EDEXCEL GCSE BIOLOGY
Booklet for Topic 1:
Key concepts in Biology
Resources to use with this booklet:
BBC Bitesize: https://www.bbc.co.uk/bitesize/topics/ztvrrwx
Name:……………………………………………………………..
Form:……………………………..
Date started:…………………..
Date completed:………………
1
Specification
KEY CONCEPTS STATEMENT Indicate with a Tick / Cross /or a ?
Completed
Explain how the sub-cellular structures of eukaryotic
and prokaryotic cells are related to their functions,
including:
1.1
1.2
a
animal cells – nucleus, cell membrane, mitochondria
and ribosomes
b
plant cells – nucleus, cell membrane, cell wall,
chloroplasts, mitochondria, vacuole and ribosomes
c
bacteria – chromosomal DNA, plasmid DNA, cell
membrane, ribosomes and flagella
Describe how specialised cells are adapted to their
function, including:
sperm cells – acrosome, haploid nucleus,
a
mitochondria and tail
egg cells – nutrients in the cytoplasm, haploid
b nucleus and changes in the cell membrane after
fertilisation
c
ciliated epithelial cells
1.3
Explain how changes in microscope technology,
including electron microscopy, have enabled us to see
cell structures with more clarity and detail than in
the past and increased our understanding of the role
of sub-cellular structures
1.4
Demonstrate an understanding of number, size and
scale, including the use of estimations and explain
when they should be used
1.5
1.6
Demonstrate an understanding of the relationship
between quantitative units in relation to cells,
including:
milli (10−3)
micro (10−6)
nano (10−9)
a-e
pico (10−12)
calculations with numbers written in standard
form
Core Practical: Investigate biological specimens using
microscopes, including magnification calculations and
labelled scientific drawings from observations
1.7
Explain the mechanism of enzyme action including
the active site and enzyme specificity
1.8
Explain how enzymes can be denatured due to
changes in the shape of the active site
Explain the effects of temperature, substrate
concentration and pH on enzyme activity
Core Practical: Investigate the effect of pH on enzyme
activity
1.9
1.10
2
Understood
Remembered
KEY CONCEPTS STATEMENT Indicate with a Tick / Cross /or a ?
Completed
1.11
Demonstrate an understanding of rate calculations
for enzyme activity
1.12
Explain the importance of enzymes as biological
catalysts in the synthesis of carbohydrates, proteins
and lipids and thei*--/****-r breakdown into sugars,
amino acids and fatty acids and glycerol
1.13B
Core Practical: Investigate the use of chemical
reagents to identify starch, reducing sugars, proteins
and fats
1.14B
Explain how the energy contained in food can be
measured using calorimetry
1.15
Explain how substances are transported into and out
of cells, including by diffusion, osmosis and active
transport
1.16
Core Practical: Investigate osmosis in potatoes
1.17
Calculate percentage gain and loss of mass in osmosis
3
Understood
Remembered
Key word list
Microscopes
Word
Pronunciation
Eyepiece lens
Magnification
Mag-nif-ick-ay-shun
Objective lens
Resolution
Rez-O-loo-shun
Stain
Meaning
The part of the microscope you look down.
How much bigger something appears compared with
its actual size
The part of the microscope that’s closest to the
specimen
Smallest change that can be measured using an
instrument. E.g., in a microscope it’s the smallest
distance between two points that can be seen as two
points and not blurred into one point.
A dye used to colour parts of a cell to make them
easier to see.
Plant and animal cells
Word
Aerobic
respiration
Pronunciation
Air-O-bick
Cell
membrane
Cell sap
Cell wall
Chlorophyll
Klor-O-fill
Chloroplast
Klor-O-plast
vacuole
Vack-you-ole
Chromosome
Krow-mO-sOwm
Mitochondrion My-tow-kon-dree-on
Ribosome
rY-bow-sowm
DNA
Prokaryotic
pro-kar-ee-ot-ick
Eukaryotic
You-kar-ee-ot-ick
Meaning
Respiration in which oxygen is used to release energy
from glucose
Membrane that controls what goes in and out of a
cell. Often called the cell surface membrane as
eukaryotes contain other structures with membranes
Liquid found in the permanent vacuole of plant cells.
A tough layer of material found around some cells
which is used for protection and support. (It is stiff
and made of cellulose in plants. Bacteria have a
flexible cell wall.)
The green substance inside chloroplasts. It traps light
energy.
A green disc containing chlorophyll. This is where a
plant makes glucose during photosynthesis.
A storage space in a cell. Plant cells have a large
permanent vacuole to help keep them rigid.
A structure found in the nucleus of cells. Each
chromosome is made of one long DNA molecule.
A structure inside a cell (organelle). Found in the
cytoplasm of eukaryotic cells where aerobic
respiration occurs. (Plural is mitochondria.)
Tiny organelles (structures inside cells) that make
proteins.
A substance that contains genetic information. Short
for deoxyribonucleic acid.
A cell without a nucleus. There are no membranebound organelles.
Eukaryotic cells contain a nucleus and other
membrane- bound organelles.
4
Specialised cells
Word
Pronunciation
Meaning
Acrosome
Ack-rO-sO’m
A small vacuole in the tipoff the head of a sperm cell
which contains enzymes.
Adaptation
Add-app-tay-shun
The features that something has to enable it to do a
certain function (job).
