Cell Structure
Cells are the basic units of life. All living things, whether plant, animal,
fungus or bacteria, are made up of cells.
Plant and animal cells have a cell membrane, cytoplasm, nucleus,
mitochondria and ribosomes.
In addition, plant cells possess a cell wall made of cellulose, a permanent
vacuole and may contain chloroplasts.
Animal and Plant Cell Structure

Insert and complete the Animal and Plant Cell Ultrastructure diagram
from your pack into your notes.

Copy & complete the table below:
Cell
In plant or animal
Structure cell or both
Function
site of protein synthesis
controls cell division and cell chemistry
controls the movement of materials into and
out of cells
site of photosynthesis
site of aerobic stages of respiration
supports the cell
site of chemical reactions

Carry out Practical 1 (Observing Cells Under The Microscope)
Research
Use http://www.cellsalive.com/cells/cell_model.htm to find out about cell
structures and their functions in plant and animal cells.
1
Structure of Bacterial and Fungal Cells
Bacterial Cell structure
Bacterial cells are different from plant and animal cells as they do not contain
a membrane bound nucleus or mitochondria but they do have a circular
bacterial chromosome and they have ribosomes. Some bacterial cells contain
an extra ring of DNA called a plasmid. Bacterial cells are enclosed in a
membrane, a cell wall and a capsule and some have flagella for movement.

Insert the Bacterial cell diagram from your pack into your notes.
Fungal Cell Structure
Yeast is a single-celled fungus. Penicillium is a multicellular filamentous
fungus. Fungal cells do not contain chlorophyll and therefore cannot make
their own food – they have to be supplied with food in the form of sugar.
Except for yeasts which are unicellular, the bodies of fungi are constructed of
units called hyphae. Hyphae are minute threads composed of cell walls (made
of chitin) surrounding a plasma membrane and cytoplasm. The cytoplasm
contains many organelles including mitochondria, nucleus, ER and ribosomes.


Carry out Practical 2 (Observing Fungal Cells)
Insert and complete the Bacterial and Fungal Cell Structure diagram
from your pack into your notes.
2

Copy and complete the table below.
Cell organelles present (√)or absent (x)
Type of
cell
Cell
Cell
wall membrane
Nucleus
Chloroplasts Ribosomes Mitochondria
Animal
Plant
Bacteria
Fungi
3
Transport across Cell Membranes
Plasma Membrane
The plasma membrane consists of a double layer of lipids with proteins on,
in and through the lipid bilayer. The membrane is selectively permeable.

Insert and complete the Cell Membrane diagram from your pack into
your notes.

Name the 2 main components of the cell membrane.

State the name given to this model of the plasma membrane.

Explain the meaning of the word fluid in this context.

Explain the meaning of the term mosaic in this context.

Carry out Practical 3 (Chemical Nature of The Plasma
Membrane)
Passive Transport in Plant & Animal Cells
Diffusion
Diffusion is the movement of molecules from an area of high concentration
to an area of low concentration, down a concentration gradient and it does
not require energy.
Your teacher will demonstrate some different examples of diffusion.
1

Explain what is meant by the term concentration gradient.

Insert and complete the Diffusion & Cells diagram from your pack into
your notes.
4
The Importance of Diffusion
Animal and plant cells depend on diffusion for the movement of substances
into and out of cells. Substances can only diffuse if they are dissolved in
water first.

Explain why diffusion is important to living cells.

Name 2 substances which enter cells by diffusion.

Name 1 substance which leaves cells by diffusion.

Insert and complete the Importance of Diffusion diagram from your
pack into your notes.
Osmosis
Osmosis is a special kind of diffusion, involving only water molecules.
Osmosis is the movement of water molecules from a high water
concentration to a low water concentration, across a semi-permeable
membrane down a concentration gradient.

Describe the role of the cell membrane in osmosis.

Describe a 0.5M sucrose solution compared to a 1.0M sucrose solution,
with reference to:
 water concentration
 solute concentration.

