting of barley is a
necessary step in beer making because yeast cells cannot use starch as a
food source.
Note 2: Eliminating competition of yeast - unwanted microbes killed by
boiling the wort (the unfinished beer) before the yeast is added.
Note 3: To maintain a suitable temperature, the fermentation vessel is
controlled by a THERMOSTAT.
What to do
1. Stick a copy of the diagram over the page into your jotter
and fill in the missing blanks.
2. Is the below process small scale or commercial?
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Barley Grains
Water
Soaked barley grains allowed to
germinate in the malt house.
See note
1
Dead sprouted grains (called malt) crushed into
mash in the malt mill.
Water
Sugar in the mash dissolved in water to form a
sweet liquid called wort in the mash tun.
See note
Extra Sugar
Hops added for flavour and wort boiled to kill
bacteria in the wort kettle.
2
Hops
Sterilised wort cooled for fermentation in the
cooler.
Live Yeast
See note
3
Sugar fermented to alcohol by the anaerobic
respiration of yeast in the fermentation
vessel.
Beer allowed to mature at low temperatures in
the storage tank.
Sediment removed from the mature beer in the
filter.
BEER
BEER
BEER
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Batch Processing
Brewing of beer is carried out by a series of steps called batch
processing.
Batch processing was mentioned previously in the ‘Enzymes’ section of the
course.
Your teacher can show you the stages of brewing beer in a short video.
Produce a poster advertising your own brand of beer. Your poster must
include information on some of the stages in brewing beer.
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Production and use of biofuels
LI – To understand the use of biofuels as an energy source.
Alcohol and methane are products of fermentation/anaerobic respiration.
Each of these can be use as a fuel. They have some advantages over using
fossil fuels.
The aerobic bacteria in a sewage works gives off a gas which is mainly
methane. Methane or biogas burns well and is used to drive machinery in
modern sewage works.
In developing countries animal and plant waste matter is fermented by
anaerobic bacteria in special biogas digesters. The gas is collected and
used for cooking, lighting and other energy-requiring purposes. In some
countries such as Brazil alcohol is used as a fuel for cars, either on its
own or mixed with petrol as gasohol.
The alcohol is obtained by fermenting sugar with yeast. The sugar comes
mainly from sugar cane plantations but could also come from sugar-based
waste from industries such as sugar refineries.
The huge advantages of using alcohol as a fuel as opposed to fossil fuels
are that it doesn’t cause pollution and is renewable, it can be replaced,
unlike fossil fuels. However it involves using a lot of land which could be
used for growing crops.
We can compare the level of pollution caused when fossil fuels and alcohol
burn by carrying out a very simple experiment.
What to do
1.
Collect
- 2 x watch glasses
- Dropping bottle of alcohol
- Dropping bottle of petrol
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- heat proof mat
- SAFETY GLASSES
59
2.
Instructions
a) Add 3 drops of alcohol to one watch glass and 3 drops of petrol to
the other watch glass.
b) Place the watch glasses on the heat proof mat and set the fuels
alight using a taper.
c) Observe each as it burns.
1.
What is meant by the term fermentation/anaerobic respiration?
2.
State 2 advantages of using alcohol as a fuel over fossil fuels
such as petrol.
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Yoghurt Production
LI – To make yoghurt using beneficial bacteria
There are thousands upon thousands of different bacteria living on Earth.
Many of them are essential for our body to work correctly, while many
others are dangerous and cause disease. However, some bacteria can be
useful to us if used in the correct way.
What to do
Today you are going to use a microscope to see live bacterial cells in
yoghurt.
1.
Collect
- Yoghurt
- Microscope
- Distilled Water
2.
- Nigrosin Stain
- Microscope Slide
- Dropper
Instructions
a)
b)
c)
d)
Prepare a suspension of bacteria using 2-3 drops of yoghurt and