Ciliated
epithelial cell
Sill-ee-ay-ted
Ep-ith-ee-lee-al sell
A cell that lines certain tubes in the body and has cilia
on (hair like structures)
Digestion
Dye-jes-shun
Process that breaks molecules into smaller more soluble
substances.
Diploid
Dip-loyd
A cell with two sets of chromosomes.
Haploid
Hap-loyd
A cell with one set of chromosomes e.g. sperm or egg
cell.
Embryo
Em-bree-O
A mass of cells that’s developed from a fertilized egg or
zygote
A substance that speeds up the rate of a reaction in
living things. A biological catalyst. It never gets used up.
Enzyme
Gamete
Gam-meet
A cell used for sexual reproduction
Fertilisation
Fert-ill-I-zay-shun
Joining of a male and female gamete (nuclei fuse)
My-cro-vill-us
A fold on the surface of an epithelial cell on a villus.
These folds increase the surface area so food can be
absorbed more quickly.
Word
Pronunciation
Meaning
Flagellum
Fla-jell-um
A tail-like structure that rotates allowing a bacterial cell
to move. Plural is flagellum.
Plasmid
Plaz-mid
A small loop of DNA found in the cytoplasm of bacteria.
microvillus
Inside Bacteria
Chromosomal
DNA
A large circle of DNA found in bacteria. (not inside a
nucleus)
Enzymes
Word
Pronunciation
Meaning
Biological
catalyst
Bio-loj-i-cal
cat-a-list
A substance found in living organisms that speeds up the
rate of a reaction (enzyme)
Monomer
Polymer
A small molecule that can join with other molecules like
itself to form a polymer.
A long molecule formed by joining many monomers
together.
5
Substrate
A substance that is changed during a reaction. (It binds
to an enzyme’s active site)
Product
What is made during a reaction.
Synthesis
Sinth-eh-sis
To build a large molecule from a smaller one.
Active site
The area on an enzyme where the substrate fits during
an enzyme-catalysed reaction.
Denatured
When the shape of an enzyme’s active site is changed so
the substrate no longer fits and the reaction can no
longer happen.
Lock and key
model
Model that describes the way an enzyme catalyses a
reaction when the substrate fits within the active site of
the enzyme.
Transporting substances
Word
Diffusion
Pronunciation
Diff-you-zshun
Meaning
When particles spread out and mix with each other
without anything moving them.
Active
transport
Movement of particles across a cell membrane from an
area of low concentration to high concentration. This
process requires energy.
Osmosis
Movement of water molecules across a partially
permeable membrane from a dilute solution to a
stronger one.
Oz-mO-sis
Concentration
gradient
The difference between two concentrations. Molecules
move down the concentration gradient.
Passive
Process that does not require energy.
Solute
Sol-yoot
The solid that dissolves in a liquid to make a solution.
Solvent
The liquid in which a substance dissolves to make a
solution.
Hypotonic
When the solution is weaker than the other
Isotonic
When the concentration of two solutions is equal
Hypertonic
When the solution is stronger than the other
6
Cell Structure

Use Bitesize Key Concepts in Biology, Cell Structure pages 1-3
Lesson objectives
You should be able to;


Define prokaryotic and eukaryotic cells and know the differences between them.
Label diagrams of plant, animal and bacteria cells and describe the functions of the main
organelles in each cell type.
Prokaryotic and Eukaryotic cells.
Eukaryotic cells
A cell with a nucleus and other membrane-bound organelles is described as a eukaryotic cell. They
are more complex than prokaryotic cells.
e.g. Plant and animal cells
Animal cell

Label the following cell and describe the function of each of the parts
cytoplasm
Size of average animal cell = 10-30 µm (micrometers) = 0.01-0.03 mm
7
Plant cell
Label the following plant cell and fill in the function of the organelles
Ribosome
Size of average plant cell =10-100µm (micrometers) = 0.01 – 0.1 mm
QUESTIONS:
State 3 similarities between a plant and animal cell
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------State 3 differences between a plant and animal cell
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Suggest why the nucleus and mitochondria are so important in all cells.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------8
PROKARYOTIC CELLS (e.g. Bacteria)
Prokaryotic cells lack membrane bound organelles such as a nucleus or mitochondria. They are
thought to be the first forms of life on Earth.
e.g. Bacteria
Label the following bacterial cell
Size of average prokaryotic cells 0.2-2µm
9
Complete the following:
nucleus
membrane
plasmids
genes
microorganisms
Bacteria are single celled________________________. Bacteria contain cytoplasm and
have a ________ _______________ surrounded by a cell wall. The ________________ are
NOT in a distinct _______________________ and Bacterial cells do not have mitochondria
or chloroplasts. They may contain small loops of DNA called ___________________.
Underline in blue features of this definition that make a prokaryotic similar to a
eukaryotic cell and underline in red features that make it different.
A prokaryotic cell has cytoplasm surrounded by a cell membrane. The organelles inside the cell are
not surrounded by membrane. It also has a cell wall that is not made of cellulose. The genetic
material is in a large DNA circle that is free in the cytoplasm and not enclosed by a nucleus.
Sometimes there are one or more small loops of DNA called plasmids.
Watch the video on prokaryotic and eukaryotic cells
https://www.youtube.com/watch?v=RQ-SMCmWB1s (4 min video)
Summarise using the table.
