View
217
Download
1
Category
Preview:
Citation preview
Pete KennedyFrank SochackiSue Hocking Mark WinterbottomSeries Editor: Sue Hocking
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
A2
Pete Kennedy and Frank SochackiSeries Editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
In Exclusive Partnership
OCR
Biology
Course GuideAS A2
Heinemann is working exclusively with OCR to produce an exciting suite of resources tailored to the new OCR GCE Biology specification. Written by experienced examiners, OCR AS and A2 Biology provide you with tailored support for teaching the revised specification. Comprehensive support for AS and A2, and motivating exam preparation in our unique Exam Café, will give your students every chance of success.
Exciting resources developed in exclusive partnership to support the new GCE Biology specification
Course Structure
AS
AS Student Book with Exam Café
CD-ROM
Pete Kennedy and Frank SochackiSeries Editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
AS Teacher Support CD-ROM
22
AS Revision Guide
Richard Fosbery and Ianto StevensSeries editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
Exclusively endorsed by OCR for GCE Biology
This revision guide is tailored to the OCR specification and exclusively endorsed by OCR for GCE Biology. It is written by experienced examiners and teachers, giving you:
complete coverage of the specification for the exams content organised by module and unit to follow the structure of the
specification and exams bite-sized chunks of information to make it easier to organise your
revision time quick-check revision questions so that you can test your own
knowledge easily hints and tips from examiners to help you avoid common errors lots of practice exam-style questions for each unit all the answers to questions so that you can check that you’re on the
right track.
Titles in this series:OCR AS Biology student book and exam café CD-ROM 978 0 435691 80 6OCR A2 Biology student book and exam café CD-ROM 978 0 435691 90 5OCR AS Biology Teacher Support CD-ROM 978 0 435691 77 6OCR A2 Biology Teacher Support CD-ROM 978 0 435691 91 2OCR AS Biology revision guide 978 0 435583 70 5OCR A2 Biology revision guide 978 0 435583 73 6
AS
Second Edition
01865 888118www.heinemann.co.uk
In Exclusive Partnership
I S B N 978-0-435583-70-5
9 7 8 0 4 3 5 5 8 3 7 0 5
AS
01865 888118
In Exclusive Partnership
ISBN 978 0 435961 77 6
Mike WinterbottomJenny Wakefi eld-Warren and Frank SochackiSeries Editor: Sue Hocking
Teacher SupportExclusively endorsed by OCR for GCE Biology A
Series Editor: Sue Hocking
A2
A2 Student Book with Exam Café
CD-ROM
Pete KennedyFrank SochackiSue Hocking Mark WinterbottomSeries Editor: Sue Hocking
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
A2
A2 Teacher Support CD-ROM
AS Revision Guide
A2
Exclusively endorsed by OCR for GCE Biology A
01865 888118Mike WinterbottomJenny Wakefi eld-Warren and Frank SochackiSeries Editor: Sue Hocking
In Exclusive Partnership
ISBN 978 0 435961 91 2
Teacher Resource CD
Winterbottom • Wakefi eld-Warren • Frank SochackiSeries Editor: Sue Hocking
l OCR and Heinemann working in exclusive partnership to provide better support for you.
l Engaging resources written by experienced examiners and tailored to the new specification.
l A full ready-to-use teaching scheme that can be customised to give you total freedom and flexibility.
l Innovative Exam Café CD-ROM provided FREE in the back of every Student Book.
What you can expect from Heinemann’s OCR AS and A2 Biology
3
Student Book
Peter Kennedy
Frank SochackiHelen Eccles
Sue Hocking
Peter Kennedy
Frank Sochacki
Mark Winterbottom
Exam Café CD-ROM
Frank Sochacki
Jenny Wakefield-Warren
Robert Duncan
Robert Duncan
Frank Sochacki
Karen Stephens
Jenny Wakefield-Warren
Teacher Support CD-ROM
Frank Sochacki
Jenny Wakefield-Warren
Mark Winterbottom
Frank SochackiJenny Wakefield-Warren
Mark Winterbottom
Revision Guide
Richard FosberyIanto StevensJennifer Gregory
Richard FosberyIanto StevensJennifer Gregory
Authors
Our authors have been specially selected because of their expertise and experience as examiners and practising teachers, and are dedicated to providing you with a set of resources that meet your needs in the classroom.
AS
A2
Series EditorSue Hocking
82
83
Exercise/diet/smoking
Health aspects oflifestyle
Lungs
Exchange withcells
Tissue fluid
Blood vessels
Heart
Animals
Animals
Transpiration
Translocation
Leaves
Roots
Plants
Diffusion throughoutcell
Surface of body usedfor exchange
Exchange andtransport links
Digestivesystem
Low demand foroxygen and nutrients
Large surface-area-to-volume ratio
Single-celled organismsand small multicellular
organisms
Xylem
Plants
Phloem
Need fortransport
system
Need forspecial
exchangesurface
High demand foroxygen and nutrients
Small surface-area-to-volume ratio
Large multicellularorganisms
Living things
1.2 Exchange and transport summary
1 (a) State the names of the tissues labelled A–D below. [4]A
B
C
D
Figure 1
(b) Name the organ represented by Figure 1. [1]
2 (a) State the name of the type of muscle found in theheart.[1] (b) Explain why the muscle surrounding the left ventricle isthicker than that surrounding the right ventricle. [2] (c) Name the blood vessels that: (i) carry blood away from the ventricles; (ii) carry blood back towards the heart. [2]
3 (a) State two features of a good gaseous exchangesystem.[2] (b) Describe the route taken by air as it is inhaled. [3] (c) Name the air sacs in the lungs. [1]
4 (a) What immediate effect does exercise have on the heartrate?[1] (b) What happens to the tidal volume of the lungs duringexercise?[1] (c) Name two other exchange surfaces. [2]
5 Complete the following paragraph by filling in the blankspaces.Blood is .................................... in the lungs. The redpigment .................................. has a high affinity foroxygen. The pumping action of the ..........................creates pressure which pushes the blood around the body.In the tissues the partial pressure of ..................................is low. This causes the ................................ of theoxyhaemoglobin. In the tissues, the oxygen is used in theprocess of ................................. . Most of the carbondioxide produced in this process enters the.............................................. cells. Here it is converted to carbonic acidby the action of the enzyme carbonic anhydrase. Thecarbon dioxide is transported as .....................................back to the lungs.