a small amount of water. This will thin the yoghurt down enough
to see individual bacterial cells.
Add one drop of this suspension
to a microscope slide.
Add to the slide a tiny drop of Nigrosin stain. This will allow you
to see bacterial cells more clearly.
Using the microscope, try to focus in on some bacterial cells.
3. Draw a sketch of the bacterial cells as you saw them under the
microscope. Don’t forget to label your drawing and include the
magnification you were using at the time.
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Bacteria can also carry out anaerobic respiration. Certain bacteria can
use LACTOSE sugar found in milk as a food source; in the process they
turn the lactose into LACTIC ACID that turns the milk sour. Souring of
milk is therefore called bacterial fermentation of lactose.
The manufacture of YOGHURT also requires the fermentation of lactose
by bacteria. The lactic acid produced makes the milk thicken and changes
the taste, forming yoghurt. Making yoghurt in this way is a method of
preserving milk.
We are going to use bacteria to make yoghurt.
What to do
1.
Collect
- Fresh Milk
- Yoghurt Sample
- Sterilised Beaker
- Sterilised Stirring Rod
- Water Bath @ 43oC
2.
Instructions
a) Add a generous sample of bacteria (natural yoghurt) to a beaker
of fresh pasteurised milk.
b) Stir the bacteria through the milk.
c) Place the beaker carefully in a water bath set at 43 oC (your
teacher will ensure the milk gets 12 hours of treatment at this
temperature).
d) Refrigerate the product.
3. Draw and label the 4 step guide above so that someone reading your
jotter would know how to carry out the experiment.
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Cheese Production
LI – To understand that bacteria are beneficial in cheese
production and the use of enzymes to produce
cheese.
As well as being used to make yoghurt, milk is also the source material
from which cheese is made.
Bacteria is added to pasteurised milk (in the same way as making yoghurt)
before being treated with a chemical called RENNET. This chemical clots
the protein in milk and splits it into two parts, a solid part called CURDS
and a liquid part called WHEY.
The CURDS are separated from the whey and pressed into a mould, after
having salt added. They are then left for several months to mature and
develop in flavour. WHEY is a waste product of the cheese making
industry.
Today you are going to make your own cheese in the lab.
1.
What to do
Equipment and Materials Required
- 2 Clean Beakers
Starter culture (yoghurt)
- Rennet
- Water Bath at 40oc
- Whey Cloth
- Cling-Film
- Weight
- 10ml Syringe
- Full cream milk at room temperature
2.
Instructions
a) Add 100ml of milk to a beaker.
b) Place the beakers in the water bath allow the milk to heat to the
temperature.
c) Add a spoonful of starter culture (yoghurt) to each beaker.
d) Leave the milk for 10 minutes.
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e) Add 0.5ml of rennet to each beaker.
f) When mixture firms cut into sections by cutting in one direction
and then across (like noughts & crosses).
g) Stir very slowly for 10 minutes, stirring slowly every 2 minutes.
h) When curds start to firm, pour the mixture into the cheese cloth
and drain whey into a tray.
i) Leave the curds for about 10 minutes.
j) Line a second beaker with cling-film and pour the curds into this
beaker.
k) Wrap the cling-film around the cheese and place large weight on
top.
l) If the cheese is left for 3-4 days in a fridge it will start to firm
and become like cheddar.
1. Write a report on the making cheese activity. Include all the
details on how cheese is made and explain what rennet does.
Your teacher will now show you a short video on BBC learning zone
clips about how cheese is processed.
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Rennet Issues
LI – To investigate the use and production of different
types of rennet.
Now that you know how rennet is used to make cheese you are going to
consider some of the issues which surround the different types of rennet
and how they are made.
Read about the 3 forms of rennet on the information sheets, then copy
and complete the ‘Rennet Summary Sheet’ using the information to help.
Rennet Information
Calf Rennet

