Summary The entire specification for AQA A-level biology topic, 7 population genetics, evolution and ecosystems
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Course
Unit 7 - Genetics, Populations, Evolution
Institution
AQA
I meticulously created these AQA A-level Biology notes during my studies, and they helped me achieve an A*. Organised according to the 8-unit specification, each unit has its own dedicated A4 page with all relevant information, making your study sessions streamlined and efficient. Within each unit,...
INHERITANCE
POPULATIONS IN ECOSYSTEMS
living in aa
ns a dinybrid : inherited characteristics dermined by 2 genes
biodiversity varteyotorganisms PEDIGREE ANALYSIS
:
gene : Short section of DNA that codes for a specific poplypepride chain
Loci= the position of a gene on a chromosome
offspring
meediagramscan Shunypesttamiymes a
fertile
·
of similar organisms that can reproduce to > -
species group :
me sam someone in = versions
individuaospeesin a habitat atinteractions
alle of the same genes
population all in
:
time
genotype-generic mone up of a n organism
adominant
proving wait tand have
·
"
characteristics as a result of genotype + environment
Phenotype = observable
in environments
of the bidicliving) + abiotic living) factors +
l
unaffected e an
ecosystem : al
me
some
-
awe s recessive wait
a
To
·
Interspecti differences between se proving a
-
variation are different
tow alldes
heterozygous :
x2 unaffected parents and an affected child
species
different ave l s of genes for
in
population dominant always expressed
: allee
proving a
e ex linked trait
generic diversity no of
-
: -
avele expressed
of all aweles for species in population recessive : only in homozygote more males are affected as remales act as carriers
wonangunawsamanismns
gene pool complete
no : ,
driving evolution multiple alleles : where a gene has more than 2 alleles affected females
·
+ affected son
Coodominant alleles which born contribute
: to the
phenotype if occur together -
autosomal linked
monohybrid cross : cross with 1 gene
generic males and remales astected equally , effected
·
mothers and unaffected sons
individa
environment : the surroundings where all organisms live abiotic/biotic
see
linkage-expressionofanave dependent o megender of me
carrying capacity population size of species that are supported
maximum
diploid organisms , the specic
:
climos community : mas amount for a given environments community
size ·
in a alleles at a locus may homolgous or netwozygous
be
Niche : role of organism in an ecosystem determined by adaptations to pioialabiotic factors maintain >
most organisms are diploid and corry 2alles for each gene they posses on each chromosome
-
to a
viable population size
excursion principle : species occupying same niche in an environment SEXLINKAGE
competitive
Biosphere :
regions of surface/atmosphere of earch which enclosed-elf contained ecosystems
2300 chromosome : Desclinke chromosome , where X chromosome is
larger than the Y
sizes ↳ X chromosome has more genes + DNA and cannot bivalate with the Y :: can't form homologous pairs .
variation in population
e e s linked waits are located on the X chromosome with mere
most equivilant
:Empumummmapical
aspian is locus on the Y :
-
abioric factors
remalls are carriers of 2 alleles of see linked gene but makes being no
only carry a
single a l e.
e
I
humidity 1 0 + species transpiration
water + , ↓ translocation , photosynmesis - remain uuersforaline
easts
caused by X linked recessive ander
,
linked disorders
,
~ most s e e are on
bioric factors :
parasites diseases predators competitions
, ,
chromosome
non-homologous
,
sec tions on X
individuals forresources inlimed sup carrying capay i
AUTOSOMA) LINKAGE
stugbetween
competion: and everyone
we navzamosomal
homogous chromosomes inherits 2 copies b a
-
,
7 TYPES OF COMPETITION ↑ talk about NS in questions It
genes are om
n e same autosomal .