Prokaryotic cell
Eukaryotic cell
10
Comparison of Eukaryotic and Prokaryotic Cells
Tick the appropriate box if the cell contains any of the components listed.
Cell component
Cell wall
Cell membrane
Ribosome
Cytoplasm
Plasmid
Flagella
Mitochondria
Nucleus
DNA
Chloroplast
Vacuole
Is the cell Prokaryotic?
Is the cell Eukaryotic?
Plant cell
Animal cell
Bacterial cell
Quick quiz
1. Name one structure you found in a plant cell but not in an animal cell?..................................
2. What process happens in a mitochondrion?........................................................................
3. What is one function of a permanent vacuole in a plant cell?.............................................
4. In which part of a cell is cell sap stored?..............................................................................
5. In which part of a cell would you find chromosomes?.........................................................
6. What is a picture taken down a microscope called?............................................................
11
Specialised cells

Use Bitesize Key Concepts in Biology, Cell Structure page 4
Lesson objectives
You should be able to;


Explain how specialised cells are adapted for their function.
Explain the need for differentiation in a multicellular organism.
Cell Differentiation and Specialisation
sperm
differentiate
development
specialised
tissue
individually
function
As an organism develops, cells ___________________ to form different types of
specialised cells. Most types of animal cells differentiate at an early stage of
__________________. whereas many plant cells retain the ability to differentiate
throughout life.
As a cell differentiates it gets different subcellular structures to enable it to carry out
a particular _____________________. It has become a ________________ cell.
Some specialised cells such as egg and ___________ cells work ____________.
Others are adapted to work as part of a __________________, an organ or a whole
organism.
Diagram 1 shows a typical animal cell
Diagram 2 shows ciliated epithelial and goblet cells
Nucleus
Mitochondria
cytoplasm
Cell membrane
Ribosome
12
In multicellular organisms, cells are specialised to carry out particular functions.
e.g., There are two types of cells lining the windpipe.
1. Goblet cells produce mucus. Mucus contains a sticky protein that traps
microorganisms and dust particles
2. Ciliated cells have cilia on their surface. The cilia use energy to move the mucus out
of the windpipe (trachea). Ciliated cells are also found in women’s’ oviducts. They
“waft” or move the egg from the ovary to the uterus.
Questions
1. Suggest one cell organelle that you would expect to find a lot of in the cytoplasm
of ciliated cells.
Cell part ____________________________________________________________________
Explanation________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
__________________________________________________
2. Suggest one cell organelle that you would find a lot of in the cytoplasm of goblet
cells.
Cell part ____________________________________________________________________
Explanation________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
__________________________________________________
13
Specialised animal cells
Complete the following tables.
Picture
Name
14
Function
Features
Specialised plant cells
Picture
Name
Function
15
Features
Microscopes

Use Bitesize Key Concepts in Biology, Cell Structure pages 5 and 7
https://www.bbc.co.uk/teach/class-clips-video/biology-ks3-gcse-microscopy/znykmfr
Lesson objectives
You should be able to;




Explain how changes in microscope technology, including electron microscopy, have enabled
us to see cell structures in more detail and increased our understanding of sub- cellular
structures.
Demonstrate an understanding of the use of estimations and explain when they should be
used.
Demonstrate an understanding of the relationship between quantitative units in relation to
cells.
Use prefixes centi-, milli-, micro-, nano- (for example use micrometres and nanometres in
calculations).
Label the following light microscope.
16
Light microscopes
Light microscopes are the simplest, least expensive and most widely used microscopes.
They consist of a light source and at least one lens. Compound microscopes use two or
more lenses to focus the light to obtain high magnification. Specimens viewed under the
light microscope can be living or dead.
Light microscopy typically has a maximum resolution of about 200nm (0.0002 mm) and can
magnify specimens up to 2000 times (although school microscopes usually have a maximum
resolution of x400) which enables the viewer to see cells and some structures but not see
details of organelles.
The resolving power of the light microscope is limited by the wavelength of light.
Electron microscopes
An electron microscope uses a beam of electrons instead of light. These electrons can be
detected by using photographic film. The electrons are easily deflected so the specimen
must be viewed in a vacuum, meaning that the electron microscope can only be used to
view dead (abiotic) specimens.
The wavelength of the beam of electrons is 0.005nm and so a Transmission electron
microscope (TEM) can resolve details 0.2nm apart. This is the most common form of
electron microscope and is used to view ultra-thin sections of cells. The scanning electron
microscope (SEM) scans an electron beam onto the surface of a specimen and collects
electrons reflected from the surface.
SUMMARY COMPARISON:
LIGHT MICROSCOPES are cheap/easy to use/ and easy to
transport/carry.
ELECTRON MICROSCOPES are expensive/ complex to use/ too large to
carry.
ELECTRON MICROSCOPES HAVE A HIGHER RESOLUTION THAN LIGHT
MICROSCOPES. (enable us to see very small things clearly)
17
Light vs electron microscopes
electrons
thousand cheap but high
but lower
million
light
Light microscopes are relatively_________________ and can be used almost
anywhere. They use a beam of _________________ to form the image of an
object. They may magnify things several ______________ times.
Electron microscopes use a beam of ______________________ to form an
image and can magnify objects up to around two _________________ times.
