Y10 Family Trees Revision A Variation – Inherited or Environmental ...

Answers
A You got it off a parent or ancestor
I (a) cc, homozygous recessive
You got it from something that happened to you (not (b) Cc, curly hair
inherited) (c) Moose
Inherited: Environmental Both – just about
C
c
eye colour, skin Scars, tattoos, anything
colour, hair colour piercings, injuries nowadays
c Cc
cc
hair wavyness,etc plastic surgery,etc
Fang
Curly Straight
B traits which have only 2 or a few specific possibilities
Traits which have a continuous range of possibilities
c Cc
Curly
cc
Straight
Either/Or Continuous (d) 2 Cc : 2 cc or, ½ Cc to ½ cc or 50% Cc to 50% cc
Tongue roller Height or 1Cc : 1 cc
Widow’s Peak Weight (e) 2 curly : 2 straight, or ½ curly to ½ straight, or
Earlobe shape Length of any particular 50% curly to 50% straight, or 1 curly : 1 straight
Blood Group bone in the body (f) to get homozygous dominant (CC) the baby needs to
get a C from each parent – Fang hasn’t got any C’s
C
(g) the chances are always 50:50 for each baby so
any baby always has a chance of being straight.
(h) This tells us they both have Cc.
We know this because to get a straight haired baby
it must have a genotype cc since c is recessive and
only shows up when the genotype is a pair of c’s.
D 46 23 70000 23 23
The baby only gets 1 c from each parent so they
must both have one to give.
Since both parents have the curly haired phenotype
and the genotype for curly can be either CC or Cc
(because the allele for curly is the dominant C),
their other allele must be C, giving Cc.
46 cell nucleus sperm egg 23 zygote
E Mitosis
Meiosis
Mitosis. skin, hair follicle, stomach lining, blood, growing
baby (any 4 answers)
Meiosis gametes or sex cells. sperm egg (either order)
F Asexual identical budding, cloning, cuttings, grafting
Sexual reproduction in mammals, flowering plants,
Birds, fish, lizards, insects, etc
Quick, simple
Since all offspring identical then all could die from the
Same disease or conditions – all could easily die
Variation in the population, some could be tolerant to a
disease or conditions, can identify each other
Natural. The individuals which can’t tolerate a disease
or conditions don’t survive to breed – those which
can do survive to breed
G sex. X Y (either order). XX XY. Egg cells can only
X, sperm cells can have X or Y so it’s sperm cells
which make a baby be XX or XY.
H