chromosome
· interspecifibetweenindividuals samespecie
a
occupy samenin ap
niche overlaps
PEDIGREE ANALYSIS :
prove that a Wait is ,
↓ talk about impact of
dominant-dominant heterozygouswith
parents
e ch as
a
matnaveidenticanichestotanyoucomet arecessi
competition excursion on
principle
speci
animal that eats another animal
predator :
time lags , repeated > predator populations X linked makes more effected m a n females females : carriers attected momers > effected sons
cycles , prey
-
,
Oscillates
Describe graph for predator prey relationships
: ,
↑ Autosomal linked malest remales effected equary , affected mover t non-affected son
as preyt , + predatation survive
predators , " prey are eaten so more predators
prey↓ , more predatation
less prey eaten >
- starves
predator v ,
1. unlinked genes 2 different 1 Autosomal linked , without crossing over . Autosomal linked , with
on chromosomes 3
crossing over
biodiversitysloto predatorspreysamesea
dependan pops
.
wh
9 3:3 /
decompostion - photosynmesis Living
- N : :
,
-
-
UNLINKED EPISTASIS
recessive epistasis : if one gene has
it
2 recessive alleles
may result in an owner gene not
dominant epistasis : presence of one epistatic
dominant gene mashs the expression complimentaryepistasismepresence adominal
pha
a
being expressed I even if it has a of the other genes is
each gene =
dominant a l l
A
-
linear Enzyme 1 Enzyme 2
Spillway Enzyme 1 metabolic >
BY
/Enzymea
linear : > :
metabolic : Enzyme AtorAa pathway
AtorAa BB or
pathway AtorAa
BB ~Enzyme
I Phenotype =
genotype
.
-
Bare Roch Bb Phenotype = genotype
Erosion and pioneers decompose
min
Rock whire aaBB , aaBb , aabb
, Aabb
-
nostile Climass whire AAbb
green Aabb , AAbb
·
Inumus) and soil deepens community AbBb , AABB , AABb , AaBB
pioneer
Soil forms bure
·
established
·
Aabb, AAbb AaBb AABB
↓ + abrent
120algea inches
is · a
green Spillway
·
,
aaBb , aaBB
,
Enzyme 1 i
Natural sec tion : >
colonize by ·
↓ hostile AtorAa
Biodiversity
↑ as variety of food AaBbxAaBb ~
·
eg
photosynthetic a
+3 imit 2
:
Biodiversi
-
asescual reproduction Sources + habitats to support
more niches Enzyme 2
maneseeds a ·
·
↑ indest of
population
diversity
size
>
BB or Bb
X
tolerance
↑ species richness
Start 8 : 00
POPULATIONS EVOLUTION M
SPECIATION AYSomanespassontonetL E
genationandsome o bychan, ity GENETIDRIFT
:
-
this causes phenotypes to dissapear tomers more common , mist
as perfec n a
generic diversity and
mutations ; meosis random rusion of gamers Phencypevariationenable to adapt to senvironments > exclinchintion or evolution + Speciation
speciesexistasomomorepopulist
, -
· species
generic diversity SPECIATION Repeciation has occurred if evolution has I allele frequency so m u ch t h at individuals
:
occupying a particular place at a particular time increases
can no longer interbreed > service offspring
successfuly
-
that can
potentially .
interbreed
aspecies
~range otdistentve by :
> caused
behaviour al = different courtship patterns not recognized : Xmate
name a
HARDY WEINBERG
provides mathematical mode to predict that a l l l e freg
~.
speciescationinphenomesadapanons
~ as
prenorsaprantgenoe
.
·
a
will not change from generation to generation
.
↓ differential - selection pressures
populationsina
· large
set natural selection' reproductive
these factors
random assumptions
succes
· making directional , stabilising , disruptive
-competitiona
-
Alloparic
no
·
migration -
↓
evolution
:theYinbreedingpopulationaisulation
paichvinpeny
·
temp ·
p+ q =
1 p2 +
q2 + 2pq = /
I
gradual change in allele frequency - ·
pr
d t a given place t time)
in a populative ·
Food sources
drift
inansivedominativesAs ↓
genetic
can effects
·
geographical isolation prevents ge flow
evo t i o n
speciation random reproductive success
reproductive Isolation
·
Sympatric
inzenkatapenal organis :ocurswimout geographicalisdain
is
syparinogesanon
·
,
nations within a
population,
·
mutations prevents individuals breeding with non-mutant
individuals causing reproductive isolation
-
-
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