Ocr a level biology student book 2

334 Pages·2016·53.46 MB·English

by  Schmit, Adrian;Fosbery, Richard;Wakefield-Warren, Jenny

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2
OCR
A LEVEL
BIOLOGY
Richard Fosbery
Adrian Schmit
Jenny Wakefi eld-Warren
9781471827082.indb 1 07/07/16 3:15 PM
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© Richard Fosbery, Adrian Schmit, Jenny Wakefield-Warren 2016
First published in 2016 by
Hodder Education,
An Hachette UK Company
338 Euston Road
London NW1 3BH
Impression number 10 9 8 7 6 5 4 3 2 1
Year 2019 2018 2017 2016
All rights reserved. Apart from any use permitted under UK copyright law, no part of this
publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying and recording, or held within any information storage
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Cover photo © kzww – Fotolia
Typeset in 10.5/12 pt Bliss Light by Integra Software Services Pvt., Pondicherry, India
Printed in Italy
A catalogue record for this title is available from the British Library
ISBN 9781471827082
9781471827082.indb 2 07/07/16 3:15 PM
Contents
Get the most from this book iv
Chapter 1 Communication and homeostasis 1
Chapter 2 Excretion as an example of homeostatic control 14
Chapter 3 Neuronal communication 37
Chapter 4 Hormonal communication 54
Chapter 5 Animal responses 66
Chapter 6 Plant responses 85
Chapter 7 Photosynthesis 98
Chapter 8 Respiration 118
Chapter 9 Cellular control 140
Chapter 10 Patterns of inheritance 158
Chapter 11 Manipulating genomes 185
Chapter 12 Cloning and biotechnology 218
Chapter 13 Ecosystems 246
Chapter 14 Populations and sustainability 273
Chapter 15 Maths skills 297
Index 318
QR codes for free online material 322
Acknowledgements 324
Go to www.hoddereducation.co.uk/OCRABiology2
to find the following two chapters:
Chapter 16 Preparing for practical assessment
Chapter 17 Exam preparation
9781471827082.indb 3 07/07/16 3:15 PM
Get the most
from this book
Welcome to the OCR A Level Biology 2 Student’s Book. This book covers
Year 2 of the OCR A Level Biology specification.
The following features have been included to help you get the most from
this book.
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Figure 4.5 Section of pancreas tissue and student drawings. (a) photographed at x 200.
AAccttiivviittiieess
57
TThheessee pprraaccttiiccaall--bbaasseedd aaccttiivviittiieess
wwiillll hheellpp ccoonnssoolliiddaattee yyoouurr lleeaarrnniinngg
and test your practical skills.
E
Exam practice questions a) i) Suggest suitable controls for this x
investigation. (2) am
1 Aiwn hcsrype etachsieee ssp eiosxp piunoltanroteidnoutnic aoellfdy t.i hWnitsho si cpah en cseitewast heinamcbreietnaatst eeasxn?pdla ins b) iIdi)e ntSdifteyar ittvehe etdh evena dvrieiarpboelnenm dfoeernn ttth avials rciinoavbneldesi ttaiignoadnt isto hmne. ost( 2) pra
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EYchoxaupa wtmeirl.l Tfiphnedrs aeE xcfao tmliloc pwer a tchqteiuc seet yqsluete oisotf iotnhness daitf ftehree netn tdy opfe se voefr y 2 WlpABCol oghatAdPmPitcrooiii hsntowppph griuuilems dapll aaeynciocttrelopeii doortsaua cnnarolnaal ynfgggltle reiuodaoo croi onwasstdf pitutc n hlphrahageeot yaliariepsoen st udngoaphl.eslanaaw si tnarf?ai to ooay rnlf so l u iawslnsoixzei gendeaasge r.rc niasatsc hniatm ibleeeis c w .ahree n d) cIewlinuennoasiaa tsetntresd h otttcbsaeehgt yit e enf iponpn leofe l oltrausuoh.u tnrruessi.t nr, D s gwseb. reu auoascstwcnht rade tiablhs sfs e aoo o fe fhfld co oibeneuwpassr ceo ibntncseeiittttrseor i otna iltsg iehta ersreneo,n dcngf ily oenofcunt ult noeorh.gdu neTi sl hfy oi sr(( 37)) estions
questions you might see in your examination, including D The actual numbers of individuals can be read 4 Carabid beetles are one of the largest families
easily from the graph. (1) of animals; many live in forest ecosystems.