[8]
6 (a) Explain the role of elastic tissue in the alveoli. [2] (b) Name the two types of cell found in the epithelium ofthe airways.[2] (c) Describe the action of the cilia in bronchi. [2]
7 (a) In a plant, name two tissues that may act as a source.[2] (b) Name the tissue that is used to transport sugars in aplant.[1]
8 (a) Explain why a large organism with a lowsurface-area-to-volume ratio needs a special surfacefor gaseous exchange.[3] (b) Explain how a higher concentration of carbon dioxidein the blood can cause extra oxygen to dissociate fromoxyhaemoglobin.[4]
9 (a) Describe how sucrose is loaded into the sieve tubeelement.[4] (b) Explain, using the term water vapour potential gradient,why increasing the wind speed will increase the rate oftranspiration.[3]
10 (a) Explain the importance of the Purkyne tissue incoordination of the cardiac cycle. [3] (b) Describe and explain the role of the coronary arteries.[3]
Practice questionsModule 2
Exchange and transportPractice questions
936 biology.U1 M2.indd 82-83
10/3/08 11:40:13 am
Student Books
8
9
1.1 3 Electron microscopes and cell details
Module 1Cells
Electron microscopes and cell details
By the end of this spread, you should be able to . . .
State the magni� cation that can be achieved with the electron microscope.
Explain the need for staining samples for use in light microscopy and electron microscopy.
The use of electronsLight microscopes have low resolution. This means that if the magnifi cation is above
×1500, the image isn’t clear. The wavelength of visible light ranges from about 400 to
750nm, so structures closer together than 200nm (0.2 m) will appear as one object.
We can achieve higher resolution with electron microscopes.
• Electron microscopes generate a beam of electrons.
• A beam of electrons has a wavelength of 0.004nm, 100000 times shorter than a light
wavelength.
• Electron microscopes can distinguish between objects 0.2nm apart.
• These microscopes use magnets (instead of lenses) to focus the beam of electrons
onto a prepared specimen.
• Electrons are not visible to the human eye. The image produced from the
electron beam is projected onto a screen or onto photographic paper to make a
black-and-white image (sometimes referred to as a ‘greyscale’ image).
• Such images are called electron micrographs.
• The resolution of an electron microscope is about 500000 times greater than that of
the human eye.
Two types of electron microscope
Transmission electron microscope (TEM)
• The electron beam passes through a very thin prepared sample.
• Electrons pass through the denser parts of the sample less easily, so giving some
contrast.
• The fi nal image produced is two-dimensional.
• The magnifi cation possible with a TEM is ×500000.
Scanning electron microscope (SEM)
• The electron beam is directed onto a sample. The electrons don’t pass
through the specimen.
• They are ‘bounced off’ (refl ected off) the sample.
• The fi nal image produced is a 3D view of the surface of the sample.
• The magnifi cation possible with an SEM is about ×100000.
Advantages and limitations of the electron microscope
• The resolution is 0.1nm (2000× more than in the light microscope).
• This means the electron microscope can be used to produce detailed images
of the structures (organelles) inside cells.
• The SEM produces 3D images that can reveal the detail of contours and
cellular or tissue arrangements – this is not possible using light microscopes.
• Electron beams are defl ected by the molecules in air, so samples are placed
in a vacuum.
• Electron microscopes are extremely expensive items.
Coloured electron micrographs
Electron micrographs are sometimes shown in colour. The fi nal image produced from an
electron microscope is always black, white and grey; the colours are added afterward
using specialised computer software. Such images will be labelled as ‘false-colour’
electron micrographs.Figure 1 Electron micrograph of an
insect grasping a microelectronic
component in its mandibles
Figure 2 Electron microscope in outline
Electrongun
Condenserlenses
Projectionaperture
Stigmator
Scan coils
Objectivelens
Detector(ESD)
Specimenstub
Specimenstage
Specimenchamber
Gas inlet
Questions1 List the similarities and differences between light and electron microscopes.
2 Explain why both light and electron microscopes are used widely in biology.
3 Describe the main limitations of the electron microscope.
4 Describe the limitations of the light microscope.
Figure 3 Preparation and viewing of
samples for scanning electron
microscopy
Figure 4 False-colour electron micrographs of pollen grains and red blood cells
Examiner tip
You may be asked to calculate the
actual size of a specimen. Measure the
size of the image in mm and then
convert it to m. Then divide it by the
magnifi cation.
Key de� nition
Staining in microscopy refers to any
process that helps to reveal or
distinguish different features. In light
microscopy, stains may be colours or
fl uorescent dyes. In electron
microscopy, they are metal particles or
metal salts.
Preparing specimens to be viewed in an electron microscope is complicated.