Rennet is found in the stomachs of newly born calves.

Rennet contains enzymes which break down the protein in milk to make
it digestible to the animal.

The calves rennet which we use in cheese making is usually obtained
from calves which are being used for veal production.

The lining of calves stomachs is processed to produce this product.

The calves are killed by being stunned electrically.

Calves rennet is the natural enzyme doing the same job in the calves
stomach as it does in the cheese factory.

This is the type of rennet which has been successfully helping to make
cheese for hundreds of years.
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Fungal Rennet

Some fungi were found which produced enzymes which clotted milk
proteins.

These fungi can be grown in fermenters to produce large amounts of
the enzyme

This was the first ever product which allowed true vegetarian cheese
to be made.
Many people find it unacceptable to eat a product which has been
made from animals.


Fungal rennet is a natural enzyme found in the wild.

Between a third and a half of the total world cheese production is now
made with fungal enzymes.

This is the cheapest form of rennet.
Rennet from genetically modified yeast

The gene from calves which allows them to make rennet has been put
into genetically modified yeast cells.

The genetically modified yeast cells then produce pure rennet which is
identical to the animal enzyme

The genetically modified yeast cells can be grown in fermenters.

When this rennet is added to milk it behaves in an identical way to calf
rennet.

There is no need to slaughter animals to produce this form of rennet.

The vegetarian society has given their approval to products made from
this form of rennet.

Tests have taken place on all aspects of the production process and
the products are approved by the Ministry of Agriculture,
Fisheries and Food.
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Rennet Summary Sheet
Form of Rennet
Calf
Fungal
GM Yeast
How is this
product
produced?
Give some
advantages of
this product
Give some
disadvantages of
this product
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Ethics of Calf Rennet Production
Using a laptop, follow these steps to access a word document with a
useful web link: Student resources – S4 Biology – National 4 –
Microbes in Industry – Useful weblinks.doc
What to do
Find the web link titled “How to extract Rennet from a calf (baby
cow) using a traditional farmer’s methods”.
1.
Your teacher will assign you a viewpoint.
2.
Write a 3 minute speech for one of these two people who are
speaking to the Scottish Parliament where a bill has been tabled
which would ban Rennet made from calves stomachs being made or
sold in Scotland.
3.
Begin your speech with: “This House proposes that Rennet from
Calves Stomachs (should / should not) be banned.
3.
You may be asked to present your argument to the Parliament in
a real debating situation which will be put to a vote.
You will be able to access a link for more information on the below
viewpoints in the same web link document
Viewpoint 1:
A committed vegan – who refuses to eat foods which are made from
animals.
Viewpoint 2:
A Scottish descendant of Christian Hansen, the inventor of pure Calf
Rennet who’s product replaced the farmer’s handmade efforts and wishes
to carry on operating a small business producing delicately flavoured,
specialised cheeses using Hansen’s method.
They also import real Parmesan cheese from Italy – which by law there
has to be made using Calf Rennet.
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Photosynthesis
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Making Food
LI To explain what food substance is contained in plants
and how plants make food
Everywhere we look we see plants. What important part do plants play in
food chains and webs? Discuss in pairs.
Testing foods using Iodine
1. Collect the following apparatus:
What to do





Dimple tray
Rice Krispies
Bread
Cornflakes
Iodine
2. Copy this table into your jotter to record your results:
Food
Iodine Start
Colour
Iodine End
Colour
What is
contained in
the food?
Rice Krispies
Bread
Cornflakes
3. Place a each food type in a separate dimple
4. Add a few drops of iodine to each
5. Record results in your table
1. What does the iodine colour change in the food show?
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2. Why is there starch in the food?
Plants make starch using light energy. Light energy is trapped in special
structures in green plants called chloroplasts. Chloroplasts contain
chlorophyll.
1. Draw this plant cell in your jotter and label the following
structures using the list below:






Cell Membrane
Cell Wall
Nucleus
Cytoplasm
Chloroplast
Vacuole
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What is needed for Photosynthesis?
LI To explain the 3 conditions needed for plants to carry
out photosynthesis
Plants contain starch. They create food by carrying out a process called
photosynthesis. Photo means light, and synthesis is to build. So
photosynthesis means – to build using light.
Your teacher will show you two different plants. As a class, discuss what
has been removed in each case.
Plant 1
Sunlight
Plant 2
White
Green
Plant
Bell
Jar
Green
Solution to
absorb CO2
Variegated Plant
(Half green; half white)
Teacher Demo – Testing a leaf for starch for plant 1 and plant 2
1. Note what happens to plant 1 and plant 2 in each case
2. Working with your partner, brainstorm how you might be able to
investigate if plants need sunlight to carry out photosynthesis
You are going to set up your own leaf to investigate if plants need
sunlight to photosynthesise
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What to do
1. Collect the following apparatus:
 Black Paper
 2 paper clips
2. Cut out two pieces of black paper
3. Cut a simple shape in one piece of black card
4. Attach two pieces of card, one with the shape cut into it, on either
side of a leaf.
5. Leave the plant in sunlight until next lesson
Example:
Other possible shapes:
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Testing a Leaf for Starch
LI To carry out an investigation that shows sunlight is
needed for photosynthesis
You are going to test a leaf for starch using the same technique your
teacher showed you yesterday.
What to do
1. Collect the following apparatus:
 Leaf covered in Black Card
 Test tube
 Beaker
 Iodine solution
 Dimple Tile
 Wooden Splint
 Test tube rack
2. Half fill the test tube with Ethanol and place it in a beaker half filled
with boiling water from the kettle
3. Take the black paper off your leaf and place it in the beaker of hot
water for 10 seconds (this will remove the wax from the leaf)
4. Take the leaf out of the beaker using the wooden splint
5. Place the leaf into the ethanol for approx. 1 minute – the green colour will
be removed from the leaf
6. Take the leaf out of the ethanol and place in hot water for another 10
seconds to remove any ethanol
Waste ethanol (green) should be placed in the waste solvent bottle
7. Take the leaf out of the hot water and lay it flat on the dimple tray
8. Add several drops of iodine to the leaf
1. What does the iodine colour change show?
2. What part of the leaf has changed colour?
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3. Draw a picture of your leaf in your jotter and shade in the part of the
leaf that has had the colour change.
It might look something like this:
4. Find the photosynthesis equation and photosynthesis word cards in your
pupil diagram pack. Arrange the cards to show the raw materials,
essential requirements and products of photosynthesis
5. Make this key in your jotter:
Red – Raw materials
Green – essential requirements
Blue – Products
Underline the raw materials, essential requirements and products in your
photosynthesis equation in the correct colours.
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Limiting Factors for Photosynthesis
LI To state the factors that can limit photosynthesis
You find out that photosynthesis requires carbon dioxide, light,
chlorophyll and water. A limiting factor is something that reduces the
rate of photosynthesis because it is in short supply. There are three ways
of measuring rate of photosynthesis: rate of oxygen bubbles released;
Carbon Dioxide uptake; and increase in dry mass.
A limiting factor is something that reduces the rate of photosynthesis
because it is in short supply. The three main factors that could affect
the rate of photosynthesis are:
 Light intensity
 Temperature
 Carbon Dioxide Concentration
Your teacher will show you how to measure the rate of
photosynthesis by counting the rate of oxygen bubbles released
from cabomba (an underwater plant) at different light intensities.
Oxygen
Green plant
(Cabomba)
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1. Collect the following apparatus:
What to do





