10 Once you have correctl1y c.ollected, organized, transform1ed and
pres,ented your data in a table, plot a graph of your mean results.
Make sure you have:
• a suitabfe title
• a suitabl'e scare on both axes
• both axes l:abelled (induding unirts)
• poi'nts accuratefy plotted
• points jojned together in the most suitabl1e manner.
11 Apply a Une of best fit to your mean data.
How to make the different neutrase concentrations:
' Desired neutrase How much 5% neutr ase 0
concentration/% solution do I need7/ml 1
2
5 5 3
4
4 4
3
2 3
2
1
1
Safety: Wear eye protection at all times and wash your hands after
handling the neutrase solution.
For the results of an investigation to be valid, variables other than
the independent and dependent variables need to be controlled,
the experiment should be repeated to improve reliability, and the
experimental method should be appropriate for the research question.
Questions and assessment
• What were your independent, dependent and control variables?
• What were the values of your dependent va'tiable7
• How did you enisure the reliability of the experiment?
• Accurately int1erpret your data and explain your results using corr-ect
scientific reasoning.
• Evaluate the val,idity of the hypothesis based on the outcom.e of the
investigation.
• Evaluate the validity of the method based on the outcome of the
invest ig.ati an.
• What was the main hazard in the experiment and how did you eliminate
this hazard?
• Expla1in improvements or exte.nsiions to the method that would benefit
the investigation .
+ Assessment opportunities
.2 What chemkal processes support life?
ACTIVITY: Investigating the Hypothesis
e1 ffect of temperature on rate of
1Formul1ate and explain a testab le hypothesis using
reaction correct scientific reasoning.
ATL Q1 uestions and assessment
• Crit~cal~thi nkin~;rskills:;lnt erpret ;data • What made the dough rise?
This experiment investigates the effect of temperature • Describe the effect of temperature on the volume of
dough produced.
on the expansion of dough.
• Ac,curately interpret you1r data and expl,ain your
Information results using correct scientific reasoning1•
• Yeast 1is a sing.le-celled fungus, a type of micro-
• Evaluate the validity of the hy1Pothesis based on the
organism. outcome of the investigation.
• When it is short of oxygen yeast breaks down glucose • Ev·aluate the validity of the method based on the
outcome of the investigation.
in anaerobic respi rat1io1n to release e·n.ergy, carbon
d.i:oxi.de and ethanoJ. (Try to smel Ithis.) • Explain improvements or extensions to the method
that would benefit the jnvestigat1io1n.
• Respiration is controlled by enzymes.
+ Assessment opportunities
• The yeast suspension contains yeast and glucose.
• The carbon dioxide given off forms bubbles which EXTENSION
make the dough rise. 1 Why can the yeast cell s use sugar but not
• Y'uur paste ·wil I be runny. flour as food?
• You wi II carry out the experiment at 20,, 30, 40., 50, 60 2 What do yeast cells produce that enables
them to use the sugar?
and 70 °C.
3 Why is yeast used in bread making?
Safety: Do not carry out the experiment if you are
allergic to yeast. Take care when using the water baths
at temperatures 50, 60 and 70°C as hot water can scald.
1
Take a beaker Make up a Pou r 25 cm1 of your
and weigh out
25 g of fl our. s·uspenS1ion of ye ast ru nny paste i·nto a
large glass me,asuring
a-nd add a sug1ar
cyli1nder. P~ace ,in the
so~utio n. Usin-g a correct water ba,th.
noting the ti,me.
measuring cylinde,r, After 30 m1in urtes
add SO cm3 of yeast record the vol ume of
suspens,ion to the
fl our and stir well t he dough.
until you 1have a
smooth paste.
• F'i,gure 2.•.28 Sett1in9 up the·yeast experi1me,nt
Biology for the IB MYP 4&5: by Concept
ACTIVITY: Enzyme Enzym@ pjcture bank
poster Use these diagrams to help you make your poster:
ATL
1111 ·:.torrfrnuriicafihri skills:;'.
.• t. , , .
·Mak~·eff~ctiy~~sun1mary·
·hbf~·s;· ofganize .a'nd.depict·
:inforrnati9n.lQgi ~all y. Enzyme
Your task is to produce a poster Substrate
about enzymes. En zyme-substrate ll nchanged enzyme
Points to cover: Enzyme comp I.ex
• What type of biological molec1ul1e. Sal,ivary ·
are enzymes made of?
amy lase
• Are an e·nzymes the same sha p-e?
,- -Arginase
If not, why not? (Think about
what you know about the type Pepsfn
of bio,logica[ molecule they are Acidic 10 11 12 Opt imum
made from.) pH Basic.
• What 1is s:pecial about enzymes temperatu re
(e.g. what piroperties do they
have)? (They are known as 10 20 30 40 0
biologi(al catalysts - what does Temperature (°C}
this mean?)
• Why is the shape of atn enzyme • !Figure 2.29 Enzyme pkt ure bank
im,portant? EXTENSION
• What is the ' tock-and-key' Certain chemicals can in hi bit the action of enzymes. There a re two
hypothesis? A diagra·m1 may help types - competitive inhibitors and non-competitive inhibitors. Find
you to describe this ...
out about these different types of inhibitors: des(ribe and explai,n
Words to use: enzyme, substrate, how they work and then add notes about them to your en.zyme
enzyme-substrate complex, poster.
products, active site.
+ Assessment opportunities ,
• What factors affect how well
(or badly) enzymes work? There
are two majn factors for you to
describe.
• How are enzymes used. in
respi,rati,on and photosynthesis?
• Can you find out anything else
about e1nzym,es? (For example,,
enzymes of d.igestion.)
• Make sure you 1explain how the
.structure of enzymes relates to
their function .
.2 What chemkal processes support life?
H I LIF
u
In Chapter 1 you explor,ed whether art,ffidal ~ife is possibl,e. Biochemical reactions
that occur wijth~n ceUs are ieomplex and ddven by enzy1mes. Would it be poss1ible
to replkate these che1m,kai r1eactions outside cells7
• What do you think? !Exchange your ideas w1ith your ne,~ghbour.
Reactlons such as respiration can be represented 1in the ~ab by burning g~ucose
in tile presence of oxyg,en'" but this r,eleases aH the ,energiy in one go rather than
rep~~cating the gradual and carefully co11troH,ed release that occurs wiith~n celis.
Chemical r1eactions can certainly be manipulated, and are lbe,ing used to meet our
food and fue! needs. We wiU ,explore thiisfurther ~n the next aciivity.
ACTIVITY: Increase the grovvth of plants
ATL
· Org_aniza,ti~n skllls:· ·Plan a:l_qn_·g:-term a.$si.gnment
Global food production will need to increase by more than
50 per cent before 2050 to meet the food and fuel demands
of an increasing population. Are there ways of improving
photosynthesis to increase crop yjeJds? In Chapter 11 we
will explore how DNA can be modified and exchanged
between different speeies - it is possibie that genetic
modification can be used to improve crop yield. But would
such changes be allowed - what do you think?
Currently, crop yield can be improved by using • Figure 2.,30 Tomatoes be~ng grown ~n a gre,enhouse
greenhouses. Using your knowledge of photosynthesis
In th is activity you need to plan an experiment to
and enzymes, how can the rate of glucose production in
investigate how to increase the growth of a plant, and
plants be increased? What variables could be changed/
increased? then carry out an experiment to test your hypothesis.
Biology for the IB M Y P4&5: by Concept
DISCUSS
Discuss within a small group this question:
• How can the (envi,ronmen.tallsoci,al) coinsequences
of man.ipu lating chemi.,al reactions to solive our
food and energy problems be justified?
SUMMARY REFLECTION
• What have you learnt 'in this chapter about how
the systems of life are supported by bi,ochem ica·1
reactions?
• What are the transformations of energy that
,occur within cells?
• What are enzymes and how do they work1 What is
meant by 'optimal conditions' for enz·ymes?
• How can ,innovations i·n science read to biochemical
reactions being utilized to meet growi·n·g' energy
and food needs?
• What have you learnt about you:rse,lf as an inquirer:
how you nurture curiosity, and develop skills ·fo·r
i·nquiry and research?
1 Plan an experiment to change one variable to 9 Correctly coflect, organize and present your data.
10 Accurately interpret your data and explain the resu l1 ts
investig.ate 'its effeet on plant growth.
2 Explain the question1to be tested in the investigatio,n,4 usi·ng correct scientific reasoning.
3 Which spedes of ptant wi'II youi use? 11 Evaluate the validity of the hypothesis based on the
4 Formulate and explain a testable h·ypothesis using
outcome of the experiment.
correct scientific reasoning~ 12 Evaluate the validity of the method based on the
5 Decide how you will change your independent outcome of the ex:p,eriment.
variable. 13 Ex,plain the improvements o.r extensions to the
6 How will you measure the plant growth? method that would benefit the investig1ation.
7 Ex.plain how to 1manipulate the variab1les, and expl,ain
+I Assessment opportunities
how sufficient, relevant data wll Ibe col1lected.
8 Design a logical, com,plete and safe method in which
you seh~ct appropriate materja Is and equi,pment.
Now carry out the experiment. Think about how you will
record your resuIts.
.2 What chemkal processes support life?
Biology for the IB MYP 4&5: by Concept
EU L THESE PROBLEMS CAN BE USED TO EVALUATE YOUR
TT LEARNING IN CRITERION A TO LEVEL 3- 4
Use thes,e problems to apply and extend your leairn~ng in Figure 2.33 shows,a variegated 1geranium leaf that has
been destarched. A b,ack strip of paper covers part of
this chapter. Thes,e problems are designed so that you can
evalluate your ~,earn~ng at d~fferent leve~s of achjev1ement in the 1eaf and the ~e·af ~s then exp,osed to tight. The leaf is
te,sted for stairch.
Criterion A: Kn owi,edge a11d u11derstanding.
Whkh parts of the piant re.suit ~n a pos~tive test for
THESE PROBLEMS CAN IBE USED TO EVALUATE YOUR starch and whkh do not? Justify your answer using
LEARNING IN CRITERION A TO LEVEL 1- 2 your knowledge of photosynthesis.
State fue chemical equation for photosynthesis. 'Sugg1est why the plant was destardl,ed before the
expe,rim,ent.
State ~he .clhem~cail equation for aerobic r,espiration.
Black pa.per ~ -_,,,,
c What do you no,tjce about the equaitions f.or {on both sides of leaf)
photosynthesis and a,erobic respiration?
An exper~ment jnv,estigiated combust ion by burning
glucos,e inside a glass cylinder c,onta~ning oxygen.
...,___ _ Edg.e of l:eaf
lacks chloro·phyll
• Fi g1 ure 2.. 32. Burning gilucose • Figure 2.33 Photosynthesis experi:ment. Before the
Suggest what products wrn be coUected Jns1ide the ,experiment the plant had been put 1in a dark roorm for
g~ass cyHnder. two weeks to destarch the plant {i.e. ensure that the
Suggest what would happen if a hi1gher leaves did not contain starch)
concentr,a1tion of oxygen was. used inside the glass
C.atalase is an enzynle that occurs naturallly 1in ,cells.
cylinder. It breaks down hydrog,en p,eroxide into water and
oxygen:
Give two similari1ti,es and one ditfer,ence,betw,een
combusti1on (shown in Rgure 2.32) and respiration. 2H20 2 .....:, 2H20 + 0 2
3 Outl1ine reasons why an~mals need to eat food, whereas
The rate of react~on can be measured by m,easurJ11g the
plants do not.
volum,e of oxygen produc,ed per m1inute. Figure 2.34
ovedeaif shows.the experiment a11d daita that were
c olle c t e d .
