Subtopic (b) Inheritance
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Transcript of Subtopic (b) Inheritance
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Subtopic (b) Inheritance
SQA questions
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Inheritance WYSK• Certain characteristics are determined by g_______
i_________ received from both p_______ e.g. fur c______ , blood g______, stem l_______ and shape of l______ or seeds
• Each inherited characteristic can appear in a number of forms called p__________.
• Phenotype is the a__________ of an individual• An organism which is t________ b________ e.g. TT
or gg produces only o___ type of gamete e.g. _ or _• The F1 offspring of a true breeding cross have
u_______ phenotype – all the same
eneticnformation arentsolour roup ength
eaves
henotypesppearance
rue reeding ne T g
niform
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• A d_________ gene or phenotype always shows• A r__________ gene or phenotype can be hiddenA m__________ cross is between two true breeding
parents which have d_______ phenotypes of the s_______ characteristic E.g. Black (BB) x brown (bb)
• The symbol for parental generation is __• The symbol for first offspring is __• The symbol for second offspring is __The expected ratio in F2 is _____ ( ¾ : ¼ )Expected ratios don’t always happen because
f____________ is a r_________ process
ominantecessiveonohybrid
ifferentame
PF1
F23 : 1
ertilisation random
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• A parent contributes o___of the two forms of a gene to their o________
• A g________ is a sex cell which carries o___ of the two forms of a gene
• Gametes contain a s________ set of chromosomes• Body cells contain a d________ set of chromosomes
– t___ matching sets• The r_________ in the number of chromosomes
occurs at g_______ formation• At fertilisation chromosome numbers d________
when the m_____ nucleus and the female n_______ fuse together
neffspring
amete ne
ingleouble
eductionamete
oubleale ucleus
wo
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• A g____ is part of a chromosome. T___ forms of a gene control each inherited characteristic
• The genotype is all the g______ an organism contains. Its genetic m____ - up.
A______ is the name given to the two forms of a gene
• The __ and ___ chromosomes determine sex• ___ is male and ___ is female• The male gamete (s______) may contain an __ or a
__ chromosome• The female gamete (e___) always contains an ___
chromosome
ene wo
enesake
llele
X YXY XX
perm XY
gg X
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Llama and camel successfully interbreed to produce baby
Scientists believe he will be infertile
XYXX
XY XX
G
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tongue rolling sex blood groups ear lobes
Presence of operation scars
G
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√ gametes
√
√ doubled
G
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horns
F1
G
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gold body black body
black body
bb BB
Bb
bbBB or Bb
G
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4 : 1
84 black body : 21 gold body
Divide by 21: 84÷ 21 21 ÷ 21
= 4 : 1
G
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√
discontinuous
gametes
G
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taster non taster
√
G
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Use the letters T for tasting and t for non tasting to show the forms of gene present in the sex cells of Rab and Audrey
t t
G
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gametes
√
X YX X
Down’s syndrome
G
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X X X Y
female male
F1
G
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genotype
gamete
variation
G
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Two/double Two/double
Two/double
one/single one/single
gametes
fertilisation
G
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X XXY
XY XX
female female
G
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discontinuous
Arranged in distinct / clear cut groups
C
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195 yellow seeds + 65 purple seeds = 260 seeds
% yellow : 195÷ 260 = 0.75 X 100 = 75%
75%
alleles
radiation
C
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GG
Gg
5418
¼ of 72 = 18 black
¾ of 72 = 54 grey
C
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Fertilisation is a random process
alleles
C
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TT tt
Tt
3 1
C
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4 1
Fertilisation is a random process
C
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alleles
bb Bb
Fertilisation is a random process
C
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bb
Same coat colour
discontinuous
C
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all
nonesome
RR rr
Rr Rr
1RR : 2Rr : 1rr
C
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496
Fertilisation is a random process
Rrrr
ratio is 3 red : 1 white
1488 ÷ 3 = 496 white
C
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alleles
Can be arranged into distinct (clear cut) groups
C