MODULE 01
Classification Cells and Cell Structure
This module starts with an introduction. The first two points below only carry about 4% of the
marks and it is assumed that these are the sorts of things you have learnt at KS3 (pre GCSE)
Characteristics of living things
Characteristics of various groups of living things and how they
differ from each other.
Simple keys
Cell structure
Differences between plant and animal cells
Levels of organisation in living things
Movement of substances in and out of cells
Higlighted page references are from Mackean
Italic pages are from the 2nd edition of theIGCSE book
Italic pages are from the 3RD edition of the IGCSE book
Characteristics of living organisms

These are listed on {Ch1 pg 2} Ch1 pages 2-3 page 292 . Make a list of these
in your note book with a brief explanation of each one.

We sometimes use MRS GREN as a memory aid (M –movement Rrespiration S – sensitivity or responding to the environment G – growth Rreproduction E – excretion N – nutrition or feeding)

Note that breathing should always be referred to as GAS EXCHANGE.
• You need to learn these definitions
Movement
 as an action by an organism or part of an organism causing a change of
position or place
Respiration
 as the chemical reactions that break down nutrient molecules in living cells
to release energy for metabolism
Sensitivity
 as the ability to detect stimuli in the internal or external environment and
make appropriate responses
Growth
 as a permanent increase in size and dry mass by an increase in cell number
or cell size or both
Reproduction
 as the processes that make more of the same kind of organism
Excretion
 as removal from organisms of toxic materials, the waste products of
metabolism (chemical reactions in cells including respiration), toxic
materials and substances in excess of requirements
Nutrition
 as taking in of nutrients which are organic substances and mineral ions,
containing raw materials or energy for growth and tissue repair, absorbing
and assimilating them
Classification and diversity of living organisms
Concept and use of a classificatory system
 State that organisms can be classified into groups by the features that they share
 Define species as a group of organisms that can reproduce to produce fertile offspring
 Define and describe the binomial system of naming species as an internationally agreed system in which the scientific
name of an organism is made up of two parts showing the genus and species

{Chapter 1} Chapter 1 Chapter 30 pg 268 explains how living things are divided
up into different groups

They are classified according to a system called the binomial system, Chapter
1 page 5 this gives each species a name (genus and species eg Vibrio cholerae).

The binomial system is an internationally agreed system of naming species in
which the scientific name of an organism is made up of two parts showing the
Genus and species.

Note that genus begins with a capital letter and both the genus and species
name are italicised or underlined

Learn the definition of species as a group of organisms that can reproduce to
produce fertile offspring
• Explain that classification systems aim to reflect evolutionary relationships
• Explain that classification is traditionally based on studies of morphology and anatomy
Classification systems have been developed from people observing and
drawing organisms and realising that some of them share similar
characteristics Chapter 1 page 4
In other words the study of morphology (shape) and anatomy (the study of
bodily structures)
• Explain that the sequences of bases in DNA and of amino acids in proteins are used as a more accurate means of
classification
• Explain that organisms which share a more recent ancestor (are more closely related) have base sequences in DNA that
are more similar than those that share only a distant ancestor
Since modern techniques have been developed to analyse DNA this technique
has been used to compare organisms and see how closely related they are.
Chapter 1 page 3-4
This technique is also used in the detection of crime and to discover the
parentage of people.
Features of organisms
 List the features in the cells of all living organisms, limited to cytoplasm, cell membrane and DNA as genetic material
 List the main features used to place animals and plants into the appropriate kingdoms

Chapter 2 page 13 describes the structure of cells- you need to know about
cytoplasm, cell membrane and DNA as genetic material. These are the main
features of cells that all cells possess.


Organisms are classified into 5 kingdoms two of which are plants and animals
The cells in organisms in the different kingdoms have different structures
present for example plants have a cell wall a large central vacuole and
chloroplasts which animal cells do not
 List the features in the cells of all living organisms, limited to ribosomes for protein synthesis and enzymes
involved in respiration

Cells of all living organisms also contain ribosomes which are structures which
are involved in protein synthesis.

Protein synthesis is essential for the production of enzymes which control all
the metabolic reactions (chemical reactions) in the body
 List the main features used to place all organisms into one of the five kingdoms: Animal, Plant, Fungus,
Prokaryote, Protoctist

Organisms are placed into one of 5 kingdoms and the cells of these organisms
are slightly different according to which kingdom it is placed in.