Describe the effect of tim1e on the vo~ume of OiX:Ygen
produced.
The rate of reaction can be measured using the slope
of the ,curve- the ste1eper the curve, the f,aster the
rate of reaction. Suggest why the,rate of rea,cbon
s~ows .as,time increases.
.2 What chemkal processes support life?
The test: tube is tipped up De,l,ivery tube
to mjx the enzyme sol1u"bion
with the substrate . . - - - - Oxygen produced,
coll:ected by down\vard
Catalase - ---------:~~--.!E=' 15;-~-,
so~ution disp1acement of \\tater
0 in an inverted
Hydrogen- -
peroxide m~asuring cylind~r
sol.u.ticm
(10 voh.Jme) 0
The rate of an ·enzyme 0
reactton is greatest at the
rtart, the initial rate. ,R~corded
30 IResuIts pIotted Tlme/s Gas volume
30 col Iected/cmi
C 25
60 '6
(V 90
120 12
S 20 1·50 16
180
0 210 19
240 2.2
EtV 15 270
300 23
-:II
24
0 25
10 2 5.S
.26
5
60 120 180 240 300
Tlme/s
• Figure 2.34 Measuring the rate of reaction using catalase
Biology for the IB M Y P4&5: by Concept
THESE PROBLEMS CAN BE USED TO EVALUATE YOUR Sugges,t how the polyp animal benefits from having
LEARNING IN CRlTERION A TO LEVEL 5- 6
algae lii~ing jnside its body.
Coral reef is one ,of the most extenS,We ecosystems on b Coral bl,eaching occurs when the ail9ae leave the
Earth (Figure 2.35). It 1is made by .srmall animals caUed polyp animal5,, and the coral turns whit,e. ,Global
p,o~yps tha1t secrete ia hard skeleton of caldum .carbonate warming is ~ncreasing the te,mperature of the oceans
for protection. lns~de the ain~mals 1many mi,aroscopic where the coral is found, and increagng the depth ,of
algae l~v,e - these·protoctists contaln colourfiul pigm,ents the water. Suggest why these factors iead to coral
that aHow the·algae to photosynthes1ize (Figur,e 2.36). ble:achi ng .
1 Amylase is an enzyme found in your saliva. It digests
• Figure 2.. 35 C,oral reef starch into maftose.
A series of water baths w,ere set up in t he lab at 10,
20, 30, 40 and 50°C. Two test tubes, containing Scrn3 of
starch and 1cm3 of amylas,e resp,ectively, were heated ~n
each water for S m inutes. When the starch and am1ylase
had reached the correct temperature, the starch .and
am1ylase were mixed to-g1e1her and a stopwatdh started.
After one minutes one drop ,of fue reaction mixture was
added to jodjne on a spotting Uie to test for the presence
of starch. If starch were prese,nt, the reaction mixture
turned blue/black. When 1he iodine no !longer changed
colour (j,,e. no starch present) the t~me wa1s recorded.
The results of the expedm,ent are shown below.
30°c
No digeS"tion 5 minutes
12 m,in·utes
8 mi,nutes 10 minutes
• fjgure 2.37 Spotting tlHes us,ed to measure how
quickly amylase digests starch to maltose ai different
temperatures
• Figure 2.36 Coral polY1PS containing orange algae
.2 What chemkal processes support life?
o-\-......,..----~--~ ----~ -- Th,e rate of photosynthesis was m,easur,ed by countingi
the number of bubbles of oxyg,en produced per minute,
10 20 30 40 and fight intensity was var1ied by putting the lamp at
Ternperature/OC d~fferient distances from the pondweed.
• f igure 2.,38 Results showing the e,ffect of Evaluate the method and c,o,m:ment on how the
temperatur~ on the rat~ of d~giest~on of starch by experiment could be ~mpro,ved to produc,e more
accurate results.
amylase Three separate experiments were carried out wjth three
differ,ent con centrabon5 of carbon dioxide in the water.
Explain the effect of temperatur,e on the rate of Data are shown in Hgure 2.40.
react~on £hown in Figur,e 2.38. Analyse the graph and then answer the foH,owing
Explain how the experim,ent cou,d have been made quest1ions.
mor,e reUabl,e.
4
'State three vari1ables that should be kept constant 4
in this experimen1. 4
"i Expl:ain why thes,e variabll,es should be kept
constant I
Evaluate the exper~ment and expilain how 1he I
results oouldl have been made rmore accurate. I
I
TH,15 PROBLEM CAN BE USED TO EVALUATE YOUR
LEARNING IN CIRITERI ON A TO LEVEL 7- 8 I 0.09o/o C02
An exp,eri1ment was carried out to m,easure the effeiet of 0.04o/o C02
light intensity on rate of photosynthesis. The fo,!,owing Light intensity - - - - - - ---
equipment was uSJed. • Figure 2~40 The effect of ~1ght intensity and carbon
dioxide concentration on rate of phoitosynthes~s
, _ _ __, Oo o ..........._._ _
'State the factor that limits the rate,of photosyn~hesis
00
betw,een light intensity o and points A, Band C.
0
Exp,Jain your answer.
0 'State the factor that limits the rate of photosynthesis
0 from points A, Band C onwards for e,ach ,graph.
Explain your answers.
Explain why the rate of photosynthes~s rincreases
f rom 0.04o/o through to 0 .14% carbon diox~de.
- - - Pond water
• Flgure 2.39 Experiment to measure,the ,effect of lright
intens~ty on rate o1 f photosynthesis
Biology for the IB MYP4&5: by Concept
In thischapter we have l1earnt about how the system1s of Ufe are supported by
biochem~cai reacttons, and the transf1ormations ,of energy that occur within ceUs.
We have seen how enzymes work and exp,ained what is m1eant by 1optima1i
conditions' for chemkal reactions in (jells. We have exp~ored how innovabons irn
science can le.ad to biochemical reactions being utilized to meet growing energy
and food needs. We have 1,earint about our role as an inquirer, and how to nurture
currrosity and deve~op skiIIs for inquiry and research.
~fi~Uili'i'.'! t:l:'l;:n..;1,i'.(:iil;:J".~IO;,il"r:~yi•1i1;.;.i;~,,.J r~i11n1,~iu,~·.i..1l ~mJU•1c:.iai - I
Ques1ions we asked Answ,ers we found Any further quest~ons now? -
Factua l: \Mha:t aire some chemiica~ rea,ctjons \Nhj,dh occur ins1de,
c,eHs7 What ,occurs 1in the· process of celliular respjratton7 What
occurs ~n the process of photosynthesis? What factors are needed
for photosynthesis? How can the rate of photosynthesis be
meas.ured7 What are enzymes and how do ·they work? How do
chemkal and physkal reactions in cellls determine the surViival of
org anj·sms7
Conceptua l: Why aire ,enzymes needed? Why do,som1e or,ganisms
n,eed to feed tl1emse~ves whereas others do not? Cain the chemicaill
re·a,ct~ons of li~e occur outside ceUs? Can b~ochemkal reacti1ons be
re~ ica·ted 1in the l1ab7
Deb ata ble: Should chemkat reactions be 1manipulated i1n order to
1m1eet our food and 1uell needs?
ApproachesJto ~earning you used irn this chapter De5cr~ptlon - what new ski lJs How well did you rmaster t he
d~d you learn7
skiUs?
... ·-a-g i.~ .... ·.=a1
:>0z fB c...... it
....;;J L.!.J
Cri tica l-thinking s kill s
O rgani zatio n skills
Informat io n Iiteracy skil Is
Communication skills
Self-m a nagem e nt s kill s
Learner profite attrribute(s) How d~d you demonstrate your slktlls .as an ~nquirer in this.
Inq ui rer
,chapter?
.2 What chemkal processes support life?
'Systems
CONSIDER AND ANSWER THESE • Figure 3..1 A ba~anced diet ~s
QUESTIONS: needed to sustain a healthy body
Factual: What nutrients do organisms need to survive? IN THIS CHAPTER, WE WILL ...
What occurs during the pr1ocess of digestion? What F1i·nd out:
occurs du ring the process of gas exchange? How are
substances transported around an organism? How do • how 1he body can achieve a ba!anced diet:
substances move in and out of ce!is? What are diffusion, • whether people should use drug1s to ieontrol their
osrnos.is and active transport? What is homeostasis?
How do elements essential for Iife cycle between the weight.
environment and organisms?
Expfore how food reaches the ceUs in our bod~es
Conceptual: What processes are ijnvoived in movement after jt has been ,eaten.
Take action by campaigningi to promote healthy
and transport? Why do the conditions within organisms eating in our local co1mmunity.
need tn be kept in balance? balanced diet nutriti o naI
concentration gradient oxygenated
Debatable: Should people use drugs to try to control homeostatic
cycle vessel
their weight? deoxygenated molecule
Now share and compare your thoughts and ideas w~th
your partner, or with the whole class.
Biology for the IB MYP 4&5: by Concept
These Approaches to Learning (ATL) THINK- PAIR- SHARE
skills wiU be useful ... Think about the types of food that you need to eat
• ·critical-thi nkihg·skills to maintain a healthy body. They can be divided into
seven groups - think what they are. What are these
• :Creative-1:hinkin~ :.skills different food groups needed for in the body? Now
share and discuss your ideas with your neighbour.
• ·Communication skills
ACTIVITY: Your daily intake
• Transfer skills..·.
..~ ·. . ·. .. You can keep track of your daily intake of nutrients
• .I nf9rmation literacy:SkiUs using these onli ne resources:
·collabor~t'ion ski lls Phone ap1ps:
www.fooducate.com
Consider the food you eat 011 .a daily basis. Do you thijnk
about why you eat or what the meals you eat (your diet) www .s ho pwe II. co m/m obii eapp
contai1n? To maintai1n a healthy body there are certain types
Ontine softwaire:
of food that you need to eat
www.supertracker.usda .govldefauIt.a px
• Figure 3..2.A baiianced diet
3 How do org1anisms sustain t1hemse~es? www.supertracker.usda.gov/.foodtracker.aspx
These programs can be used to track all aspects of the
food you eat. You can use them to keep a record of the
food you eat and to analyse its nutritional content.
Are you eating a balanced diet? You can use them to
compare your daily intake to the recommended intake.
Use one of these programs to explore the nutrients you
eat over the current week.
• Keep a d1iary of the meals you eat each day. Do this
for a week.
• Use the software to ana lyse the nutritiona1
contents of each meal -the amo'Unt of
carbohydrate, protein, lipid, vi'tami,ns and minerals.
• Use the software to calculate the q"uantity of
ene1rgy you are consuming each day, and ove'r the
course of a week.
The estimated a1vera1ge daily requ ireme1nts for
energy are:
o Males, 15- 18 yeairs 11 510 kJ
a Females, 15- 18 years 8 830 kJl
• As a consequence of your cakulat1io:n ot jntake of
essential nutrje1nts n0 1 a typical day, an.alys.e and
comment on how approp.riate your think your diet
is, and why.