Syringe
Dropper
Small Beaker
Medium Beaker half filled with calcium chloride
Stirring rod
2. Add 5cm3 of algal culture to a beaker using a syringe
3. Add 5cm3 sodium alginate to the algal culture using the syringe and
stir gently
4. Using the dropper, collect roughly 5 cm3 of Algae and sodium
alginate mixture
5. Carefully drip the algae and sodium alginate mixture into a beaker
containing calcium chloride (this will harden the mixture into
beads)
Dropper
Algae and sodium
Alginate mixture
Calcium Chloride
Solution
Gel pellet containing
immobilised Algae
6. Allow the beads to harden for 5min and then add them to a sieve
and rinse them under the tap
7. Sit the beads in distilled water – we will use these in an
investigation next lesson.
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Immobilised Algae investigation
LI To carry out an investigation to show light intensity can
affect the rate of photosynthesis
Hydrogen Carbonate indicator – a chemical used to test for Carbon
dioxide concentration. Colour change:
What to do
Indicator Colour
Purple/Red
Carbon Dioxide Concentration
Zero
Red
Very Little
Yellow
Significant increase
1. Collect the following apparatus:
2. Add 20 algal pellets to the bottle
3. Add 10cm3 Hydrogen Carbonate indicator to the bottle
4. Six groups:
Group 1 – Dark
Group 2 – 20cm from the light source
Group 3 – 40 cm from the light source
Group 4 – 60 cm from the light source
Group 5 – 80 cm from the light source
Group 6 – 100 cm from the light source
5. Note the starting colour of each groups bottle
6. Leave for 20min
7. Note the end colour of each groups bottle
1. What does the colour change show?
2. Which Group’s bottle showed the greatest change in Hydrogen
Carbonate colour? What do you think this shows?
3. What has affected the rate of photosynthesis in this experiment?
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Limiting Factors
LI To interpret date and present it as a line graph
We have investigated how light intensity can limit the rate of
photosynthesis. As you already know photosynthesis is also limited by
carbon dioxide concentration and temperature.
What to do
Study the results of three investigations below and plot 3 separate line
graphs for them on graph paper
1. Light Intensity
Light intensity (units)
10
20
20
40
50
60
70
Rate of
0
6
15
26
35
35
35
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0
3
6
9
11
11
11
Temperature (°C)
0
5
10
15
20
25
30
Rate of
0
2
5
9
14
18
18
Photosynthesis
(bubbles per min)
2. CO2 Concentration
CO2 Concentration
(%)
Rate of
Photosynthesis
(bubbles per min)
3. Temperature
Photosynthesis
(bubbles per min)
1.
On the Light intensity graph, note an x on the slope – this is where light
intensity is limiting. What two factors do you think are limiting photosynthesis
when the graph levels off?
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2. Can you do the same for the CO2 concentration and temperature curves?
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Transport of Water
LI To describe how water travels up the stem of a plant
You know that for a plant to carry out photosynthesis it needs water. If
photosynthesis takes place in the leaves of a plant, how do you think the
water gets to the leaves and where does the water come from?
1. Take the example of the Californian Redwood’s, some of them can
be 20 meters high, how does the water get to the leaves?
Discuss in pairs
What to do
1. Collect the following apparatus:




Celery Stalk
Beaker with 3 ml of red dye
Scalpel
White tile
2. Make a clean straight cut across the bottom of the celery stalk
and place in the dye for 5minutes
3. Remove the celery rinse and cut the end
4. Cut across and down the middle of the stalk
5. Draw a diagram of what you see – use a red pencil to show where
the dye is.
6. Copy and complete the following sentences in your jotter:
Water is a ………….. material used in photosynthesis. It is transported in
the plant from the ………….. to the ................ Water only travels ……….
the stem not down.
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Transport of Food
LI To describe how a plant uses sugar made through
photosynthesis
You already know there is a transport system in the plant to transport
water from roots to the leaves. Sugar is made in the leaves and will be
used by different parts of the plant.
1. Discuss the following questions with your neighbour:
a. What would the plant use the sugar made for?
b. Can the plant roots carry out photosynthesis?
2. Following class discussion, note 4 uses for sugar in the plant
What to do
3. Stick the plant diagram in your jotter:
4. Make the following key:


Blue – water transport
Orange – Sugar transport
5. Draw the blue arrows on your diagram to show the movement of
water
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6. Label the diagram using the following statements about how the
plant uses sugar:




Sugar is used for growth
Sugar is used for growth of shoots and young leaves
Sugar is used by roots for growth or storage
Sugar is used to supply energy for leaf cells and other plant
cells
7. Draw orange arrows to show the direction of sugar movement in
the plant, starting at the leaves
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Respiration
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Aerobic Respiration
LI – to understand how to obtain energy from Aerobic
Respiration.
Aerobic Respiration is a process that happens in every cell in every tissue
of your body. Aerobic respiration is important because it provides the
energy needed for all the chemical reactions that happen inside you to
keep you alive. Aerobic respiration uses oxygen to release energy from
our food and produces carbon dioxide as a waste product.
Discuss the following questions with your elbow partner:
1. Suggest 3 reasons why you need energy.
2. Where do we get energy from?
3. How does your body get the energy out of your food?
In your jotters write your answers in full sentences.
Activity 1 – Teacher demonstration
Watch while your teacher demonstrates a jelly baby burning.
What to do
Answer the following questions in sentences;
1. What did you see when the jelly baby burned?
2. What type of energy was released from the jelly baby?
3. What important gas is needed to make the jelly baby to burn?
4. Which gas do you think was released from the burning jelly baby?
5. How do you think we could prove it was this gas?
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6. Conclusion
When food is burned in ______________ it releases ______
____________ and ____________and energy. This process is called
a______________ r________________. The energy released from
food during a___________ r______________
Is used for ___________________, ________________________
and _________________.
Use the words in the wordbank to help you;
growing
repairing
aerobic respiration (X2)
water
carbon dioxide
moving
7. Aerobic Respiration can be written as the word equation
g______ + o_______
c_______ + w______ + E_____
d________
Extension
Write an equation to show the energy conversion that you saw when
the jelly baby burned.
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Factors which influence the aerobic respiration rate
LI – To investigate factors which affect the rate of
aerobic respiration
An organism’s rate of aerobic respiration depends on its level of activity
and environmental factors such as temperature, food availability and the
seasonal fluctuations in day length. Body size and stage of development
also affect respiration rates, as does an organisms behaviour.
Activity –undertake an internet search and make suitable notes on one of
the following;

Examples of humans surviving being submerged for a time in
water under ice.

Basal metabolic rate (BMR) and the factors affecting it.

The difference between breathing and respiration.