For example, to prepare a thin section of liver tissue, you might need to:
• fi x the specimen in glutaraldehyde to make the tissue fi rm
• dehydrate it to replace the water with ethanol
• embed the dehydrated tissue in a solid resin
• cut very thin slices using a diamond knife
• stain it using lead salts to scatter electrons differently – this gives contrast
• mount it on a copper grid
• place the specimen on the grid in a vacuum in the microscope.
When electron microscopes were fi rst developed, many scientists thought that the
complicated preparation of specimens produced artefacts. Artefacts are structures that
result from the preparation process. They are not true representations of the
specimen’s original structure.
Even in the 1980s, scientists were arguing about the true value of electron microscopes,
but their technology and quality has improved in recent years. Scientists have also used
X-ray crystallography to investigate cell structure. This has confi rmed that electron
microscopes do give a true insight into the internal workings of cells.
How science works
4
Pete Kennedy and Frank SochackiSeries Editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
We listen to teachers’ needs...
Sample pages from OCR AS Biology Student Book.
Exclusively endorsed by OCR, these Student Books offer accessible and engaging material to help students understand the underlying principles of science. Careful explanations of key principles, plenty of worked examples, practice questions and exam-style questions all ensure that students have plenty of opportunities to improve their skills.
Examination tips.
Text is structured in line with the new OCR specification, by Unit and Module.
Integrates How Science Works throughout the book to help students understand the underlying principles of science.
82
83
Exercise/diet/smoking
Health aspects oflifestyle
Lungs
Exchange withcells
Tissue fluid
Blood vessels
Heart
Animals
Animals
Transpiration
Translocation
Leaves
Roots
Plants
Diffusion throughoutcell
Surface of body usedfor exchange
Exchange andtransport links
Digestivesystem
Low demand foroxygen and nutrients
Large surface-area-to-volume ratio
Single-celled organismsand small multicellular
organisms
Xylem
Plants
Phloem
Need fortransport
system
Need forspecial
exchangesurface
High demand foroxygen and nutrients
Small surface-area-to-volume ratio
Large multicellularorganisms
Living things
1.2 Exchange and transport summary
1 (a) State the names of the tissues labelled A–D below. [4]A
B
C
D
Figure 1
(b) Name the organ represented by Figure 1. [1]
2 (a) State the name of the type of muscle found in theheart.[1] (b) Explain why the muscle surrounding the left ventricle isthicker than that surrounding the right ventricle. [2] (c) Name the blood vessels that: (i) carry blood away from the ventricles; (ii) carry blood back towards the heart. [2]
3 (a) State two features of a good gaseous exchangesystem.[2] (b) Describe the route taken by air as it is inhaled. [3] (c) Name the air sacs in the lungs. [1]
4 (a) What immediate effect does exercise have on the heartrate?[1] (b) What happens to the tidal volume of the lungs duringexercise?[1] (c) Name two other exchange surfaces. [2]
5 Complete the following paragraph by filling in the blankspaces.Blood is .................................... in the lungs. The redpigment .................................. has a high affinity foroxygen. The pumping action of the ..........................creates pressure which pushes the blood around the body.In the tissues the partial pressure of ..................................is low. This causes the ................................ of theoxyhaemoglobin. In the tissues, the oxygen is used in theprocess of ................................. . Most of the carbondioxide produced in this process enters the.............................................. cells. Here it is converted to carbonic acidby the action of the enzyme carbonic anhydrase. Thecarbon dioxide is transported as .....................................back to the lungs.
[8]
6 (a) Explain the role of elastic tissue in the alveoli. [2] (b) Name the two types of cell found in the epithelium ofthe airways.[2] (c) Describe the action of the cilia in bronchi. [2]
7 (a) In a plant, name two tissues that may act as a source.[2] (b) Name the tissue that is used to transport sugars in aplant.[1]
8 (a) Explain why a large organism with a lowsurface-area-to-volume ratio needs a special surfacefor gaseous exchange.[3] (b) Explain how a higher concentration of carbon dioxidein the blood can cause extra oxygen to dissociate fromoxyhaemoglobin.[4]
9 (a) Describe how sucrose is loaded into the sieve tubeelement.[4] (b) Explain, using the term water vapour potential gradient,why increasing the wind speed will increase the rate oftranspiration.[3]
10 (a) Explain the importance of the Purkyne tissue incoordination of the cardiac cycle. [3] (b) Describe and explain the role of the coronary arteries.[3]
Practice questionsModule 2
Exchange and transportPractice questions
936 biology.U1 M2.indd 82-83
10/3/08 11:40:13 am
8
9
1.1 3 Electron microscopes and cell details
Module 1Cells
Electron microscopes and cell details
By the end of this spread, you should be able to . . .
State the magni� cation that can be achieved with the electron microscope.
Explain the need for staining samples for use in light microscopy and electron microscopy.
The use of electronsLight microscopes have low resolution. This means that if the magnifi cation is above
×1500, the image isn’t clear. The wavelength of visible light ranges from about 400 to
750nm, so structures closer together than 200nm (0.2 m) will appear as one object.
We can achieve higher resolution with electron microscopes.
• Electron microscopes generate a beam of electrons.
• A beam of electrons has a wavelength of 0.004nm, 100000 times shorter than a light
wavelength.
• Electron microscopes can distinguish between objects 0.2nm apart.
• These microscopes use magnets (instead of lenses) to focus the beam of electrons
onto a prepared specimen.
• Electrons are not visible to the human eye. The image produced from the
electron beam is projected onto a screen or onto photographic paper to make a
black-and-white image (sometimes referred to as a ‘greyscale’ image).
• Such images are called electron micrographs.
• The resolution of an electron microscope is about 500000 times greater than that of
the human eye.