mhec●hvi gueaGthlnlotllrei i pegfanulehnegrnts-et wch t–qhhee uoerBr,e i aclwwsesetivii cittoeqh hlqnu o Musoeu.efsta ts dittdohiifionfsffni sciq,cs uu aultentlhtysdyat. .tiaTo eernevss te c aryoynoloodunu rSer t u crsneohdtdoceeuhrdls dat tanbonde d ianbgl e 3 TTcttikd•••n hheohhivfaepneefeeittfr MeTcTbcrs r rue iootnhhteeeen soaiadnnveneengfengerit tt atedrfeecsylaa stloree a ototg ifiimonshnc nnlmunyso onvemeeto,ratu eiro ndrnanrfbo re or itu i aynentfentnban tht hues ceteiir mcn netiemaoteroeolhs se elmtefntn se bler ,cwnw eatfctspeT olsta,m tso orere wan Titiasupnbr tla.eds neei reeoocctrp .i rd simrtotoTlafeoesti i nuhnlwoo smncalou mde fifn,oasiu efs asidts settf essehwcl e.eiuae dsoa eawrnthtcm nn swaoffttehetsdroiwn,raao o c.re aredentv aom drs xe eolfe ppf psla ufe laofepuotuecmlmnuwcoeotrmhidr icu,deoami inauesrs l e.peesn tnesgIoprot dn dnofa wef loet iedtoacnf.erhfaunliu eoreacc ersu lh t lsr .. pabDbtRdfbiSanohnp)eeie )us <r r eesdepetneeEtEbf ttar lseg0oothlilaxxirtebe h o.rmitr ppdb0ssseupcsedlli, e0s taahafl raiotoaetfive1iinehsoe nnftgetsp.sr’ ernls usertsoeelwh s oh loSsncraiitootetah ncif.ntb wfsya na a dd.selP t ttkri iae ilhfyoan faoemydcofebl bnseaoto uatehwufgrnurye oe en rwd ailitenrct end ogeyohlaitsaaanes o u naaenttt vul wn ih.gcdeco pnToeeeosa nlghcots t sn ceoohi.et f gclTscofsmesialt ma heurrc wt pl aedafetcbaaaan hreduexparsmdi l eees fbatf rr t rioohtisoptllc dyeelreh=emede ds ebrone s .c 0h etfstTe .atae6tthn gvthr9etlaeeeea 6p sgo;p efi((en 35d ))
● Orange – Questions that are a regular feature of The numbers of beetles were counted regularly. • dwellers live inside dung where they feed and
The containers were left until only one species lay their eggs
exams and that all competent candidates should be remained as the ‘winner’ in the competition. The • tunnellers dig burrows in the soil underneath
table shows the results. piles of dung
• rollers make dung into balls and roll them
able to handle. Econnvidriotniomnesntal Pcoerncteaninteagrse ionf Pcoerncteaninteagrse ionf away to bury in the soil.
which T. castaneum which T. confusum Researchers investigated the numbers and
was the ‘winner’ was the ‘winner’ biomass of each of the three types of dung beetle
● Purple – More demanding questions which the best A, hot and wet 100 0 in two fields: one grazed by sheep and the other
B, hot and dry 10 90 grazed by cows. The results are in the table.
candidates should be able to answer. C, warm and wet 86 14 c) The researchers did not kill all the beetles to
D, warm and dry 13 87 obtain the biomass figures. Suggest how they
derived the results in the table. (3)
● Stretch and challenge – Questions for the most EF,, ccoolldd aanndd dwreyt 290 10701 d) Eecxoplsayisnt ethmes rgorlaez oefd dbuyn lga rbgeee htleersb iinv ogrreass. sland( 4)
able candidates to test their full understanding e) Comment on the results. (5) 229933
and sometimes their ability to use ideas in a novel
situation.
Dedicated chapters for developing your Maths and Practical skills and
Preparing for your exam can be found at the back of this book or online.
v
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Authors Acknowledgements
The authors would like to thank the following for their help during the
writing of this book:
Dr Clare van der Willigen
Gaynor Frost (Lincoln Minster School)
Maria Jose Rosello (The Grange School, Santiago, Chile)
Mary-Kate Jones (Cymdeithas Eryri - Snowdonia Society)
Barry Blackburn (The School of Law, Criminal Justice and Computing at
Canterbury Christ Church University)
Carwyn ap Myrddhin (Snowdonia National Park Authority)
Maria Dayton (Edvotek - The Biotechnology Education Company)
Francesca Gale (Wellcome Trust Sanger Institute)
Professor Mark Reiger (University of Delaware)
Dr Paquita Hoeck (San Diego Zoo)
Ian Couchman (Cambridge International Examinations)
John Luttick and Laurence Wesson (James Allen’s Girls’ School)
Medina Valley Centre for Outdoor and Environmental Education
(www.medinavalleycentre.org.uk)