You need to know VERY simply what are the basic characteristics of each of
the groups:- PLANTS, ANIMALS, FUNGI, PROKARYOTE, PROTOCTIST. Chapter 1
page 6-8

You also need to know about VIRUSES

Make a simple list of each group and their characteristics – you could do this
on a table.

The link called CLASSIFICATION AND CELL STRUCTURE will give you more
details on this and on the cell structure – look at the table on the bottom of the
linked page.
 List the main features used to place organisms into groups within the animal kingdom, limited to
- the main features of the following vertebrates: bony fish, amphibians, reptiles, birds and mammals
- the main groups of arthropods: myriapods, insects, arachnids, crustaceans
 List the main features used to place organisms into groups within the plant kingdom, limited to ferns and
flowering plants (dicotyledons and monocotyledons)

Chapter 1 page 9-12 Page 5 You need to know the features of the main
groups of vertebrates, namely bony fish, amphibians, reptiles, birds and
mammals

You also need to know the features of the main groups of arthropods
namely:- myriapods (many legs), insects(six legs), arachnids(8 legs),
crustaceans (some like crabs and lobsters (have 10 legs)
• List the main features used in the classification of the following groups: viruses, bacteria and fungi, and their
adaptation to the environment, as appropriate
 List the features of viruses, limited to protein coat and genetic material

You need to know VERY simply what are the basic characteristics of each of
the groups:- FUNGI, BACTERIA, VIRUSES Chapter 1 page 7-9.

Make a simple list of each group and their characteristics – you could do this
on a table.

Make notes on each group, you could try to find pictures of one example of
each to make your notes more attractive. You specifically need to know about
the main characteristics of viruses. You will find information for this in chapter
1 page 1-12 Chapter 1
Dichotomous keys
• Construct and use simple dichotomous keys based on easily identifiable features

Chapter 1 Pg 11 Chapter 1 page 15-16 You should be able to identify
organisms using a simple key.

Try and construct your own key using some common kitchen utensils. Use to
example in your book as a guide. Each question you choose should divide your
objects into two more or less even groups. groups.
Organisation of the organism
Cell structure and organisation
• State that living organisms are made of cells
Page 13-14 chapter 2 Chapter 2 page 18 Chapter one starts off with an
introduction explaining that all living things are made up of cells.
Make notes on this and the fact that microscopes are used to look at cells
• Describe and compare the structure of a plant cell with an animal cell, as seen under a light microscope, limited to cell
wall, nucleus, cytoplasm, chloroplasts, vacuoles and location of the cell membrane
• State that the cytoplasm of all cells contains structures, limited to ribosomes on rough endoplasmic reticulum
and vesicles
• State the functions of the structures seen under the light microscope in the plant cell and in the animal cell
Page 13-14 chapter 2 Chapter 2 page 20-22 Make a large drawing of a plant
and an animal cell and label nucleus, cytoplasm, cell membrane, cell wall
(plant) chloroplast (plant), vacuole (plant) and mitochondria.
In addition for the supplementary material you need to know about
ribosomes on rough endoplasmic reticulum and vesicles
Chapter 2 page 20-22
You can convert your diagram to an annotated diagram by making a note of
the function (what it does) of each structure at the side of each label.
You will find information about this on Chapter 2 page 20-22
You may need to supplement your notes from the internet.
pages 14-16.
The two types of cell shown on page 19 & 20 page 14 are a liver (animal) cell
and a palisade cell (plant) cell
Draw a table showing the differences between plant and animal cells page 21
Pg 16
• State that almost all cells, except prokaryotes, have mitochondria and rough endoplasmic reticulum
• Identify mitochondria and rough endoplasmic reticulum in diagrams and images of cells
 You need to be able to compare prokaryotic cells (cells with no nucleus) with
the cells of other living organisms where there is a nucleus present.
 Look back to Chapter 1 page 8 for a comparison.
You could construct a table
to do this.
• State that aerobic respiration occurs in mitochondria
• State that cells with high rates of metabolism require large numbers of mitochondria to provide sufficient energy
. Mitochondria are very important to cells as they are the sites of respiration.
Make sure you can define respiration. Chapter 2 page 22
We can tell which cells are very active and are using lots of energy by the
number of mitochondria present
Levels of organisation
• Define:
• tissue as a group of cells with similar structures, working together to perform a shared function
• organ as a structure made up of a group of tissues, working together to perform specific functions
• organ system as a group of organs with related functions, working together to perform body functions using examples
 You need to learn these definitions and be able to give examples
 tissue - a group of cells with similar structures, working together to
perform a shared function
 organ - a structure made up of a group of tissues, working together to
perform specific functions
 organ system - a group of organs with related functions, working
together to perform body functions using examples
Relate the structure of the following to their functions:
• ciliated cells – in respiratory tract
• root hair cells – absorption
• xylem vessels – conduction and support
• muscle cells – contraction
• red blood cells – transport of oxygen
 palisade mesophyll cells – photosynthesis
 nerve cells – conduction of impulses
 sperm and egg cells – reproduction