How can diet be affected by personal and cultural
choices? Choose a couple of countries/religions/cultures
to explore the diet (restrictions and requirements) and
to compare and contrast the effect of these on the
nutritional content.
T T IENT 0 Carbohyd ra,tes
u I EEDT • Elements: carbon, hydrogen and oxygen.
IVE? • Smallest unit: molecules such .as glucose (a simple1
From the starter activiity you wm have found that the ,ssugar, m,eaning h made of one unit). GIucose
foUow~ng are needed for a balanced diet: contai1ns six carbons and so ,cain be drawn, f or si1mpUdty,
as .a1hexagon.
• Carbohydrates (or sugars) - for energy. • Macromole,cufe: starch, for ,example, ~s a
macromolecule that is made from many units of
• Proteins - heJp your body repair ce·ils and make new g1iucose combined together. 01 ther macromolecules
ones.
~ncllude celiu~ose and 1glycog,en.
• Fats (also known as li pids}- stor,e of energy; 1insulat,on.
• Minerals ~elem1ents such as ~r,on - to,make hemroglobin • Figure 3'..3 Starch is made from many gllucose units
in blood, and reaiidum - to make bone). Proteins
• Vitamins - chemicals that ensure cells function • E~ements: carbon, hydrogen, oxy9en and nitrogen
properly, for exa1mple vitamins C and D. (some contain sulfur).
• Fib re - helps tran sjt of food through t he gut (so,~ubl,e
Smail,est unit: amino acids. There are 20 different
fibre lowers cholesterol).
am~no adds in your diet - y,our body can make some of
• W ater~ about 80o/o of your body ~s w.ater. You ne,ed them but the majorilty must be conta~ned ~n your diet
to regularly dnnk water to ,ensure processes in the body
• Macrom1oleoul,e: prot,e1in molecules ar,e made from many
are functioning properly .and you rema~n hydrated.
·(up to thousands) of am~no adds. The sequence of
Molecules c,ontained in your food aire either large {caUed
macromolecules, made from combjnang sm1ali,er units am~no adds ,O ;e. the types. of a1m~no acid and the order
together), or the indhAdual units themseives. The bigg,er 1n which they are Joined 1ogether) det1ermines the shape
molecules are made from the smaHer building blocks (the and properti,es of the protein.
,ndiv~dua~ units).
Different food typ,es conta~n different el1,ements, although
th,ey aH have carbon. hydrogen a1nd oxygen in c,om1mon.
llhi1s se,ction is a sum1m1ary of each of the three main food
groups and what each is 1made from.
Biology for the IB MYP 4&5: by Concept
Polypept1de eh ai n Glycerol Fatty adds
H 0 H H HH H H H H H H H H H H H
H-t--0.~-~-t-!-t-J- t-J....!-t-t-.t-t-t-t-t-!-H
i iI I I I II
AA
H HH H HH
0 H H H MH HH H H H H H MH M
H-·•---0 ~-At-!-t---A-JA-tA-l-i!-A~-At-At-!A-t~t-!-lt-lM
0 H HHHHHH HH k
-~-t-!i-J---1-t-t-!_J_!~4''r4": /&{&) -!H-
-C--0jH- H
A -
H
I~
Amino adds His: ~'istidi,ne Ser.: Serin,e • Figure 3.5 Lipids are made from g~yce,ro,i and
three fatty acids
Ala: Alan ine lle: lso lerucine Thr: Threonine
Leu: Leucine Trp: Tryptophane ACTIVITY: Which vitamins and
Arg: Argtnine Tyr. Tyrrosine
Lys : lysine minerals do vve ne,ed and vvhy?
Asn: Asparagine Met: M1ethionlne Val; Valrine
Asp: As1partic acid Phe: Phenylalanine ATL
Cys ~Cystetne Pro: Praline
Gin~ Glutamine • info.:r·rn-atioi, ,lifera_cy.skills: Access·inforriiatidn :.fo..·
be inf6rmed:a,td·1irif.or·mothers
G[u ~Glutamk add
• ·cq,la. bora~.ion·s~ills:-Woik:coU~porat.iv~I.Y, tn t~ams
• Figure 3..4 Proteins ,are made from longi cha~ns of am~no
In this activity you need to work in small groups to
adds. Ther,e are 20 djfferent a1mi1no, ,adds - the structure find out about vitamins and minerals.
and function of the protein depends 011 the a1miino adds • Dedde which vitamins. or m,inerals you want to
research . You must:
it is made fro,m and the order in which they are put o fi nd out about the source of the vitam in or
minera l
together o find out t he function of the v itamin or m ineral
o explain the ro Je 011 the vitam.in or m,ineral in
Lipid's the body.
• Elements: carbon, hydrogen and oxygien. • ·Once the resea·rch has been earned out, summarize
the results hn a poster or other format so that the
• Sm,aUes.t un~ts: glycerol. and thr,ee fatty acids (long
:rest of the class can1see what you have found.
chains of carbon ,and hydrogen).
• Macromo~ecu,e: the ,g1lycerol molecul,e ~s combined with + Assessment opportunities
1hre,e f,atty adds to 1make the fat molecule. Fatty adds
can be saturated or unsaturated. In unsaturated
fatty adds some of the carbons are joined by doub~e
bonds, igivjng a bend in the chain, whereas in saturated
fatty acids aH the carbons are comb~ned wi1th hydrogen
ato,ms,. Saturated and unsaturated fatty acids have
different propert1ies.
In add~tion to 1hese three main f,ood groups., your diet
shouldl also contain minerals (elements such as iron for
your blood) and vitamiins. V~tam!,ns are only needed in
tiny amounts, but wjthout them your body would not
function prop,erlry.
3 How do org1anisms sustain t1hemse~es?
llhe vitamins you need, and sourc,es of eadh, and why you need them, are • Table 3. 2 Minerals needed as part
summ.adzed in the follow~ng1table. of a balanced diet
• Ta ble 3~·1 Vita1mi11s needed as part of a ba~anced diet
----------- Cak1iu1m 0.'9 g
1.5g
..f-~.{~·.. !I;,"~:• - - • -
3 .2g
~,~ l_OJ) ; Phosphorus
.3.491
A Ftsh lriver oUs; animal iliiv,er, Requmred ·for no,rmal immune system Potass~um 5.2g
made n body from ·C:arotene i unct~on and for pmduction o'f c,e~Is tn Sodium 0 .3g
14.0mg
t he ret~na of the eye C h lor~ de 11 .4m,g
D Fish ljver oi~s. butte~ eigg y,o,lk., Needed for the absorpt rion of calcium ~n Magnesium
made jn the body by action of t he body
sun~~ght Iron
E Piant ,oils Anti,o~idant Z~nc
K Dark gireen lea,fy v,egetablesl Needed fo:r bl,ood dottirng
made by bacteria of ,g1ut
Needed fo:r an enzyme used io Flluor1de 1.82mg
1.63m1g
r,es p~ rat1ion Copper 0 .06m1g
Saen~um 0 .024m,g
W ide~ occurr~ng Needed for an enzym.e us,ed ~n Iodine 5.0mg
0 .09m1g
re sp~ rat;on Mangianese
Chr,o,mjum 0 .3·mg
Bj Meat, y·e.ast extract, potatoes, Needed to rn.ake enzymes.,nvoliVed ~in Cobai1t
m.ade from, ttle amino add r,esp1iratrion
tf)fptophan
Bs W~dely occurr~ng Needed t,o m.alke an enzyme invoived rin
resp~ rat~on Examples of why mineralis are needed
Mea1. fish, eg,gs. some· Needed to make an enzyme 1nvdv,ed in by the body:
veg.e·ta b1l,es t he·formation 01 aim;no adds Pho·sphorus js needed in the
Liver, yeast, not found in Needed to rn.ake an enzyme involve-d production of DNA and ae!I
p~ant:s with ,ce111d~v~sion; for ne,rve·iunction1
membranes.
fojtc add Uv,er, white fish, raw ~eat Needed to make an enzyme involved ~n
H (bio1jn} v,eg~·ta bh~s DNA replkati1on • Caldum 1is needed for he,a~thy
Uve-r, yeast, 1egig white, made Used ·to make,an enzyme jnvolved with teeth and bones.
by bacterria ~in the hurman gut
metabolk reactions • Sodium and ch~oride ions are us,ed
in the control of 1he compos1t1on
C (ascorbirc Po1a1oes, gireen veigetables, Used to rmake an enz~mies needed for of body ftuids.
add} fru ~1:s
pro1@1n m,etaboli.sm; involved in iron • Iron is needed to make
hemo,globin - the oxygen-ca1rryin9
.absor1J'trion
molecule in r,ed blood ceHs.
About 15 minera~s are known to be essentrral for a healthy body (lable 3.2).
They are obtained from food sources where they are present in low concentrations.
Biology for the IB MYP 4&5: by Concept
ACTIVITY: Food tests Testing for protein
ATL 1Bi·uret
Blue - - - - - - -__... Purpl·eJ1iilac
• cri-~fc.~f:th!n~~n·g sk~lls:__ln~·~rpret ~~ta A purple'lilac
colour means that
Food can be tested for carbohydrates, protein and lipids, Na OH
using the following food tests. snd - -~ protei• n 1I s present.
CuS04
Solution - ~ .Pwrple/I j.'lac
to test colour
Testing for starch (a complex carbohydrate) • Fiigure 3.8 Test for prote~n
lo din ~
Red/brown - - - - - - - - . - Bl!utYb~ack
i A blue/black Testing for Upids
••Fe\lV drops ----- colour means A simple test for Iipid is to put a little of your sample
onto a piece of paper. If it leaves a greasy mark when it
iodine starch is present. is dry, lipid is present.
Substan.ce BIuelb1lack Alternatively, an emulsion test can be carried out.
to test A smal I quantity of alcohol is added to the test solution -
co·lour the mixture is shaken vigorously, A milky-white emulsion
is formed if fats are present.
• Figur e 3..6 Starch test
Your teacher will provide you with a 'mystery solution'
Testing for glucose (a simple carbohydrate) containing at least two different food groups. Can you
work out which groups it contains?
Benedict's
BI ue - - - - - - - - - - Orangeibrown
Blu~ A orange/brown Safety~Wear eye protection. Take care with the water
Benedict's --+- bath when carrying out the Benedict's test. Wash your
reagent colour means that
hands at the end of the practical.
S0l1ution - - - - glucose is present.
to test • Ca·rry out each of the food tests on the mystery
Orangelbrovvn so]utio n and observe, the resu Its.
Heat c o1lo u r
• Accurately inter,pret your data and expl,ain results
• Fi1gu·re 3~7 Test for glucose - ,a si1mple sugar. A water using correct sdentifi1c reasoning,.
ba1th set at 70°C can be used to heat the sotuti1on + Assessment opportunities
DI SCUSS REVIEW
Discuss in a small group what you have learnt about • What are the seven food groups that make up a
the nutrients organis·ms need to survive. What are
macromolecules? What are the building blocks of balanced diet?
macromolecules? • What are the constituent parts o·f carbohydrates,
3 How do org1anisms sustain t1hemse~es? lipids and proteins?
• How do you test food ·for:
o starch o protein
o glucose 0 lipid?