Carry out Practical 4 (Osmosis in Plant Tissue)
A Step Ahead
The water concentrations of two solutions can be compared using the expressions:
 Hypotonic
 Hypertonic
 Isotonic
Use any resources available to you to find out what they mean and make notes.
5
Osmosis and Cells

Insert and complete the Osmosis & Cells diagram from your pack into
your notes.

Carry out Practical 5 (Plasmolysis in Plant Tissue)
6
Active Transport in Plant and Animal Cells
Active transport requires energy for membrane proteins to move molecules
against the concentration gradient.
Active transport is the mechanism by which plant root hair cells take up
nutrients such as nitrates from the soil against the concentration gradient.
In animals, nerve cells depend on active transport of sodium and potassium
ions to maintain a concentration difference across the membrane.
Active
(needs energy)
Passive
(doesn’t need energy)
Watch http://www.youtube.com/watch?v=dPKvHrD1eS4&feature=player_embedded to
find out more about active transport.
Energy is needed for active transport to take place.

Describe the conditions which are needed for energy to be released in
cells.
7
Producing New Cells
Each cell in an organism has two matching sets of chromosomes in the nucleus,
the diploid chromosome complement.
All cells in an organism, except
gametes, have exactly the same number and type of chromosomes in the
nucleus so that they will have a complete set of genetic information for their
species.
Every species has its own characteristic chromosome complement. This means
it has the same number and type of chromosomes e.g. humans have 46
chromosomes, fruit flies have 8 chromosomes and pea plants have 14
chromosomes.
Multicellular organisms begin as a single fertilised egg cell but grow with an
increase in cell number by a type of division called mitosis. This division is
controlled by the nucleus.

Insert and complete the Producing New Cells diagram from your pack into
your notes.
 Observe prepared microscope slides of root tip cells using the
microscope or Bioviewer.
 Examine the photographs of mitosis.
 Sort the cards to show the sequence of events in mitosis.
 Insert and complete the Mitosis diagram from your pack into your
notes.

Carry out Practical 6 (Mitosis in Root Tips)
8
Cell Production by Cell Culture Techniques
Some cells may be grown on a small scale in medical labs for diagnosis or
treatment of various conditions e.g. tissue from a biopsy.
Cells can also be grown on an industrial scale in fermenters to produce food
products such as yoghurt or mycoprotein, alcoholic drinks such as beer or
wine, hormones such as insulin or antibiotics such as penicillin.
These cells must be grown using aseptic techniques to ensure that only the
required cells are present.
The cells must be grown in an appropriate medium which may be solid or
liquid e.g. agar jelly or nutrient broth. Cells need energy to grow and divide.
The medium provides the soluble food, water and essential nutrients for
this.

Insert and complete the Cell Production Using an Industrial Fermenter
diagram from your pack into your notes.

Use the information on the next page to help you interpret the diagram of
an industrial fermenter and explain suitable conditions for
fermentation.
9
Aseptic technique:
a pipe filled with steam is fed into the fermenter in
between sessions to sterilise the fermenter.
Nutrients: at the start of the process, nutrients are fed in through pipes
which can be opened or closed using valves.
Optimum Temperature and pH: (detected by probe and data logger)

During fermentation heat is given off, so to prevent the
contents overheating, a cooling water jacket surrounds the
fermenter maintaining the optimum temperature for
growth.

The pH of the contents can be kept constant by adding acid or
alkali as needed.
Stirring paddles mix the contents to keep the microbes in the liquid
exposed to the nutrients that are fed in. This agitation helps keep the
temperature uniform throughout the fermenter.
10
DNA and the Production of Proteins
Inside The Nucleus
Drosophila body cell
 From the drawing of a fruit fly body cell above, what is the chromosome
complement of the fruit fly, Drosophila?
 Draw the fruit fly body cell and label a pair of matching chromosomes.
 How many chromosomes are present in a human liver cell?
 How many pairs of matching chromosomes are present in a human skin cell?
11
Chromosomes & Genes
The threadlike chromosomes in the nucleus of a cell are made from tightly coiled
molecules of a complex chemical called DNA. DNA is a double stranded helix
(spiral).
Each of the two strands has a chainlike backbone structure to which
molecules called bases are attached.
There are four different types of bases within a DNA strand.