Transmission electron microscopes give 2D images ______________________
magnification and resolution. Scanning electron microscopes give 3D images
_____________________ magnifications.
18
Core practical: Using microscopes
You are going to make a slide of some plant or animal tissue and examine it using a microscope. You
will then make an accurate drawing of one or more of the cells that you see and add labels and a
scale bar to your drawing.
Method:
Collect the following equipment
Microscope slide
Cover slip
Toothpick
Pipette
Methylene blue
Disinfectant
Paper towel
Sterile cotton bud
Gloves
Safety
Handle slides with care. Anything you put in your mouth must be sterile and placed in disinfectant after
use. Wear gloves and safety glasses if using stains.
TASK 1
A.
B.
C.
D.
E.
F.
G.
H.
Using a pipette, add a small drop of water to the slide.
Peel a small piece of onion skin from the inside of an onion
Put on gloves and use a pipette to add a small drop of iodine stain. This will make the cells
easier to see.
Place the coverslip at a 45 degree angle on one edge of the drop and lower slowly with the aid
of a toothpick.
Use the paper towel to absorb any liquid that spreads out from under the cover slip.
Use the lowest magnification lens to observe the slide.
Estimate the size using your field of view diameters from task 1.
Make a drawing and label the structures.
Task 2
A. Using a pipette, add a small drop of water to the slide.
B. Stroke the inside of your cheek gently with a sterile cotton bud
C. Use the end that has been in your mouth to stir the drop of water on the slide. Place the used
cotton bud in disinfectant.
D. Put on gloves and use a pipette to add a small drop of methylene blue stain. This will make the
cells easier to see.
E. Place the coverslip at a 45-degree angle on one edge of the drop and lower slowly with the aid
of a toothpick.
F. Use the paper towel to absorb any liquid that spreads out from under the cover slip.
G. Use the lowest magnification lens to observe the slide.
H. Make a drawing and label the cell structures.
19
Drawing of cheek cells
Drawing of onion cells
20
Units of measurement
Most cells are so small you can only see them using a microscope. Many small
organelles cannot be seen with a light microscope. The diagram below shows
the relative sizes of various specimens. It also shows the range of what we can
see using the naked eye. a light microscope and an electron microscope.
Order of Magnitude
Orders of magnitude are used to make approximate comparisons between numbers or
objects. If one number is about 10 times bigger than another, it is one order of magnitude
bigger. You show orders of magnitude using powers of 10. If one cell or organelle is 10 times
bigger than another, it is an order of magnitude bigger or 10¹. If it is approximately 100 times
bigger it is two orders of magnitude bigger or 10².
Example
100 =10
A small animal cell has a length of around 10 µm (micrometres)
10
A large plant cell has a length of around 100µm.
So, a large plant cell is an order of magnitude of 10¹ bigger than a small animal cell.
Conversion table of measurements
1 kilometre (km) = __________________ metres (m)
1 metre
(m) = ___________________centimetres (cm)
1 centimetre (cm) = ___________________millimetres (mm)
1 millimetre (mm) = ___________________ micrometres (µm)
1 micrometre (µm) = ___________________ nanometres (nm)
21
How to convert between measurements
Complete the following diagram
1) Complete the table below to show the corresponding value nanometres, micrometres and
millimetres for the measurements given in each row. The first row has been completed for you.
Ensure that your answers use the correct unit symbols.
Nanometre
Micrometre
5
0.005
Answer in
standard
form
5 x 10 ⁻³
Millimetre
0.000005
Answer in
standard
form
5 x 10 ⁻⁶
1
1
1
3
7
0.5
2) When studying cell structure using a microscope the smallest unit of measurement commonly
used to describe findings is the nanometre. Explain why.
_________________________________________________________________________________
_________________________________________________________________________________
_______________________________________________________________
22
Magnification and Resolution
1) Define the following terms: (Tip: Use your key words list at the beginning of the booklet)
Magnification:
……………………………………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………..
Resolution:
……………………………………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………..
Now you have an idea of the units of measurement, put these in size order starting with the biggest
(which will be 1) to the smallest (to 9)
Organelle
Cilia
Mitochondrion
Sperm cell
Ribosome
Human Kidney
Nerve cell from giraffes’ neck
Red blood cell
HIV virus
Human egg cell
size
10 µm
2 µm
55 µm
20 nm
13 cm
3m
9 µm
100 nm
100 µm
Order
Put these in order (biggest to smallest): Chromosome, nucleus, gene, cell.
_______________ _________________ _________________ __________________
Calculating total Magnification of a compound light microscope
Eyepiece
Objective
Overall
Magnification Magnification Magnification
X10
X4
X10
X10
X10
X40
X10
X100
23
Calculating Cell Magnification from images
The diagram below is a drawing of an organelle from a ciliated cell as seen with an electron
microscope.
A
B
× 20 000
Calculate the actual length of the organelle as shown by the line AB in the diagram.
Express your answer to the nearest micrometer (m).
Show your working.
Answer = ........................................... m
The diagram below is a drawing of an alveolus together with an associated blood capillary.
blood
capillary
alveolus lined with
squamous epithelium
A
B
cell X
The line AB in the diagram represents an actual distance of 1.5 µm.
Calculate the magnification of the drawing. Show your working.
Answer = × .................................................
24
The diagram below shows the general structure of an animal cell as seen under an electron
microscope.