Two types of electron microscope
Transmission electron microscope (TEM)
• The electron beam passes through a very thin prepared sample.
• Electrons pass through the denser parts of the sample less easily, so giving some
contrast.
• The fi nal image produced is two-dimensional.
• The magnifi cation possible with a TEM is ×500000.
Scanning electron microscope (SEM)
• The electron beam is directed onto a sample. The electrons don’t pass
through the specimen.
• They are ‘bounced off’ (refl ected off) the sample.
• The fi nal image produced is a 3D view of the surface of the sample.
• The magnifi cation possible with an SEM is about ×100000.
Advantages and limitations of the electron microscope
• The resolution is 0.1nm (2000× more than in the light microscope).
• This means the electron microscope can be used to produce detailed images
of the structures (organelles) inside cells.
• The SEM produces 3D images that can reveal the detail of contours and
cellular or tissue arrangements – this is not possible using light microscopes.
• Electron beams are defl ected by the molecules in air, so samples are placed
in a vacuum.
• Electron microscopes are extremely expensive items.
Coloured electron micrographs
Electron micrographs are sometimes shown in colour. The fi nal image produced from an
electron microscope is always black, white and grey; the colours are added afterward
using specialised computer software. Such images will be labelled as ‘false-colour’
electron micrographs.Figure 1 Electron micrograph of an
insect grasping a microelectronic
component in its mandibles
Figure 2 Electron microscope in outline
Electrongun
Condenserlenses
Projectionaperture
Stigmator
Scan coils
Objectivelens
Detector(ESD)
Specimenstub
Specimenstage
Specimenchamber
Gas inlet
Questions1 List the similarities and differences between light and electron microscopes.
2 Explain why both light and electron microscopes are used widely in biology.
3 Describe the main limitations of the electron microscope.
4 Describe the limitations of the light microscope.
Figure 3 Preparation and viewing of
samples for scanning electron
microscopy
Figure 4 False-colour electron micrographs of pollen grains and red blood cells
Examiner tip
You may be asked to calculate the
actual size of a specimen. Measure the
size of the image in mm and then
convert it to m. Then divide it by the
magnifi cation.
Key de� nition
Staining in microscopy refers to any
process that helps to reveal or
distinguish different features. In light
microscopy, stains may be colours or
fl uorescent dyes. In electron
microscopy, they are metal particles or
metal salts.
Preparing specimens to be viewed in an electron microscope is complicated.
For example, to prepare a thin section of liver tissue, you might need to:
• fi x the specimen in glutaraldehyde to make the tissue fi rm
• dehydrate it to replace the water with ethanol
• embed the dehydrated tissue in a solid resin
• cut very thin slices using a diamond knife
• stain it using lead salts to scatter electrons differently – this gives contrast
• mount it on a copper grid
• place the specimen on the grid in a vacuum in the microscope.
When electron microscopes were fi rst developed, many scientists thought that the
complicated preparation of specimens produced artefacts. Artefacts are structures that
result from the preparation process. They are not true representations of the
specimen’s original structure.
Even in the 1980s, scientists were arguing about the true value of electron microscopes,
but their technology and quality has improved in recent years. Scientists have also used
X-ray crystallography to investigate cell structure. This has confi rmed that electron
microscopes do give a true insight into the internal workings of cells.
How science works
5
Sample pages from OCR AS Biology Student Book.
Pete KennedyFrank SochackiSue Hocking Mark WinterbottomSeries Editor: Sue Hocking
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
A2
Don’t forget our A2 resources coming in the Autumn Term!
End-of-module summary pages help students link together all the topics within each module.
Practice exam questions provided at the end of each module. Answers are in the back of the book.
In our unique Exam Café, students will find plenty of support to help them prepare for their exams. They can Relax and prepare with handy revision advice, Refresh their memories by testing their understanding and Get That Result through practising exam-style questions, accompanied by lots of hints and tips.
An Exam Café CD-ROM is included FREE in the back of every Student Book.
6
Sample screen from OCR AS Biology Exam Café CD-ROM.
Links to how students can use New Scientist to reinforce their learning.
Sample questions and answers to each module with tips on how to improve, examiner tips and advice to students on practical skills.
Questions to test understanding. Also vocabulary tests, a glossary, and revision flashcards.
Study and revision skills to support students making the transition from GCSE to A Level.
What do students think about Exam Café?
“Three stages is a great idea – something you can work through.”
Sophie Wilson, student, Headington School.
“A really great and original way of encouraging students to revise and study for exams.”Marie-Lise Tassoni, student, Bexhill College.
“I think it’s an extremely positive idea to make students see their potential.”Sophie East, student, Oxford.
7
Student answer activities focus on improving subject knowledge.
Three stages allow students to see questions against answers and examiner feedback.
Links directly to the module and specification.
Sample screen from OCR AS Biology Exam Café CD-ROM.
Teacher Support CD-ROM
The AS and A2 Teacher Support CD-ROMs help you plan and deliver the new specification with confidence. Each provides you with:
l weekly teaching plans and guidance sheets to help save time
l customisable student practical sheets with accompanying teacher and technician notes
l a media bank of all the diagrams and learning objectives in the Student Book, all ready to use in PowerPoint format.
8
Sample Lesson Plan from OCR AS Biology Teacher Support CD-ROM.
Pete Kennedy and Frank Sochacki
Series Editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
9
Sample screen from OCR AS Biology Teacher Support CD-ROM.
Pete KennedyFrank SochackiSue Hocking
Mark WinterbottomSeries Editor: Sue Hocking
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
A2
Easy-to-use content menu and search box to help you locate your required content.
Split into 30 Weekly Plans.