A – adenine

T – thymine

G – guanine

C - cytosine
It is useful to think of them as shapes and letters which
make up a code. The diagrams show ways in which
the shapes can be drawn.
The two strands are held together by
complementary base pairs.

A always pairs with T

C always pairs with G
12
The DNA carries pieces of coded genetic information. An individual section
of DNA with a single piece of genetic information is called a gene.
Chromosomes can therefore be thought of as chains of information called
genes.

What does DNA stand for?

Draw the shape of a DNA molecule.

Name the bases found within a strand of DNA.

Name the complementary bases that pair together to hold the 2 strands of
the DNA molecule together.

Describe what a gene is.

Insert and complete the Chromosomes & Genes diagram from your pack
into your notes.

Carry out Practical 7 (Isolating DNA from Kiwi Fruit)
A Step Ahead
The DNA molecule has a chemical backbone structure
to which the bases are attached.
Use any resources available to you to learn more about the backbone structure and
make notes. Why do you think this structure is called a ‘backbone’?
 Consolidate your learning here:
http://www.nobelprize.org/educational/medicine/dna_double_helix/index.html
Have some fun with this at home!
13
The Function Of DNA
The genetic information coded into DNA in the genes gives the cells the
instructions to make a whole range of protein molecules. Some of these
proteins form the structures of cells and organisms while others form
enzymes which control activities in cells and organisms.
DNA molecules in the nucleus carry the genetic instructions which allow the
cell to make specific proteins for its own structure and function and also that
of the organism as a whole.
Specific proteins are made from amino acid units linked together to form
long chains. There are about 20 different types of amino acids and the
differences between proteins are due to the different amino acids they
contain.
The base sequence on the DNA molecule determines the amino acid
sequence in the protein.
peptide

State what the genetic instructions of a DNA molecule code for.
14

Name the sub-units which are joined together to make this molecule.

Describe the genetic code carried on a DNA molecule, with reference to:


the sequence of chemical bases

why these are in a particular sequence

the number of bases coding for an amino acid

the number of different amino acids

how these amino acids are linked together.
Insert and complete the Function of DNA diagram from your pack into
your notes.

Insert and complete the Genetic Code diagram from your pack into your
notes.
15
DNA to Protein Task to demonstrate secure learning.
Use all you know (and the extra help information in Student Favourites /Biology
/Nat5 /Unit 1/DNA to protein task) to make a poster to show how DNA codes for
proteins by following these instructions:
1.
Choose one of these DNA sequences (or make up your own)
TACTCGAATCGATTTATC
TACAGCCGTGTCCCAATT
TACTTAGGCCATGGGACT
2.
Arrange the DNA sequence into triplets
3.
Use the protein decoder (see below or in class) to identify the amino acids
coded for by your triplets
4.
Arrange the amino acids in the correct order to form a protein
Your poster must be colourful, informative and in easy to follow steps to show
you understand how DNA codes for a protein.
16
The Role of mRNA
DNA remains in the nucleus as the molecule is too large to get out. Proteins
are assembled from amino acids on the ribosomes in the cytoplasm. A
copy of the code for a single protein must be carried from the nucleus to the
cytoplasm by a smaller molecule called messenger RNA (mRNA).
Use any resources available to you to find out about one of these scientists
and the work they did to discover the structure and function of DNA:
Watson and Crick, Rosalind Franklin, Maurice Wilkins, Chargaff.
 Present your findings as a two minute talk or presentation
 Include a note of the sources of your information.
 Starter: http://www.favscientist.com/video_rosalindfranklin.html
A Step Ahead
The production of proteins in cells is called Protein Synthesis and this is divided
into two stages.
Use any resources available to you to find out the names of the two
stages and make a short note stating what happens in each stage.
17
Proteins and Enzymes
Protein Structure & Function
In proteins the amino acids are folded and twisted to give the molecules three
dimensional shapes.
The sequence of amino acids, determined by the
sequence of bases on DNA, is important in the creation of these shapes. The
overall shape of the protein molecule is important in determining the
molecule’s function. In enzymes, the folding of the chains forms the active
sites which make enzymes specific to their substrates.

