DO NOW (Just write answers)
 What is incomplete dominance
 Define recessive
 Where does the variation in gametes arise




from in meiosis
What is the purpose of meiosis
What is mitosis
What is an allele
What does homozygous and heterozygous
mean
THIS TERM
Week 1: GENETICS
Week 2: GENETICS
Week 3: GENETICS
Week 4: ANIMALS
Week 5: EXAM WEEK
Week 6: ANIMALS
Week 7:ANIMALS
Week 8: PLANTS
Week 9: FIELD TRIP
Week 10: PLANTS
THIS TERM
 HOMEWORK – BIOZONE AND EXAM
QUESTIONS (past test results)
 IN CLASS WORK ETHIC
 HELP: WED LUNCHTIMES
REVIEW – USE WHITE BOARDS
 Write the combinations for gametes for the
following crosses
 HhBB x HHBb
 PpHh x ppHh
 RrFf x rrFF
TO DO ON BOARDS
IF FINISHED GRAB
WORKSHEET FROM
FRONT
 In summer squash, white fruit
colour (W) is dominant over yellow fruit colour
(w) and disk-shaped fruit (D) is dominant over
sphere-shaped fruit (d)
 If a heterozygous white coloured sphere
shaped squash was crossed with a yellow
coloured homozygous disk shaped squash
what would the phenotype ratio of their
offspring be?
EXAM QUESTION 2004
 In horses, black coat colour is influenced by the dominant allele
(B) and chestnut coat colour by the recessive allele ( b). Trotting
gait is due to dominant gene (T), pacing gait to the recessive
allele (t).
 A horse trainer wanted to find the genotype of a black trotter
she bought..
a) Give the genotype and phenotype of the horse she would use to
find out the genotype of a black trotter. Explain your answer
b) Use a punnett square to work out the phenotypic ratio of all
possible offspring when a black male heterozygous for both
traits is mated with a female heterozygous for both traits.
c) Explain why, when breeding chestnuts together she would not
get any black foals, but when breeding black horse she could
get chestnut foals
SEX LINKAGE
 This occurs when genes are located on the
sex chromosomes either the X or the Y
chromosome (note: autosomes are the other
chromosomes)
 Example: Colour blindness
 Sex linked gene located on the X chromosome
 N = normal
 XN = normal vision
 Y = male
n = colour blind
Xn = colourblind
PROBLEM:
 Can a woman with normal vision whose father
was colour blind have colour blind children if she
marries a normal visioned male?
 Genotypes?
 Do a cross?
 Continue with extra questions