H T OCCU TH
oc S 0 7
•
Large insoluble molecules in our food must be broken down
into sman soluble ones, so that they can be absorb@d from
our giuts int o the blood and ultim.ately int o ce,Hs. The process
of digestion involves the physical (for exam p~e, t,eeth) and
ohem~cal (enzymes) br,eakdown of food.
ACTIVITY: Mod,elling digestion in the gut Glass rods
ATL
• ·'<;:.ri.tical..thinklng.s~.ill~: ~se:m.oc;lels ~o expl.Qr~ - - -- - - - - - Visking ----- --
c6:m·p1ex·&ste111s ' ' ' ' ·' tuhings
Dialysis tubing (also known as visking tubing) can be used Beakers
to model the digestion and absorption of foods in the - ---Distilled- -
intestine. Dialysistube is an artificial partially permeable
membrane made from cellulose or cellophane. water
You will need for this model: • Figure 3.:9 Making a model gut
• 10 cm3' of a 1°/o • Test tubes Safety: Wear eye protection when handling iodine
starch solution • A 10 cm3 p·ipette solution and Benedict's reagant. When c.arrying out
• 110 cm3 of a 1°/b • Dialysis tubing the Benedict's test, take care when using a water bath
to heat the solution.
amylase so lution • Iod ine solution
• Distil'led water • Bened.iet's reagent
• Beaker"S • Water bath
Use the dialysis tubing to model absorption of digested • How did you test for starch in the water surrounding
the visking tub ing1
food in the intestine. You could tackle this task and
• How did you test for maltose in the beaker water'?
group discussion with others in your class.
Design an experiment to: + Assessrnent opportunities
• demonstrate whether a carbohydrate food item*'
such as starch, is able to 1pass across a selectively
permeabJe membrane
• find out what happens when the starch is digested.
Can the products of digestion cross the m@mbran@
and i'f so w·hy'?
Evaluate how accurate your model is in demonstrating In this activity we have used a biological model to
demonstrate a complex system (see page 64 for an
how digestion and absorption happens in the gut.
evaluation of models).
Biology for the IB M Y P4&5: by Concept
THINK--PUZZLE- EXPLORE
ATL
·to' 'new• .~n·owle~"g~·
·Cr:~g~~e~.l·i~e~fr·:.atbteinki_ng'i.dskeiUa'ss: f,\pply _e;;isting - ' ' ·. . ' . . 1Maltose
. . . ·. . .
• ,Inf9rmatiop Iiter~cy s~Uls::-Acc~s~,.infe>rmatipn;to· Starc h
be inf.ormed
· ··
Look at the diagram of the digestive system below.
Prote1ns Amrno acids
,,.,,,,.
~IJ
Fatty adds and glycerol
• Fi,gure 3.10 The hum.an d~gesdve s.yst,em Lip ids/Fats
What do you think you know about the digestive
system aIready? • Figure 3.11 The breakdown ,of food int,o sm,aHer
What is the role of the digestive system? What do the
various parts do and why? molecuIe·s,
• What questions or puzz,les do you have? The digestive system1takes large moiecul,es and breaks. them
• Are there parts that you do not know about? What down into s1maller un~ts. Figure 3.11 show·s how this is done.
questions can you th1ink of to help you explore Earllier ~n thischapt,er we saw what the major food groups
these parts further? are made from - djges1ion breaks these mo~eoules down
• How can you explore this topic?
• Where cou Id you find out further information to into the~r smalllest ,c,omponent parts.
answer the questions you have?
But how is this done? Figure 3.12 shows ho,w ,and where
Make summary notes (for example, diagrams, Iists,
mind maps) on what you al ready know about the diifferent 1mdl,ecules ar,e broken down.
digestive system.
Bile, produced in the liver and stor,ed in the gall bladderl
+ Assessment opportunities helps to break down lip~ds through a process called
3 How do org1anisms sustain t1hemse~es? emulsification.
The bUe breaks down the Hp1ids into smaUer droplets so
that Iipase has a larger surface area to act on - th~s sp,eeds
up the djgestion process r(Figur,e 3.13). The issue of surface
area: volum,e ~s ,addressed in miore detail ~n Chapter 4
(pages 94~95).
The bile is also alk.aljne, which neutraHze,s the stoimach adds,
e,nsuriing the enzymes in the small intestine have·the
correct pH (pH 7-8) t,o work in.
Mouth
Breaks up food particles physically
.and chemically
Esophagus
Transports food
Liver Stomach
Breaks down and builds up many Stores antl churns food
biological molecules
Stores vitamins and iron Pepsin digests protejns
Destroys old blood cells
Destreys poisons - • • •... Hydrochloric add (HCI) activates
Bile aids in digest1on enzymes and k.Hls germs
Mucus protects stomach wall
Gall biadder
Stores and concentrates bile ~,-+.. . . JPan,reas
Hormones r-egulate blood glucose levels
SmalI intestine - --.---- Bicarbonates ne utralize stomach acid
Cempletes digestion Proteases sE?creted
Muc U$ protects gut wa11
Amylase secreted
Absorbs nutrients, and most water ..._ _ _lllliiiiliiiili•
t.i pases secreted
Proteases digest proteins
Lipases diges t liptds -.--11 Large intestine
Reabsorbs some water and ions
Amylase digests stareh to maltose ~orms and stores faeces
MaJtase. d1gests maltose to glucose
Anus
Opening for eliminatton of faeces
• fi,gure 3.12 What happ,ens where in the digiestive system
l arge tipid droplet SUMMARY REFLECTION
• What have you l'eamt about what occurs du ring the process of digestion?
• What new ideas or concepts have you learnt in thirs section?
Bil e REVIEW
• Figure .3:..13 Bile emulsif~es fats, • What three types of enzym.e di·.gest carbohydrates, Npfds and proteins?
cr,eat~ng a ~arger surfaiee area for • What does amylase do?
• What 'is the role of biile7
Ii pase to1 act on • Why does fo,od have to be digested?
Biology for the IB MYP 4&5: by Concept
CU DU I G THE ROC OF
H G?
In Chapter 2 w,e saw how oxygen is needed to fuUy release energy from glucose.
Ho,w do,E?s oxygen rea,c:h the ceUs?
WHAT MAKES YOU SAY THAT?
ATL What do you see that makes you say that?
• >Cr.e'ative·~thi.11king.~kill_s:·At>"p·1y:exi_stin·g k'iiowledge . Now ex'plain the features you have noted. Aim for at
-t~ ·gen,.e..ra't.·e·. nevi:id~as · · least five different adaptations. What features can
'• you explain that enable the breathing system t o move
~:e• .Inform.a~gn Ii1;er~sy IIs::·.f\cc.~~s;i_nf(':rm_a.~i.on: .p·e. oxygen into the blood at a fast enough rate to maintain
i n'f o°f11i"ed
life processes?
What's going on7
+ Assessrr1ent opportunities
Look at the diagram of the human breathing system.
Its role is to get oxygen into the blood and remove
carbon dioxide. The oxygen needs to be continually
supplied for respiration in cells - without this constant
input we would quickly die. Describe the way that the
breathing system is adapted to its function .
lnterc:ost.a l mus-de
Alveo li
• F'i,gure 3M14 The hum1an breathing syste,m
3 How do org1anisms sustain t1hemse~es?
ACTIVITY: Hovv does air enter --Bell jar-
and leave the lungs?
Thin .rubber ---=--~
ATL sheet
• .cr1tic~l~th'in~ing ·.s.~·~lls: Use mod;els t~.~}(pl~~~: • F1igu,re 3~15 A m1odel of the hu1man br,eathing s.y.stem
·comp~·ex-syst'ems
Pull down on the rubber sheet -what happens and why7
• Tfahsfe{skil Is: Make CorfnectiOhs bet:we~'n st1bJects . • What is missing from this model of the hum,an
:a~~.:· di~~1p_O,ne,~: breath inQ' s·ystem?
Air is drawn into the lungs by pressure changes in the
Create a model of the breathing system, as follows: thorax.
• Take a bell jar and attach a thin rubber sheet to the --------------------
open end. + Assessment opportunities
• Fi'x a ~v' sha_ped g·lass tu be to the top of the jar and
attach t wo ballioons to the end of the two branches.
What is represented by:
• the cavity of the beU jar
• the Y-shaped tube
• the balloons
• the rubber sheet'.?
Models are used to show the structure or
workings of a system .
The strength of models is that they are easy to
understand and can simplify complex process. Their
limitations are that they may be over simplified and
miss out essential details, and be less accurate than
the actuaI system .
ln,halation (breathing in) Ch,est wall lntraple,urall
• lntercostal muscles contract, pulUng the r1ibs. up and and ri.b cage space
out. Negative pressure
hreathing
• The d iaphragm contracts a1nd moves down (flattens).
• Figure 3.,16 Inhalation
• The volume o,f the thorax 1inareases, and so the
pressur,e decreas,es (see F~gure 3.16), drawing air into
the lungs.
• The pleural membranes surround~ng the lungs and
thoradc cavity ,ensures that the thorax is air-t~ght,,
enabling the pressure changes to oiecur.
Biology for the IB MYP 4&5: by Concept
Expiration (breathing out) How does the breathing system achiev,e the follow~ngi
• lnte·rcostal musd,es relax, moving the ribs down and in. th~ngs?
• The diaphragm re~ax,es and moves up (jnto a dom,e • A large surface area
• Concentration gradient (betwe,en a!ve,olar air and blood
shape).
capillaries)
• The vol1ume of the thorax decreases, and so the A smaH distanc,e for diffusion
pressure ,ncreases. These three1 factors ensure that ,oxygien diffuses fast enough
• Air is forced out of the lungs.
into the blood, and carbon dioxjde out from it.
Ventilation ,of the lungs (breath~ng) ensures there js always
fresh air entering the alveoli, which m1eans there is aiways EXTENSION: Fick's lavv
a1 djff,erence in ,oxy,gen concentration (i.e. a concentration
What can you find out about Fick's law, and how
gradient) between ~he alveolar air and the blood. Carbon
it relates to the rate of d iffusion of molecules?
dioxJde m1oves in the opposite direction, from .a higher
concentration ~n the blood t,o ,a ~ower ,concentration in the DISCUSS
alveolar air (see Figur,e 3.17). Diisc.uss with your neighbour how the human
• Why ~s there mo,r,e carbon dioxide in the blood enteringi breathing system maximizes gas exchange.
ihe lungs than in the a~veolar air? What has produc,ed
• Wihy does oxygen need to move into the blood?
1he ,carbon di1oxide?· • By what process does oxygen move into t he blood"
• Why do large 1organ~sms ne,ed a speda1Uy adapted gas and carbon diox,ide out from it?
exchange sys.tem7 • Why does carbon di oxide need to be removed from
• H,ow ls the breathing s,ystrem adapted to th~ job it the bl,ood.
• Excretion is t he process by wh1ich the waste
does?
products of metabolic reactions in cells are
- - - B'lood ,i,n
capfll la:ry removed from the body. Why is the remova l of C02
an excretion process?
• Why do we need a breathing system, whereas
smaller organisms do not? (This will be addressed
iin the next chapter.)