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Chapter 1
Communication and
homeostasis
Prior knowledge
● Animals have two communication systems: the nervous system and the
endocrine system.
● The nervous system transmits electrical impulses.
● The endocrine system produces hormones.
● Responses controlled by hormones are usually slower and longer lasting
than responses controlled by the nervous system.
● The human body works to maintain steady levels of temperature, water
and carbon dioxide and this is essential to life.
● The core temperature of the human body is maintained at 37 °C.
● Heat can be gained by respiration, shivering, exercise, and conserved by
decreasing sweating, raising of hair/feathers or reducing blood fl ow near
to the skin surface.
● Heat can also be gained or conserved by certain behaviours, e.g. exercise
or (in humans) wearing thicker clothing.
● Heat can be lost by sweating, or by increasing blood fl ow near to the
skin surface.
● Heat can also be lost by behaviour, e.g. panting or (in humans) wearing
less clothing.
Test yourself on prior knowledge
1 Which two organ systems are involved in communication in an animal?
2 Why is the maintenance of a relatively constant core temperature an
advantage to organisms?
3 Explain how sweating can lower the temperature of the blood.
4 How does the body control blood flow to the body surface?
Introduction
Although you may often wish you did not sweat as it can feel unpleasant
(see Figure 1.1), it is vital for keeping you alive. A lot of people think that
sweating cleanses your body of toxins, but in the scientific community that
is widely regarded as a myth. However, a scientific study in the Archives of
Environmental and Contamination Toxicology in 2010 seemed to indicate
that heavy metal toxins were preferentially excreted in sweat. These results
have not yet been widely replicated, but in any case we know that sweating
is essential as a means of cooling you down and keeping your body
temperature constant.
1
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As multicellular organisms have increased in size and complexity over
the course of evolution, they have developed specialised cells and
tissues. These structures are found in organs in specific parts of the
body, yet each organ performs functions that relate to the whole body.
These different specialised structures may also have roles that interact
with one another. For these reasons it is essential that the different
cells, tissues and organs in the body are able to communicate with one
another. In addition to internal coordination, animals and plants need to
respond to changes in the environment, yet the cells that bring about
the response are nearly always different from those that detect the
change, and communication is needed to transfer information about the
stimulus to the responding cells.
Animals show a wider range of responses than plants and generally have a
greater variety of specialised cells. They have two communication systems:
a nervous system, which is capable of rapid responses, and an endocrine
system, which tends to carry out longer-lasting communication.
Both hormones and nerves are examples of cell signalling, by which
individual cells communicate with others in a different location in the
body, but the method by which hormones transmit those signals is very
Figure 1.1 Next time you have sweat different from that of nerves. The nature of the signal is different as it is
dripping into your eyes, remember it is chemical rather than electrical. The method of transfer is different too;
helping to keep you alive. via the bloodstream rather than via nerves. The transmission via the
blood is significant, because as the blood system penetrates all parts of
the body, a hormone in the blood can reach and affect many different
Key terms organs and tissues. Although this is useful, it demands a system by
which the action of the hormone can be restricted only to relevant
Endocrine gland A gland that
cell types. This is done by hormone-specific receptors on the plasma
secretes its product directly into membranes or in the cytoplasm of target cells, which are absent on
the bloodstream, rather than via others. Hormones are only removed from the blood when they are used
a duct. by target cells, and so action over a long period is possible, especially
Homeostasis The maintenance of as hormone levels can, if necessary, be continually ‘topped up’ by the
a condition of equilibrium or of relevant endocrine gland.
near-constant internal conditions.
The ability of hormones to act over a prolonged period of time is significant
Receptor A structure in the body for homeostasis. The human body, like that of all mammals, maintains a
that can detect changes in its nearly constant body temperature. The concentration of the blood, in terms
environment and react to stimuli. of both glucose and water content, is kept within a slightly greater but
Effector A structure in the body restricted range, as are the levels of oxygen and carbon dioxide. In order to
s
si that responds to a stimulus do this, it must be possible to detect changes in the factor to be controlled.
a
st and brings about a response. In This is done by receptors. The receptors then send a signal, either directly
o
e or indirectly, to organs and tissues that actually do the controlling, and
m animals, muscles and glands are
ho common effectors. these are the effectors. The transfer of information may be either via
d hormones or nerves.
n
a
n Cell signalling
o
ti
a
c
ni If a multicellular organism is to function in a coordinated way, the cells
u
m of which it is made must communicate with each other. This is called cell
m signalling, and it may occur between cells that are adjacent (or very close
o
C to each other) or between cells in different parts of the body.

r1 In order for cells to communicate, one cell must produce some sort of
e
t signal that can be detected by another cell and induce a response. This
p
a signal is nearly always a chemical (although some nerve cells communicate
h
C by electrical impulses at electrical synapses) and the receiving cell has
special receptors in its cell membrane, which can detect that chemical.
2
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