Describe the structure of a protein, with reference to:
 a description of the 3-D shape
 what the shape depends on
 why this shape is important in the functioning of the molecule.

Insert and complete the table Some Proteins and their Functions from
your diagram pack into your notes.
18
Enzyme Action
Enzymes as Catalysts
Catalysts speed up chemical reactions by lowering the energy required to
start the reaction and they allow reactions to take place at lower
temperatures. Catalysts are unchanged by the reaction so they can be
used over and over again.
All living cells in all living organisms contain biological catalysts which
they make themselves. These catalysts are called enzymes and are made of
proteins.
 State three properties of a catalyst.
 State the general name which is given to biological catalysts.
 Explain what enzymes are made of and where they are found in a living
organism.
 Explain why enzymes are needed for the functioning of all living cells.
2
Your teacher will demonstrate an example of a catalyst in action.
19
Specificity of Enzymes for their Substrates
An enzyme molecule acts on a specific substrate by binding with it at its
active site to form an enzyme-substrate complex.
A product (or
products) is formed but the enzyme remains unchanged.
The active site is the part of the enzyme molecule into which the substrate
fits to allow the reaction to take place. The active site is complementary to
the substrate as a key is complementary to a lock.
 Explain the meaning of the following terms:
 substrate
 product
 active site.
 Explain the meaning of the term specific, with reference to:
 enzyme
 substrate
 active site.
 Insert and complete the Lock and Key diagram from your pack into your
notes.

Carry out Practical 8 (Investigating Enzyme Specificity)
A Step Ahead
The Lock and Key model helps to explain some features of enzymes.
Another model of enzyme action is ‘the induced fit’ model.
Use any resources available to you to find out how
this model differs from the lock and key model and
make notes.
20
Types of Enzyme Reactions
The chemical reactions in a cell involve either breaking down (degrading)
large molecules or building up (synthesising) large molecules.
Breakdown reactions convert large molecules into small molecules. For
example the carbohydrate starch is a very large molecule which cannot pass
through the membranes of cells. To be used as an energy source the starch
must be broken down to smaller soluble molecules. In the digestive system
of humans this process starts in the mouth when the food is mixed with
saliva containing the enzyme amylase.
Amylase breaks down starch molecules into smaller, soluble molecules of
a sugar called maltose. Starch is the substrate in this reaction, maltose is
the product and amylase is the enzyme which is involved in the reaction
but which is not changed by the reaction.
amylase
starch molecule
maltose molecules

Name the 2 different types of reaction which enzymes control.

Describe an example of a breakdown reaction, with reference to:


the name of the enzyme involved

the site of production of this enzyme

the name of the substrate

the molecular size of the substrate

the name of the product

the molecular size of the product

the effect of the reaction on the enzyme.
Draw a diagram to illustrate this breakdown reaction.
21
But where does starch come from in the first place?
Green plants convert light energy from the sun into chemical energy in
glucose.
Glucose is a small soluble molecule which can easily diffuse in and out of
cells so it is unsuitable as a storage molecule. To overcome this, the
glucose molecules can be combined to form starch for storage as in the
potato plant.
The leaves make glucose.
Some glucose is
used by the leaf
cells for energy.
Some is transported to
the roots for storage.
Once in the roots the glucose is converted
to glucose-1-phosphate. (G-1-P)
The potato enzyme, phosphorylase, joins
many G-1-P molecules together with the loss
of the phosphate group to form starch.
The starch molecules are stored in
the potato tuber to be used later.


Describe an example of a synthesis reaction, with reference to:

the name of the enzyme involved

the site of production of this enzyme

the name of the substrate

the molecular size of the substrate

the name of the product

the molecular size of the product

the effect of the reaction on the enzyme.
Draw a diagram to illustrate the synthesis reaction described above.
22

Carry out Practical 9 (A Synthesis Reaction)
The build up of starch from glucose is one example of a synthesis reaction,
but there are many others. Some are important because they let an organism
build up storage chemicals which will be broken down later on when they
are needed. Others allow the organism to make the structural chemicals
that will be used to build its body.
Some synthesis reactions in human cells
23
Factors Affecting Enzyme Activity
Two factors which can affect the activity of an enzyme are pH and
temperature.
Effect of pH

State what is meant by the symbol pH.