10
Revision Guides
l Clearly written and well designed to aid revision.
l Written by experienced examiners and tailored to the new specification.
l Packed with examiner tips.
l Targeted at ensuring understanding with quick-check questions on each topic and end of unit exam-style questions.
�
�
Hint
Phospholipids form a
bilayer: ‘heads out,
tails in’ – see page 5.
Quick check 1✔
Key words
fluid mosaic
hydrophobic
hydrophilic
phospholipid bilayer
partially permeableMod
ule
1
Module 1
1 Explain why membranes are described as fluid mosaic.
2 Explain how phospholipids and proteins influence the permeability of a cell surface
membrane.
3 Describe the distribution of membranes within animal and plant cells.
QUICK CHECK QUESTIONS ?
Cell surface membranes surround all cells and control what enters and leaves.
Membranes divide up the cytoplasm of eukaryotic cells into separate compartments.
Membranes are very thin
Membranes are visible in the TEM at magnifications of ×100 000 as two dark lines
separated by a clear space. The distance across the membrane is about 7 nm.
Membranes are made of two layers of phospholipid, known as a bilayer, plus protein.
The polar heads of the phospholipids are hydrophilic and are attracted to water. This is
why they face towards the cytoplasm and towards the exterior of the cell. Both these
areas are dominated by water. The hydrocarbon tails of the two layers are hydrophobic
and are held together by weak hydrophobic bonds. Proteins are scattered about the
membrane, and transmembrane proteins pass right through from one side to the other.
Carbohydrates are attached to protein and lipid, and face the outside of the cell. This
structure is called a fluid mosaic.
Component of cell
membrane
Functions
Phospholipidsform a bilayer that acts as a barrier between cytoplasm and cell exterior
are fluid, so components can move within the membrane
are permeable to non-polar molecules such as oxygen and fatty acids
are permeable to small polar molecules such as ethanol, water and carbon dioxide
are impermeable to ions and large polar molecules such as sugars and amino acids
Cholesterol (only in
eukaryotic cells – much
more in animal cells
than in plant cells)
stabilises the phospholipid bilayer by binding to polar heads and non-polar tails of phospholipids
controls fluidity by preventing phospholipids solidifying at low temperatures and becoming too fluid at
high temperatures
reduces permeability to water, ions and polar molecules
Proteinsare transmembrane proteins acting as channels and carriers
are receptors for chemicals made by other cells, e.g. hormones
Glycolipids and
glycoproteins
(lipids and proteins
with carbohydrate
chains attached)
are carbohydrate chains only found on the exterior surface of cell membranes
act as receptors for signalling molecules (e.g. hormones) and for drugs
act as cell surface markers that identify the cells to others (also known as cell surface antigens)
are involved in ‘sticking’ cells to one another (cell adhesion)
Functions of cell surface membranes
Membranes are partially permeable because some substances pass through but
others do not. The permeability of a membrane is determined by the phospholipids and
proteins. Membranes are selective about what passes through. Cell surface membranes:
act as a barrier to many water-soluble substances
keep many large molecules, such as enzymes, within the cell
are permeable to small molecules such as water, oxygen and carbon dioxide
are permeable to selected molecules such as glucose and ions
permit movement of substances by endocytosis and exocytosis
permit recognition by other cells, such as those of the immune system
provide receptors for signalling molecules such as hormones
are often extended into microvilli to provide a large surface area for the absorption
of substances by animal cells.
Membranes within cells
The membranes within cells:
divide the cell into compartments where functions can occur more efficiently
isolate potentially harmful enzymes in lysosomes
provide a large surface for pigments, such as chlorophyll, involved in photosynthesis
in chloroplasts
provide a large surface for holding the enzymes and coenzymes for forming ATP in
mitochondria and chloroplasts
surround vesicles that transport molecules between parts of the cell, e.g. that
transport proteins from rough endoplasmic reticulum to Golgi apparatus.
Cell membranes
Examiner tip
Most of the organelles
you need to recognise
are made of membrane
– see page 4.
Hint
Some proteins are
anchored in
membranes and do not
move; others move like
boats in a sea of
phospholipid.
Examiner tip
You should be able to
draw and label a
diagram of a
membrane like the one
in the figure at the
bottom of this page.
Examiner tip
Do not confuse
microvilli with cilia –
see pages 4 and 16.
Quick check 2✔
Quick check 3✔
Hint
When answering quick
check question 3, look
back to the table of
organelles on page 4.
Cell membranes
1UNIT
Outside
Carbohydrate chain
of glycoprotein
Phos
phol
ipid
bila
yer
Inside(cytoplasm)
Glycolipid
Glycoprotein
Why fluid mosaic?
Fluid: phospholipids are liquid – think of a membrane as like a thin layer of oil.
Mosaic: this is a picture
made of many small pieces
of tile. Proteins are like the
pieces of tile surrounded
by phospholipids, which
are like the cement holding
everything together.
The phospholipid bilayer is
split open to show the proteins
that pass right through the
membrane.
Hydrophilic head
Glycolipid
Carbohydrate part of
glycoprotein
Glycoprotein
7–10nm
CholesterolChannel protein Carrier protein
Hydrophobictail
Phos
phol
ipid
bila
yer
A cross-section through a cell surface membrane
Sample pages from OCR AS Biology Revision Guide.