How and why the body is cooled during open heart surgery.
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Measuring Respiration
LI – To measure the rate of respiration in organisms.
The rate of respiration can be measured using a respirometer.
This measures the speed at which oxygen is used up by
respiring cells.
What to do
1. Collect the following apparatus:
a)
b)
c)
d)
e)
f)
respirometer tube
1 boiling tube with small amount of Soda Lime in bottom
pen for marking glass
cotton wool
living organisms (woodlice or maggots)
small beaker with small volume of coloured liquid
2. Observe as your teacher sets up the apparatus as shown below:
(absorbs all of the
CO2 produced by
the respiring
organisms)
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3.
Copy the diagram on the previous page into your notes.
4.
Why did the liquid level change in the respirometer?
5.
What control could be used with the experiment?
6.
How could values for a rate of respiration be calculated using the
above experiment?
7.
How could the reliability of the results be improved in the
experiment?
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Aerobic respiration in plants
LI – To understand the process of respiration in plants
Photosynthesis is the process that traps the suns energy and uses it to
make all the materials in the plant as well as providing the base for food
chains. Photosynthesis uses carbon dioxide which is a product of
respiration.
Read “release of carbon dioxide” in SG Biology (page 72-73)
1. Do plants respire?
2. Thinking about the equation for aerobic respiration, how could you
investigate this?
3. In groups prepare a suitable investigation with the aim “to
investigate if plants can respire aerobically.”
4. Use the information from the SG textbook and your ideas to write
up a suitable investigation as a poster in your groups – your poster
must still be in scientific investigation format – it must include an
aim, method, results and conclusion. Each group member must play
an active role in the process.
Plants respire all the time, in the light and dark and they continually
produce carbon dioxide. This carbon dioxide is used as a substrate for
photosynthesis; when the light intensity is sufficiently high it is
converted into glucose.
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Respiration in the absence of Oxygen
LI – To understand that respiration can occur in cells with
or without oxygen.
Respiration is the process that takes place inside organisms to release
chemical energy and enable energy conversions. Respiration can occur in
cells with or without oxygen.
Carry out the following investigation. You will need to work in pairs and
your partner will need to write down the results of the investigation and a
stopclock for timing.
1. With your hand by your side, make a clicking sound by flicking your
thumb and forefinger together for 2 minutes.
2. Repeat the experiment two more times, once iwth your arm
extended horizontally and then finally with you hand above your
head.
3. You should record your results as follows;
Time (seconds)
Number of clicks
Loudness
4. What do your results indicate?
5. How did you feel during the exercises and following the exercises?
6. Plot a graph of your results.
7. Conclusion – use the information below to write a suitable
conclusion in your jotter.
Exercise places demands on your circulatory and respiratory systmes
since the high levels of oxygen are needed. Blood carries oxygen to the
muscles. Its also transports dissolved food stored in the muscles. During
light exercise the muscles receive sufficient oxygen to release energy
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for the activity. Heavy exercise relies on high levels of oxygen which the
circulatory system is not always able to supply.
Read “muscle fatigue” in SG Biology (page 147)
8. How does muscle fatigue occur? You should use the words oxygen
and lactic acid in your answer.
Anaerobic Respiration in animals can be written as the word equation
g______
c_______ + l______ + E_____
d________
Anaerobic respiration leads to the production of lactic acid in the muscle
cells. At this point, the activity should be stopped as muscle fatigue and
pain develop.
Anaerobic respiration occurs in animals to produce lactic acid.
9. Think back to a previous topic, discuss with your neighbour. What
other organism respires anaerobically to produce lactic acid?
What useful products can be produced using this process?
10. What do yeast produce when they respire in the absence of
oxygen? What do they produce? What is the equation for this
process?
All living things are energy changers. Anaerobic respiration in plants
results in the production of ethanol, an alcohol, instead of lactic acid.
The alcohol produced by yeast is of particular importance in the brewing
industry. In the baking industry the carbon dioxide produced by yeast
cause the dough to rise and develop a spongy texture.
What to do
11. Complete the card sort activity and identify all the respiration
equations;
a) Aerobic respiration in animals, bacteria, yeast and plants.
b) Anaerobic respiration in animals, bacteria, yeast and plants.
Teacher check!
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Copy and complete the following table into your jotter to summarise the
respiration equations.
Organism
Aerobic respiration (with
oxygen)
Anaerobic respiration
(without oxygen)
Animal
Bacteria
Yeast
Plants
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The role of enzymes in respiration
LI – To understand the role of enzymes in respiration
We are going to investigate the effect of temperature of the activity of
yeast.
W
h
at
to
d
o
What to do
When live yeast cells are placed in sucrose solution their rate of
respiration increases and they release bubbles of carbon dioxide. The
gas gathers as a froth of bubbles above the yeast culture. The larger
the volume of froth produced, the greater the activity of the yeast cells.
We are going to carry out an investigation into the effect of temperature
on the activity of yeast.
1. Collect;

3 measuring cylinders (10cm3)

Yeast suspension

sucrose solution

Water baths (25’C, 35’C, 50’C)
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2. Instructions;
a) Label 3 measuring cylingers 25’C, 35’C amd 50’C and add your
initials
b) Shake the yeast suspension and add 2ml to each measuring
cylinder.
c) Add 10ml of sucrose solution to each measuring cylinder.
d) Place the 3 glass measuring cylinders into the appropriate water
baths.
e) Prepare your table of results (as below) in your jotter.
f) After 15-20 minutes, collect the 3 measuring cylinders and record
the volume of froth produced into your table fo results.
g) Record results from another group.
3. Copy and complete the table of results into your jotter;
Temperature
(°C)
Volume of froth (ml)
Start
Group 1
– End
Group 2
- End
Average
Group 1 & 2
End result
Difference
between
start and
Average
(End)
25
35
50
4. What is a suitable conclusion for this experiment?
5. Why is there no froth prodcued at 50’C?
6. What does this tell us about the process of respiration?
7. Why did we use the results from 2 groups?
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Respiration is a series of reactions controlled by enzymes and so the rate
of respiration is affected by temperature.
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