State the pH number range for acid, alkali and neutral solutions

Explain what happens when an enzyme is exposed to extremes of pH.

Explain what is meant by optimum pH.

Describe the effect on the rate of reaction of pepsin when:
 the pH is 2.5
 the pH becomes more acidic (less than 2.5)
 the pH becomes less acidic (greater than 2.5).

Carry out Practical 10 (pH and Enzyme Activity)
Effect of Temperature
Enzymes are made of proteins. Like all proteins, the rate at which an enzyme
works depends on the temperature.

Describe the activity of an enzyme at:

very low temperatures

a temperature of about 40oC.

higher temperatures

Explain what is meant by the term optimum temperature.

Insert and complete the Effect of pH & Temperature diagram from your
pack into your notes.

Carry out Practical 11 (Temperature & Enzyme Activity)
24

Explain what happens to enzymes at temperatures of above 40oC, with
reference to:
 chemical bonds which hold the amino acids together
 active sites
 ability to form enzyme-substrate complexes
 term used to describe enzymes in this state
 activity of the enzyme.

Explain the rate of reaction of an enzyme at a temperature of 55-60oC.

Insert and complete the Denaturing Enzymes diagram from your pack
into your notes.
Summary of Enzymes …so far!
Copy & complete the table below which summarises all the enzymes you
have met in this topic.
Type of
Reaction
Enzyme
(synthesis or breakdown)
breakdown
Where it is
found
optimum
pH
substrate  products
pH 6
glucose-1-phosphate  starch
mouth
Protein  peptides or amino
acids
pepsin
A Step Ahead
Enzyme activity can be affected by factors other than temperature
and pH.
Use any resources available to you to find out about poisons that affect enzyme
activity. How do they work?
25
Genetic Engineering
The bacterium Agrobacterium is harmful to plants and useful to scientists. It
transfers DNA into plant genomes. Found in soil worldwide, this bacterium
causes disease in plants by transferring its own DNA into plant cells – it acts
as a natural genetic engineer. However scientists use this bacterium in the
laboratory to move all sorts of genes into plants and this makes the
bacterium the standard tool for investigating plant genetics and modifying
crops.
Listen to your teacher’s talk on genetic engineering then use all the
o
information you have to make your own notes:

Name an organism used in genetic engineering.

Name the material upon which normal control of bacterial activity
depends.

Give an example of a product manufactured using genetic engineering.

Describe the use of this product in humans.

Describe what a plasmid is.

State 2 advantages in using bacteria for genetic engineering.

Insert and complete the Genetic Engineering diagram from your pack
into your notes.

Carry out Practical 12 (Genetic Engineering Simulation)
Genetic engineering appears to have many advantages when it comes to
producing bacteria capable of carrying foreign genes, however, inserting genes
into plants and animals to improve a characteristic has proved more difficult
and can be controversial.
26
Tomatoes with a
longer shelf life
Golden Rice an effective
source of
vitamin A
In your group, choose one of these genetically engineered products or
another of your choice and research it using the Internet.
Making sure everyone has a role, prepare a 5 minute presentation for the
rest of the class including:

A statement of what the product is – include whether it is available or
being developed now

Information about the host organism

Information about the source of the added genetic material

The case for the product

The case against the product

The group’s opinion of the product

A list of References to show that the information you present is from
a reliable source.
Less toxic
rape seed oil
Blight resistant
potatoes
27
Humulin effective
control of
diabetes
Photosynthesis
Photosynthesis Revision Summary

State the name of the raw materials needed for photosynthesis.

State the name of the products of photosynthesis.

State what other essential requirements are needed for photosynthesis to
take place.