_________
5m
1) Calculate the magnification factor of the diagram
2) Calculate the actual length of structure G
3) Calculate the diameter of the nucleolus (structure B)
4) Calculate the diameter of the nucleus
5) Calculate the diameter of the cell at its widest point
25
The diagram below shows the general structure of a plant cell when viewed under and
electron microscope.
___________
40m
1) Calculate the magnification factor of the diagram
2) Calculate the thickness of the cellulose cell wall.
3) Calculate the length of the cell.
4) Calculate the length of structure C.
5) Calculate the length of the vacuole.
26
ENZYMES

Use Bitesize Key Concepts in Biology, Enzymes pages 1-6
Lesson objectives
You should be able to;
 Explain the mechanism of enzyme action including the active site and enzyme
specificity.
 Explain how enzymes can be denatured due to changes in the shape of the
active site.
 Understand the effects of temperature, substrate concentration and pH on
enzyme activity.
Complete the following;
3000
speed up
activation
active site
substrate
specific
Biological catalyst.
protein
denatured
There are about ___________________ enzymes in the human body catalysing
reactions that otherwise wouldn’t occur. Their role is to _______________ the rate of
a reaction. They do this by lowering the ____________________energy required for a
reaction to start. They are therefore known as __________________
__________________
Enzymes are 3D molecules made of a chain of amino acids folded up making a
______________. Within this shape there is an area called the _____________
____________. This is where the ___________________ fits the enzyme at the start
of the reaction. Different substrates have different shapes and therefore different
enzymes have different active site shapes so they can fit together. This explains why
enzymes can only work with _________________ substrates that fit the active site.
27
Lock and key model.
https://www.bbc.co.uk/teach/class-clips-video/biology-ks3-gcse-enzymes-and-active-sites/zd2f47h
This model explains how the enzyme and substrate fit together.
The reaction can be used to synthesise (make) larger molecules, or break down large
molecules into smaller molecules.
e.g., to make carbohydrates, proteins and lipids; or break them down into glucose,
amino acids, fatty acids and glycerol.
EXAMPLES OF ENXYME REACTION:
Starch
 Maltose
by the enzyme AMYLASE
Proteins  amino acids
Fats
by the enzyme PROTEASE
 fatty acids and glycerol
by the enzyme LIPASE
Factors affecting enzyme activity.
Enzymes are affected by the conditions in their surroundings such as;
 ………………………………………………..
 ………………………………………………..
 ………………………………………………..
Changes in pH and temperature can affect how the protein folds up and so can affect
the shape of the active site. If the shape of the active site changes too much, the
substrate will no longer fit. The enzyme will not be able to catalyse the reaction and
so we say the enzyme has been denatured.
28
ENZYME ACTIVITY graphs
DESCRIBE (How does the pattern of the line change?) and
EXPLAIN (WHY does the pattern of the line change?) the following;
DESCRIBE………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
EXPLAIN…………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………………………………………………..
DESCRIBE………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………
EXPLAIN…………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………………………………………………..
DESCRIBE………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………
EXPLAIN…………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………………………………………………..
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
1. What are enzymes
made from?........................................
……………………………………………………………………
Questions
2. What is the name of the part of the enzyme into which the
substrate fits?...........................................................................
3. Which term describes an enzyme in which the active site has
permanently changed shape?..................................................
4. Enzymes are specific to their substrate. What does this
mean?................................................................................................
.........................................................................................
29
Core practical
pH and enzyme activity
https://www.bbc.co.uk/teach/class-clips-video/science-biology-gcse-explain-this-effect-of-ph-on-enzymeactivity/zk73gwx
Amylase is an enzyme that is made in the salivary glands in your mouth and in the pancreas.
Amylase catalyses the breakdown of starch to smaller maltose molecules. The iodine test identifies
the presence of starch but does not react with sugar molecules. You will use this test to show how
effective amylase is in digesting starch.
Aim
To investigate the effect of pH on the rate of digestion of starch by amylase.
Prediction
I predict that amylase at pH …….. will digest the starch the fastest because
……………………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………………
……………………………………………………………………………………....
Apparatus
Collect the following apparatus;
Safety
Wear eye protection
Amylase solution
iodine solution
Stirring
solutions pf specific pH
Test tubes + rack
spotting tile
syringe or pipette
stop watch
Starch
solution
and water bath
Of
amylase
into one testThermometer
tube and 5cm³
Method
1. Prepare the spotting tile by placing one drop of iodine solution into each well.
2. Measure 2cm³ of amylase into one test tube.
3. Add 1cm³ of a solution of a particular pH into the tube.
4. Add 2cm³ starch solution into the tube and place it carefully into the water bath.
5. Start the stop watch and stir the mixture
6. Every 20 seconds take a small volume of mixture and place one drop of it into a fresh drop of
iodine solution in the spotting tile.
7. Stop testing when the iodine solution stops changing colour.
8. Repeat the experiment using a different pH solution in step 3.
30
Results
Complete the table for your results in the space below
Time taken for the amylase to digest the starch
(when no colour change is seen) (seconds)
pH
Trial 1
Trial 2
Trial 3
Plot a graph of your results here:
31
Trial 4
Mean
Lesson objectives
You should be able to;
 Demonstrate an understanding of rate calculations for enzyme activity.
 Explain the importance of enzymes as biological catalysts and how they are
involved in the breakdown of carbohydrates, proteins and lipids and the
products of their breakdown.