• Figure 3.·17 Oxygen (red .arrows), diffuses ~nto the·blood
at the .alveo~us, and carbon dtoxide diffuses from brood
(blue arr,ows)
3 How do org1anisms sustain t1hemse~es?
ACTIVITY: DIY circulatory
system
. ATL
• Cgerenaetriavtee.;:.tnh~inwk.iindgea·s·k~;.i:lmls:aU~ese·-uvhis_eu~ael cdl_ie~·ag:r.,aomnsrtieoctibhs-
JI T E Cl UL J RV .b..e_t\l'{~~n i.~.~.as; ~ppf,r.~xi~·iflg ~IJ.PWlep_g~ 10
ST M? gener,ii'te:W1ew ideas:· ..
Blood, Gontaining vital nutrients and oxygen, must be carri,ed Your task is to desi·g·n an organ system for the body that
to each ,ceH in the body·. Large multkeUular organisms are too does the fol lowing things:
~r,ge for 1his to happen without ass,s-tance. How then does • p.icks up oxyge·n,, glucose and other nutrieints, and
c.ircutates them ar,ound the body
food trav~ from the gut, where it is digested, to the eelIs
where it ~Si needed for rTieta boHe reactions? • supp lies oxyg1en, glucose and other nutrients to the
The organs of the body are composed of tissues whose ce Jls
cells are al~ve,. That m,eans they need glucose, ,oxygen and • gets rid of waste products from cells and takes them
o1her nutr~ents to perform their vari1ous jobs. and produce
to areas for export out of the body.
waste in the process (see Chapter 2).
So you need to invent a drculatory system!
The ce,Hs of the body nccupy fixed positions, far from
You need to draw a diagram of your design, and add
the source of fiood, oxygen and water. Also, the waste labels to show how it works.
products will poi1son them if they are not removed quick!y. Things to think about ...
An efficient system1is, therefore, needed to servic,e aU ceHs.
a) Getting oxygen into the body
• What vessels w'ilJ pick up oxyg·en,. and where will
they be located?
• How thick will these vessels be?
• What substance w in they conta in to carry the
oxygen?
• What other featute·s of these vesse,ls will speed up
the diffusion of oxygen into them? (Why would th,is
be 1important?)
• Figure 3.18 The human cir,cu~atory sys.tem
Biology for the IB MYP 4&5: by Concept
b) Getting glucose into the body f) Vessers under low pressure
• What vessel's wiU pick up g:lucose, a1nd where wiill they • Once the IUquid carrying the nutrients has passed
be focated? through th etissues which need them, the liquid will
• How thick willl these vessels be? have lost much of its ,pressure. (Thi.nk of a big river
that has split :into lots of smiaUer ones - tlhe speed
• What substance wiU they contai'n to carry the gl·ucose?
WiU this be the same as the substance that ca~ries the of the river slows down, due to fricti10,n and other
oxygen?
rea s o ns .)
c) Moving glucose, oxygen and other nutrients, to
• What adaptations wi11 the vessels of your circulatory
where they are needed system have now? How will they deal with the lower
• What structure wilil pump the substances needed by pressure, and .stop the liquid they contain ffowing
backwards'?
the body to where ·they are needed? What wo uId it
look like, and where would it be located? We will • Where wUI these vessels deltiver the liquid back to?
explore this important organ further on pages 69-71.
---------------------
d) Vessels under high pressure
• The o;rgan you have designed fn (c) above wiJI have 1+ Assessment opportunities
to move the nutrients ,n,eeded by the eel Is over large 6 ·- -- Pulmonary
distances (to the head and to the fu1rthest pa.rts
',I:! vem
of the body -hands and toes). The 11,iquid car,rying
the nutrients will, therefore, have to be under high r,:i
pressure g,oin g away from thi.s organ.
• What features wiH the vessels carryin,g: liquid away ]
from this organ have t o have t o deal with this high
·o
ptessure7
Pulmonary artery
nc:J::
_0g
c:.:., Vena cava
Heart
r hw..~ of"~~1t&fti.o~ trlAt R;titt V~tL k~!r htg ~res.s WOl.tLd Hepatic ve_in ...... - -l"IN!oiiiilll, .....~+--- Liver
Renal vein Mesenteric
~mtt t0 ~~e. arteries
J"'t:li~~ - t - - Stomach
e) Derivering the nutrients to the ceHs
• Once the nutrients arrive at the· ceUs, how wHI the - - - -- Renal artery
nutrients get into the cells? ~H-f-- - Kidney
• What vessel1s wiU ca rry the nutrients to the cells? • Figure 3~'19 The drculatory system1
(WiU they be the sa me as those in (d) above - or do the
adaptations of the vesse1ls und er h'igh pressure mean
that they can not be used to delive,r nutrients aII the
way to the celfs7)
3 How do org1anisms sustain t1hemse~es?
Facts about blood vessets: • Veins ,carry blood from the ca pilllaries back to the
heart.. under low pr·essur,e.
• Arteries carry blood ait high pressure aw·ay from the
hear1. • Veins do not have increases and decreases in
• Arteries abso,rb the heart beat (whi1ch we can feel Jn pressure and are adapted to stop blood from flowing
our pulse) - their contents increase and decreas,e in backwards, due to the low pressure. Veins have valves
pressure as th@ heart contracts and r~laxes. that stop the blood flowing backwards.
• Capillaries supply nutrients and oxygen to the ceHs by
diffusjon. They iearry away waste products from the cells.
ACTIVITY: The blood vessels
ATL Artery
.. .. -
• :,Cri~lc'al~thi nkin·g.~k_ills: Dr_aw reason~_ble·:c;ond~sio:n·s·
:anct ger"fer·aIiz ati ons·:
Using the information above, identify the following Capil'la rri es
blood vessels, and explain your choices to your • Figure 3.21 The blood vessels of the drcu~aitory
neighbour. system
Thick. el·artic wa ll - - - - P Explore the circulation of blood around the body further
A Small lurnen - - - - - - here: www.kscience.co. uk/animations/bJood _system~htm
Thin Weill _ _ _ _ __.,. + Assessment opportunities
Large lu.men _ _ _ _...,.
B
Valve - - - - - - -
C
• fi,gure 3~20 Differences between the different
bllood vessels
Biology for the IB MYP 4&5: by Concept
H JI THE TRUCTU RE ND FUN TIO
0 T EH T?
We have already investigated the rolle ,of the circulatory system1, and how it i1s
adapted t,o its role. Now let's ~ook miore dos,ely at the organ that is central to the
w,orki1ng of the drieuiatory system -the heart!
The heart is a doub~e pumip that pushes blood first to the lungts under low
press1ure, and then to the rest of the body under high pr1essure.
The heart contains two types of chamber:
• The atria - receive blood into the heart
• The ventrifles - push b~ood to lungs and rest of the bodry.
Heart valves, as in the v,eins, prevent blood from going the,wrong dlrecd-on.
ACTIVITY: The heart • For one of these, eh oose a colour that you feel best
i - ATL represents or captures the essence of that idea.
• For another one, eh ouse a symbol that you feel best
• Cr,e·~~i_ve..t~inidng ski}is:'A.pply~existi_n_g·k~owleclge.·
,to generate,_newJdeas represents or captures the essence of that idea.
-lnfo.·rmatton literacy ~kills: Accessinformation·to_,be : • For the other one, choose an image that you feel best
rep,resents or captures the esse·nce of that idea.
Tnto·rn,ed
iCOLOUR-SYMBOL- IMAGE With a partner or group first share your colour and then
Find a source of information about the function of the share the item that it represents. Say why you choose
heart (this may be in a book, on the Internet or in a that colour as a representation of that idea. Repeat the
magazine). As you read about the heart, make notes of
things that you find interesting, important, or insightful. sharing process until every member of the group has
When you finish, choose three of these items that most shared his or her colour, symbol and image.
stand out for you.
Your colour, symbol and image may each focus on
different roles that the heart plays. The heart:
• pumps bl1ood to lungs and to the rest of body
• allows blood to be pumped to lungs at lower pressure
than it is pumped to the rest o·f the body
• keeps oxygenated bl1ood (from lungs) separate from
deoxygenated blood (from the rest o,f body)
• maximizes the efficiency of oxygen delivery to tissues
• makes sure blood t1ravels in one direction thro,ugh the
body..
Now watch how the heart contraction moves blood
through the heart here: www.kscience.eo.uk/a nimatio ns/
heart.htm
3 How do org1anisms sustain t1hemse~es?
Fig1 ure 3.23 shows a labeUed and annotated heart. EXTENSION
Pulmonary veins ~ --....11 - - - - M1itral valve What controls the contraction
of the heart? Use these search
from lungs - - - Sem1ilUrnar valve terms: pacemaker, AN, AV
node, electricaJactivity.
Super,ior vena cava _ _,,,
Practise·labelling the heart here:
Atrial septum---~
www.kscience .co. uklanimations/
Tricuspid valve ~~---+
heart_label ling.htm
SemH u1nar va!v • Oxyge11-richi blood Ventricu lar
D Oxygen-poor blood REVIEW
septum
• How do nutiri,ents and oxygen
AO -1 Ao,rta reach the celtls of the body?
PA =Pu11mon ary arte,ry • How do the three different
LA = Left atrium blood vessel,s, arteries,
RA;; Right atrium capiHariies and veins, vary in
lV = · Left ventricJe
RV -= Right ventri de s·tructure a1nd function?
• Figure 3..2,3 The anatomy of the, heart • Draw and label a d1ia,g1ram of
The heart ensures that each cell ~n the bod~ rece,v,es a constant supp~ of oxy9en the heart. Elcplain how blood
and food, and has waste products remov1ed such as urea and carbon dioxide.
passes from the h1 eart to the
To lung To lung lungs, back to the heart, and
From lung From lung then to the rest of the body.
• Figure 3.24 Blood
From lower body DOxygenated blood flow through the
heart
D Deoxygenated bl'ood
Biology for the IB MYP 4&5: by Concept
REVIEW
Look at the fol lowing two diagrams:
., ~.Lungs Supply of bJood to luings CapiUaries in lungs where
(puImona·ry circult)~
.L shorte.r distance to gas exchange occurs
.I' I'f'
II hear-t .so lower Aorta.
pressure necessary Left atrium
' Pulmonary
PU'lmonary Left ventricle
Pulmonary vein
artery artery
A Vena ca.va. - - -
I
Heart - - - -
- - - -· I Right a,tr1ium
Right ve n.tricle
Very [ow pressure RA= Right atrium
RV ::: Right ventricle
Aorta IA !!!:! Left atrium
High pressure
lVeins LV Left ventr1c'le Suppfy of bfood to
rest of body
Arteries r~ Tricusptd valve (systemi·c circu it):
) ~}Arterioles greater distance
QVenules r ~ 6icu~1d valve Key
· -.· Semilunar valve~ from heart requi.res
'-.__ Capillaries - Oxygen-rich.
(02-poor blood higher p.ressure
Low pressure
;;;;; Oxygen -poor. CapHlaries in tissues for
gas exchange and supply
C02-rich blood of nutrients to ceJls
@
• Figure 3~2.S The pas5age aif blood through the· heart • f ,ig'uire 3.26 Blood supply·to and from the heart
• What have you learn,t about how substances a·re • What have you learnt about the structure and
transported around an organ·ism? function of the hea,rt?
• What have you learnt about how·the structure of the
ci'rculatory system .is related to its function1
3 How do org1anisms sustain t1hemse~es?
0 D UB TA M
I OUT F LL ?
