Download - KS4 Variation

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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%


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.



/aking fa(es



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.



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.



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?



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



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



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 !



Contin"o"s or dis(ontin"o"s!

C ti i ti



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 !




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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C t t



Contents

What is ariation!

Ca"ses of ariation

#nestigatingariation

Variation $"i%


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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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!



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endel chose to e%periment on pea plants for two reasons1

;. &hey could be easily grown in large numbers.


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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%


Variation

Variation ,"lti'le;(hoi(e $"i%


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Variation ,"lti'le;(hoi(e $"i%

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