Chapter 2 page 25-26 Chapter 2 pg 18 Page 7 shows how cells are organised
and grouped together to form tissues, organs and organ systems and
eventually organisms.

Draw a flow diagram linking all these together with a brief description of each.
You need in particular to understand how the structure and adaptation relates
to the function of each of the following types of cells:







ciliated cells – in respiratory tract
root hair cells – absorption
xylem vessels – conduction and support
muscle cells – contraction
red blood cells – transport
palisade mesophyll cells – photosynthesis
nerve cells – conduction of impulses
sperm and egg cells – reproduction
Chapter 2 page 25 in your text book has a table showing the position and function
each of these types of cells. You may find further information on the internet - try the
GCSE Bitesize website.
• State examples of tissues, organs and organ systems from sections 6 to 16
• Identify the different levels of organisation in drawings, diagrams and images of familiar material
• Identify the different levels of organisation in drawings, diagrams and images of unfamiliar material

You need to give examples of these levels of organisation and be able to
identify them from drawings etc.

Look through your text book for some organ systems - eg circulatory system,
digestive system.

As we go through the course you will gain more knowledge of this aspect of
organisation.

look at the web link LEVELS OF ORGANISATION
Size of specimens
• Calculate magnification and size of biological specimens using millimetres as units
 You also need to learn the skill of drawing biological specimens
Chapter 1
page 14 activity 1.2 Chapter 1 page 7. You need to know how to calculate
the magnification of objects even if you don’t have access to a microscope.
Chapter one page 8.
 You can draw a leaf for example and then measure it and your drawing and
work out the magnification of your drawing.
• Calculate magnification and size of biological specimens using millimetres and micrometres as units
 You need to have some concept of sizes and the units used to measure cells.
Chapter 2 page 23

Because are very small we often use much smaller units than the millimetre –
the next smaller unit is the micrometre which is 1000th (10-3) of a millimetre or
1,000,000th (10-6) of a metre.
Movement in and out of cells
Diffusion
• Define diffusion as the net movement of particles from a region of their higher concentration to a region of their lower
concentration down a concentration gradient, as a result of their random movement
• Describe the importance of diffusion of gases and solutes and of water as a solvent
• State that substances move into and out of cells by diffusion through the cell membrane
 Chapter 3
page 28-29 Chapter3Pg20 Chapter 4 page 26 is all about
movement of substances in and out of cells. Read this chapter and makes
notes on diffusion, osmosis and active transport.
 You must learn the definition of diffusion as the net movement of molecules
from a region of their higher concentration to a region of their lower
concentration down a concentration gradient, as a result of their random
movement. Chapter 3 page 29 Page 20-22
 You must make sure you know the importance of diffusion in both gases and
liquids and also the fact that water is a very important solvent for living things
 Look at the experiments in your text book Chapter 3activities 3.1, 3.3 73.5
and the activities on the CD chapter 3 and also in MacKean Chapter 4 (if you
have a copy of this) and familiarise yourself with them.
 If you can get hold of the things needed then have a go at some of them.
 Remember that substances can pas through the cell membrane by simple
diffusion.
• State that the energy for diffusion comes from the kinetic energy of random movement of molecules and ions
• Investigate the factors that influence diffusion, limited to surface area, temperature, concentration gradients and
distance
 Remember that the energy for diffusion to occur comes from the kinetic
energy (energy of movement) that all the particles (molecules, atoms, ions)
possess.
 Chapter 3
page 28-29 Chapter 3 Pg20 work through this chapter making
notes and making sure you understand these very important processes.
There are several experiments which you need to familiarise yourself with.
Osmosis
• State that water diffuses through partially permeable membranes by osmosis
• State that water moves in and out of cells by osmosis through the cell membrane

Chapter 3 page 30-31 Chapter 3 Page 23 Osmosis is VERY important in terms
of water uptake REMEMBER that diffusion can apply to any small molecule but
osmosis only applies to the movement of WATER and occurs across a partially
permeable membrane. Make sure you thoroughly understand this.