Substances must move from the jntestlnes and lungs into These diagrams show how molecules move,from hi,gh
the blood. Carbon dioxide must mov,e from the biood ~nto
to low concentrad,on - this i1s ,called diffusion. Through
the alveoli. How does this. happen? random move,ment, more molecul,es are ,going to m,ove
from a h~gher concentratlion to,a lower one than vke versa.
Look carefuUy at the following tw,o diagrams:
Oxygen moves from the alveoli in the lungs into the blood,
- Lumen of sma:11intest~ne and carbon dioxide from the blood into the alveo~i ,(this
is known as g.as e~change). In the intest~ne (g1ut), food
.fillm
molecuJes such as glucose move from the lumen (the space
- - -..............~ ,,__- !:pitn~Ma,I: cell
in the middle of the intestine where the food moves) ~nto the
• fig u:re 3.27 Movement of glucose from lrnmen of smaU ceUs fh1i1ng the gut (epitheHal ceHs) and then ,nto the blood.
inte,stine to epithelial ceH .and ,on into b~ood
Look ,agdin at the lower part of Fi1gure 3.27. There is a higher
concentration of giucose in the b~ood than 1n the ep irthel1ial
ceUs. How can gluc,os,e move from the ceHs into the b!ood?
The answer lies in a1dijfferent way in which molecules ,can
move, caHed active transport. Active transport moves
o.e.molecules from lower to higher concentrati,on against
their concentration gradient) - th~s needs ener9y from
respiration .
Active trarisport is a process in
cells that moves substances
against a concentration
gradient, from IONer to higher
concentration. This process
requires energy from respiration .
a. . • f 'igure 3..28 Imagine you are try:ing to push
J. a ca,rt 1up a hJ:11 - you wi1II need a
IMovement of lot of energy to get to the top!
(01
carbon dioxide • Figu re 3..29 Acbve 1ransport requ~res energy
02
f rom1lbfiood, There ~s .a furth,er way in which molecules are moved-
(02 (02
and oxy,9en osmosis. We wm ~nvest~gate this in the follow~ng acUvity.
(Oz
~nto blood .at
C02 a,v.eolus
Biology for the IB M Y P4&5: by Concept
ACTIVITY: Osmosis
Osmosis is the diffusion of water through a partially permeable membrane. DISCUSS
Because water is very important to living things, we give the movement of Describe to your neighbour what
water into and out from cells a special name. The cell membrane is partially is happening in the following
permeable because it lets some molecules through freely but not others.
diagrams:
Look at the following diagram. Can you describe and explain what is
happening?
30 minutes 30 mi1nutes
later
later
3~70 saI.t soJ.ut1•on
Partial:ly
permeable ------"r--
m e m b ra11 e -----
Disti·lled - ~ Pure Sucrose Sucrose Pure
solution water
vvater water soluti.on
• Figure 3.. 30 An ,osmometer. The· par1ial~y permeable membrane 1c:ould be • Figure 3.31 Osmosis jn actijon
viski11g tubing
Complete the following diagram
The water can pass through the partially permeable membrane because by adding similarities and
it is small enough to fit through the pores in the membrane, but the salt differences between the th ree
cannot as it is too big.
processes:
• How does this model what happens in cells?
• What would happen if you put an ani·maI cell i'n pu.re water?
+ Assessment opportunities
SUMMARY REFLECTION • Fig ure 3~32 Comparing
• What have you learnt about how substa nces move in and out of ce ll!s7 diftus1ion; osmosis and act~v,e
• What processes are irnvo1lved in move·ment and transpo rtl
• What are diffus.ion, osmosis and active transport? transport
• What have you learnt about the process of osmosis? How is it different
to diffu.sion?
3 How do org1anisms sustain t1hemse~es?
H JI HOME I? ACTIVITY: Keeping conditions
Your body needs to keep irts·elf wi1thin stdct limits - ~t the constant
,conditions stray outs~de these lirmits then your health, and
ultimaite~y your Hfe, may be in danger. ATL
Keepjng cond,tJons balanced wi1hin the body ~s eaUed to• Cre~ti_v,e..thin.~i-ng -_s~i lls: Apply existi'ng.knowl~gge
homeostasi s. .generate:;ri-ew·ide'as. . . ' ..
.· ·
The foHowingi factors must be kept in balance: Discuss the following with your partner:
tempe,rature 1 Why must te.mperature be kept the same? Use your
• pH knowledge ·of enzymes (pages 40- 45) to explain
• wat,er leve~s in blood and fliuids surrounding tissues wh·y.
• sugar leve·ls in blood 2 How is tempe'rature kept constant? Thi1nk about:
• Co2 !levels in blood. a What happens when you get too hot?
b What happens when you get too cold?
The f0Uow~ng1activ~ty ,gets you to think about why you must Search terms: vasodilation, vasoconstriction,
keep conditions constant wi"thin your body. sweat, s ivering, piloerection.
3 Why must the pH of your blood be kept co nstant1
Temperature and pH rmust be k,ept constant to ensure that Use your knowledge of enzymes to explain why.
enzymes have the opti1mum cond~tions to work in and do 4 Why must the water level i·n your blood be kept
not denature.
constant? Use your knowledge of osmosis (page 73)
Carbon dioxide, when dissolved in blood, lowers the pH and to help you~
crea1t~s an acidic enViironment. The carbon dioxide must S Why must the sugar level i1n your blood be kept
constant? Use your knowledge of respiration
therefore, be removed by breathing it out. (pages 28-32) and osmosis to explain why.
Too much ,or too littlre water in the blood creates osmotic Analyse and evaluate the knowledge you have
learnt in this chapter about how organisms sus-tain
effects - water wm ejther move into ceHs in the biood (too
themselves. Appl.y this understanding to make
much water) causing them1to, burst or move out of cel~s 1
(too little,water) by osmosis. E~ther can be damagi~ngi for
scientifically supported judgements about how
the body. organisms keep their internal environment constant.
Your blood sugar level must be constant because,too much + Assessrnent opportunities
sugar m1etU'IS1that there ~s a lower water concentr,a1ion in the
blood, and so water moves into the blood from the tissues
leading to the body becoming dehydrated. Resp~ration ~n
cells needs a reguJar supply of gllucose in the dght quantitijes
-too much sugar can be as serious as too little.
Biology for the IB M Y P4&5: by Concept
How is sugar 1,evel controlled? EXTENSION
• After a meall, digested sugar enb~rs the blood. How does the kidney filter urea from the blood and
• Higher blood-sugar level is detected by the pancreas.
contro I water levels in the body? Exp lore further
• The pancreas r1eleases the hormone insulin. here: www.kscience.co.uklanimations/kidney.htm
• Insulin tiravells around the body in the blood. EXTENSION
• At musde and Hver ce,Us, ins.uUn ~nstructs ceUs to stor1e
How does the body regulate temperature?
glucose as iglycogen. Find out about the thermoregu latory horn eostatic
• The blood sugar levei returns to normal. mechanisms: awd ilatian, vasoc;onstri etion,
A second hormone is used ~f blood-sugar l,evels ar,e too swea ing, hivering, piloerection .
low. GJucagon instructs ceUs to bre,ak glycogien down into
glucose. How do poikilothermic (co ld-blooded) organisms
regulate their temperature?
Mainy homeostatic mechanisms use ho,rmones in this w.ay.
Produce a summary poster of how
Explore further here: www.abpischooJs.org.uk/pageJ
modu res/d ia betes/d ia betes 4.cfm t hermoregulation works.
Raise:s .§>r,:..,@ Hi g h
bi ood r ~) ·~
b lood
sugar @
sugar
Glucagon SUMMARY REFLECTION
s~mo,ates breakdoivn • What have you learnt about ho meostasis?
• Why do the conditions within orga nisms need to be
of gly<:Og,en
'kept in ba lance?
StimuJartes format\on
of glycogen
--- -- - --- ------- -
Stimulates gitucose REVIEW
t1ptake from bJood
Describe and explain how and why the following
\ \.· Tis.s ue ceMs
(muscJe, kidney, ·fat) conditions in the body must be controlled:
.(j
Low • temperature
Lowers - . ~ " bl ood • pH
, blood
:_~ © s uga r· • wat er leve1ls in blood and fluids surro,unding fiss ues
• sugar leve ls in blood
sugar
• Co2 levels ·in blood.
• Fig ure 3~33 lnsullin .and giucag1on control sjugar i,ev,ells ~n
the blood
3 How do org1anisms sustain t1hemse~es?
ACTIVITY: Investigating the
carbon cycle
H JI T EC ON CYCLE? Think about the following:
• What biolog"ica l molecules (ontain carbon'? (,Remind
AlI e~em,ents in I~Vlng things, such as carbon, oxygen and
·yourself on pages 56-57.)
hydrogren, cycle between the physiieal environment and the • What pro,cess releases carbon dioxide from l1iving
biotic (Le. Hving) part ,of ecosystems {i.e. the community). things? (See pages 30-31 if you need hel'p here.)
Without such cycl1ing, nutri1,~nts would end up in dead • What process takes in carbon dioxide and conve1rts it
orgi3nisms, faeces and waste, and not get returned to living into glucose? (Reminder on pag1es 33-34.)
matter.
• How does carbon pass from o,ne o,rganism to the next
In this section we will inves.-ti,gate how two elements- in a food cha jn?
,carbon and n~trogen - cyde.
• Bacteria. fungi and other decomposers feed ,on
dead organi·sms and waste material (such as faeces).
How would these organisms return carbon into the
atmos;phere7
• Under the iright conditi,ons, carbon i·n dead o·tganism,s
is locked up in coal., oiit gas and other f ossi I fuels.
Hi·gh pressure and incomp.lete decay ,lead to the
production of such fossil f ue:ls over thousands of
years. How is the carbon in these materials being
returned to the atmosphere?
Now complete the diagram on the next page.
Words to use: respiration, photosynthesis, combustion,
carbon dioxide, decomposition, consumption/eaten by
Biology for the IB MYP 4&5: by Concept
DODD
ODD D D
DD
• Fi g1 ure 3.34 The carbon cyde 1+ Assessrnent opp1ortunities
EXTENSION
• What role does limestone play in the ca rbon
cycle?
• Can you find out how much ca rbon is
stored in each of the reservoirs in which it is
found (for example, the ocean, fossil fuels,
the atmosphere, sedimentary rock., the
Earth's mantle)?
• How are human activities affecting the
ca rbon cycle?
3 How do org1anisms sustain t1hemse~es?
ACTIVITY: The nitrogen cycle
ATL You will find that the whole nitrogen cycle is driven by
• .lfifotmation liferacfskills; .Access infofmatio11.to four types of bacteria - but which bacteria does what,
:b.e.info:rmeg and how do they Iink together to make a cycle?
Your task in this activity is to find out about the nitrogen EXTENSION
cycle and make your own :summary diagram to show • How do waterlogged soi Is affeet the
how nitrogen moves from the atmosphere and into nitrogen cycle?
• Why do earn ivorous plants, pitcher plants,
living things, and how it is then returned to the physical
sundew, Venus flytrap exist?
environment.
+ Assessment opportunities
Find out about the nitrogen cycle using these search
terms: decomposers, nitrogen-fixing bacteria,
nitrifyi ng bacteria, den itrifyin g bacteria, ammonia,
nitrite, nit~ e.