Copy and complete the equation for photosynthesis, using the word
bank.
Photosynthesis Equation
+
water
+
chlorophyll
Word bank
Sugar
carbon dioxide
Products

light energy
raw materials
oxygen
essential requirements
Circle the raw materials in red
essential requirements in yellow
products in blue.
Chemistry of Photosynthesis
Photosynthesis is a series of enzyme controlled chemical reactions occurring in
two stages:
1. the light reaction
2. carbon fixation
28
The Light Reaction
During the light reaction light energy from the sun is trapped by chlorophyll
in the chloroplasts and converted into chemical energy in the form of ATP.
The light energy absorbed by the chlorophyll is used in the photolysis of water
to split water molecules into hydrogen and oxygen. Chemical energy is
released in this reaction and used to combine ADP and phosphate to form
ATP.
Excess oxygen diffuses out of the cells and is released from the leaves.
The ATP and hydrogen are used in the carbon fixation stage of
photosynthesis.

Describe the role of chlorophyll in the light reaction and the energy
change which takes place.

Explain what happens to the hydrogen which is released.

Insert and complete the Light Reaction diagram from your pack into
your notes.
Oxygen is released as a by product. The hydrogen and ATP are used in the
carbon fixation stage.

Carry out Practical 13 (Photolysis of Water)
Carbon Fixation
Carbon fixation is an enzyme controlled series in which sugar is formed
from CO2 plus the hydrogen and energy from the ATP produced during the
light reaction.

State where carbon fixation takes place.

Name the molecule which combines with the CO2.

Name the end product which is formed.
29

Insert and complete the Carbon Fixation diagram from your pack into
your notes.
The fate of the sugar
The sugar made during carbon fixation can be used as an immediate source of
energy in respiration or to make structural carbohydrates such as cellulose for
cell walls or it can be stored as starch. Carbohydrates can then be used in the
production of fats and proteins.

Insert and complete the Fate of Carbohydrates diagram from your pack
into your notes.

Carry out Practical 14 (Observing Starch Grains)
Factors Affecting the Rate of Photosynthesis
Carbon dioxide concentration, light intensity and temperature act as
limiting factors on the rate of photosynthesis. If any one of these factors is in
short supply the rate of photosynthesis will be limited.

Insert and complete the Limiting Factors diagram from your pack into
your notes.

Carry out Practical 15 (Effect of Light on the Rate of Photosynthesis)
A Step Ahead:
Use any resources available to you to find out about producing early crops in
horticulture or agriculture.
Explain how early crops can be produced in horticulture, with reference to:
supplementary lighting
carbon dioxide enrichment
heating.
30
Respiration
Aerobic Respiration Revision Summary
Respiration is the series of enzyme-controlled reactions going on in all cells
by which chemical energy is released from glucose.

State the name of the raw materials needed for aerobic respiration.

State the name of the products of aerobic respiration.

Copy and complete the equation for aerobic respiration, using the word
bank.
Aerobic Respiration Equation
+ water +
+
Word bank
glucose
carbon dioxide
products
energy
oxygen
raw materials
 Carry out Practical 16 (Release of Carbon Dioxide in Respiration)
31
Chemistry of Aerobic Respiration
Aerobic Respiration is a series of enzyme controlled chemical reactions in
which oxygen is needed to release chemical energy from glucose to form ATP.
There are 2 main steps to this process:

Glycolysis

Breakdown of pyruvate to carbon dioxide and water
Role of ATP
ATP is a molecule which acts as an immediate chemical energy store.
When energy is released from the breakdown of glucose it is used to form
ATP from ADP and phosphate. The chemical energy stored in the ATP can
be released when the ATP breaks down to ADP and phosphate again. The
energy is used for a range of cellular activities including muscle cell
contraction, cell division, protein synthesis and transmission of nerve
impulses.
ATP is regenerated during respiration when more glucose is broken down
and the energy released combines ADP and phosphate.

Describe 3 uses of ATP in cells.

Briefly describe how ATP is formed and write the word equation for
this.

Insert and complete the ATP diagram from your pack into your notes.
32
Glycolysis
The first stage in aerobic respiration involves glycolysis. This is the
breakdown of glucose, in the absence of oxygen, to form pyruvate. This
process occurs in the cytoplasm of all cells. During this process one
molecule of glucose breaks down to form two molecules of pyruvate and
enough energy is given out to produce 2 molecules of ATP.