Rate graphs
Most graphs showing enzyme activity are drawn as rate graphs.
Rate graphs are produced by calculating the how quickly a substrate is broken down
or a product is formed. For example, if 100g of starch was broken down in 5 minutes
at 30˚C, then the rate of reaction would be: 100⁄5= 20g/min
Digestion and enzymes
Digestion is ………………………………………………………………………………………………………..
32
Our digestive system
Without enzymes the process of digestion would be too slow to meet our metabolic
demands.
The large molecules (polymers) that need to be digested are;
 Carbohydrates (including starch), also called polysaccharides.
 Proteins, also called polypeptides.
 Fats, also call lipids.
The other food substances in a healthy diet including _______________ and
________________ are small enough to diffuse through the small intestine.
33
Maltose
Using the above diagram to help answer questions 1-6
1. Name the substrate of protease and the products of the reaction it
catalyses.
Substrate…………………………………. Product………………………………………(2)
2. What is the enzyme used to break down lipids?................................(1)
3. What is the polymer that amino acids join up to make? ..................(1)
4. What is the enzyme that is needed to produce fatty acids and glycerol?
……………………………………………………………………………………………………….(1)
5. What is the polymer that is broken down to release glucose?
........................................................................................................... (1)
6. Which substances in the table are able to pass through the small intestine?
………………………………………………………………………………………(1)
And a bit more challenging……
7. What are the subunits of enzymes?.................................................. (1)
8. What is the substrate for amylase?................................................... (1)
9. What is an enzyme? ………………………………………………………………………....
……………………………………………………………………………………………………….(1)
10.Starch synthase is an enzyme that catalyses the synthesis of starch. Explain
what this means.
………………………………………………………………………………………………………(1)
34
11. Complete the labels to describe why the curve is this shape. (2)
At low substrate
concentrations, rate
of reaction increases
because……………………
………………………………
………………………………
………………………………
………………………………
……………………………
At high substrate
concentrations, rate
of reaction doesn’t
change because
…………………………………
…………………………………
…………………………………
…………………………………
…………………………………
12.In an experiment, 100g of starch was broken down by the enzyme amylase
in 8 minutes. Calculate the rate of this reaction in terms of amount of
substrate broken down over time (g/min)
……………………………………………………………………………………………………………
………………………………………………………………………………………………………………………
……………………………………………………………………………………………(2)
13. How does temperature affect the rate of an enzyme controlled
reaction?.................................................................................................
……………………………………………………………………………………………………………
………………………………………………………………………………………………………(2)
14. Where in the digestive system does the digestion of protein begin?
………………………………………………………………………………………………………(1)
15.What is the optimum pH for the digestion of protein using pepsin?
………………………………………………………………………………………………………(1)
16. Name two organs in the body that produce digestive enzymes.
………………………………………………………………………………………………………(1)
Total =
/20
35
Lesson objectives
You should be able to;
 Use chemical reagents to identify starch reducing sugars, proteins and fats.
 Explain how the energy continued in food can be measured using calorimetry.
Core practical
Food tests
Apparatus
Collect the following equipment;
Safety
Wear eye protection
3 test tubes
Benedicts reagent
Iodine
Dimple tile
Dimple tile
Biuret solution
Pipettes
Water bath 70˚C
Bread
Cheese
Starch solution
Glucose solution
Albumin solution
Test for glucose.
To test for glucose you use …………………………………………………Reagent
 Add 5cm³ of the reagent to 3 test tubes
 Add some cheese to one test tube, bread to the second tube and 2cm³ glucose
solution to the third tube.
 Place all three test tubes in a hot water bath for 5 minutes
Results
Colour of solution
at start
Colour of solution
at end.
Bread
Cheese
Glucose solution
36
Glucose
present? Y/N
Test for starch
To test for starch you use…………………………………………………………solution
 Add 2 or 3 drops of the iodine solution into 3 separate wells on a dimple tile.
 Add a small piece of cheese to one well with iodine in, a piece of bread to
another and 2 drops of starch solution to the third.
Results
Colour of solution
at start
Colour of solution
at end.
Starch
present? Y/N
Bread
Cheese
Starch solution
Test for protein
To test for protein you use…………………………………………………………………Reagent
Which is made of sodium hydroxide and hydrated copper (II) sulphate solution.
 Add 2 or 3 drops of the reagent into 3 separate wells on a dimple tile.
 Add a small piece of cheese to one well with iodine in, a piece of bread to
another and 2 drops of albumin solution to the third.
Results
Colour of solution
at start
Colour of solution
at end.
protein
present? Y/N
Bread
Cheese
Starch solution
Question
Circle the word which best describes the results of the food tests. Explain why.
Quantitative
Qualitative
Because ……………………………………………………………………………………………………………
37
Calorimetry
https://www.bbc.co.uk/teach/class-clips-video/biology-ks3-gcse-food-as-fuel/zjmy92p
Heat energy can be given out or taken in from the surroundings during chemical
reactions. The amount of heat energy transferred can be measured, this is called
calorimetry.
If heat is given out it is called an ________________________ reaction.
If heat is taken in it is called an __________________________reaction.
Diagram
The energy transferred to the water can be worked out using the following equation;
Energy transferred (J) = Mass of water (g) X 4.2 (J/g˚C) X temperature increase (˚C)
Calculate the energy in the food you tested.