Help is also available here: www.classzone.com/books/
ml_science_share/vis _sim/em05_pg2D_nitrogen/en10S_
pg2 O_nitrogen .swf
HE DISCUSS
C E? D,iscuss with your neighbour what you found out about the nitrogen cycle.
Check your understanding using the following figure:
As we have se,en earlier 1n the
dhapter (pages 56- 57), nitrogen
1is needed in Uving things to make
pr,ot,ein. Organisms have diffkulty in
using ni1Jrogen gas directly from the
atmosphere - it is a v,ery unreactive
gas and only one group of bacter~a
have evo~ved the abiIrty to use nitrogien
directfy to make ,other c,ompounds.
• f ·igure 3.,35 The nitrogen cyde
Biology for the IB MYP 4&5: by Concept
In thiSi chapter we have investigated how a healthy djet There, are many diets available to help people lose we~ght.
Their@ are also legal drugis that p,eople can take to aid weight
provides the,body with alI the nutne11ts it needs to,function
loss. These drugs can:
properfry. som,e peopie have metaboiic conditions that mean
• suppr,ess appetite (peop~e feel l,ess hungiry s,o eat i,ess)
that they put on wei1ght and can become overweight. Other
people may become obese because they have an unhealthy • ~nhjbit fat absorption 1n the intest~ne (less fat is,
absorbed jnto the b~ood and, hence, rinto ceHs)
diet where the amount of energy they consume jn their
• ~ncrease ceU m,etabolism (so more food is broken down
food is not ba~anc,ed by the amount of energy they expend. in eelIs to rrelease energy).
THINK- PUZZLE- EXPLORE
• Fi·gure 3..36 Pharmae:eutkal drugs can be used to aid Consider what 'legal' means and why some drugs are
weigrht loss. Examples of .such drugs indude orl~stat legal but others are not.
(Am or Xenkall), sibutram ine (Merjdia) and lorcaseriin
(Be1lviq) In your group, prepare a presentation of what you have
found. The presentation should educate the public
ATL about these drugs-their use and possible abuse. Should
people use legal drugs to try to control their weight?
• c'.omm_1.H1k_a;tion_Jk:ills: Use a·~~rrety·ofmedi·a ~o ·
Allocate roles in your group. Communicate together and
.·communicate'.with.a.tangf ofaud ience~;'·.Negotiate
with your teacher to assess the information and weigh
up the evidence.
Aim to use a variety of media in your presentation -
for example, as well as the presentation itself (which
could be a PowerPoint) you could also have hand-outs
available so that people can take away and read the
information you have provided. Make the information
visually interesting, and be aware of the sensitive nature
of the material you will be talking about,
+ Assessment opportunities
icl~S:·~ith .·pe~r·s and.teache{S .
In smaU groups, research ight-con rol drug ,
and rec,ord your findings. Which people ar,e 1generaUy
prescribed these drugs, and why?' Should overweight
p~iap~e, rn g,enera!~ hav9 access to these drugs? Are there
dang1ers in using these drugis?
www.drugs.com/artic le/pres cri ptio n-we ig ht-loss-drugs. html
www.n hs. uk/Con di t i ons/0 besity/Pages/Treatment .as px
3 How do org1anisms sustain t1hemse~es?
REVIEW
Brainstorm a list of at least 12 questions about the
topk. Use these question-starts to help you think of
interesting questions:
• Why ...?
• How wouJd it be different if ...7
• What are the reasons ...?
• Suppose that ...?
• What 1if ...?
• What if we !knew ....?
• What is the purpose of ...?
• What ·would change if .u?
Review the brainstormed list and star the questions
that seem most interesting. Then, select one or more
of the starred questions to discuss for a few moments.
• What new ideas do you have about the topic that
you didn't have before?
What have you learnt about yourself as a
knowledgeable scientist? How have you developed
and used conceptual understanding, and explored
knowledge across a range of disciplines?
Biology for the IB MYP 4&5: by Concept
OMES M TIV P BL s Which food groups w,ere present in each food sample?
Justify your answers us~ngi evidence fro,m the results
T give,n.
Use thes,e problems to apply and extend your leairn~ng in THESE PROBLEMS CAN BE US OTO EVALUATE YOUR
this chapter.Thes,e problems are designed so that you can EARNlNG IN CRITERION A TO LEVEL 5-6
evalluate your ~,earn~ng at d~fferent leve~s of achjev1ement in 6 a Descr1ibe two ways ~n whkh the mouth can break
Criterion A: Kn owi,edge a11d u11derstanding. down starchy foods.
THESE PROBLEMS CAN IBE USED TO EVALUATE YOUR b Describe hO\N the liver he~ps to digest fats.
LEARNING IN CRITERION A TO LEVEL 1- 2
c Describe one ro~e of bile ,other than help~ng to digest
1 State the seven components in a balanced diet. fats.
2 State the elements found ~n prote;ns.
7 D1esc:rjbe how oxygen fri0m1the air reaches. c,eUs ~n our
3 a Suggest why snack1lng on chocdlate, crisps aind soft body.
dr~nks is an unsuitdbie d~et for ch1ildren who are not 8 The following dii,agram shows four ways in whtch
mollecules may move tnto and out of a,cell. The,dots
very active. represent the concentration of the dffferent molecules.
b Su1ggest the lhea,th problems that might develop ~f
AB
children have too n1u,ch fat in their diet.
CD
THESE PROBLEMS CAN IBE USED TO EVALUATE YOUR
EARNING IN CRI ERION A TO LEVEL 3- 4 • Figure 3 . 31 Movem,ent of mo!,ecu~es into and out fro:m
4 outUn1e the ro,ie of diges'tio,n in the body. a cel l
5 Three different foods w,ere tested for different food a Whkh arrow represents movem,ent of oxygen
groups,. The fol lowing results were found: molecul,es?
: 1fo od sample Test Res ult b Whtch arrow represents movement of carbon
Oran9e/brown
Food 1 diox~de?
c W hkh arrow represents the active transport of
Benedict's sclut~on Blue,
glucose moll,ecul,es?
Bi1uret test Purpl,e/tlilac
9 D·esc1ribe the drfferences betw,een arterir·es, capmar1i1es
Food2 Paper test Greasy mrark present and ve,ins.
Iodine solution
Bluelbllack
Benedkt's sotut~on B,!ru,e·
B,iuret test Blue
Food 3 Parper test No change
lod~ne so! ution Orangelb:rown
Benedkt's sdut•on Orange predpitate
B,~uret test Blue
Paper test No change
3 How do org1anisms sustain t1hemse~es?
1 The f,ollowung diagram1shows ttie drculatory systems of three differ,ent an1imals:
a Gtll capilliaries b l ung and skin c:apillaries c Lung:cap il1ar,ies
Artery
Heart:
Ventride (V} -
Atrium (N - -
Vein - - -
Systemk capi,llaries Systemic. GlpiUairiies Systemi,c capill aries
• Figure 3.38 The drcu~atory systems of a fish~b amphibians and c mammals
a Descri:be the,diff,erences betw,een the three di1fferent drcuiatory systems.
b Suggest what is meant by 'systemk1 capiUaide,s.
c Su,ggest the advantages,of having a mammalian heart c,ompared to an
a1miph~bjan or .a fish heart
Biology for the IB MYP 4& 5: by Concept
THESE PROBlEMS CAN BE USED TO EVALUATE YOUR 1 An experiment was ,carried o~t to investi,gat,e osmosis
~n potatoes. Chips were, removed from a potato
lEARNING IN CRITERION A TO lEVEL 7- 8
(Figure 3.41 ).
1 An 1expedment was set up to inves1iga1e os1mosis.
The foUowijng equipment was us,ed:
,---------- le·vel of solution
at the stairt of
the investigation
~ -1-- - Visking tub~ng • Figure 3.,41 Preparing potato chijps for osmosi,s
,exper~ rment
cointah,ing
The ,chips were cut to 30m,m ~n length and the mass
corice·ntrated of each recorded. Each ch~p was placed in a different
concentration of sucrose so,fution, from 0.0 to
salt solution
1.0moldm-3 . After 40 m~nutes, the,chips wer,e rem,oved
• Figure 3.39 lnvest~giating, osmosis
and re-weighed. The perce,11ta9e change 1in mass wa5
a What is osmos~s?
calculated fo1r an chips (the dh.ange in mass di~ded by the,
b Describe and exp1fain what wm happen to the iev,el
odgin,at mass, multripHed by 100). A graph was plott,ed
of solut1ion in the cap~Hary tube during the experiment. showtng percentarge iehainge ~n m,ass against sucrose
c R,ed bfood ceHs were put ~nto different concentrations concentration (Fig1ure 3.42 overl1eaf).
of sa,t solution. F1i,g1ur,e 3.40 show·s th~ app,earance of
the bl,ood ceHs after 10 minutes.
Using,your knowl,edge·,of osmo,s,is, suggest
reasons for the app,earance of the ce,Us in ,each
solut~on, Ai B and C.
ii Expla1in the appear.anc,e of a plant ceU placed in a
sotution of pur,e water.
Solution A- pure water Solution 8 medium sah solution SoJution C - strong sa~ so'lurtio:n
-- _____,-_·...\Cell bursts Ce'II outline
- becomes
crinkled
CeII so,lution be cornes
ma're coneentrated
• Figuire 3.40 Red blood ceHs, ~n ai range of different c1oncentrations o1 f salt
3 How do org,anisms sustain t1hemse~es?
25
20
15
I 1(}
·-E s
Gima, 0 I Ou ,;
C II I Sucrose concentration 11
....1c11 5 (mol/ dml')
"' 15
C
l - 1:;
-Ln
-I
• Figure 3.42 Graph showh1g percent changfl 1in m,ass of
p,otato1 ,ch,ps a1t different sucrose concentrations
a Describe and exp,lain the results shown jn
Fi,gure 3.42.
b EvaIuate the e,xpedment.
How could the r,eliab~iity have been improved?
ii What were ~he !limitations of the experiment?
iii How would Umitations have affected th,e accuracy
of the result?
H,ow could the experiment have been ~mproved to
reduce t hese limitat~ons and ~mprove accuracy?
Biology for the IB MYP 4& 5: by Concept
R
In this chapter we have explored how the body can ach~eve a balanced di,et, -.,
and how the nutrients we need reach our cells. W,e have seen how el,em,ents Any 'further questions.now?
pre,sent in our food and bodies cyde between the environment and Uviing matter.
We have discus.sed how ,oxygen is aibso~bed and transported to cells, and how
waste products ar,e remov,ed, so that a state ,of ba~ance can be m1aintained in
the body. We have app~iedlour knowledg.e to discuss whether people should
use drugs to contro~ their w,eight, and how we can promote heaithy eating
in our local community. We have learnt how to develop .and us,e conceptual
understanding, and focused on the role of kno~edgie tn sdentif~c endeavot,r.
t~r.m11:.1.itl.W.n.-:i"i rnM.;.';~~.-;~•..:.-1T,,;111dr~ 1nni'r;Ki11i11n~ n:T; e)l"d~ ·-· ,I
Quest1ions we asked Answers we found
f actu al: What nutnents do organismis need to survive? What
occurs duning the process of d~ges:bon? What occurs dur~ng1the
process of gas excha nge? How are substances transported around
an organ•sm7' How do substances 1move i1n and out of ceHs7' Wha1
are d1rffus~o1n. osmos~s and actijv,e transport? What ~s homeos1arsi,s7
How do e~e;meints essential for life cyde lbetw,een the ,environment
aind organisms?