The partially permeable membrane in the case of cells is the cell membrane
• Define osmosis as the diffusion of water molecules from a region of their higher concentration (dilute solution) to a
region of their lower concentration (concentrated solution), through a partially permeable membrane

You should be able to define osmosis as the diffusion of water molecules
from a region of their higher concentration (dilute solution) to a region of their
lower concentration (concentrated solution), through a partially permeable
membrane Chapter 3 page 31
• Describe the importance of osmosis in the uptake of water by plants, and its effects on plant and animal tissues
plants
• Investigate and describe the effects on plant tissues of immersing them in solutions of different concentrations
• State that plants are supported by the pressure of water inside the cells pressing outwards on the cell wall

The movement of water is very important to plant and animal cells Chapter 3
page 32-34 Chapter 3 Pg 25 and 26 Page 30.

Make some simple notes on this and how water allows plants to support
themselves without a skeleton.

The pressure of the water inside the plant cells is called turgor pressure and
allows plants to support themselves. The turgor pressure is created because the
plant cells have a cell wall

Animal cells don’t have cell walls so animals need external or internal
skeletons in order to support themselves.

Make notes on the importance of osmosis to plants and animals form Chapter
3 page 33-34 page 25-26.
• Explain the effects on plant tissues of immersing them in solutions of different concentrations by using the
terms turgid, turgor pressure, plasmolysis and flaccid

Look at the experiments to investigate the effects of different solutions on
plant cells – try these out if you can. Chapter 3 page 34
• Explain the importance of water potential and osmosis in the uptake of water by plants
• Explain the importance of water potential and osmosis on animal cells and tissues
• Explain how plants are supported by the turgor pressure within cells, in terms of water pressure acting against
an inelastic cell wall

It is important that you understand that a water potential gradient is set up in
plants which allows them to take up water. This is explained on Chapter 3 page
31 page 23. We will come back to this when we look at transport in plants.
Active Transport
Chapter 3 Page 29 Chapter 3 page 35-36
• Define active transport as the movement of particles through a cell membrane from a region of lower concentration to a
region of higher concentration using energy from respiration
• Discuss the importance of active transport as a process for movement across membranes:
– e.g. ion uptake by root hairs and uptake of glucose by epithelial cells of villi and kidneytubules
• Explain how protein molecules move particles across a membrane during active transport
Make sure you understand the importance of active transport in the
uptake of ions into plant roots and nutrients into the digestive system.
Chapter 3 page 35-36 Page 29-30
In both these situations the uptake is AGAINST the concentration
gradient. (ie low to high concentration) using energy supplied by
respiration)
You should define active transport as movement of ions in or out of a
cell through the cell membrane, from a region of their lower
concentration to a region of their higher concentration against a
concentration gradient, using energy released during respiration
Active transport is a VERY important process, particularly in the ion
uptake by root hairs and uptake of glucose by epithelial cells of villi and
kidney tubules. We will come back to study these in other modules.
The particles are moved across the membrane by ‘carrier’ protein
molecules in the cell membrane. They act a little bit like a revolving
door, changing shape to allow particles across the cell membrane.
Try and find out how the movement of substances in and out of cells is affected by
TEMPERATURE, CONCENTRATION GRADIENT, AND SIZE (SURFACE
AREA TO VOLUME RATION)
ASSIGNMENT – Osmosis and potato strips
Try the experiment on the CD Activity 3.6 on the CD
Activity 3.5page 28.
Write this up in full. Refer to the document called ‘writing up experiments’
and send it to me. Explain what is happening in terms of osmosis and the
movement of water. Send me your explanation of this and your experimental
write up as your first piece of work.
You will find a document to fill out in the ASSIGNMENT BLOCK