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KS4 Biology
Variation
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Variation
Contents
What is ariation!
Ca"ses of ariation
#nestigating ariationVariation $"i%
Classifying ariation
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Variation &etween s'e(ies
Variety is the spice of life!
Variation is the differences between different living things.
How many differences between living things can you name?
What causes the differences between species?
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Variation &etween s'e(ies
Genes are the &iologi(al (odefor different characteristics.Humans have human genes.
Bananas have banana genes.
Gerbils have (yes youve guessed it" gerbil genes!
#pecies are different because their genesare different.
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Variation within s'e(ies
$o two people are e%actly the same. How is this possible?
&he current population of planet 'arth is more than
si% thousand million people!
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Variation within s'e(ies
embers of the same species also show variation.
&hese differences are called (hara(teristi(s.
How many human characteristics can you thin) of that
show variation?
What causes each persons uni*ue characteristics?
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Contents
What is ariation!
Ca"ses of ariation
#nestigating ariationVariation $"i%
Classifying ariation
Variation
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S'ot the fa,ily likeness
Mum Dad
sondaughter
Which parent do these children loo) more li)e?
+f the son grows up to have children who might they loo) li)e?
embers of the same family often loo) similar-
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#nherited (hara(teristi(s
Mum Dad
son
Humans li)e all living things inherit(hara(teristi(sfrom
their parents. How are characteristics passed on?
Why do members of the same family loo) similar?
daughter
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#nherited (hara(teristi(s
,i)e all babies this little boy carries a uni*ue set of genes
half from his mother and half from his father.
&his newborn babys characteristics are passed in
the genes it has inherited from its parents.
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/aking fa(es
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Ca"ses of ariation
But areyour characteristics only affected by your genes?
What else will influence the characteristics of this baby
as he grows up?
-eople are different because they inherit different
characteristics from their parents.
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Ca"ses of ariation
our "'&ringingand the eniron,ent in which you live
also affect how you turn out as an adult!
When he gets older this baby might support a different
football team (li)e /ulham" or not even li)e football.
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Ca"ses of ariation
0ifferences in some characteristics are
due to a combination of &othinherited
and eniron,entalfa(tors.
$ame three e%amples of this type of
characteristic.
our uni*ue characteristics are caused by1
2 the uni*ue set of genesyou haveinherited from your parents
2 the eniron,entin which you have
developed.
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Ca"ses of ariation
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Variation in 'lants
-lants inherit characteristics through their genes 3ust
li)e humans and other animals.
What characteristics have these plants inherited?
4re plants also affected by their environment?
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What (a"ses ariation in 'lants!
-lants are affected by four )ey eniron,entalfactors.
5an you name them?
-lants are affected by their environment in a big way.
With a little more moisture light or warmth the si6e of a
plant can do"&le- (+magine if that happened to us!"
water
s"nlight
te,'erat"re
n"trients in soil
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What (a"ses ariation in 'lants!
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Contents
What is ariation!
Ca"ses of ariation
#nestigating ariation
Variation $"i%
Classifyingariation
Variation
l if i i
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ow to (lassify ariation
5haracteristics can be classified in different ways.
How would you categori6e variation in eye (olo"r?
5ould you categori6e variation in heightin the same way?
Variation in eye colour can be easily categori6ed in distinct
groups. ou either have a certain eye colour or you dont.
Height variation doesnt fall into separate groups as it covers
a range of values. our height changes as you grow.
t l if i ti
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ow to (lassify ariation
4 feature that (an &e ,eas"redand given a value from
a range of al"esshows .
4 feature that (annot &e ,eas"redbut is one of a few
distin(t o'tionsshows dis(ontin"o"s ariation-
Which type of variation are eye colour and height?
5haracteristics can be classified into two types1
discontinuous variation
C ti di ti !
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Contin"o"s or dis(ontin"o"s!
C ti i ti
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Contin"o"s ariation
What is !
&his type of feature varies overa continuous range of values.
'%amples of continuous variation
include mass height s)in colourintelligence and leaf area.
5ontinuous variation is due to the
combined effects of genes
andthe eniron,ent.
0oes this mean the value of such a feature is fi%ed
or can it change?
Bar (hart to show the range of,asses in a r"g&y tea,
78 98 :8 ;88 ;;8 ;
@
,ass kg
n",&erofr"g
&y'layers
C ti di ti !
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Contin"o"s or dis(ontin"o"s!
i ti i ti
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is(ontin"o"s ariation
What isdiscontinuous variation?
&his type of feature can onlybe one of a few distinct options.
'ither you have this type of
characteristic or you dont.
'%amples of discontinuous
variation include blood group
natural eye colour and inherited
diseases.
0iscontinuous variation is the result of genes only.
Bar (hart to show the fre$"en(yof &lood gro"'s in a r"g&y tea,
5 B 5B8
;
@
&lood gro"'
n",&erofr"g
&y'layers
0oes this mean the value of such a feature is fi%ed?
C ti di ti !
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Contin"o"s or dis(ontin"o"s!
C t t
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Contents
What is ariation!
Ca"ses of ariation
#nestigatingariation
Variation $"i%
Classifying ariation
Variation
C i & t i ti
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How do we )now about inherited variation and how it wor)s?
eet 6regor /endel the first person to trace patternsof characteristics and predict how they were passed on.
C"rio"s a&o"t ariation
6regor /endel
1+221++4
#urprisingly endel was not a scientist but a mon) who
lived in 56echoslova)ia (now called the 56ech Aepublic".
/endel8s e9'eri,ents
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/endel8s e9'eri,ents
endel was inspired by wal)ing in the monastery garden.
He became curious about variation in plants and how
characteristics were passed on to new generations.
4nother surprising fact about endel is that for his
ground2brea)ing wor) on variation he carried e%periments
out on the humble garden 'ea!
/endel8s e9'eri,ents
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/endel8s e9'eri,ents
endel chose to e%periment on pea plants for two reasons1
;. &hey could be easily grown in large numbers.
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/endel8s e9'eri,ents
endel studied several pea characteristics including1
2'ea sha'e (smooth or wrin)ly"
2'ea (olo"r (yellow or green"
2'od sha'e (inflated or constricted"
2'od (olo"r (yellow or green"2ste, length (tall or short"
4ll these characteristics showed dis(ontin"o"s ariation.
Why did this ma)e them easier to study?
endel also investigated one characteristic at a time.
Why was this important for his e%periments to be successful?
S,ooth and wrinkly 'eas a(tiity
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S,ooth and wrinkly 'eas a(tiity
/endel8s res"lts
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/endel s res"lts
endels investigations into seed shape (smooth or wrin)ly"
produced the following results1
'arents:
first
generation: x100%
do,inant re(essie
se(ond
generation:
(ross;'ollination
self;'ollination
x
7)% 2)%
/endel8s (on(l"sions
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/endel s (on(l"sions
endel published his wor) in ;9@@ and made several
conclusions about inheritance1
5ertain traits can be do,inantor
re(essie. Aecessive traitsmay
not show but can still be passed on.
5ertain traits can be inherited in'redi(ta&le 'atterns.
+nherited traits are passed on as
bits of information called Cfa(torsD.
What are these CfactorsD now called?
endel did not )now it but he had predicted the e%istence of
genes more than >8 years before genes were discovered!
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Contents
What is ariation!
Ca"ses of ariation
#nestigating ariation
Variation $"i%
Classifying ariation
Variation
Variation ,"lti'le;(hoi(e $"i%
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Variation ,"lti'le;(hoi(e $"i%