Conceptual: What processes are ~nvotved ~n mov,em,ent and
1ranspo:rt? Why do the condidons w1ith~n organ•sms need to be kept
in bafance?
Debata ble: Should peopl,e use dn.11,gs to1 try to contrdl their we~ght?
A ppro aches to learn~ng you 1used ~n this d1ap1er Descript~on - what new s.kms How wel~d id y,ou rmaster the
d~d you learn? skiHs?
I.
QJ
... ·-.....0
C:
Q)
t:
C:
(l)
'8 -~ni.:.,.
!z d:
Crit ica 1-th inking skills
Creative-thinking skill s
Communicatio n skiIIs
Transfer skil Is
Jnformati on literacy skills
Collabor atio n skills
Learn.er p rofile attr4bute(s) How d~d you demonstrate betng know1,edgeabie En this
Knowledgeable
chapter?
3 How do org1anisms sustain t1hemse~es?
CONSIDER AND ANSWER
THESE QUESTIONS:
• f jgure 4 . 1 An African ,e~ephant - an example of a (very)
lar,ge organi1s1m
IN THIS CHAPTER, WE WILL ...
• Find out how the ·s~z,e of an organism p!ays
an important rr0le in its rellat1onsh1ip Wlth the
environment, and issues they face as 1hey get bigg,er.
• Explore how d~ff,er,ent animals and plants are
adapted to the environm,ent they live in.
• Take action by planning how endangered large
an~malsl such as elephants and t~gers, can be
protected in the wiid or in zoos, so as to meet thek
needs and support surv1ival.
Biology for the IB MYP 4&5: by Concept
• f ,ig1ure 4 .2 A sele·ction of plants and animals. How are In the examples shown rn Figure 4.2,: each or,ganism is
they .adapted to the,ir respect~ve envir,o11ments?
adapted to rits envir,onment, aUow1ing them to survive
These Approaches to Learning (ATL)
o.ften rin extr,eme cond~tions. Adaptations can be phys~cal
skills wi!I be useful ... featur,es such as s~ze ,and shap,e, behavioural characterirsttcs
such as how .an an~mal lives. with others in its group, or
• ·criti.c:al-thipking ~kH~·s
physiological adaptatirons whi,ch !nvo,lve the function ,of the
• Creat.iv~thinki,ngskills . organjsm's body, such as temperature regulation. Can you
identify the different adaptations for ,each organism? What
adaptation physiological about other adaptat~ons that you may not be able to see in
behavioural sp eci aIi zed
implications the photos?'
In the ~ast chapter we·explored how an~mals maintain ,a
constant ,~nvironment jn th~fr bodles - the process known
as homeostasJs. Adaptat~ons in animais ,enable the,m
to ma.in:tajn ho,meostas~s, even in e,xtreme env~ronments.
Organisms that are adapted to spedfic. env~ronments are
known by c,ertain terms, such as speci,es of plants adapted
to dry conditrions which ar,e known ,as xerophytes ,(from
'xerot whi,ch means dry, and 'phyte' wh~ch me.ans p~ant}i.
In Chapter 7 we wUI exp~ore the wonk of nijneteenth-
centu ry scienttst- adventur,er Charles Darw1n. He m1ade the
link between animal adapta1t~ons and specie·s' survival, and
what happe·ns to spedes when thefr environment changes.
In order to survive and reproduce, an organism1must be
perfectliy adapt,ed to their sunound ~ngs- if not then it wi~I
not s.urvive and pass on jts genes to the next generat~on
(somethjng we wrn look at further in Chapter 6),.
4 What issues do largier organi·sms fac,e?'
What's going on? Su p e r . o r -....lt .------._ Mitra! valve
ve na ca,va
Choose an organism, and find a photo of it that clearly Atri,al ------1 ---...._ Se miru nar
septum va lve
shows its adaptations.
Tncuspid Ventri cular
http:/lwaynesword.pa Iomar.edu/1mexe10 b.ht m septum
valve
Des,cribe the way of life that the organism is adapted
to (for exam pie, 'adapted to life in the desert' if it is a lnferio1r
camel). List all the environmental factors that may affect
vena - -----
the organism (such as a regular supply of water if it is a
plant, or temperature if is an animal living at the North cava
or South Pole). AO =· Amta RA; R.ight atrium
• Oxygen-rich bl'ood PA;;:: Pul'mortary artery
LV = Left ventrid e
D Oxygen- poor brood LA;:; Left atrium RV ;:; Right venitrk le
• Fig,ure 4.3 Th e human heart
What do you see that makes you say that? ( ,j:li ary
Now describe and ex.plain the features that adapt. the muscle - --
organism to its environment (for example, the hump on
~ ~ - - Vitreo us
a camel that stores fat and which can be broken down hum our
to release energy and a source of water). Aim for at
least five different adaptations. What features can you • Fig,ure 4m4 The huma1n eye
• What's go ing on? What is the role of the org:an 1in the
describe and explain that enable them to overcome the
environmental factors you have listed? body?
• What do you see that makes you say that7
Alternatively, forth is activity, you could choose to talk
What adaptations can you see in the organ that
about an organ from within an organism, such as the enable it to ·fuHil its function?
heart or eye (Figure 4.3 and Figure 4.4).
+ Assessment opportunities
Biology for the IB M Y P4&5: by Concept
The ,envirorunent that an organism is adapted to can include
many d~ff@rent factors- temperature, the ava~labiljty of
water, the amount of sunUght, food - depend~ngi on the
type of organism and the way i1 Hves. Adaptations.may be
outwardly v1stble, such as the hump (or humps), on c,amels
(one hump on a dro,medary a1nd two orl a1bactirian). Other
adaptations are hidden within the body: think of the four-
chambered heart in mammais that separates oxygenated
and deoxygenated blood and enables oxygen-ndh blood to,
be deHvered to all ceUs, for example,(see Chapter 3), or the
reti1na cells.at the back of the eye that ,enable us to see {see
Clhaipter S).
• Figure 4 .i6 Dromedary camiel
• Figure 4,.S Bactr1.an ,cam,el • Figure 4.7 A huimpback whale· .and her calf. How i1s a
4 What issues do largier organi·sms fac,e?' whale adapted to its environmient7
What specialized structures
do larger animals have
inside their bodies? SPECIALIZED STRUCTURES IN
How do they help LARGER ANIMALS
animals survive?
Tw,o essential ingredients needed for surv1ival are food and
oxy,gen (as we exp~ored in Chapter 2). What adaptations do
animals have to jncrease the rat,e at w hich these life-giving
substance5 can be taken into the body?
THINK- PAIR- SHARE Pl'ace,nra
ATL PtaJ;:enta
Fetus' blood
vessels
• .critical-thin~ing skills::Dr~W reasonable .cond usio~ns Place'nta l
and. g·:'~. ne. raliz. ..ati9n·.s1 membrane
Look at the four figures shown here. How is each organ UmbilicaJr
adapted to increase the rate of movement of substances., cord
such as food or vital gases (oxygen in animals and carbon J&'-1'-- Intervtll'ous Umbiilical
dioxide in plants) into the organism? Pick one of the space
co rd
organ systems. Think about explanations yourself, then Mother's
share them with your neighbour, and finally feed your b'lood vesseIs
ideas back to the class.
• Figure 4. 9 The p,acenta1
• The placenta grows from the embryo and implants
itsetf in the uterus (womb) of the mother~ what role
does it play,for the em.bryoJ
• Look carefully at the shape of the placental
membtan:e (which absorbs food and oxygen from the
mother): why is it highly folded in this way?
er What substances does the p.lacenta remove fro:mthe
embryo? (Thi1 nk about waste products that m:ust be
removed from the body because they are toxic.)
• Fi'gure 4~8 Human br,eathing systemr
• What key substance is provided by the lungs, needed
by alll cells to survive?
• What waste product is re·moved by the lungs" which if
left in the blood would decrease the pH of the blood?
• Remind yourself of the structure of the breathing
system in humans: ca n you name al I the diffe·tent
parts?
Biology for the IB MYP 4&5: by Concept
Smalll intestine
Epidermis - - -;::............,....._...,.._.........~~::..,.......;r: / A--- Xy'lem
Palisade mesophyll r1r--- Ph loem
Oxygen
• fjgure 4.11 The structure of a leaif
Mkrovil li Vein • The leaf has severa l different layers -what do you
think each of thes,e ·1aye rs 1is for?
"' :=;;;.-:=:..:;;.....;.;;~:::::;:;:.;:~::- - Arte1Y
Lympiiatic duct • Carbon dioxide, needed for photosynthesi,s, enters the
Jeaf t hrough stomata (plural of stoma), and oxygen
Ce ll membrane
leaves. There are airspaces between t he cells i,nthe
• Figure 4.·10 The sm1alll 1intestjne spongy mesophyU ,layer that i'ncrease t he su·rface
• look care·fuUy at t he lining of the small intestine, area for cHffusion of gases.
through whic'h digested food i:s absorbed into the • Wh.y are these a daptatio:ns needed7 There js one
blood. What are villi? What essential adaptation do common feature in all four org.ans that enabl!e the
t hey have to increase the rate of absorption?· urganism to survjve - can you identify what it is?
• Now look carefully at t he ceHs t hat line t he intestine
on t he surface of the villi -what adaptations do they • All these adaptati:ons are ·found in larger organisms.,
have? not sma Uer ones such as single-celled amo,eba -why
is th.is?
+ Assessment opportunities
4 What issues do largier organi·sms fac,e?'
WHAT FACTORS SPEED UP THE
RATE OF DIFFUSION?
Diffusion is the movement of molecules from hi1g:her to
lower concentration. Think of an air...freshener that you
spray rinto a room1- it taike,s s,everal seconds for the,scent to
reach aHpairts of the room~ as the partlides spread out from
the can from a higher to lower 1concentration (concentr.atilon
is a measure of number of molecul1es per unit volume).
ACTIVITY: What factors speed
up the rate of diffusion?
Air-freshener
Stand at one corner of your classroom during a lesson.
Spray air-freshener into the room. Who can smell the
air-freshener first? What happens to the smell of air-
freshener eventually? Can you explain your observations?
• Figure 4~12 Air-freshener di:ffusing through air • Figure 4.13 Potassium permanganate diffusing
Potassium permanganate throug1h water
Put a few crystals of potassium permanganate into a
Adding more crystals to the water would speed up
grass or Petri dish containing water. Watch what happens
to the purple molecules of potassium permanganate. the rate at which the purple reaches all parts of the
container. This is because there is a greater difference in
What happens to the purple colour eventually?
concentration between the area where the crystals were
How could you speed up the rate at which the purple added and the rest of the water, and also because the
colour reaches all parts of the glass/Petri dish? Can you greater number of crystals would have a greater surface
expl1ain your observations?
area compared to only a few. Distance is also important
-the students nearest to the air-freshener will smell the
scent first as it ha5 less distance to travel.
Biology for the IB M Y P4&5: by Concept
The words you are searching are inside this book. To get more targeted content, please make full-text search by clicking here.
IB MYP 4 & 5 Biology.compressed
Discover the best professional documents and content resources in AnyFlip Document Base.
Search