Describe the process of glycolysis including:
 the name of the molecule which is broken down (substrate)
 the product formed
 the number of molecules of substrate and end products
 the number of ATP molecules generated

Insert and complete the Glycolysis diagram from your pack into your
notes.
Breakdown of pyruvate to carbon dioxide and water
This second stage of aerobic respiration goes on in the mitochondria of all
cells. The pyruvate molecules are broken down in the presence of oxygen to
form carbon dioxide and water and 36 molecules of ATP are made. All of
the reactions in respiration are controlled by enzymes.

Calculate the total number of ATP molecules formed during the whole
of aerobic respiration of one glucose molecule.

Explain how you got this total number of ATP molecules with reference
to the number of molecules of ATP formed during each stage of aerobic
respiration.


Describe what would happen if oxygen was absent.
Insert and complete the Aerobic Respiration - The breakdown of
pyruvate diagram from your pack into your notes.
33
Anaerobic Respiration
The Fermentation Pathway in Animal Cells
When there is no oxygen available glucose can still be broken down to
pyruvate in the cytoplasm by glycolysis.
In animal cells, in the absence of oxygen, glucose is broken down to
pyruvate then lactic acid. By this fermentation pathway, enough energy
is released from the glucose to form only 2 molecules of ATP.
Describe the fermentation pathway in animal cells including:

where this takes place in the cells
 whether oxygen is required
 the breakdown of glucose
 the product formed
 the number of ATP molecules formed.
A Step Ahead:
Athletes sometimes have a problem with lactic acid (lactate) build up. What effect
does lactic acid have on muscle?
Using any resources available to you find out what is meant by the term oxygen debt,
with reference to:

whether this process is reversible

the name of the compound formed from the conversion of lactic acid.
oxygen debt
builds up
lactic acid
pyruvate
oxygen debt
repaid
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The Fermentation Pathway in Plant and Yeast Cells
When there is no oxygen available in plant and yeast cells glucose can still
be broken down to pyruvate in the cytoplasm by glycolysis.
In plant and yeast cells, in the absence of oxygen, glucose is broken down
to pyruvate then alcohol (ethanol) and carbon dioxide. By this
fermentation pathway, enough energy is released from the glucose to form
only 2 molecules of ATP.
 Describe the fermentation pathway in plant and yeast cells including:

where this takes place in the cells
 whether oxygen is required
 the breakdown of glucose
 the products formed
 the number of ATP molecules formed.
 Carry out Practical 17 (Products of Fermentation)

Copy and complete the summary word equations for the different types of
respiration.
Types of Respiration
Anaerobic
Yeast
__________  __________ + __________ +
(fermentation)
Animals
Aerobic
__________  __________ +
little
energy
little
energy
Plants & __________ + __________  __________ + __________ + lots of
energy
Animals
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Comparison of Respiration via Aerobic and Fermentation Pathways

Copy and complete the following table:
Aerobic Respiration
Fermentation
Need for Oxygen
Substrate
Plants
End Product(s)
Animals
Energy Yield
Site of respiration in a cell
Cells such as muscle cells, nerve cells and sperm cells in animals and
companion cells in plants have a high energy requirement compared with
other cells.
When examined under the electron microscope these cells
have many more mitochondria than other cells.
outer membrane
inner membrane
crista
Mitochondrion
Central matrix
containing enzymes
36

Insert the “Mitochondria” diagram from your pack into your notes.

Label it with the following parts:

inner membrane

outer membrane

crista (plural: cristae)

central matrix.

State what is meant by anaerobic conditions.

State what is meant by aerobic conditions.
Glycolysis and fermentation are anaerobic processes and they occur
in the cytoplasm of the cell.
The breakdown of pyruvate to carbon dioxide and water is aerobic and
this occurs in the mitochondria of a cell.
A Step Ahead:
Use any resources available to you to find out how the matrix and cristae
of the mitochondria are involved in aerobic respiration.
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