Temperature at start = …….. Temperature at end = ……. Temperature increase = …..…
Mass of water ( 1cm³ = 1g) =……………….
Energy transferred =
=…………… J
Question
Circle the word which best describes the results of calorimetry. Explain why.
Quantitative
Qualitative
Because ……………………………………………………………………………………………………………
38
Diffusion

Use Bitesize Key Concepts in Biology, Transport in cells pages 1-9 and link
https://www.bbc.co.uk/bitesize/articles/zbvdwty to lesson on osmosis and diffusion-just first section
on diffusion including case study video
Lesson objectives
You should be able to;
 Define diffusion.
 Explain how temperature, concentration gradient and surface area affect the
rate of diffusion.
 Give examples of substances that can move in and out of cells by diffusion.
Diffusion is……..
Kinetic theory
COMPLETE THE GAPS USING THE FOLLOWING WORDS:
HIGHER, FASTER, CONCENTRATION, DIFFUSION, RANDOM, HIGHER,
HIGHER, KINETIC, EVENLY
Molecules are in constant ________________ movement due to their ____________
energy. This allows dissolved molecules to move around until they are
________________ spread out. This process is known as _____________.
The strength of the bonds between particles in a solid are very high, this is why
diffusion only occurs in liquids and gases.
The ___________the temperature the more energy the particles have, the
__________they move. Other factors that affect the rate of diffusion include the
surface area over which diffusion can occur and the ___________ gradient. The larger
the surface area the ___________the rate of diffusion. The steeper the concentration
gradient the ____________the rate of diffusion.
39
Questions.
1. What four important substances move across your membranes by
diffusion?
…………………………………………………………………………………………………….…(4)
2. In which part of your body does oxygen diffuse into your blood?
……………………………………………………………………………………………………….(1)
3. Which specialised cell transports the oxygen?
…………………………………………………………………………………………………….…(1)
4. What cell structure does the oxygen have to diffuse across to enter the
specialised cell for its transport?
……………………………………………………………………………………………………….(1)
5. The oxygen is delivered to every living cell in the body. What is the name of
the process which releases energy from glucose using the oxygen?
……………………………………………………………………………………………………….(1)
6. In which organelle does this process occur?
……………………………………………………………………………………………………….(1)
7. Explain why diffusion takes place faster when there is an increase in
temperature.
………………………………………………………………………………………………………………..……
…………………………………………………………………………………………………………..…………
………………………………………………………………………………………
……………………………………………………………………………………………………….(3)
8. Explain in terms of diffusion, why so many cells have folded membranes
along at least one surface.
……………………………………………………………………………………………………………..………
……………………………………………………………………………………………………..………………
…………………………………………………………………………………………………..…………………
……………………………………………………………………....(3)
Total: ____
15
40
Osmosis

Use Bitesize Key Concepts in Biology, Transport in cells pages 1-9 and link
https://www.bbc.co.uk/bitesize/articles/zbvdwty to lesson on osmosis and diffusion-second
section on osmosis including video and slide show
Lesson objectives:
You should be able to;
 Define osmosis
 Apply knowledge of osmosis to unfamiliar situations and make predictions.
Osmosis is……..
41
OSMOSIS: KEY WORDS
Define the following key words. You should aim to use them in your answers.
WORD
DEFINITION
Solute
A SOLID that dissolves
Solvent
Solution
Strong/concentrated
solution
One with MANY SOLUTE molecules
Weak /dilute solution
Isotonic
Hypertonic
When the concentration of two solutions are EQUAL
When the solution is STRONGER than the other
Hypotonic
Partially /selectively
permeable
membrane
Membranes allow only some substances (molecules
or particles) to pass through.
Plasmolysed
Plant cells that have lost lots of water and the cell
membrane has peeled away from the cell wall. The
cells are soft and floppy.
Turgid
flaccid
42
Why is osmosis important?
Animal cells
The concentration of solutes in the cytoplasm of cells must remain fairly constant for
the cells to remain healthy.
Reactions in cells can use up water or produce it. So, to keep the water balance in a
cell correct, water is always diffusing across the cell membrane (a partially permeable
membrane) by osmosis.
In animals, cells are surrounded by fluids and our activities can change the
concentration of solutes in these fluids. For example, eating a bag of salty crisps and
losing water in sweat could raise our solute levels while drinking a bottle of water
could dilute and lower the solute levels in the fluid.
A process called homeostasis (a later topic) maintains a constant internal
environment and prevents these changes have a serious osmotic effect on our cells.
Plant cells
In plants, the cell sap has quite a high concentration of solutes in it, so water moves
into plant cells, filling the vacuole and pushing the cytoplasm against the cell walls.
The cell walls prevent the plant cell from bursting.
Pressure builds up until no more water can physically enter the cell. The cell is hard
and rigid and in this swollen state is how stems and leaves stay firm (turgid). If plant
cells lose water by osmosis, the pressure is lost and plants start to wilt (flaccid). If too
much water is lost the cell membrane peels away from the cell wall and the cell
becomes plasmolysed
43
Investigation into Osmosis in Potatoes
Core practical
https://www.bbc.co.uk/teach/class-clips-video/science-biology-gcse-explain-this-osmosis-in-planttissue/znpbrj6
Aim
To investigate any change in mass of potato cylinders after they have been soaked in solutions of different
concentrations.