Richard Fosbery and Ianto StevensSeries editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
Exclusively endorsed by OCR for GCE Biology
This revision guide is tailored to the OCR specification and exclusively
endorsed by OCR for GCE Biology. It is written by experienced examiners
and teachers, giving you:
complete coverage of the specification for the exams
content organised by module and unit to follow the structure of the
specification and exams bite-sized chunks of information to make it easier to organise your
revision time quick-check revision questions so that you can test your own
knowledge easily hints and tips from examiners to help you avoid common errors
lots of practice exam-style questions for each unit
all the answers to questions so that you can check that you’re on the
right track.Titles in this series:OCR AS Biology student book and exam café CD-ROM 978 0 435691 80 6
OCR A2 Biology student book and exam café CD-ROM 978 0 435691 90 5
OCR AS Biology Teacher Support CD-ROM978 0 435691 77 6
OCR A2 Biology Teacher Support CD-ROM978 0 435691 91 2
OCR AS Biology revision guide
978 0 435583 70 5
OCR A2 Biology revision guide
978 0 435583 73 6
AS
Second Edition
01865 888118
www.heinemann.co.uk
In Exclusive PartnershipI S B N 978-0-435583-70-5
9 7 8 0 4 3 5 5 8 3 7 0 5
Clearly linked to the specification.
Where appropriate, information is presented in tables or simple clear diagrams in order to aid understanding.
Enables students to check their knowledge and understanding. Answers are provided at the back of the book.
Hints and tips help students avoid common errors.
11
�
�
Hint
Phospholipids form a
bilayer: ‘heads out,
tails in’ – see page 5.
Quick check 1✔
Key words
fluid mosaic
hydrophobic
hydrophilic
phospholipid bilayer
partially permeableMod
ule
1
Module 1
1 Explain why membranes are described as fluid mosaic.
2 Explain how phospholipids and proteins influence the permeability of a cell surface
membrane.
3 Describe the distribution of membranes within animal and plant cells.
QUICK CHECK QUESTIONS ?
Cell surface membranes surround all cells and control what enters and leaves.
Membranes divide up the cytoplasm of eukaryotic cells into separate compartments.
Membranes are very thin
Membranes are visible in the TEM at magnifications of ×100 000 as two dark lines
separated by a clear space. The distance across the membrane is about 7 nm.
Membranes are made of two layers of phospholipid, known as a bilayer, plus protein.
The polar heads of the phospholipids are hydrophilic and are attracted to water. This is
why they face towards the cytoplasm and towards the exterior of the cell. Both these
areas are dominated by water. The hydrocarbon tails of the two layers are hydrophobic
and are held together by weak hydrophobic bonds. Proteins are scattered about the
membrane, and transmembrane proteins pass right through from one side to the other.
Carbohydrates are attached to protein and lipid, and face the outside of the cell. This
structure is called a fluid mosaic.
Component of cell
membrane
Functions
Phospholipidsform a bilayer that acts as a barrier between cytoplasm and cell exterior
are fluid, so components can move within the membrane
are permeable to non-polar molecules such as oxygen and fatty acids
are permeable to small polar molecules such as ethanol, water and carbon dioxide
are impermeable to ions and large polar molecules such as sugars and amino acids
Cholesterol (only in
eukaryotic cells – much
more in animal cells
than in plant cells)
stabilises the phospholipid bilayer by binding to polar heads and non-polar tails of phospholipids
controls fluidity by preventing phospholipids solidifying at low temperatures and becoming too fluid at
high temperatures
reduces permeability to water, ions and polar molecules
Proteinsare transmembrane proteins acting as channels and carriers
are receptors for chemicals made by other cells, e.g. hormones
Glycolipids and
glycoproteins
(lipids and proteins
with carbohydrate
chains attached)
are carbohydrate chains only found on the exterior surface of cell membranes
act as receptors for signalling molecules (e.g. hormones) and for drugs
act as cell surface markers that identify the cells to others (also known as cell surface antigens)
are involved in ‘sticking’ cells to one another (cell adhesion)
Functions of cell surface membranes
Membranes are partially permeable because some substances pass through but
others do not. The permeability of a membrane is determined by the phospholipids and
proteins. Membranes are selective about what passes through. Cell surface membranes:
act as a barrier to many water-soluble substances
keep many large molecules, such as enzymes, within the cell
are permeable to small molecules such as water, oxygen and carbon dioxide
are permeable to selected molecules such as glucose and ions
permit movement of substances by endocytosis and exocytosis
permit recognition by other cells, such as those of the immune system
provide receptors for signalling molecules such as hormones
are often extended into microvilli to provide a large surface area for the absorption
of substances by animal cells.
Membranes within cells
The membranes within cells:
divide the cell into compartments where functions can occur more efficiently
isolate potentially harmful enzymes in lysosomes
provide a large surface for pigments, such as chlorophyll, involved in photosynthesis
in chloroplasts
provide a large surface for holding the enzymes and coenzymes for forming ATP in
mitochondria and chloroplasts
surround vesicles that transport molecules between parts of the cell, e.g. that
transport proteins from rough endoplasmic reticulum to Golgi apparatus.
Cell membranes
Examiner tip
Most of the organelles
you need to recognise
are made of membrane
– see page 4.
Hint
Some proteins are
anchored in
membranes and do not
move; others move like
boats in a sea of
phospholipid.
Examiner tip
You should be able to
draw and label a
diagram of a
membrane like the one
in the figure at the
bottom of this page.
Examiner tip
Do not confuse
microvilli with cilia –
see pages 4 and 16.
Quick check 2✔
Quick check 3✔
Hint
When answering quick
check question 3, look
back to the table of
organelles on page 4.
Cell membranes
1UNIT
Outside
Carbohydrate chain
of glycoprotein
Phos
phol
ipid
bila
yer
Inside(cytoplasm)
Glycolipid
Glycoprotein
Why fluid mosaic?