Theory:
Water moves by a special type of diffusion called OSMOSIS. Water will move from a region where there is a
lot of water (a DILUTE SOLUTION) to a region where there is less water (a STRONG SOLUTION).
Method:
1. Collect your apparatus:
cork borer, white cutting tile, knife, ruler, boiling tubes, potato, labels.
2.
3.
4.
5.
6.
7.
8.
CAREFULLY bore a potato cylinders (SHARE POTATOES IF POSSIBLE)
Cut the cylinders to the SAME length (3cm)
Pat dry each cylinders before WEIGHING the mass. Write the mass on a sticky label.
Put SUGAR SOLUTIONS in boiling tubes to the same volume (10cm3)
Put one cylinder in each boiling tube with SUGAR SOLUTION (label)
Leave the cylinders for 20 minutes, then remove the cylinders and pat them dry and WEIGH.
Record your results in the table and work out the DIFFERENCE in mass (this could be a NEGATIVE
NUMBER!).
9. Work out the % difference so you can compare your results.
RESULTS
Sugar Solution
(M)
Initial Mass of
potato cylinder (g)
Final mass of
potato cylinder (g)
Difference in mass
(g)
% difference in
mass
IM
FM
FM -IM
FM-IM x 100
IM
0
0.2
0.4
0.6
0.8
1.0
44
10. Draw a LINE GRAPH to show SUGAR CONCENTRATION against the % change in mass.
DESCRIBE the trend (pattern/ shape of graph) (use figures to illustrate your observation)
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
45
EXPLAIN the trend using theory about OSMOSIS (think - why has the potato chip gained or
lost mass)
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
DESCRIBE possible sources of error that may have occurred during your practical
experiment
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
Write a statement to explain each of the following:
Independent variable:
……………………………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………………………….
Dependent variable
……………………………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………………………….
Controlled Variable
……………………………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………………………….
46
Model of Osmosis
Task
Look at the diagram above, then decide whether the following statements are
True
or
false.
1. All molecules are the same size
True
False
2. Water molecules are smaller than sugar molecules
True
False
3. Water molecules can pass in and out of the bag
True
False
4. Sugar molecules can pass in and out of the bag
True
False
5. There are more water molecules in the bag
True
False
6. Water molecules move from low to high concentration
True
False
7. Water molecules move into the bag
True
False
8. Sugar molecules move out of the bag
True
False
9. The volume of the bag increases
True
False
10. The level of the liquid in the tube rises
True
False
47
Active transport
Lesson objectives
You should be able to;
 Describe how active transport occurs
 State examples of active transport in plants and animals and explain the
importance.
high
against
respiration
proteins
energy
low
Active transport allows the movement of substances from an area of
______________ concentration to an area of __________________concentration
__________________ a concentration gradient. This process is carried out by
transport _________________ in cell membranes. They capture certain molecules
and carry them across the membrane. This process requires ___________________
which is released through _______________________.
48
Importance of active transport
Describe how active transport is used in the following;
In the gut
…………………………………………………………………………
…………………………………………………………………………
………….……………………………………………………………
…………………………………………………………………………
……………………….………………………………………………
…………………………………………………………………………
In the kidney
…………………………………………………………………………
…………………………………………………………………………
………….……………………………………………………………
…………………………………………………………………………
……………………….………………………………………………
…………………………………………………………………………
In the root hair cells
………………………………………………………………………
………………………………………………………………………
……………….………………………………………………………
………………………………………………………………………
……………………………….………………………………………
………………………………………………………………………
……………………………………………………………………..
49
50
Q1.
(a) The diagram shows four ways in which molecules may move into and out of a
cell. The dots show the concentration of molecules.
The cell is respiring aerobically. (Meaning it needs OXYGEN)
Which arrow, A, B, C or D, represents:
(i)
movement of oxygen molecules;
....................
(ii)
movement of carbon dioxide molecules?
....................
(2)
(b)
Name the process by which these gases move into and out of the cell.
............................................................................................................
(1)
(c)
Which arrow, A, B, C or D, represents the active uptake of sugar molecules by the cell?
...........................................................................................................
Explain the reason for your answer.
............................................................................................................
............................................................................................................
............................................................................................................
(2)
(Total 5 marks)
51
Learning/Revision Techniques
METHOD
Used
regularly?
YES
NO
1. Read through your notes?
2. Read text books?
3.
Re-write your notes using key words/ phrases and
bullet-points?
4. Reduce your notes onto index cards?
5. Highlight key words in notes?
6. Underline headings and subheadings in colour?
7. Chant lists or texts aloud?
8. Number points?
9.
Record yourself asking questions and answers and
listen again?
10. Have question and answer sessions with friends?
11. Draw pictures/mind-maps/flow charts/graphs?
12. Make flash cards?
13. Test yourself using past papers?
14. Design your own questions?
Use mnemonics or acrostics? (lists of letters that make
up memorable words/phrases)
Convert notes into cartoon strip pictures?
16.
(for certain topics)
15.
17. Pace about whilst reciting information?
18. Use interactive computer revision programmes?
19.
Make lively posters and put them on your
walls/ceiling?
20. Revise to the sound of music?
21. Ask a teacher?
22. Ask a parent/tutor/older student?
Other methods?
52
Will try in
the future?
YES
NO