Fluid: phospholipids are liquid – think of a membrane as like a thin layer of oil.
Mosaic: this is a picture
made of many small pieces
of tile. Proteins are like the
pieces of tile surrounded
by phospholipids, which
are like the cement holding
everything together.
The phospholipid bilayer is
split open to show the proteins
that pass right through the
membrane.
Hydrophilic head
Glycolipid
Carbohydrate part of
glycoprotein
Glycoprotein
7–10nm
CholesterolChannel protein Carrier protein
Hydrophobictail
Phos
phol
ipid
bila
yer
A cross-section through a cell surface membrane
Sample pages from OCR AS Biology Student Book.
Pete Kennedy and Frank Sochacki
Series Editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
Pete KennedyFrank SochackiSue Hocking
Mark WinterbottomSeries Editor: Sue Hocking
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
A2
Summary of contents
iv
v
Introductionvi
UNIT 1 Cells, exchange and transport (F211)Module 1 Cells
21 Living organisms consist of cells 42 Cell size and magnification 63 Electron microscopes and cell details 84 Cells and living processes 105 Organelles – structure and function 126 Organelles at work147 Biological membranes – fluid boundaries 168 The fluid mosaic model 189 Communication and cell signalling 2010 Crossing membranes 1 – passive processes 2211 Crossing membranes 2 – active processes 2412 Water is a special case
2613 New cells – parent and daughter cells 2814 Two nuclei from one3015 Cell cycles and life cycles are not all the same 3216 Cell specialisation3417 Organising the organism 36Summary and practice questions 38End-of-module examination questions 40
Module 2 Exchange and transport 421 Special surfaces for exchange 442 The lung as an organ of exchange 463 Tissues in the lungs484 Measuring lung capacity 505 Transport in animals526 The structure of the mammalian heart 547 The cardiac cycle568 Control of the cardiac cycle 589 Blood vessels6010 Blood, tissue fluid and lymph 6211 Carriage of oxygen6412 Carriage of carbon dioxide 6613 Transport in plants6814 Xylem and phloem7015 Plant cells and water7216 Water uptake and movement up the stem 74
17 Transpiration7618 Reducing water loss – xerophytes 7819 The movement of sugars – translocation 80Summary and practice questions 82End-of-module examination questions 84
UNIT 2 Molecules, biodiversity, food and health (F212)Module 1 Biological molecules 861 Biochemistry and metabolism 882 Biochemicals and bonds 903 Carbohydrates 1: simple sugars 924 Carbohydrates 2: energy storage 945 Carbohydrates 3: structural units 966 Amino acids – the monomers of proteins 987 Proteins from amino acids 1008 Levels of protein structure 1029 Proteins in action
10410 Lipids are not polymers 10611 Essential oils?10812 Water – a vital biological molecule 11013 Practical biochemistry – 1 11214 Practical biochemistry – 2 11415 Nucleotides – coding molecules 11616 DNA – information storage 11817 Reading the instructions 12018 Enzymes are globular proteins 12219 Inside and out – where enzymes work best 12420 Enzyme action
12621 Enzymes and temperature 12822 Enzymes at work – pH effects 13023 Enzymes at work – concentration effects 13224 Enzymes at work – inhibitors of action 13425 Enzymes at work – coenzymes and prostheticgroups13626 Interfering with enzymes – poisons and drugs 13827 Investigating enzyme action – 1 14028 Investigating enzyme action – 2 14229 Enzymes and metabolism – an overview 144Summary and practice questions 146End-of-module examination questions 148
Module 2 Food and health 1501 Nutrition1522 Diet and coronary heart disease 1543 Improving food production 1564 Microorganisms and food 1585 Organisms that cause disease 1606 Transmission of diseases 1627 The worldwide importance of certain diseases 1648 Non-specific responses to diseases 1669 Antibodies
16810 Communication between cells 17011 The specific immune response 17212 Vaccination17413 Finding new drugs17614 The effects of smoking 17815 Smoking – nicotine and carbon monoxide 18016 Cardiovascular diseases 18217 The evidence linking smoking to disease 184Summary and practice questions 186End-of-module examination questions 188
Module 3 Biodiversity and evolution 1901 Biodiversity1922 Sampling plants194
3 Sampling animals1964 Measuring biodiversity 1985 Classification and taxonomy 2006 The five kingdoms
2027 Classifying living things 2048 Naming living things2069 Modern classification20810 Variation21011 Adaptation21212 Natural selection21413 The evidence for evolution 21614 Evolution today21815 Conservation of species 22016 The effect of global climate change 22217 Conservation in situ
22418 Conservation ex situ22619 International cooperation 228Summary and practice questions 230End-of-module examination questions 232
Answers234Glossary256Index268
ContentsContents
936 biology.prelims.indd 4-5
10/3/08 11:35:26 am
iv
v
Introductionvi
UNIT 1 Cells, exchange and transport
(F211)Module 1 Cells
2
1 Living organisms consist of cells 4
2 Cell size and magnification 6
3 Electron microscopes and cell details 8
4 Cells and living processes 10
5 Organelles – structure and function 12
6 Organelles at work14
7 Biological membranes – fluid boundaries 16
8 The fluid mosaic model 18
9 Communication and cell signalling 20
10 Crossing membranes 1 – passive processes 22
11 Crossing membranes 2 – active processes 24
12 Water is a special case26
13 New cells – parent and daughter cells 28
14 Two nuclei from one30
15 Cell cycles and life cycles are not all the same 32
16 Cell specialisation34
17 Organising the organism 36
Summary and practice questions 38
End-of-module examination questions 40
Module 2 Exchange and transport 42
1 Special surfaces for exchange 44
2 The lung as an organ of exchange 46
3 Tissues in the lungs48
4 Measuring lung capacity50
5 Transport in animals52
6 The structure of the mammalian heart 54
7 The cardiac cycle56
8 Control of the cardiac cycle 58
9 Blood vessels60
10 Blood, tissue fluid and lymph 62
11 Carriage of oxygen64
12 Carriage of carbon dioxide 66
13 Transport in plants68
14 Xylem and phloem70
15 Plant cells and water72
16 Water uptake and movement up the stem 74
17 Transpiration76
18 Reducing water loss – xerophytes 78
19 The movement of sugars – translocation 80
Summary and practice questions 82
End-of-module examination questions 84
UNIT 2 Molecules, biodiversity, food
and health (F212)
Module 1 Biological molecules 86
1 Biochemistry and metabolism 88
2 Biochemicals and bonds 90
3 Carbohydrates 1: simple sugars 92
4 Carbohydrates 2: energy storage 94
5 Carbohydrates 3: structural units 96
6 Amino acids – the monomers of proteins 98
7 Proteins from amino acids 100
8 Levels of protein structure 102
9 Proteins in action104
10 Lipids are not polymers 106
11 Essential oils?108
12 Water – a vital biological molecule 110
13 Practical biochemistry – 1 112
14 Practical biochemistry – 2 114
15 Nucleotides – coding molecules 116
16 DNA – information storage 118
17 Reading the instructions 120
18 Enzymes are globular proteins 122
19 Inside and out – where enzymes work best 124
20 Enzyme action126
21 Enzymes and temperature 128
22 Enzymes at work – pH effects 130
23 Enzymes at work – concentration effects 132
24 Enzymes at work – inhibitors of action 134
25 Enzymes at work – coenzymes and prosthetic
groups136
26 Interfering with enzymes – poisons and drugs 138
27 Investigating enzyme action – 1 140
28 Investigating enzyme action – 2 142
29 Enzymes and metabolism – an overview 144
Summary and practice questions 146
End-of-module examination questions 148
Module 2 Food and health 150
1 Nutrition152
2 Diet and coronary heart disease 154
3 Improving food production 156
4 Microorganisms and food 158
5 Organisms that cause disease 160
6 Transmission of diseases 162
7 The worldwide importance of certain diseases 164
8 Non-specific responses to diseases 166
9 Antibodies168
10 Communication between cells 170
11 The specific immune response 172
12 Vaccination174
13 Finding new drugs176
14 The effects of smoking 178
15 Smoking – nicotine and carbon monoxide 180
16 Cardiovascular diseases 182
17 The evidence linking smoking to disease 184
Summary and practice questions 186
End-of-module examination questions 188
Module 3 Biodiversity and evolution 190
1 Biodiversity192
2 Sampling plants194
3 Sampling animals196
4 Measuring biodiversity198
5 Classification and taxonomy 200
6 The five kingdoms202
7 Classifying living things 204
8 Naming living things206
9 Modern classification208
10 Variation210
11 Adaptation212
12 Natural selection214
13 The evidence for evolution 216
14 Evolution today218
15 Conservation of species 220
16 The effect of global climate change 222
17 Conservation in situ224
18 Conservation ex situ226
19 International cooperation 228
Summary and practice questions 230
End-of-module examination questions 232
Answers234
Glossary256
Index268
Contents
Contents
936 biology.prelims.indd 4-5
10/3/08 11:35:26 am
NewScientistIn partnership with Heinemann
Free, up-to-date news articles......and guidance on how NewScientist.com can suppport the delivery of the new Science specifications.
In Exclusive Partnership
Pete Kennedy and Frank Sochacki
Series Editor: Sue Hocking
AS
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
Pete KennedyFrank SochackiSue Hocking
Mark WinterbottomSeries Editor: Sue Hocking
Exclusively endorsed by OCR for GCE Biology
In Exclusive Partnership
A2
Evaluation PacksEach OCR Biology Evaluation Pack is available on 60 days free evaluation and contains:
l Student Book and Exam Café CD-ROM
l Teacher Support CD-ROM
l Revision Guide (New Edition)
OCR AS Biology Evaluation Pack OCR A2 Biology Evaluation Pack 978 0 435692 05 6 | £149.00* | April 2008 978 0 435692 30 8 | £149.00* | January 2009
Course componentsOCR AS Biology Student Book and CD-ROM 978 0 435691 80 6 | £17.99* | March 2008
OCR A2 Biology Student Book and CD-ROM 978 0 435691 90 5 | £17.99* | December 2008
OCR AS Biology Teacher Support CD-ROM 978 0 435691 77 6 | £149.00* (+VAT) | April 2008
OCR A2 Biology Teacher Support CD-ROM 978 0 435691 91 2 | £149.00* (+VAT) | December 2008
OCR AS Revise Biology (New Edition) 978 0 435583 70 5 | £6.99* | April 2008
OCR A2 Revise Biology (New Edition) 978 0 435583 73 6 | £6.99* | January 2009*Prices are provisional until publication.
Sign up for our eNewslettersFor all our latest news and offers, sign up for our FREE termly Science eNewsletter. Visit www.heinemann.co.uk/signup today!
OnlineYou can save up to 15% on all orders through our website! Visit: www.heinemann.co.uk/science
PhoneCall our friendly customer services team on 01865 888034 or email them on myorders@pearson.com
Local Sales ConsultantRequest a visit from your local Heinemann Sales Consultant and find out about our latest discounts. You can contact them via our website: www.heinemann.co.uk/reps
3 easy ways to order!
N35
2
08ST
T002
4
Recommended